98 Legacy GT 2.5L misfire code problem

[GT6]

Hello, all. This is my first post. Sorry for the length, but having spent a considerable amount of time going through this forum, I've learned that the goal is to explain the problem as clearly as possible. I am a pre-computer car guy. My daily driver is a 1973 Triumph GT6, so needless to say, there is no ECU in it. It does, however, have airbags, but I have to blow them up myself.

 

My niece has a 1998 Legacy GT with the 2.5L engine with about 140K miles. The engine was completely rebuilt about two years ago. A few months ago, she started having her check engine light come on. The codes thrown were related to the downstream O2 sensor, the MAP sensor, the MAF sensor, the speed sensor, the crankshaft position sensor, and an occasional neutral safety switch code.

 

First, a little background on what has been done:

 

The MAF sensor was cleaned, and all the other sensors, with the exception of the MAP sensor were replaced. The MAP sensor code disappeared as I worked my way through the other sensors. Prior to the replacement of the O2 sensor, the car would be thrown into limp mode - a particularly insidious thing on the Seattle hills. As each sensor was cleaned or replaced, the CEL codes disappeared.

 

When I went in (under) to change the O2 sensor, I found that one of the wires had worn through due to contact with the heat shield and, I assume, shorted out. Once it was replaced, limp mode was thankfully gone. I wondered if the shorted out O2 sensor caused problems with some of the other sensors, in particular the speed sensor due to its proximity.

 

Other work done: Thoroughly cleaned the throttle body and the IACV, new plugs, new spark plugs and wires (NGK), new air and fuel filters, some new hoses (all were checked for leaks), and a new coil pack.

 

When she began having problems, the first thing I checked were the plug wires (again, old car guy). After removing the number four plug wire from the coil pack, I noticed a considerable amount of oxidation on the terminal. I cleaned both the terminal and the wire. It made no difference, which isn't surprising, since there was no related code.

 

Once all the above work was done, the car ran like a champ. I now understand why Subaru people love their cars. Additionally, all CEL codes were cleared and gone.

 

Now, to the current problem which occurred prior to replacing the coil pack, plugs and plug wires.

 

One day, at freeway speed, the CEL started flashing - yes, a very bad thing. She pulled over and called me and said that the codes being thrown were P0303 and P0304, cylinder misfire codes. I asked her to try to clear the codes. She did, and they were gone. I asked her if she felt the car could make it home. She said, other than the flashing CEL, the car was running perfectly. It was as if nothing at all was wrong. I told her to stay off the highway. The CEL didn't return. I asked that she stay off the highway until I could figure out what was wrong. Remembering the oxidation on the number 4 coil pack terminal and plug wire, I decided to replace both the coil pack, plugs, and plug wires. As the car has a wasted spark ignition system, I recalled the oxidation on the number 4 terminal. As the codes being thrown were specific to the 3 and 4 cylinders, I thought the problem was due to some problem with the coil pack. I replaced the coil pack, put in new NGK plug wires, and replaced the existing NGK V-Power plugs with new V-Power plugs. She took the car on the highway, and the CEL eventually came back on, but it didn't flash. I thought that indicated progress.

 

A word about the heritage of the car. The VIN idicated it was built in Indiana. As the speedometer featured KPH rather than MPH, it was meant for export to Canada, as were most of the Indiana cars. I mention that because every forum response I read sang the virtues of NGK plugs. I then read a single post that claimed that Champion plugs, generally vilified in most posts, worked well in Legacys built in Indiana. I bought and installed the Champions. The CEL didn't come back on. I was cautiously optimistic.

 

We were always able to clear the codes. The P0303 and P0304 codes never affected how the car ran - it ran, and continues to run beautifully. After doing a lot of research on the misfire codes, I never came across an entry that wasn't associated with a rough-running vehicle. I was lost, but since the car ran well at all speeds, I thought the problem was solved.

 

Well, today she texted me that the CEL light came on again at highway speed but wasn't flashing. The odd thing about it is that instead of the P0303 and P0304 codes, the codes thrown were now P0301 and P0302.

 

Summary: The misfire codes only come on at highway speeds. They in no way affect how the car runs. Again, it runs like a champ. The switch from the P0303 and P0304 codes to the P0301 and P0302 is a mystery to me.

 

I am at a loss as to how to solve the problem. You're my last chance before I have her take the car to a mechanic. I love doing the work for her (my "no charge" labor is significantly less that that of local mechanics), and as is common for a 20-something, she needs to keep repair costs down.

 

Note: The ECU was reset every time after every time the battery was disconnected.

 

I would very sincerely appreciate any help you might be able to provide us with solving this problem. And if any of you have any mechanical questions about vintage Triumph GT6's, I'd be happy to offer whatever help I can.

 

Thank you! And again, sorry for the length of this post!

 

Nick

[SBT]

Welcome to the site and glad you could join us.

 

I'm moving this over to the 2nd Gen Tech forums so our members can provide you with answers to your questions.

 

And have always wanted a GT6. Slowly restoring a 1967 MG that's been in my family since it was new. 52K original mile SoCal car.

 

Again, welcome.

[GT6]

Thank you for the welcome and for putting my post in the proper place.

 

The GT6 is a fun car. Being a 6 cylinder and, through tuning directions from the Triumph forums, it has considerable power (for 73, of course). My sister bought it new in 73 and I bought it from her about 26 years ago. I'm spoiled by its simplicity and how easy it is to work on. As you know, the bonnet tilts forward to about 90 degrees. That provides complete access to the engine. I can change all six spark plugs in about ten minutes. I have yet to match that time with my niece's car!

 

You've got a great car for restoration. I've always liked MG's. 52K original miles and a SoCal car? Sweet!

 

I've enjoyed the challenge of working (and learning) on a car 25 years younger than mine. And, as I've said, I love the power and handling of her car - a great benefit of being her personal mechanic.

 

Thanks again!

[twisty]

i had similar issues with one of my wagons with the blinking CeL and no change in the performance of the car, changed everything as well and no fix. mine ended up being the timing sprocket, the PO had changed out the crank pos sensor with a cheapo one that was a bit longer than the original, and at first run after that it chewed up the teeth on the timing sprocket. i didnt find it until i pulled the timing stuff to repair the leaking seals.

[SBT]

Twisty - was thinking that it had to be something with "timing", so good call on the crank position sensor. Could even be a bad/intermittent connection at that juncture.

 

GT6 - do you have an FSM for this?

 

Attached is a picture showing location of the Crank Position Sensor

[GT6]

Twisty and SBT - Thanks for the responses. When I started working on the car one of the first codes I addressed was the crankshaft position sensor. I did compare the old one to the new one I installed, and they matched.

 

SBT - I don't have a FSM but I picked up a Haynes. Between the Haynes manual, the forums and other online sources, I've been able to get a lot of information. Thanks for the illustrations!

 

It's interesting that you both mentioned timing. It makes me think back to something I considered early on. When revving the engine, I would sometimes hear a kind of grating sound. If I heard that in my Triumph, I would have checked the timing chain. It sounded as though a timing chain was slapping against the cover. As the car doesn't have a timing chain, I checked all the belts. I couldn't find any visible damage to the outside of the belts or the inside teeth. All were in good shape. I asked her about the noise, and she said it had been like that "forever." I looked online, and found that heat shield rattling is a pretty common issue. I put checking that off to address the codes being thrown, and until I could get the car up on jackstands.

 

The problem being a timing issue does make some sense to me. It seems possible that a very minor timing problem could be amplified at highway speeds at least enough to throw the codes. But honestly, that's just a desperate reach of a guy who's searching for any solutions right now. I was surprised to find that the computer sets the timing. I really like being able to adjust the timing on the Triumph with a light. Again, old car guy.

 

With a timing problem, wouldn't it show up in how the car runs? Again, it runs perfectly, at least to me. The ECU obviously has another opinion.

 

Thanks for the suggestion to check the connection to the crankshaft position sensor. It would obviously be a great relief if the problem was just that I didn't clean the connectors well enough. Either way, I'll clean the connectors again and check it with the Fluke.

 

My big concern is that she could be doing some damage to the car when it's throwing those codes. She doesn't spend much time on the highway, but her parents live about an hour away (freeway hour) and her mom is having some health problems, so I'm pretty anxious about giving her another way to visit other than the train. She loves the train but it's obviously not as spontaneous as a car.

 

I'll check the connections to the crank sensor this weekend.

 

Thanks, guys, for your help on this. I (we) really appreciate it!

[RustyRuu]

it could have an idler pulley or some bearing on the timing belt that is out and causing these issues, causing drag on the belt, not causing visible damage just extra drag. if everyone thinks it timing then this could be something to look into.

 

they should be replaced every timing belt replacement and i still have the original equipment after two timing belt replacement, they are very noisy and are in the middle of replacement/ engine refresh.

[SBT]

My 98 BD has an on/off idle rattle from the DS heat shield. I just haven't been able to get under there and check it out.

 

If it sounds like it's (the "grinding" sound) coming from behind the TB covers, then it's likely one or more of the idler pullies. These should have been checked/replaced at the 105K mile TB change, along with the water pump and the oil pump checked for leaks and resealed or replaced and a new thermostat.

 

Have you done a compression check/leak-down test on the engine. These Phase 1 engines, if not properly maintained can (and will) develop HG leaks. If you're getting misfires, it's possible that the HGs are leaking and causing the misfires.

 

Not sure if you used an OEM O2 sensor, and OEM coilpack and wires. I know that many have had issues with non-OEM on these - they are happier with OEM in my experience. Denso is the only aftermarket (AM) O2 sensor that I'd use, if I weren't buying OEM. Non-OEM stuff has been known to cause CELs because impedance and or voltages aren't within tolerances. AM coilpacks are the biggest offenders with plug wires being the 2nd.

[SBT]

Couple of EndWrench articles for you.

 

The Subaru On-Board Diagnostic PDF is about the Subaru's Select Monitor - basically a code reader on steroids, but there's some useful info in there about what all is available codewise in Subaru's OBDII system.

 

Good luck with the trace-down.

Direct Ignition Ops & Testing SUM2000.pdf

Ignition Coil Testing Fall98.pdf

Subaru On-Board Diagnostic Systems Nov98.pdf

[GT6]

Thanks for the input, RustyRuu. Again, not used to Subarus and their associated sounds, but it sounds more like a very fast rattle rather than the grinding of bad bearings. That being said, it could easily be an idler pulley making the noise. The sound seems like it's coming from underneath at the rear of the engine, but having traced sounds on my Triumph, the source of sounds can be deceiving. The noise is also much more prevalent when revving the engine while it's cold. Again, as my niece said that the sound had been there "forever," and the codes only recently appeared, I was/am concerned about it, I didn't link it to the newest codes. AH!!! I just realized something that I didn't mention about the sound. The sound isn't there while revving the engine, it happens as the engine is returning to idle speed after revving. I apologize if that changes the game.

 

SBT, the O2 sensor I used is a Bosch. The plug wires are NGK's, and the coilpack is an AIRTEX/WELLS. The wires and coilpack were from Rock Auto. The plugs, as I mentioned, are the Champions that I saw recommended for Indiana cars. I put them in after the the P0303 and P0304 codes reappeared after I put in the NGK V-Power. All was well, including freeway driving until just recently. Then the codes came back, but this time they were P0301 and P0302. Until that time, I thought the combination of the coilpack, plug wires and plugs had done the trick. I still don't understand the code switch from 3 and 4 to 1 and 2. Is it possible I'm still not using the right plugs? If it were only that simple...

 

I haven't done a compression check on the engine. As it was rebuilt just over 2 years ago by a very reputable, respected garage and only has about 12K miles put on since the rebuild, I didn't think the problems were with the engine. As it was out of the car for the rebuild, I checked everything I could think of that might have gone wrong with the move - vacuum leaks, electrical connections, etc. Nothing was found. When I cleaned the IACV and throttle body, I found that they used top quality gaskets rather than cheapo ones. That find was a little comforting. The torque values I checked were right on. There are no leaks anywhere. As I thought they did a good job, so I looked elsewhere.

 

I'm out of town for a few days right now, but as soon as I can get together with my niece, I'll thoroughly clean the crankshaft position sensor. SBT, thanks for the PDF's! I'll go through them this weekend.

 

Two additional things I forgot to mention that I cleaned the (surprisingly clean) EGR valve, and replaced a pretty new looking PVC valve.

 

The Haynes manual I picked up for the Subby is beginning to get broken in, but it has a long way to to to match the Haynes for the GT6, which is dog-eared, has nearly black page edges, a new cover built from manilla folders (covered with tape), taped, missing, and torn pages, and lots of highlighting. If I stood on it, grease might squeeze out between the pages. It's well-used, indispensible and I understand the information in it. That brings me to my beginner's skillset with cars controlled by ECU's. What's my point? This: Thank you guys for all the help. I am admittedly, for the most part, lost here, and I greatly appreciate all the help/time/direction you guys have given me. Now if you would all go out and buy vintage Triumphs, I would probably be able to give something back!

 

Thanks again!

[SBT]

Given that the code migrated, post-coilpack, I'd start there.

 

And are you running the NGK Platinums or NGK Copper spark plugs?

 

The GTs and DOHCs require the Platinums and will misfire on the coppers, though not that soon - typically - after replacement. Apologies if I missed that. I only run NGKs in our Subarus, so I can't speak to any other brands, but, I do see in the FSM, that Subaru recommends the Champion RC10YC4 as the primary plug for the 2.2L SOHC, NGK BKR6E-11 is the alternate plug for that application. The NGK BKR6E-11 is the "copper" plug that I was referring to above.

 

For the GTs and DOHCs, the FSM prescribes the NGK PFR5B-11 Platinum plugs. The "P" in the part number stands for Platinum

 

And they are set - again, typically - from the factory to proper gap. At least the OEM Subaru NGK PFR5B-11 ones are. NGK does not recommend the "coin-type" gap tool on their Platinum (DOHC NA) and Iridium (DOHC FI) plugs. They recommend wire-style gap tool, like the K-D 2327 so the precious metal isn't debrided during gapping.

 

Not sure what the Haynes calls for WRT plug electrode gap, but the FSM prescribes 0.039-0.043". Outside of those parameters, and I'd expect some misfire counts.

 

Also, just a "check-point" - have you checked the connectors to the injectors to ensure that they are all tight? If yes, again, back to coilpack.

 

Since it's running well, I tend to think it's the coilpack, but do recommend checking the rest and that the new coilpack is within the specs outlined in that End Wrench article above.

 

GL and keep us posted.

[SBT]

And another thought I had was that the valves may need to be adjusted, especially if they weren't rechecked post-overhaul. A tight exhaust valve can/does cause misfires so that would also be one area to check. Easier with the engine out of the car, but it's doable in the car. Engine must be cold for this check.

[GT6]

Yeah, the code migration has just completely thrown me.

 

When the misfire codes first appeared I put in the NGK V-Power copper plugs. I had read a lot of good things about them. Btw, the plugs I pulled looked great. The electrodes were all the same, even color, and the right color at that.

 

When the P0303 and P0304 codes came back, I thought back to the oxidation I found on the number 3 terminal. That's when I decided to replace the coilpack. It seemed like the logical thing to do. And as long as I was at it, I decided to get the NGK wires and new plugs. I mentioned that I saw that Subbys made in Indiana used Champion Double Platinum plugs. Thanks for letting me know that those were for the 2.2L. I guess you can't trust everything you see on the internet. Hey, I was desperate!

 

The codes disappeared for about a months Then the codes came back, but this time, as you know, they migrated to P0301 and P0302. That's when I signed up here.

 

One of the reasons I've always liked working on cars is that there is a logic to it. You do A, B, and C, and D happens. Well, most of the time, anyway. As I look back at the chain of events, the coilpack and/or plugs do seem to be the logical source of the problem. The initial codes could have been from the plugs. The V-Power plugs aren't what the FSM indicates for the 2.5L. Neither are the Champions.

 

The logical next step is to test the coilpack and replace the plugs with the NGK PFR5B-11's. In other words, the right plugs for the car < this may be my "Doh!" moment. Haynes calls for a .044 gap. The plugs come pre-gapped to that. With it being only a .001 difference, I wonder if I'm better leaving them as is for the purpose of having them all exactly the same, or closing the gap slightly? Of course, I'd check them straight out of the box. I've got the NGK PFR5B-11's on order. They'll be there when I get back into town in the next two or three days.

 

Speaking of checking the coilpack, are AIRTEX/WELLS considered decent coilpacks? What's considered the best?

 

As to the injector connectors, yeah, I cleaned them all with contact cleaner. Everything was secure.

 

Adjusting the valves doesn't sound very appealing to me! In my GT6, I can sit on a tire and adjust the valves. Yes, I'm living in the past, but with the exception of what's going on with my niece's car, I'm just fine with it! I know you understand, as you're rebuilding your 67 MGB. If I don't get this problem resolved, I will forever believe that ECU's are evil. Again, living in the past...

 

Thanks for all your help, SBT, I really, really appreciate it!

[SBT]

If a coilpack is carboning-up on the tips, I first check it against the coilpack test above to make sure that it's good, or that it's not grounding-out. If it's good, I take it off and clean all four poles and the mounting surfaces with a Dremel wire brush and recheck the power/signal connector for good connectivity to the CP. You could clean the poles with some 0000 steel wools as well.

 

I then clean (unless new) the inside of the sparkplug wires - both ends - with a smaller Dremel honing stone.

 

Following that, I wipe everything down and then liberally coat everything with dilectric grease before reassembly. This cleaning will typically last a long time, especially since I've started using liberal dilectric grease I just repeat the process if I start to see carbon-blackening again. So far so good.

[Thor294]

Not sure what you've done, but does the car have a MAF? I know subarus like to not have MAFs.

 

if the code traveled, I think it has something to do with the intake side, not plugs/wires/etc. Check for vacuum leaks in PCV/intake manifold, make sure if you have a MAF there are no leaks on the air tube. Compression test won't hurt either.

[GT6]

Hi SBT - It's a new coilpack (AIRTEX/WELLS) with new NGK plug wires. I, too, am a big fan of dielectric grease. Fantastic stuff. I use it liberally on the Triumph and now my nieces Subby. I'm hoping the plugs you suggested will resolve the problem. I'll be heading back to Seattle later today/tonight and hopefully be able to connect with my niece on Wednesday. She continues to drive the car, problem and code-free, but won't take it on the highway until I put the new plugs in. I'll also check the resistance on the coilpack and plug wires. Thanks again for the PDF's.

 

Hi Thor294 - Yeah, the car has a MAF. It was one of the codes that was thrown when she started having problems, prior to the misfire codes. I cleaned the MAF with MAF cleaner. The MAF code disappeared.

 

As I removed and cleaned both the throttle body and IACV, I was able to easily access, clean, and check hoses for vacuum leaks. In some cases I replaced the factory squeeze clamps with regular hose clamps. Your suggestion has made me think I should go back and replace all the factory clamps with screw-type hose clamps as I go back to re-check for leaks.

 

Are there 98's that don't have MAF's? If you remove it, won't you be constantly facing a MAF CEL? I don't know if you read that I'm new to cars with computers, so if that's a stupid question, feel free to mock!

 

Thanks, SBT and Thor294. I sincerely appreciate the time, input and expertise you provide.

[SBT]

I now use stepless Oetiker clamps on all of my small (<1") air, coolant and oil hoses. Better seal IME.

 

And given it's an 18yo (or possibly 19yo depending on build date) car, the hoses are probably brittle and need a critical eye on all of them.

 

All USDM 1998 Subarus have MAFs. Since you don't have an alternate way of measuring air flow, removing it would really mess with things. Might even put it into limp mode.

[twisty]

ive tested both the 2.2 and 2.5 with copper, platinum and iridium plugs. no real difference in performance, mileage had minor changes and the life of the plug was the main difference. the iridiums are almost pointless over the platinums, and i was changing the coppers too often. i was checking them at 5k intervals, and almost every time i changed the coppers due to wear and tear. i still ran them for 20k to see if it changed, but i used 3 sets of coppers for that. the platinums and iridiums were about the same to each other, and after the 20k mark i left them in the cars. i recently replaced the iridums in the 2.2 due to wearing down, it gets really hot here in AZ and it shows over time.

 

i do have 3 running subarus, two with 2.2 and one with 2.5 so i have lots of testing area to play with. i also get very bored sometimes and do stuff just to see if it will change.

[twisty]

All USDM 1998 Subarus have MAFs. Since you don't have an alternate way of measuring air flow, removing it would really mess with things. Might even put it into limp mode.

 

ive disconnected mine during idle, it will start to waver, but will run. the scanner shows a constant voltage to the ecu, but without the metering the timing flattens and the fuel trim goes a bit wild. will still run, but not at its best, and will stall occasionally.

[GT6]

I'm back in Seattle now so I'll be able to get back to the car this evening to put in the NGK PFR5B-11's and re-check hoses for possible leaks and see if I can find any candidates for replacement. SBT, I've seen those clamps, but never knew what they were called. Thanks.

 

I'll be checking the resistance not only on the coilpack, but on the new NGK wires as well (no stone unturned philosophy). I'll let you know if I find any anomalies.

 

Is there any problem with replacing intake hoses without preformed bends with bulk hose? I replaced the small hoses, like the ones that attach to the throttle body just because I could. I'd like to just replace as many as possible. Yes, she's a good niece.

 

It's unanimous - the MAF stays where it is. I admit to hoping for an answer like, "Sure, just unplug it and put a jumper across..." Yes, I occasionally like to escape from reality.

 

Speaking of reality, twisty, you speak the truth. It gets incredibly hot in AZ. I lived there for 3 years, 3 very long, hot years. The GT6 was not built for AZ. The two most common questions asked by passengers in a GT6 are, "Do you smell gas?" and, "Is it just me, or is it hot in here?" Great avatar, twisty. Speaking of AZ, I knew people in Phoenix who looked like that. Way too much sun! I drove the GT6 up and down the coast from Seattle to LA, then over to Phoenix four times. The first 3 times I did it in summer. I learned my lesson and did the trip the fourth time in the dead of winter. Crossing the Siskiyous in Oregon were a trip on their own. The Triumph isn't a snow car.

 

Again, thanks guys for all the help and the time you have put into responding, and for sharing your obvious expertise. You provide a great service to Subby owners and their uncles. Who knows, you guys may yet be responsible for me beginning to appreciate computers in cars.

 

I'll let you know if the plugs/leak detection/resistance checks solve the problem.

[Thor294]

How did you check for vacuum leaks? Just a visual? With the car running, I'd spray like brake clean or something around all the hoses (intake, pcv, etc) and see if you get a surge. If you disconnected all of them maybe one is loose or something. Can't say I haven't done that before

[Brighton96]

How did you check for vacuum leaks? Just a visual? With the car running, I'd spray like brake clean or something around all the hoses (intake, pcv, etc) and see if you get a surge. If you disconnected all of them maybe one is loose or something. Can't say I haven't done that before

 

You can do a smoke test or spray some areas in question with brake/carb clean. Just start the car and spray brake/carb clean or smoke around the engine bay and watch. There are a bunch of ways to do a smoke test, just youtube it and do whichever method works best with your situation, I used a small smoke machine but there are a few ways to make smoke.

[GT6]

Well, I put in the NGK PFR5B-11's. I checked the resistance on each plug wire. Yes, they are new NGK's, but hey, they were right in front of me. I checked the primary and secondary resistance on the new AIRTEX/WELLS coilpack found no problems.

 

An odd thing though, when re-checking the coilpack that I replaced, the Haynes manual had what might be a discrepancy. It's branded as a Diamond, but it's specs matched those for the Hitachi. When I did a search for Diamond FH0047, it took me to Hitachi. Haynes only mentions those two brands of coilpacks. The Diamond, the one I replaced, had essentially the same tolerances as the AIRTEX/WELLS that I replaced.

 

SBT, I mentioned the oxidation that I found on the number 4 terminal of the old coilpack. At the beginning of my trying to find a solution to the misfire codes, as one of them was for that terminal, I decided to replace the coilpack. I cleaned it last night. Resistance checks on it were great. It looks like new again so I guess we have a spare coilpack, which I don't mind in the least.

 

As for testing for any possible vacuum leaks, I don't have a smoke machine, so I tried to rent one. Sadly, it was one left over from the disco era, and if I rented it, I would have to had to rent the mirror ball that came with it. It was a package deal. Once I had a look at the mirror ball, I knew there wasn't any room to hang it from the open hood. Plus, a rider on the rental agreement said that I would have to wear a white suit if I was within 20 feet of the mirror ball, so that was out. I'm also not a smoker, so a cigar was out too.

 

SBT - I replaced the remaining squeeze clamps with standard screw-type ones as I had a supply of those in my toolbox (again, 73 Triumph GT6, so...). I'll check into the Oetiker clamps. Thanks again for the suggestion.

 

Thor294 and Brighton96 - Thanks for your suggestions for checking for vacuum leaks. I watched a couple of YouTube videos on the subject before I tried it myself. After watching the videos I took the fire extinguisher from my car for backup. I even read the directions as to how to use it (make that re-read). The engine was stone-cold when I started spraying the carb cleaner everywhere there could be a possible leak. Honestly, I was hoping I'd find one as it would mean that I might have found the solution to the problem. However, after spraying way more of the carb cleaner than I actually needed, there wasn't the slightest sign that there was any leakage. The idle was smooth and perfect.

 

Having replaced all the remaining squeeze clamps before checking for leaks there is a possibility that I sealed a leak by doing so. I can only hope...

 

The rattle I mentioned on deceleration after revving the engine has gone away for the time being. Odd, but I'm certainly not complaining.

 

I took the car for a short ride due to time restraints, and no CEL, so no misfire codes (we've always been able to clear them), no rattle, and it ran as well as usual. Again, throwing misfire codes only at highway speeds without affecting the car's performance is confusing to me. Hopefully the FSM recommended plugs will do the trick, or a vacuum leak that was sealed by the replacement clamps. Even without a change in performance, I'm worried about the thrown codes, especially when the CEL flashes, as I really don't want her CAT to fail.

 

My niece will take the car out on the highway on Thursday, so we'll have to see if the codes return. I let you all know. Thanks again for everyone's help. And, if any of you find that you need a mirror ball and smoke machine, let me know. I've got a source.

[GT6]

I thought I'd put a face on the subject. I took this the day I opened the hood to start tracking down the problems. Also, my GT6. Had to include it to show what I'm accustomed to. The hood (bonnet) lifts up and out of the way. The shot was taken in the middle of some rework/upgrades. Although I'm better at it now, changing the plugs on the GT6 is much simpler. My respect for you guys who deal with cars with ECU's on a daily basis has only risen from their previously lofty levels. Yes, I'm being a bit redundant with my thanks, but guys, thanks again.

[SBT]

Love the simplicity of the LBCs. Hate balancing the HS's though.

 

Perhaps a Weber DCOE is in my future.