Builds boost, but doesnt pull?? getting ready to drive it into a tree

boostedV8killer · May 13, 2002

I just did a search but could find my problem exactly... So here goes.

When i step on the gas, the car will build boost...the gauge will go to the boost level i have it set at. But the car isnt pulling the way it should, its super weak. Its like a real bad hesitation. The EGT's climb extremely fast and would go over 900c if i didnt back out of it when i do this also.

But sometimes, i nail the gas and it pulls hard as $#@. And the EGTs are in the right range between 700c and 850c.

All of the threads ive read point to a boost leak, but my question is...if its a boost leak then why will it only do this sometimes?
And also if its a boost leak, will my boost gauge still read the way it should?

Mods on the car ( 93 Talon Tsi)
- Ported Big 16g
- 3" turbo back exhuast, no cat
- ARP headstuds
- Turbo XS MBC
- Custom FMIC 30" wide by 8" high
- All mandrel bent 2.5 IC piping
- K&N filter
- ACt 2600
- 95 Ex Manifold
- 95 o2 housing ported hardcore
- very mildly ported head
- Walbro 255lph fuel pump
- Stock injectors, stock plugs and wires, gapped to .027

the car ran fine when it was first all put together, but now this hesitation almost like "fake boost" happens more than "normal" boost.

somebody please help if soooo close to abandoning this darn thing.

salTy · May 13, 2002

It sounds alot like a boost leak to me or maybe you need to check your timing. I had a similiar experience awhile back and it was the TPS that crapped on me. The car felt faster at half throttle than wot. Do you have access to a pocketlogger/datalogger?

dsm1995gst · May 13, 2002

boostedV8killer said:
somebody please help if soooo close to abandoning this darn thing.

You would give up on a car that you have done that many modifications to just b/c it has a little problem like that?

Anyway, do your lifters tick a lot? If they are ticking, then it will pull timing, so when you hit the gas it will stutter (does this in my car). Try revving the car in neutral pretty high (6000RPM) a time or two, then go WOT and see if the car pulls hard or not.

Also, check the fuel filter.

SeatownGST · May 13, 2002

I don't see what kind of BOV you have... BOV leaks are very misleading. You will still "build boost" but it has to overcome a leak on its way to the throttle body.

Also check your IC piping, you may have blown a coupling off enough to have it leak there also.

boostedV8killer · May 13, 2002

sorry i didnt mention... just Stock 1st gen BOV.... uncrushed

I dont think its a boost leak mainly because it doesnt do it all the time, but its ben getting worse lately and also the EGT's climb so high and so fast when it does this. Im wondering if its the TPS???

I dont really hear any lifter tick, so i dont think thats it. Im leaning towards a bad sensor of some sort.

dsm1995gst · May 13, 2002

Re: Re: Builds boost, but doesnt pull?? getting ready to drive it into a tree

dsm1995gst said:
Also, check the fuel filter.

What about the fuel filter? If the fuel filter is clogged your car will run lean.

Dsmman · May 13, 2002

Check your base timing, it may be too far retarted. Also, do a compression test. A few bent valves will have the same effect. Trust me

Tondar · May 13, 2002

pocketlogger

to check for sure, but sounds like you're getting knock to me.

EGT's climb so high and so fast when it does this

Retarded timing sends the combustion event out the exhaust manifold, hence the high EGT's

Could be legitimate knock or phantom (lifter tick) knock -- 99% sure of my diagnosis!!

novaboy · May 13, 2002

hey this is my first post. my gurlfriend just got a 99 gsx. and it has this same problem. i was thinking that the blow off needs to be adjusted. her car has an akimoto intake, greddy piping, greddy type s, and a greddy cat back(i think its a pe...it was on the car when she bought it...it has 3 inch diamiter so). the car hits boost @ like 3 grand and pulls really hard till about 5 and a half...then it feels like it isnt making any power. any suggestion? thanx for any help.

am00re34 · May 13, 2002

I have a 90 talon tsi and i just recently had the same problem.... my fuel was running really lean and that seemed to be the problem. i replaced my vacumn lines and reconnected all the sensors in the car and then it was fine. try that!

novaboy · May 14, 2002

are you talking to me?

am00re34 · May 14, 2002

i was talking to the person that posted the question. as for you with the 99 gsx i dont know what that would be cause you should still have the same boost and everything unless you hit something that feels like a brick wall which is fuel cut

novaboy · May 14, 2002

its not a fuel cut...it feels like when you take a car past the redline and it runs out of guts...but this happens at 5500.

dsm1995gst · May 14, 2002

novaboy said:
its not a fuel cut...it feels like when you take a car past the redline and it runs out of guts...but this happens at 5500.

Well the stock T-25 turbo does run out of guts at about 5500RPM.

Also, do you have an aftermarket boost gauge? By doing that intake work, the boost has probably risen above stock levels by itself. If you have no fuel mods, this will cause timing to be pulled, which will make this "loss of guts" even worse.

Junkman · May 14, 2002

It's probably a long shot but try by-passing the fuel pressure solenoid just pull the two vacuum lines off the solenoid and connect them together. My car did the same thing lack of power and skyrocketing EGT's but only sometimes. I hooked up a temporary fuel pressure gauge and noticed when it had the problem the fuel pressure was not going up with the boost or dropping with vacuum. I by-passed the solenoid and haven't had that problem since, or any bad side effects. Like I said it's a long shot but it doesn't cost anything to try it.

mpratt95 · May 14, 2002

I am having the same problem right now. Boost feels good when it comes on, but feels super sluggish after about 4500rpm. The exhaust tone also becomes real raspy and from what I've read sounds like it is pulling timing. I am going to replace my exhaust manny gasket, and do an intake leak test, but if that doesn't work, I need some other options. I guess I should do a leakdown test, but I guess I'll have to take it to a shop to do it. I'm getting frustrated. What makes me think it is a leak is the fact boost builds kind of slow (starts at 3k and doesn't make full boost until around 3800). Will bad sensors pull timing?

my mods are:

FP big 28 (ported)
ported manifold
ported o2
3" turbo back
magnecores
injen/k&n
ic pipes

Builds boost, but doesnt pull?? getting ready to drive it into a tree

boostedV8killer

salTy

dsm1995gst

SeatownGST

boostedV8killer

dsm1995gst

Dsmman

Tondar

novaboy

am00re34

novaboy

am00re34

novaboy

dsm1995gst

Junkman

mpratt95

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