Car jerks at WOT

[newTSIguy]

Hello, I have come across a problem with my 95 gsx, Let me stars off by saying I have done a search on my issue. I Have found some leads through my searches but my situation has some differnt symptoms that I have not come across in any of my searches. So like stated in my title, my car jerks or bucks at WOT once full boost is made. Now heres the thing I dont understand, If I start the car, and let it get up to temp, and then go out and put the hammer down its fine, I can do WOT pulls just fine with no problem all the way to redline if I want, but after about 10 to 15 min of hard driving is when this problem will arise. It will start at the higher RPM's like 6k and the more pulls I do the lower the rpm range becomes, the lowest RPM I have had this issue in is 4500 rpm in second gear, but here is the kicker, if I shut the car off, for say 5 min and go back out and do a WOT pull, it will be just fine, but after about 4 or 5 pulls the problem will come back. My RPM,s keep climbing very steady with out any hesitation, so im assuming i can rule out a fuel problem, I will change my plugs tomorrow, and I have brand new 10mm magnicore wires. By the way, I have no CEL, My idle is about 800 rpm without any surge, every now and then though I will come to a light and my idle will be around 1100 and then when I get to the next stop light it will be back to 800rpm, but no bouncing rmps, if that helps anything. And I dont seem to have any boost leaks, can the problem be my ECU, or my MAF, or do these symptoms fall in the lines of something as simple as my plugs, My car is pretty stock, I am still on the t25 with BCS, I do not have any guages or hooked up yet or tuning capabillities. Thanks in advance.

Ken

 

[805DSM]

Start off by doing a boost leak test,. And check
The fuel pressure , your fuel pump might be going out.. And is this happening with those magnacore wires?, cause i had a set of those before and i would get really bad missfires at high rpm, swapped them with some ngk's and problem solved..

 

[coryd21]

Do a boost leak test, check spark plugs and change if needed. Make sure to use NGK's gaped at .028, check for pre-turbo exhaust leaks, and finally check fuel delivery. Get your results and check back with us.

 

[JJILL95]

I had the same problem and that's how my gs got the nickname "Micheal J. Clipse". It would have random street seizures and I replaced ECU, Throttle, MAF, IAC, checked throttle cable, and was later suggested by my buddys dad who has a 95 talon that if the problem isn't constant and randomly decides to occur it might be the CPS. I searched for a month b 4 I finally tried it and magic. Also had high idle and wouldn't idle down all the time.

 

[highlandgst]

I had a simlair problem , though it happened abit more often than yours did . I had a boost leak fixed it , that help a bit , had a vac leak fixed it , also helped ,however still happened . I replace my IAC and took my throttle body off , cleaned it then put it back on put the IAC in ,reset my ecu and problem was fixed . just some ideas

 

[newTSIguy]

Thanks guys, I found out I had a boost leak our two, fixed those and thought I fixed it, but I was wrong, I am noticing that it only does it late in the evening when the air is cooler, and I am also having a high idle also.

 

[highlandgst]

i'd clan the throttle body and check for vaccume leaks

 

[tips000]

you probably have a small boost leak that seals itself up as the car gets warm... do a boost leak test but do it after the car has sat and cooled all night... maybe an injector seal going bad or something... your buck is probably fuel cutting due to the boost leak/ spike

i'd clan the throttle body and check for vaccume leaks

finally someone who suggests this! i am usually the throttle cleaning nazi around here but yes... i dont think it is related to your problem but it could b... and it never hurts to clean... it will give you better response too if it is in fact dirty...

boost leak test while cold
clean throttle body
success

idk if you have an adjustable blow off valve but try going a smidge tighter and see if it helps

 

[GsXdSmKingGsX]

Leak down test!!!

 

[newTSIguy]

Ya found out what was up with the idle, was just my throttle cable. I always over look the obvious, any way no need for a leak down test, I have perfect compression all the way across all 4, as for the bucking at wot, I'm still stumped on that, I'm thinking it might be a fuel delivery problem, or could it possibly be due to the fact that I have 10mm magnicore wires? it has only happend to me twice so far and both times it was cold outside. oh and I'm still on the stock 2g bov witch leaks at 10 psi, I did a boost leak test last sunday and fixed the leaks I did have.

 

[highlandgst]

the irony of this is ive fixed 5 boost leaks ... and i have yet to do a single boost leak test ... i need to make one

 

[newTSIguy]

I made a tester for under $ 5, got a valve stem from autozone for like $ 3 and a 2"pvc pipe cap at home depot for like $ 1

 

[cliffkemp]

are you running stock boost? Assuming you are. checking the gap and keeping it around .028 or slightly smaller should fix the problem with the topend miss. If you have any other leaks, could make it run rich enough to skip at high rpms.

Watch for bad coil packs too. I had one go bad with me and would skip at higher rpms. I replaced it and problem solved.

 

[newTSIguy]

Ruining 14 psi, I think I'm going to replace every thing from coil to plugs and see what that does, also if I accel through corners at wot I get what seems like fuel cut, just like hitting a brick wall, any ideas on this?

 

[gabureiru]

That's a bummner, try it with a friend or yourself with the help of the forums.