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New Motor swapped in, wont rev over 2k with clutch out

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N2O_ZX2

15+ Year Contributor
35
1
Feb 1, 2006
Reno, Nevada
Alright, as many of you know who have been helping me through out the last few months know about all the problem Ive had with my 91 TSi. The motor that was in it jumped timing, bent all the valves and broke two pistons. I swapped in a new one, and while I was at it I built a custom FMIC kit for it, and built a custom intake, along with throwing in an EVO III 16G. I have a small problem with it though, when i push the clutch in, i can rev it up, but when the clutch is out, the car wont rev over 2k. When i drive it, and hold the gas pedal to the floor as soon as it hits 2k it bogs and surges slightly. I think its something with the tranny. I changed out the ECU but it still does it. What do you guys think it could be? Thanks a lot, and BTW, heres a couple pics for you guys.

*UPDATED* It will rev over 2k now, but not at WOT. When the pedal is pushed to the floor the car bogs and will begin to buck back and forth badly, and stop reving, no matter the RPM, but the rpms will drop down to around 2300rpms (PS THE TACH IS OFF BADLY SO WHO KNOWS WHAT THE REAL RPM IS). *UPDATED*

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N2O_ZX2
 
this guy had a motor swap into his 240 at my buddies shop and his wouldnt rev over 2k or maybe less and i think it turned out to be the maf or the wiring to the maf u might wanna check that out... im not sure just and idea
 
Is your maf sensor plugged in? Have you done a boost leak test? Checked all of you sensors connections?
 
Yea, all the sensors that i need are plugged in i think. I have done a boost leak test, and its all fine. It'll hold boost just fine. The MAP is plugged in too.

N2O_ZX2
 
it could be somthing with ## ignition, since it only does it under load... maybe ## not getting spark or fuel
 
N2O_ZX2 said:
Yea, all the sensors that i need are plugged in i think. I have done a boost leak test, and its all fine. It'll hold boost just fine. The MAP is plugged in too.

N2O_ZX2


You think they are plugged in or they are plugged in? What "MAP" are you referring to?
 
Every one that was plugged in on the last motor is plugged in now. There are a lot of disconnected plugs around the emissions stuff though. The MAP sensor I was talking about was the one in the housing where the air filter goes.

N2O_ZX2
 
Ok, some of my DSM friends said it might be the switch on the clutch petal farthest from the firewall. I disconneded it, and now it'll rev with the clutch in any position, but not when im trying to drive it. Also, the car is low on gas, that wouldnt cause this would it. I also just discovered one of my plug wires has a small slice in it, would that cause it? Heres some more pics, i finally finished everything up.

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N2O_ZX2
 
Alright, I replaced the plug wires, cause there was a slice in a plug wire(small, but i wanted to fix it anyways), and drove it a little more. I noticed that it will rev over 2k, but when you go to WOT the car starts bogging and bucking back and forth, no matter what the rpm. Any help?? Thanks guys.

***PS*** THE TACH IS OFF BADLY, SO WHO KNOWS WHAT THE RPMS REALLY ARE ***PS***

www.dsmtuners.com/forums/showthread.php?t=226464

N2O_ZX2
 
wow that is some long intercooler pipe.. to be honest its probally a boost leak.. with that long of pipeing and those wounderful home depot couplers you probally have a boost leak.. have you pressure tested it? also if that isnt the issue normally the maf is.
 
Yea, I have pressure tested the tubes. They hold 30psi just fine. Those couplers seem to work just fine, and havent leaked boost, so i think they should be fine. I had a problem finding those two reducers, so i just used the home depot ones, but hey hold, so Im not gonna replace them yet. Ill try and unplug the sensor, and see if it changes anything. If not, then I'll know what it is. Thanks for the help, what else could it possibly be? Ive checked almost everything. Feels almost like its running out of fuel. Ill replace that part, and if it doesnt fix it I'll post a video up here of what exactly its doing.

N2O_ZX2
 
Ok, I made a probably pretty common mistake. I pressure tested each individual pipe, not the whole system :nono:. I put the boost leak tester on, and found all the leaks. It was leaking right on the bottom of the J pipe, and a couple couplers were leaking a little, so i just tightend them down. All it needs is a little welding and it should run fine. I was tipped off by my boost gauge never getting above 2 psi @ 3k. My gauges are now fixed, so i know the correct RPM now. Ill let you guys know how it turns out.

N2O_ZX2
 
that should fix it.. also if you look at the front shot of your car.. your kinda lacking ic clamps on your pipe's there.. could be an issue..

really dont feeel bad i did the same thing when i made my first ic system and i thought my car was all messed up but it was just leaks..
 
LOL yea I know there werent any clamps on it. The bumper and lights werent even bolted on when I took those, I just set them on there to take pics. Now theres clamps all over it. I dunno how im going to fix the leak where the J pipe bolts to the turbo...

N2O_ZX2
 
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