Turbo build; bad idle surge and weird throttle

[NReinsel]

Alright, the day finally came that I could turbocharge my laser. Did a stock turbo rebuild on my N/A 4g63, piece of cake. My turbo setup is that of an early AUTO turbo DSM, with the 13G and 390cc injectors. Yes, I matched the FPR, ECU and all that to match with the turbo. When it start the car, it instantly shoots to 3K and holds for about 4 seconds, then I hear a weird hiss (not BOV?) and it starts to surge between 800-1600 RPM. When I blip the throttle, it shoots back to 3k and holds again, I can never hold in between. No vac at idle as well, only boost above 4k. Any input will be appreciated

I now have vacuum at idle. It moves with the rpm obviously, I still have the terrible surge. it moves between 10-20hg between 900-1600 rpm. tried adjusting the BISS all the way out, messed with the timing. I'm completely stumped on what it could be. My vacuum goes crazy with any RPM, and never seems to hit boost. I'm almost certain at this point its a leak, but I have no idea where, and I have nothing to do a boost leak test with.

 

[hubz91talontsi]

Sounds like timing is being advanced for whatever reason. Could also just be a bad TPS. You could try to throw up some pictures maybe something obviously is the culprit that someone will spot.

 

[210 dsm]

My car dose almost the exact same thing. It has a loud intake leak sound coming from the TB and i cant seam to find a leak. Also the surging is just like you described, my car has a new idle motor but was thinking of testing the tps next. Dose anybody know what the correct resistance is supose to be on a 1990 tps? My chilton's dosent say.

 

[NReinsel]

I can hear no intake leaks once the car is running, thats what frustrates me. And it has done the same thing with two different throttle bodies. I originally had a turbo 90 TB on there, but I have since switched back to my 91+ N/T throttle body, and I like it alot more actually, much easier to work on. But I'm now throwing a code for the TPS, which it did that when I was still NT, and the car still ran fine back then. When I log it with the motor off, the TPS is constantly jumping all over the place. Time to hit the classifieds.

Put on a new TPS, didn't do a thing really. Pretty stumped at this point. Not throwing any codes, and I have no codes saved when I log.

 

[NReinsel]

I think I found the problem. I sprayed carb cleaner around the bases of my injectors, and on cylinders 2 and 3 it really bogged the engine down. Is it possible to have lower injector seals go bad to the point where enough un-metered air is getting past them and causing my idle surge? When I log, it pulls time with the surge, and it does it regardless if the IAC is plugged in or not, so it makes sense that I'm pulling in too much air somewhere. That, and its very hard to drive. It seems to decelerate only after my foot has been off the gas for around 3 seconds. New TPS, new IAC, working idle switch. Any thoughts?

 

[210 dsm]

I figured out my surging problem. But to answer your question, yes you can have a intake leak at the injector seals. I'd really really recommend getting a boost leak test done, how ever you can. I had a huge one at the gasket between the tb and manifold. Fixed it, then had to reset my timing and adjust the idle to 800-900.

 

[rEclipserGST]

1. Buy a Boost Leak Tester
2. Replace the injector seals
3. Check the throttlebody plate for excess play
4. Check & tighten Throttle cable
5. Fix Boost leaks
6. Adjust Biss correctly, should be half pinky tip deep
7. Return with results