1G Violent cutout of boost at WOT

[AngryTalon]

As the title says, that's about the only way I can describe it. During near to WOT (in gear) the rpms in the 4-5k range, pulling about 14psi, the engine will suddenly cut out and in of power with quite a jolt. I don't have datalogging capabilities, and the only extra gauge is a vac/boost. It appears the boost needle reacts with the engine as this happens. Could this be a problem with the wastegate?

 

[bryanwheat]

What are you running for engine management.

 

[1990AWD]

We need more info on your setup. Are you running a 14b on a n/t block? What's your engine management (like said), and what's your fuel system? Could be fuel cut, spark blowout, or lots of knock.

 

[bryanwheat]

Also are you running the turbo maf, ecu, knock sensor, injectors and resistor pack. Have you checked the car for boost leaks.

 

[msand951]

I had the same problem awhile back. I'm new to turbo cars but my bro in law has experience with his GSX. First thing he did was a boost leak, which I had a huge one. Turns out my rubber connector tubing was loose and would blow right off my side mount around 8-10psi. Newb mistake from my part it was a easy fix.

If it started to boost it would all of a sudden loose boost like a massive blow off and I would get fuel cut off and it would sort of stutter. I would get your connections and tighten things up.

Oh if I didnt boost it would drive fine. hope it helps

 

[AngryTalon]

Some specs, 92 FWD Talon.

Engine Management:
ECU/harness/injectors/MAF from 1 gen turbo car

Engine Internals:
6 Bolt crank/rods 2g pistons, 8.5 compression
Balance shaft delete ITM 3g Lifters Manley single coil valve springs
Graveyard valves, 3 angle grind 272/272 degree cams

Stock turbo (I don't know the trim) with FMIC
Walbro 255 pump, FPR (~40psi)

I've done a visual for vac leaks and all looks tight, but I plan to cap the induction tubing (between the MAF and TB) and pressure test it.

 

[bryanwheat]

Some specs,

Engine Management:
ECU/harness/injectors/MAF from 1 gen turbo car

Engine Internals:
6 Bolt crank/rods 2g pistons, 8.5 compression
Balance shaft delete ITM 3g Lifters Manley single coil valve springs
Graveyard valves, 3 angle grind 272/272 degree cams

Stock turbo (I don't know the trim) with FMIC
Walbro255 pump, fpr (~40psi)

I've done a visual for vac leaks and all looks tight, but I plan to cap the induction tubing (between the MAF and TB) and pressure test it.

When you do a boost leak test you want to pressurize the intake manifold also. Just put your tested on the turbo inlet and pressurize it to 20psi or higher.

 

[Dvcaptainm]

When you do a boost leak test you want to pressurize the intake manifold also. Just put your tested on the turbo inlet and pressurize it to 20psi or higher.

Exactly, I never thought of doing this on my first turbo dsm and found a leak on the tb gasket that I wouldn't have found with the plate closed

 

[AngryTalon]

Pressure tested the intake plumbing (15-20psi) and there are no leaks. I also have an unstable idle, so I checked base timing (with the ECU leads grounded) and it was showing ~12 degrees advanced. So I rotate the cam sensor to give it about -5 degrees. I'm curious though.

I thought by grounding out the ECU leads it knocks out the computer control over idle. I was still getting an unstable (oscillating) idle speed. Between 700 to 1k.

 

[Gasolinebaptism]

It's fuel cut, you need tuning capabilities or to lower your boost level.

 

[cl1ckclack]

It's fuel cut, you need tuning capabilities or to lower your boost level.

or take care of his boost leaks.

 

[GSTurbo1]

BLT, has to be your problem... get a wideband and make sure it is in the appropriate AFPR 11 while hard boosting. Monitor your fuel psi too.

 

[AngryTalon]

After pressurizing the system to 15-20psi, the only audible leak I can detect sounds like it's coming from the turbo itself. Like it's bleeding into the exhaust section.

I tore the system apart and I found and very small pin hole in the intercooler (which I welded closed) and replaced two broken clamps. What would I have to do (and/or buy) so I can do some datalogging?

 

[91mits]

since ## a 1g id highly recommend u to get a datalogger, seen them on ebay for about 80$ that includes the obd1 connector to the serial, also you said ## base fuel pressure is set to 40? if your a 1g 5spd it should be at around 37, sounds like a fuel cut to me.

 

[tron2119]

Sounds like fuel cut as others have said. Lower your boost, get some bigger injectors and get something to tune/log with.

 

[Spyderman7]

Sounds like fuel cut to me as well.Car wants more fuel but the stock ecu wont allow it.

 

[NordicSaab]

Fuel Cut +1. Be very careful and don't neglect this problem. Your current situation is the perfect way to destroy a motor.

 

[AngryTalon]

since ## a 1g id highly recommend u to get a datalogger, seen them on ebay for about 80$ that includes the obd1 connector to the serial, also you said ## base fuel pressure is set to 40? if your a 1g 5spd it should be at around 37, sounds like a fuel cut to me.

At idle, the pressure gauge was reading ~42psi. I did drop it to ~37psi.

As far as fuel cut goes, I'll make a MBC and set it to ~12psi. I'm not sure what WG spring is in it, but I have seen 15psi. And the idle still isn't right. After grounding the two leads that should knock the computer control out, the idle still occilates from 800-1.1k. And tightening the BISS all the way (slowly) does not stall the engine. It's close to stalling, idle drops to 500-800, but it keeps running - fuel smells rich.

 

[koryto2012]

Same thing that was happening to mine. Turned out to be fuel cut lije others have stated above.

 

[AngryTalon]

Question:

I've read that grounding the two leads (plug behind battery and data port) should remove the ecu control over idle. Does that mean an idle occilation issue should stop?

 

[93 talon tsi awd]

reviving this thread, I'm having a similar problem but seems to only be happening in 3rd to 4th in wot I'm running 20psi currently from what others have stated above it could be fuel cut but if anyone has had this issue and was able to resolve it and information is helpful I'll give an update after I turn the boost down to around 15 and look for boost leaks an look into getting injectors

 

[pauleyman]

Fuel cut is not from a lack of fuel.
Please fill out a vehicle profile so we know what you have.

 

[93 talon tsi awd]

Fuel cut is not from a lack of fuel.
Please fill out a vehicle profile so we know what you have.

Its been updated, also I turned the boost down to 15psi and it didn't jolt at all or what I'm thinking fuel cut went away after lowering the boost.

Any suggestions on what I could do to fix this so I can turn it back up to 20 psi?

 

[steve]

Since you have DSMLink the first thing would be to post a log of the car acting up.

 

[pauleyman]

What fuel mods are in the car?