hi all!

alright.. i'm REALLY stuck here... i've been trying to diagnose this problem for the past month or two, and i've given up and i'm now seeking help from all of you. to start off let me provide you w/ some info about my car:

- '88 NA chasis w/ '88 T2 swap
- all emission/idling related things removed including OMP (excpet warm start assist)
- pretty much new everything, spark plugs, plugs wires, vac lines, fuel lines, fuel pump, gaskets... etc.
- perfect timing
- perfect tps setting
- my vdo boost gauge reads a solid 15 to 20in mg at idle

1 day i was sitting in my car w/ it idling (it ran fine for about a month after the t2 swap), then all of the sudden i heard a little "pop" sound, followed by some air gushing sound (like a vac leak), and the car just died. the following are problems i've been having since that day:

- car would not hold idle below 2k (i have to hold the gas w/ my foot), the car would just die when i let off the throttle
- i think there's a air rushing sound, but i'm not sure due to the fact that i have to hold the rpm pretty high, which makes it difficult to listen for it
- the car sounds great from 4k to 8k, very smooth
- the car runs like **** at low rpm, VERY smelly, and back fires a lot
- boost gauge stays at around 8in mg.

now, the following is what i've done to try to fix it:

- teared down my UIM like 50 times trying to find the vac leak, no success
- got my friend to sit in the car to hold idle, while i sprayed starter fluid, and found that there's a big leak around the TB area, but could not find the leak
- the IC is fine and has no leaks

so, i REALY don't know wha'ts wrong w/ my car. i mean, i'm pretty sure that i have a vac leak, but will that make my car run this bad? and, what the hell can be leaking at the TB? i'm sure that all the vac hoses are good.
maybe this is not a vac leak at all?

thank you guys so much for your help. i'm really running out of things to try out.

howi

 

u know its leak, just have to find it....go thru all hoses from AFM to turbo and so on...

 

Check the fitting on the AFM and the front of the turbo. Ive seen those come loose a few times and cause similar problems.

 

Are you sure you capped everything off when you removed everything? If so are you sure all of your intake gaskets are good and on the right way? If all that checks out its gotta be a hose and that narrows it down some

 

I used some RTV around my plastic TB spacer. Maybe there's a leak around there?

Remember boost can pop stuff off. I'm wondering what will pop off first on my car altough I've clamped and zip tied most places down.

 

TID

 

I should have said, "Check for cracks in your turbo inlet duct." If it's still stock it's VERY prone to cracking.

 

thank you all so much for your help

i replaced the tid recently (thank you Ian ), but the problem remains.... i've also taken off the TB like another 5 times... no more... i'm so sick of it... sigh...

anyways, i'm beginning to think that it may not be a problem caused by vac leak any more. the following are my arguments:

1) well, i've checked throughout the car soooo many times.

2) the car will die as soon as the rpm drops below 2k. if this is a problem caused by a vac leak, it's GOTTA be a HUGE leak (i think i would have found it by now!). come on, i seriously dropped about 10 in mg of vacuum (around 5 psi!!); this is not a leak! it's a HOLE!

3) the A/F ratio is REALLY fucked. it doesn't just back fire like a souped up car does, it backfires SOOO loud that it sounds like a gun shot!

i don't know guys... please help me out.... instead of randomly buying replacement parts, i'd like to find the problem first (obviously). but i'm really running out of resources here...

thanks again guys

 

Check your brake booster and check valve. Also the fitting on the manifold itself.
Michael Smith

 

Seeing as how you've done quite a bit of work already, you won't mind anymore.

Take off your air filter before the throttle body. Get a PVC endcap, and fit it with an airline connection if you have access to a air compressor, or with a tire valve (so that you can use a $10 12VDC air compressor). Couple the two together using a piece of rubber hose and two hose clamps.
Now, shove something into your tailpipes to get a solid seal.

Now, hook up your air compressor or what have you with a 20 psi air regulator. You will here and feel exactly where your leak is as the air rushes out.

A bit of work to set up, but it works very simply and quickly every time after that. It'll also tell you if you ahve any exhaust leaks.