Engine stumbles under WOT

[1stGenTSi]

Here's the problem; when in 1st gear (haven't tried in other gears, but doesnt seem to happen) if i go WOT from a stop, when i get to around 4k rpms the engine falls flat on its face, and loses all power it seems. I thought it was fuel cut because I read that fuel cut feels as if you hit the brakes, (this just feels like hard acceleration and then BAM no power) so I changed the fuel filter to no avail. I have no logger so I dont know if timing is being pulled or what. I have and EVO III at about 13 psi w/ no fuel mods. Haven't tested for boost leaks in a while but I dont believe there are any. Compression on the motor is pretty low but has always run well and been fast. This has happened ever since I had to replace my ECU I believe.

 

[FORMONTOYA]

when i get to around 4k rpms the engine falls flat on its face, and loses all power it seems.

Haven't tested for boost leaks in a while but I dont believe there are any.

Hesitation and stumbling (especially around 4K) equals..........do a boost leak test, it doesn't take long and is easy to perform, then tell us what's up. A leak is probably causing it to pull timing.


Get a logger, it should have been one of the first purchases when upgrading, especially if you're trying to add a turbo without the fuel mods.

 

[1stGenTSi]

I'll go do a boost leak test real quick but im pretty sure there are none, it builds boost quick and holds it all the way to redline in other gears, but in 1st the rpms dont want to go past like 4000. Im trying to find a friend whos logger in can use. Thanks for the help.

 

[Defiant]

You're out-running your turbo. Do not try to wind it up in first.

 

[1stGenTSi]

The car has no boost leaks, boost turned down to 11 psi. Car actually stumbles in all gears at WOT. Tried taking second to redline and it loses all power somewhere around 5k. I beleieve I am hitting fuel cut, or having timing pulled. It seems this has happened ever since I replaced my ECU.

 

[KBasham03]

I would do a compression test and another boost leak test just to be sure.

 

[forcefed4]

Have you checked your plugs and wires? I had a problem similar to what you were describing and it turned out to be incorrectly gapped plugs. (buy the feeler gauge, not the cheap .99 gapper tool, )

 

[Fitz7099]

There has been some great adive in here!

First try new plugs (NGK) and new wires (MDS) - they are benificial even if they dont fix the problem. If that does not work then move on to a logger and find out what the problem is. Leaning out, fuel cut, etc..and then take the appropriate steps to fix it

 

[1stGenTSi]

I just did a boost leak test and am a little confused. I didnt have a leak tester with a valve stem on it so I blocked the turbo inlet, pressurized through the A1 nipple on the TB and all the pressure was going to the crankcase, first I noticed all air was escaping through breather hose so I plugged it. Then at around 8-10 psi on the boost gauge I heard (and could feel) air coming out of the dipstick holder. I have only found one other similar thread and they said valve seals or worn rings could cause this. Do I need to be pressurizing the system through the turbo (and build a vfaq style tester) or is the way I'm doing it okay? My engine isnt in great shape and compression is pretty low but I have always been able to boost leak test without this happening before.

ok.. so after some further reading this could just be a bad PCV so I'll check it out or replace it tomorrow, also my turbo (Evo 3 GT less than a year old with less than 8k miles) now has some definate up and down and in and out shaft play. I had checked it a couple months ago and it moved up and down very very slightly not anymore than normal I dont think, and it didnt move in and out at all. Now I can move it up and down an 8th of an inch and in and out almost as much. Maybe the GT really is a pos...

 

[92eagleTSI]

I use the nipple on the pipe coming right out of the turbo and cap the turbo inlet off, works very well except when the cap flies off at 20psi . Get your leaks fixed and get back here.

 

[MattratfTSI]

The car has no boost leaks, boost turned down to 11 psi. Car actually stumbles in all gears at WOT. Tried taking second to redline and it loses all power somewhere around 5k. I beleieve I am hitting fuel cut, or having timing pulled. It seems this has happened ever since I replaced my ECU.

Same problem here. especially in 3rd and 4th while going up hill. right around 3500 the engine stumbles for a slit second. Id dedscribe it as a quick buck.

 

[v8s_are_slow]

Probably running too rich or lean, or not enough spark to the cylinders. Wideband and a logger sure saves on headaches like this.