Need help/opinions on where to go next..

[RuBiCaNT5X]

First off, I'm not sure about posting in this category but I am all out of options. I've attempted posting in others and have gotten no responses. If it is indeed not worth, by all means, move it. Ok, here is the scenario....


I first off have a 99 Auto GSX. This spring I've put a new intake, 3" exhaust and a MBC on... In a nutshell, when the car has been driven for more than 10 - 15 miles, in 4th gear (and with OD off) around 60 - 80 it will hesitate to accelerate when 15 - 20% throttle is applied. Going WOT the car will accelerate fine, but in the lower throttle region is where the problems arise. The one thing that I do notice that is different than before I've added the above mods is more heat in my engine bay (primarily due to the new exhaust). My coolant temps are around 200 degrees. I am leaning towards either some sort of ECU malfunction that isn't tripping the CEL or the TCU is having issues. If I am not mistaken, any problem with the TCU is not linked with the ECU, they just share sensor information. So if the TCU was malfunctioning, it would not trip the CEL, correct? I have yet to hook up an analog multimeter (no cash) to the OBD2 port but this weekend I will get results ASAP. I've replaced the TPS with a known good one thinking it was the problem, however that has no alleviated the issue. Are my theories about the ECU/TCU having issues reaching? Could the tranny be on it's way out the door? I really appreciate the help and appologize if this is not an Extreme Tuner worthy thread. Thanks!

 

[Tevenor]

Thread moved.

Check for small vaccum leaks that will show up more at part throttle than at WOT due to the turbo overrunning it with boost.

 

[RuBiCaNT5X]

Originally posted by Tevenor
Thread moved.

Check for small vaccum leaks that will show up more at part throttle than at WOT due to the turbo overrunning it with boost.

Much appreciated! I think my 3" intake is a tad too much for the T25 because of all the adapter rings that come with it to connect to the turbo inlet. I'm putting the stocker back on until I get an upgraded turbo. I'll let you know what happens...

 

[97gst4sale]

check your plugs, i recently picked up plugs and put them in and they werent hot enough, it performed so bad i had multiple mechanics look at it and diagnose many problems, but all it was, was not sufficiant plugs.....get some good hot ones and see what happens

 

[Tevenor]

Originally posted by 97gst4sale
check your plugs, i recently picked up plugs and put them in and they werent hot enough, it performed so bad i had multiple mechanics look at it and diagnose many problems, but all it was, was not sufficiant plugs.....get some good hot ones and see what happens

Along those same lines, make sure the plug gap is .028-.030. No more, no less.

 

[RuBiCaNT5X]

The plugs and wires have just been replaced. I have NGK BPR7ES and new Magnecore 8.5mm plugwires. The plugs have been gapped to .028.. 99% sure those are fine.

 

[RuBiCaNT5X]

Dunno if this is gonna help, but it's worth a shot... Take a peek

http://www.dsmtuners.com/forums/showthread.php?postid=429505#post429505

 

[Tevenor]

That guy is an idiot and so is the dealer who he went to.

 

[RuBiCaNT5X]

Ok, for anyone who cares, I removed the Greddy BOV from the classic plastic IC pipe and it was in bad shape. The rubber gasket that attaches around the stcok pipe was all shredded. I am guessing that is where the boost leak was coming from... Stay tuned...

 

[RuBiCaNT5X]

Update!

I just finished installing both my UICP's as well as retro-fitting my intake pipe with a modified stocker. Good news, bad news.. Good news is, my hesitation problem has lessened a bit. Bad news is that there is still some boost leak somewhere. I still have to make a leak tester, but there are 3 places that I can think of to still look.


1 - Boost leak at the TB. The seals expand and leak around where the throttle plate is attached at each end.

2 - Lower intercooler pipe is leaking somewhere between turbo outlet and the intercooler.

3 - BOV is leaking when the membrane gets hot and expands.


Other than that, I am out of ideas... One a side note, I tapped the compressor housing nipple and used it to pressurize the lower nipple on the Greddy BOV. NO compressure surge at all. However, once I noticed my boost leak problem wasn't corrected, it did surge a tad. This problem sux (not that there is any problem that doesn't suck because then it ceases to be a problem) I can only troubleshoot when the car is hot and driven for a while.. Gimme your inputs whoever has subscribed to this thread...

 

[doug]

IRT to your original question about the TCU, I doubt that it's the problem. Sounds like you've eliminated that as a culprit anyway since in subsequent posts there's no mention of it. I also assume that since you mentioned the multimeter that you've read Charles' page at www.plymouthlaser.com on how to pull tranny codes, or are just a lot smarter than me and knew how to do that already (entirely possible).

 

[RuBiCaNT5X]

Originally posted by doug
IRT to your original question about the TCU, I doubt that it's the problem. Sounds like you've eliminated that as a culprit anyway since in subsequent posts there's no mention of it. I also assume that since you mentioned the multimeter that you've read Charles' page at www.plymouthlaser.com on how to pull tranny codes, or are just a lot smarter than me and knew how to do that already (entirely possible).

Right on the money, I did read Charles Monk's pages on testing the TCU. (I'm not a natural car guy, but I'm learning every day ). One thing that I failed to mention is that when the symptoms begin to occur, I let off the gas completely, and coast, I can hear a slight whistling sound coming from somewhere. I'm thinking it might be the BISS seal or perhaps the TB seals. My Vac reads about -20psi when I am driving (-13 to -15 in park at idle) and let off the gas completely. I've heard from a few people that it's -15 is more reasonable, rather than -20. Don't know if that helps or not. Thanks for your input..

 

[RuBiCaNT5X]

UPDATE II

I built a leaktester and with some tweaking I found where i am leaking boost. The valve cover has two small holes that are sputtering at 13psi +. I am guessing when the engine gets hot, those holes get bigger and that is what is causing the problem. Let me know what you guys think.. I am gonna get some JB weld and temporarily fix it until I can get a valve cover gasket.

 

[doug]

I'm guessing that once you get your leaks fixed, your vac readings during deceleration will be even lower-- mine reads around -28.

 

[RuBiCaNT5X]

Originally posted by doug
I'm guessing that once you get your leaks fixed, your vac readings during deceleration will be even lower-- mine reads around -28.

Does the valve cover gasket leak make sense or is that just a lucky find that is somewhat unrelated? I would like to think that it's I have found my problem, but then again...

 

[doug]

I really don't know. I wish I knew more about this stuff. I hope the JB Weld fixes the problem for you, though.

 

[RuBiCaNT5X]

Originally posted by doug
I really don't know. I wish I knew more about this stuff. I hope the JB Weld fixes the problem for you, though.

I bought a new gasket for the valve cover and a new PCV valve. Hopefully this is finally what fixes my issue..

 

[doug]

What kind of PCV valve did you get? I got a Purolator one time and the threads didn't match. Others have reported similar problems.

 

[RuBiCaNT5X]

Originally posted by doug
What kind of PCV valve did you get? I got a Purolator one time and the threads didn't match. Others have reported similar problems.

Bought one from San Rafeal Mitsu, so I have no idea who is the original maker.

 

[RuBiCaNT5X]

Found another boost leak at the TB. I don't know exaclty where it's coming from but I am guessing its the gasket. I bought some gasket material to patch it up with. Hopefully with the valve cover gasket and the above, I can have my boost problems fixed.

 

[RuBiCaNT5X]

Ok, I think this is the end all and be all of posts for this thread... After saying "I think I got it, this time.." over and over again, I must be really annoying you guys by now. Anyway, I think I am the victim of bad boost creep (unported maniflod, 3" O2 Elim Turboback and the lowly T25). The car would appear to hesitate because the turbo is boost creeping from 5 - 10 psi without me pushing down on the pedal any further. Sound like BS?? Let me know what you think of my prognosis..