05 legacy gt stumble/hard on gas no codes

[LegacyLGT05]

Hey new here just got a 05 gt sedan with 260000km . Was barely running when i got it but it was just some vac leaks at the intercooler and BOV I Fixed all the vacuum leaks and changed the plugs , no misfire code but Its lost power after 4500rpm and when taking off it bucks even cleaned MAF and idle is still jumpy and hard on gas .

Next step was to check fuel pressure but I need to mcgyver a gauge

Could a evap code cause a misfire? I got p0447.

Below are pics of the data I got when idling.

Thanks

 

 

Edited August 21, 2023 by LegacyLGT05
Added Pictures

[KZJonny]

Probably lots else there to help diagnose, but I suspect you didn't get all the leaks.

If you are at + 5.4psi manifold pressure at idle, something is very wrong. You should be at like -8 or -9 psi at idle. Even if the gauge doesn't differentiate between +/-,  5psi is not okay. Double check all those connections.

[LegacyLGT05]

Thx for the reply,  Would it be possible it would be the intake manifold gasket/ oring? Thank u

[LegacyLGT05]

My idle is 700rpm

[KZJonny]

Other may jump in here to help. 05’s are notorious for a leak at the “blue tee” under the Intercooler, kind of behind the manifold.

It’s just a plastic tee joining vacuum lines, but it has no barbs on the ends, and lines slip off. A barbed replacement is like $10. (Turkeylord/Company 23)

Definitely could be a gasket… but something isn’t right. I’d consider starting with a DIY smoke test and see if that gets you anywhere. Or pressurizing the intake manifold a little and using soapy water to find leaks…

Tests that take a little time, but not so much cash.

Other common failure points seem to be at the turbo inlet to compressor and the IC to throttle body. Take a good look there for rips in the tubing or slipping clamps.

[LegacyLGT05]

Thanks you for the information KZ.

I Re-checked the intercooler, blue t , TB and the turbo inlet clamp, they all looked fine, took it off and redid the clamp but then made a DIY smoke machine with a tire pump with the intake sucking on a cigarette lol.

This way I found a leak at the hose that comes off the charge pipe to BOV. Fixed it and now my idle still rough but MAP is now a little higher at 6.2psi. ¿

So I looked at the MAP DATA with the key off to see if the sensor was giving good readings and it was at 14.7psi wich I figured it was not normal but read online that atmospheric pressure is 14.x psi.

Last think was to check the p0447 I had and found out the previous owner had deleted the EVAP caniser or did a "delete"  took the right rear spash guard off and found no canister just hoses dangling, full of dirt. Done a quick search about canister delete and read about the purge valve could be letting unmetered air in the manifold = vac leak?  My bad for the long texts and thank you for the help

 

 

 

[KZJonny]

Okay... so if you fixed a vacuum leak and the pressure reading got higher it is probably safe to assume that the gauge is giving you the absolute number for pressure. (Eg: it is ignoring the +/- value of the number and just displaying it as a positive integer.) Looks like you are using Torque?

In either case, (-)6.2 psi is still not okay. Like I said earlier, -8 to -9 or better, maybe as low as -10 for warm idle vacuum is ideal. Remembering that your fuel delivery is referenced to vacuum/boost. So, when your engine is bogging at higher RPM, it could definitely be a result of that huge vacuum/boost leak. If the fuel pressure regulator isn't seeing the same boost psi as the intake is, then it's not adding enough fuel to keep the engine running. If you run too lean, you risk some very high heat, and engine damage can occur.

Definitely start by plugging the line going into the IM coming from where the EVAP canister used to be. If there is a failing solenoid there, or an old and leaking hose, it could certainly be causing you problems. I would do it by figuring out which port on the manifold is the culrpit and plugging it at the engine side of things, rather than where the canister used to be, and hoping there isn't a leak in the hoses that run the length of the car...

[yeltsew]

Now this is just a guess but I've always heard that MAP sensors read "absolute pressure", with 0 being a perfect vacuum, as opposed to most gauges reading 0 as atmospheric (~14.7psi) and any vacuum as a negative value. If Torque is just reading the raw value of the MAP sensor and not converting it to "gauge pressure", 6.2psi at idle does sound about right. 6.2-14.7=-8.5psi, which makes sense. That would also explain why it's reading atmospheric when the engine's off, instead of the 0.0 that an Accessport or analog gauge would read.

It might be worth finding an analog vacuum gauge and hooking it into one of your lines just to have a second opinion.

Also be sure to clear your ECU and go through the whole idle re-learn procedure after fixing your vac leaks.

Edited August 24, 2023 by yeltsew

[KZJonny]

13 hours ago, yeltsew said:

Now this is just a guess but I've always heard that MAP sensors read "absolute pressure", with 0 being a perfect vacuum, as opposed to most gauges reading 0 as atmospheric (~14.7psi) and any vacuum as a negative value. If Torque is just reading the raw value of the MAP sensor and not converting it to "gauge pressure", 6.2psi at idle does sound about right. 6.2-14.7=-8.5psi, which makes sense. That would also explain why it's reading atmospheric when the engine's off, instead of the 0.0 that an Accessport or analog gauge would read.

It might be worth finding an analog vacuum gauge and hooking it into one of your lines just to have a second opinion.

Also be sure to clear your ECU and go through the whole idle re-learn procedure after fixing your vac leaks.

Good point about the difference between 0/14.7

I've gotten quite used to using the AP instead of Torque (which I think the OP is using, but I'm not sure.) In this case it's a little confusing tho, since as he fixed a known leak at the BOV, by that logic the increase in the absolute pressure reading (subtracted from 14.7 or whatever atmospheric actually is for him...) would indicated that he lost vacuum at idle with the repair? That doesn't seem right.

Curious to hear how the EVAP line repair works out. If it is the culprit it should shed some light on the question of what the reading is vs. what the device is showing.

[LegacyLGT05]

On 8/23/2023 at 10:39 PM, yeltsew said:

Now this is just a guess but I've always heard that MAP sensors read "absolute pressure", with 0 being a perfect vacuum, as opposed to most gauges reading 0 as atmospheric (~14.7psi) and any vacuum as a negative value. If Torque is just reading the raw value of the MAP sensor and not converting it to "gauge pressure", 6.2psi at idle does sound about right. 6.2-14.7=-8.5psi, which makes sense. That would also explain why it's reading atmospheric when the engine's off, instead of the 0.0 that an Accessport or analog gauge would read.

It might be worth finding an analog vacuum gauge and hooking it into one of your lines just to have a second opinion.

Also be sure to clear your ECU and go through the whole idle re-learn procedure after fixing your vac leaks.

  I have a analog vacuum gauge and at idle it sits at -17

@KZJonny yes am using torque pro I know its not the best but my AP is married to a mazdaspeed3 and dont have that car anymore. The purge valve was already blocked off I guess so there was no leak there.. 

[KZJonny]

Seems higher than it ought to be, but all good. Can't have too much vacuum at idle, I would think.

So, if the EVAP doesn't check out as a leak... I do not think that the EVAP CEL is causing you problems, no. Unless some solenoid somewhere is opening about the same RPM where you're having problems? Unlikely, but I would still personally choose to figured out which hose it is and plug it right where it meets the manifold/intake tract, rather than hop there isn't a leak somewhere between there and the gutted components in the rear.

Nothing wrong with Torque at all. It's a good program and I use it on my other car that doesn't have and AP. *Could* be worth the money for you to send the AP in to COBB and have them reprogram it to SUB-002 or whatever it is we use. Costs less than gettin a new one, as long as they still provide the service.... Then again, the way COBB is now, maybe you just put the money towards a tactrix cable and go open source.

Did you get an idea of fuel pressure? There are a number of threads here on upgrading to the much less complicated STi FPR in place of the massive double-dampered LGT one. Also, changing the vacuum reference to a tee off the vacuum live for the recirc valve and plugging the original line on the intake runner to Cyl 2 seems to have helped many with stumbles and hiccups, but for most it was lower down in the rev range, like 2500... Just wondering if your fuel delivery is falling on it's face as the engine demands more? 18 year old original fuel pumps could pretty easily be on it's last legs..... More data would help to narrow down what it could be.

[KZJonny]

I don't remember if Torque will tell which cylinder has the misfire? If so then moving around the coil packs will tell you if that is the culprit.... Misfire will follow a bad coil. 

Easy test, just need the old 10mm socket to do it.

[m sprank]

Idle should be -10psi manifold relative pressure.  Too much is a problem.  Is the turbo wheel spinning?

The evap delete should be addressed. 

[LegacyLGT05]

Thank you everyone.  The idle is only jumpy on idle and take off. Everytime I shift it hiccups and sometime would buck on 5th gear at about 3k RPM but cruising in 4th it doesnt buck. I think the FP was 44 I forgot to wrote it down but not sure of the car specs. I removed pump screen and put a new one, the pump in the car a walbro 255lph.

Turbo is fine got a tight used vf40 ihi

No misfire codes and not sure if torque can detect if a cylinder is misfiring or not. I pulled the plugd and it looks like its a clean burn from color..  After I get past the stumbling it pulls better now since got that vacum leak fixed. But still jumpy idle and at low rpm

[LegacyLGT05]

But the exhaust smells like carbon/ little bit of raw fuel tips are really black  it backfires time to time. Really its hard to tell this guy had an aem fpr gauge and stuff maybe its a tune thats just bad? I checked injectors they are all good so my guess is a failing coil pack but no code yet?

[LegacyLGT05]

Timing adv at idle is average 10-14

[LegacyLGT05]

For some reason it pulls ok but wayy harder on a dirt road can this power loss be cause by bad alignment

[KZJonny]

No? Like unless your wheels are so badly out that being on dirt/gravel lets them get dragged along more easily than on pavement? Which sounds insane and not possible.

Can you back that up with acceleration rates from Torque? Or is that just 'butt dyno' results again. It always seems more thrilling careening around on dirt roads with questionable traction than on pavement.

Maybe you're wheel spinning a bit which is letting RPM climb, so more noise = feels faster?

[LegacyLGT05]

It just feel like it doesnt bog on shifts like it does on the road and when the pavement surface is wet  no puddle the car rear wants to sway out at like 60kmh  and  got new goodyear tires. But anyhow thanks everyone im going to order new coils and send out my AP to get it reset for better data logging  would you recommend tactrix cable ove AP ? I got the old grey one 

Edited August 29, 2023 by LegacyLGT05

[KZJonny]

Depends on the cost to reprogram. I don’t know what support there is for V2 Accessports any more. Not much, from what I’ve seen.

Not to wade into the conversation about what COBB had to do to stay in business (Greenspeed program), but there is a lot you can’t do with an AP any longer. Like, TGV deletes are no longer supported. In my case, this may be a thing, since I’m getting an intermittent code for the flaps sticking open during warmup. The simple solution would be to get rid of the failing parts, and tune around it. No longer available on AP, so I’ll be stuck replacing the motors or sensors…. On the other hand, APs are going for less $$ used now as some people are going OS or fully independent ECU if chasing big power.

If you can find someone who still tunes in OS, then it shouldn’t be a problem going forward. You’re talking in km/h, so are you in Canada? Far fewer emissions regulations/testing here generally, and easier to get away with mods than in the US. I’d start there with your research and decide on what to do when you have someone you can work with.

[LegacyLGT05]

Hey been a while but my charge pipe had a tear, map now reads 7.3 . still runs like crap, driver side motor mount has separated from the metal. At wot my timing drops to 9 and my afr drops to like 11.3 with just a blip of throttle . Is it possible that the broken motor mount is triggering knock? Or would a bad coil/plug richen the car to the point it pulls timing? I had a 05 lincoln lsv8 different animal, my first time with a turbo car but im frustrated since it ran a1 when I got it. Thx

Edited October 11, 2023 by LegacyLGT05

[LegacyLGT05]

My heat temp gauge also reading lower at 84, used to be 96c is this a bad coolant temp sensor? 

[KZJonny]

16 minutes ago, LegacyLGT05 said:

Is it possible that the broken motor mount is triggering knock?

Vehemently yes. Change that shit before you go chasing problems elsewhere.... if you're gettin knock from the engine banging around, you'll never be able to isolate anything.

 

16 minutes ago, LegacyLGT05 said:

Or would a bad coil/plug richen the car to the point it pulls timing?

You still have the AP and it works? Look for misfire on a cylinder (Cyl. Roughness). move the coils from side to side, or front to back, whatever. If the misfire follows the coil = bad coil. If the misfire stay at the same cylinder, maybe signal to the coil (wiring) or you've got mechanical problems on that cylinder.

 

Aside from that are you 100% confident you have no vacuum or boost leaks? If you've got an '05 with mainly original hoses, decent chance you've got a problem somewhere, or one brewing. Torn turbo inlet suggests the rubber stuff you have isn't in tip top shape. Can you DIY a smoke test, or read up on the other ways to see if you've got leaks. (Spraying around hose fitting with engine start spray and listening for a change in rpm, sound, etc....)
 

7 minutes ago, LegacyLGT05 said:

My heat temp gauge also reading lower at 84, used to be 96c is this a bad coolant temp sensor? 

Mine also dropped from mid 90s to 80s lately. Probably because the average outdoor air temp is lower in October than August....

 

Edited October 11, 2023 by KZJonny

[KZJonny]

Group N mounts are not much more money than standard and will firm things up a little as well....

I've got a set that need installing to match the Group N trans mount, upgraded dogbone etc.... Waiting until I do the clutch to make it a one stop shop.

[LegacyLGT05]

I replaced the charge pipe with a same one, it was a perrin and it cost me 350$CAD . The AP I had was already married to another car that is now scrap, recently found out its too old and is no longer supported but I plan onto buying tactrix OS 2.0 since its cheaper. 

Also sometime after idling for a while if I shut the car off and restart it takes like 6 secs of cranking to start idk why

will keep looking for leaks thoroughly again and spray the coils to see if theres no arcing, but have 4 new on the way and should be here in 3 days. Will be ordering the group n aswel.

 Kind of shooting blind here but I know if I had ssm or tactrix I could provide more info but the torque app is pretty basic.  thx again Kz