fatpants

Hi All,
I've searched this site and also the web but haven't found an answer so I was hoping collective consensus would prevail.

On WOT, when in any gear except first, with RPMs below 2k, I get a slight and very irregular bucking issue, almost like the clutch slips and grabs momentarily. This has happened with RPMs as high as 2.5k, which is well within the recommended rpm range. I recently had a valve adjustment, new air filter and plugs. Despite the fact that the dealer was unable to recreate, it happens every time I slam on the gas at 1.5k.

I would normally expect the engine to just grunt through this in a consistent manner, but this is a very irregular, spontaneous jerk. Not sure if it's engine or if the manual trans can slip somehow (friction modifiers maybe??) Higher RPMs are completely smooth.

If any fellow 3G manual owners can try to recreate --- WOT below 2k in gears 2-6 and report back (or explain what mechanically could be causing this) it would be greatly appreciated. If it doesn't happen for others, please let us know what type of trans fluid was last used.
Thanks-

pbook4g5

This is very similar, if not identical, to the issues that a few of us have talked about in numerous threads. I started one a week ago about this.

The current general ideas as to whats happening is that either (and these aren't in order)
a) your ECU is pulling timing due to lean conditions... gets worse in hot weather (the heat soak issue... search on here for more threads on this)
b) APP sensor is starting to malfunction
c) CDV is being a pain in the butt. Modify slave cylinder to take it out


One thing I haven't inquired about on here but have wondered in my head... what about the LSD. Would that have any effect on this issue? I've never owned a car with one and I know the TL-s has one.

justnspace

iTrader: (1)

ALL 6MT TL's have LSD, even the base models.
no automatic TL's have LSD.

I wanna get my car up and running so i can test if my car has the surge.
I dont think i ever felt it.

I do feel inconsistencies with the clutch at lower RPM's, I dont know if that's considered a surge or not

pbook4g5

I knew the Autos didn't have one, just wasn't aware that all the 6 speeds had one, regardless of model. Nice! (I learn something new everyday)

justnspace

iTrader: (1)

when i explain my car to non-enthusiast, I tell 'em it's they type-s before the type-s came out.

brembo's and LSD.

back to the surge, Ive always felt that the TL's clutch is the hardest ever to master.
I've always had inconsistencies even after I changed the clutch.
I took out the slave cylinder check valve, but still didnt help.

I just chalked it up to that's how my car is...
a characteristic if you will.
needs new driver mod.

fatpants

I think my car is totally tripping on the LSD (sorry couldn't resist). i had the manual trans fluid replaced at the dealer around when the problem may have started, I'll try the GM synchro mesh solution.. I'm assuming the LSD shares the same fluid as the transmission ??

Other than that I guess it's the CPU or CDV, I don't think it's the APP though since it does it in cruise control as well.

justnspace

iTrader: (1)

it's a Helical LSD

Jackass

Fluid won't matter. Trans fluid differences in a manual car for the most part only impact shift quality...how well the synchros works.

Cruise is a good test of the APP sensor as far as I know. Next time I drive mine, I will try to see what happens below 2k RPMs. I don't "think" mine does it and I drive with my RPMs below 2k on a regular basis.

ZOMGVTEK

I drive WOT all day <2K. I never noticed what it sounds like you're describing.

Could you record a video of the dash going into 6th at 30 MPH, and slam the pedal?

fatpants

Thanks for the comments, still curious if anyone can recreate. I tried to take a video this morning, but there was way too much camera movement to see what was going on. Despite the video being worthless, i monitored the rpms during the jerks and they make a very slight twitching movement, up by 50-100rpms then down again very quickly. It's like something slips then grabs, slamming on the pedal at 30 in 6th makes the car buck. Can a timing issue be so harsh?

On one of these attempts the CEL started blinking but went away. Anyway to check what code caused the blink? I'm guessing a knock sensor?? I'm tempted to continue doing this until the error is stored although that doesn't seem healthy..

I'll probably end up taking the TL to the dealer, although I want to be prepared when they say "everything seems normal".

pbook4g5

Blinking CEL is always a misfire, but finding out why it misfired is probably what you're after. Could be a number of things, one of which could be the knock sensor.

Regardless, since you had a code thrown, I don't think your problem is the typical heatsoak some others have experienced. Could be 02 sensors causing misreadings, or bad plugs, or bad coils, or injectors, fuel, etc. The list goes on.

I also remember there being an update to the PCM for phantom misfires. Can't remember the circumstances though, so I'm not sure if this situation qualifies.

Vlad_Type_S

iTrader: (3)

Boom, there lies the solution to your problem. Figure out why it misfires when you suddently go WOT at low RPMs.

ZOMGVTEK

Something easy to start with is pull the spark plugs. One might be ready to fall out, or one might look dramatically different than the rest giving you some indication of trouble.

fatpants

...any ideas?

ZOMGVTEK, good call, I'll check the plugs again for irregular wear.. a few thousand miles ago, when I replace the last set #4 was really loose and #5 was slightly loose. I torqued a few lbs higher than spec, then the dealer did a valve adjustment.

This pic shows how different' the first set looked.

That got me thinking, after the loose plugs, I did a full seafoam treatement including spraying some seafoam directly into the throttle body thinking it would clear any un-burnt fuel residue resulting from the loose plugs.. maybe I did some damage to the MAF or other electronics? throwing off timing??

Still not sure if a timing issue can cause such a jerkiness, although seems like an obvious place to start.

I'll be out of town for a few weeks, but will make sure this post ultimately has a clear resolution.

fatpants

just realized there's no MAF, just a MAP that probably wouldn't be effected by seafoam

fatpants

for what it's worth here's the old plugs...

pbook4g5

The top two on the right... woah... somethings up in those cylinders, especially the top right. Hows your oil level between changes? Do you lose any?

Also, did you change your spark plugs after the seafoam? Because you probably should.

fatpants

yeah the top right 2 were cylinders 4 and 5 which were loose (i'm guessing for 5 or 6000 miles). There was a good amount of carbon/crud in the spark plug tunnels and also on the coil packs. I'll double check these for new buildup/wear again as well. The plugs were changed at about 50k with brand new NGKs iridiums and then i did the seafoam... I only put on about 4k miles since then, but hopefully the sparks plugs will provide some insight.

fatpants

I kept noticing hesitation and a slight misfire under acceleration (dealer didn't think anything was wrong), finally the cel came back on and registered a misfire on cyl 4 and 1. Dealer did a compression test and cyl 4 is weak.

I'm guessing something's bent, i'll need to pay up and get it fixed... wish i had a 2nd car and a warm garage.