Fun engine issues.

[Drakuun]

Okay, let me start here ; I'm going to replace my plugs, wires, injectors, and fuel filter, and possibly the alternator. I have a 4EAT btw.

 

The issues :

 

1: Hesitation, balking, bucking when accelerating over 4000RPM's.

Sometimes, it's subtle, it's a hesitation like its not getting proper fuel

flow, other times, it is like hitting a REV limiter, it'll bounce at 4000 RPM's

about 4 times then finally shift. This issue, near as I can tell seems to be intermitant. I can't 'make it do it' reliably everytime. This morning for instance, I only got the subtle version of it, like it just seems to not be getting good fuel flow. Yesterday, on the expressway however, it kicked down from OD to 3rd while I was passing, and when I got to the top of the range, it bounced off 4000 RPM exactly 4 times, then shifted. (when I say 'bounce' I mean, the RPM's hit 4k then drop back to 3500, then jump to 4k then back to 3.5 then jump to 4k again.) When I'm not standing on the gas, it performs fine (normal acceleration) Its still there, but unless you're over 4k you don't get the symptoms above at all. If I manually shift the gears anytime it gets to or over 4k it will bounce off 4k RPM like it's trying to shift but cant. Once in gear 3, it'll hesitate untill it shifts into OD, or if I'm really standing on the gas it'll again buck against 4k RPM's. The engine does not do it if Im in park or Neutral and just revving the engine over 4k. Fuel flow seems consistent in such testing cases.

 

2: A noticeable 'psst' sound emminating from the engine compartment front of car and very fast momentary loss of power while at cruising speeds. The whole thing happens over the course of about half a second. I hear a 'psst' sound, and the engine power saps then everything is fine. It happens so fast that I can't really tell if the RPM's dip or not. It seemed to happen consistently, about every minute or so. I do believe it to be happening at lower speeds or idle as well. It's not as loud at lower speeds / idle.

 

Things I've tried thus far. One tank of Mid-grade gas with a bottle of injector cleaner. Seemed to run great till I got towards the bottom of the tank. Reset the ECU, but I'll have to do this again I think and drive it longer.

 

Some other strangeness : When we first got the car, the amount of time the car stayed in 1st gear was literally about a second. You'd give it gas even slowly, and it would lurch forward and immediately shift into 2nd gear. Since my first ECU reset, it is shifting somewhat more normally it still shifts 'quickly' in my opinion however. I'm hoping a longer ECU reset driving session can correct this problem as it seemed to respond well the first time I reset the ECU and took it for a drive. I just don't think I drove it long enough. At the time, immediately after the reset I was able to drive and manually shift the gears without the bucking. I almost wonder if the ECU is simply 'burned in' from never probably having been reset or retrained in 4 years. It's like the ECU is expecting it to shift, and simply doesn't because I'm manually selecting the gears.

 

Anyway, wanted to post this here, let you guys look it over and offer up any other things I might check or look at as well.

 

Thanks.

[Underdog]

If I had to guess, I would say this is a transmission issue. Maybe your lock-up clutch in your torque converter? It would only be active in 3rd or 4th gear and would cause some of the stuttering you are describing (by locking the impeller and turbine halves of the torque converter together). Typically, the converter will lock-up when coasting and disengage when accelerating. If it does not disengage then you will notice the power "sap" and it can cause stuttering/bucking since you are overloading the engine.

[one69chev]

what's your mileage?

 

are these items scheduled maintenance or are you trying to eliminate issues with these parts?

[Drakuun]

98,000 Miles and some change. It has had all it's regular services performed up till when I got it. I was hoping that these parts might eliminate the issue. The wires and Alternator look like they've been through hell. Rest of the engine is clean though.

 

Underdog : From what you describe, I'll add this. Last night I did a manual gear shift run, It went through first OK, I shifted to 2nd, at about 4k it bucked once, then twice - I shifted it into 3rd - it bucked 2 more times, then, when it finally shifted I noticed that I heard a metallic sounding ping noise like two metal parts hitting together. It only lasted about a millisecond. It didn't make any other noises like that afterwards, I even managed to shift up through the gears manually a few more times, but I was shifting before 4000 RPM's without any reoccurance of the noise or bucking.

 

So long as I don't go over 4000 RPM's the engine and tranny do their thing perfectly. If I go over 4k, it'll sometimes buck approximately 4 times, then shift, or on other occasions it's like the gas flow is being cut off, but the RPM's don't buck wildly..it's just like it's not getting enough power.

[Drakuun]

Lunch time drive update.

 

Took it out at lunch, and put it through some more paces, and 'spirited' driving.

 

Surface streets. Manually shifted gears, got one and two well into the 5k range with no studdering / spitting / bucking whatso ever. Gear change between 1 and 2 is sorta rough, IE doesn't shift immediately, but was fine for the most part. Shift between 2nd and 3rd was also very very clean, shifted at about 5k RPM's again with no bucking etc.

 

Same as above except, I leave it in Drive the whole time. first and 2nd are fine, but towards the end of running into 3rd gear it's so ever slightly begins the to exhibit the issue like it's not getting enough gas..it just kinda surges, RPM's DO NOT bounce, DO NOT fluctuate at all. It's slowly and steadily continues to climb, but surges.

 

Highway, manually shifting gears. Long rolling ramp, so I was in 2nd, got it again well into 5k RPM range with no bucking or otherwise, Hit 3rd shifted nice and smooth, continue to accelerate, the very second I get to 4k it starts the issue as above where it surges power wise, but again, RPM's are not fluctuating or bouncing. (I have my foot through the floorboard at this point) . It does this till I shift it into drive, then immediatly stops surging untill I get over 4k RPM's again.

 

It did not at any time during my test session buck at 4k RPM's as if it was hitting a rev limiter.

 

As for the "psst" sound I was hearing, I think it might have something to do with my Air-conditioning / Heater unit. I turned it off entirely, and since I did I no longer hear that "psst" sound.. I will continue to monitor that on the way home.

 

whee..

[Drakuun]

At this point, I've only been able to reproduce the power surging during acceleration over 4k RPMs. It's basically the exact same as if you're accelerating and letting off the gas then giving it gas.. but faster.. RPM's don't fluctuate, they slowly and steadily rise till it shifts, rinse, repeat for 3rd and 4th/Drive gears, But only those gears. 1st and 2nd are solid, and powerful all the way through their respective bands.

 

 

As for the Bucking as if hitting a rev limiter.. It's never done that if I'm just in drive and not manually shifting gears..so I'm going to call that

non sequitur at this point. Maybe as UD describes when I let off the gas to shift, then put it in gear and mash the gas the lock-up clutch must not be disengaging and causing the rpm bounce. Although, in my tests yesterday I couldn't reproduce it then either. *shrug*

 

Well todays testing will consist of a wash, an ECU reset and more driving.

[Drakuun]

Got the wash, skipped the ECU reset, took it out for a good 40 minute drive, varied speeds. Ran great, like a champ, through all gears for 35 minutes. We came to an intersection, went to pull away, and *poof* out of no where I get the hesitation, only worse, now it's there any time the rev's get over 2500, really really bad at WOT, Any gear, I go WOT and it sits there 'bouncing' like it wants to wind up but just cant.. the car slowly accelerates and the RPM's slowly rise, but they also 'bounce' the whole time. It's not like it's dieing or trying to stall.. the RPM's never flux more than about 300/500

 

This is really strange.. I guess it only happens after the motor is warm, or been run for longer than 30 or so minutes. This seems consistent in view of the length of my other 'test' runs which were all shorter. (Lunch drive and on the way home)

 

Done more searching through other forums, seen other comments that coil packs going bad can cause this. At this point.. I have no clue.

 

Tonight after dark I'll take it out and look at the engine under darkness see if I can find any sparking / arcing going on, indicative of a packs or wires being fouled / shorted and go from there.

[ebpda9]

coil packs could be the problem. My old accord used to do that too

[melayout]

You should ask on NASIOC if you haven't already.

[red beast]

my guess ........Maf sensor

[Drakuun]

melayout ; Thats where I've been getting a majority of the options I'm looking at. I tend not to post there if I can help it, call it a personal rule.

 

red beast : My ej251 is MAP

 

So far popular 'look at' possibilities are.

 

o2 sensors

plugs

wires

coil packs

Grounding

Tranny

 

The thing I feel that defines it,

It happens only after the car is good and warm.

 

We shall see.

 

Thx fellas!

[red beast]

ah ha, just a different type of air flow sensor

[red beast]

didn't you ask at http://www.rs25.com or http://www.nasioc.com ?

[Underdog]

Torque converter clutch only becomes operational after the car has warmed up.

[Drakuun]

didn't you ask at www.rs25.com or www.nasioc.com ?

 

rs25 will probably be my next avenue. Again, holding off on Nastycocks as long as possible.

 

UD : This torque converter thing.. would it cause it to happen in 1st and 2nd gear too? Because when it does start doing it, I get it in all gears anywhere from 2500 to 5500 RPMs. The only thing that seems to effect its severity is how aggressively I'm giving it gas. If I just accelerate normally, less than 50% trottle, it is relatively smooth and shifts at about 3500 RPM's. It's there, but it's not so noticeable, but I can feel it. If I mash the gas WOT the second I get around 2500 RPM's (IN ANY GEAR) It get hurky-jerky then once past 3500 it bounces like it's hitting a rev limiter.

 

The only other odd thing I got is the 'psst' noise and sudden momentary loss of power. This is why I think it might just be the wires / plugs / packs at this point. If I knew a little better what an electrical misfire's symptoms were I'd call it already. Thats my search topic for today.

 

Thanks again guys!

[red beast]

rs25 will probably be my next avenue. Again, holding off on Nastycocks as long as possible.

 

 

 

whats the matter?

 

 

afraid of a "flame job"?

 

http://www.crainium.net/jdjArchives/DIYFlameThrower.jpg

[Drakuun]

I got flame proof undies.. I simply don't like the attitude over there mostly.

Either stupid kiddies, or grumpy guss'.. I swear, I've never seen more people with an aversion to 'new information' or questions. And their cat calls of "search noob" constantly.. It's like they get pissed off that people even post new threads. I remember a while ago, someone was like 'quit flooding our site with your useless questions" And I told them if they wanted a non-changing forum for information to go buy a chiltons manual.

 

I hate interacting on that site. So I use it to search with basically.

And post here and on rs25 because yous guys r t3h b35t!!

[vxracer]

ok- torque converter microscope mode. have you checked tranny fluid level and/or fluid color? torque converters work like a boat propeller does. Also, how and when has fluid been serviced? Do you drive HARD? how many miles on car when you bought it. etc

 

Good luck!

[Drakuun]

ok- torque converter microscope mode. have you checked tranny fluid level and/or fluid color? torque converters work like a boat propeller does. Also, how and when has fluid been serviced? Do you drive HARD? how many miles on car when you bought it. etc

 

Good luck!

 

I have not checked the tranny fluid level / color as of yet.

 

"torque converters work like a boat propeller does."

 

Es'plain please?? I mean, I know what a prop does, just don't understand how it correlates to the torque converter. (by the by, I've driven a car with a bad torque converter, and this doesn't quite feel the same)

 

Again, as to service, The dealer 'claims' that the car was serviced regularly by them. It's got 98,000 on it, and mechanically, other than these few issues it's impecable, I don't even have a quarter of some of the issues I see others post with my car... So I know it's at least due for it's 100,000 service interval. I can't quite remember off the top of my head what the service interval is before the 100,000 service... 60k? 80k?

 

As for my driving it, I know what the car is capable of and operate it within those limits. I don't over drive it that is to say. Of course, I've had to reset the ECU because it was driven by a woman before me and acted as such.

The shift patterns were really funky.

[vxracer]

the torque convertor basically uses the engine power to swirl fluid up to a certain "stall speed" then the force is great enough to apply to the output side. before this happens, this is what still spins, but doesnt stall the car at a stop. as it is slowly spinning in fluid. after the friction coefficient of the fluid/blade design is passed, energy is transferred to the "gear " part of the transmission. some cars then utilize a "lockup torque converter" design to bypass to a direct drive like a manual. no parasitic fluid energy loss. fluid dynamics. like the more the force, the more like a solid fluid becomes. confusing, but any clearer?

 

i dont know alot about scooby autos, but if the fluid hasnt been changed at all, alot of automatic transmissions fail from 70000 to 120000 miles. it is not wise to "flush" the whole tranny at once. you must drain a small portion, drive 1000 or so miles, and keep doing it until all is replaced. i had 2 isuzu trucks with same drivetrain. one hadnt been done, 97,000 miles and i had the flush/fill done. it blew up 2 weeks later. the other, 93,000 miles i did a portion at a time, and it still functions well.

 

Has anyone ever had the scooby auto pan off? can you open it, and remove a large drain nut on the torque convertor? the reason i ask is that i have heard that you can service a tranny, and the torque convertor could be partially not full, and the tranny at a normal level. any thoughts?