Engine Stumbling at full boost

[Razorbac23]

Whats up guys,


OK I did a pressure test on my intake and found a bunch of leaks, repaired them, now my turbo is making all kinds of boost. The issue is when I'm at max boost, about 5500 RPM, my engine studders and almost dies until I let off the gas. I'm guessing I'm reaching fuel cutoff. My question is can I upgrade to say 650cc injectors without a controller??

I have a 255 fuel pump, fuel pump rewire, and upgraded intercooler piping.

Thanks alot.

 

[92AWDHX40]

upgrade with out a controller what kind of controller do you mean?

 

[Razorbac23]

DSMlink or some kind of fuel controller..

I have a manual boost controller now.

Sry about that...

 

[rcarbajal4]

upgrade with out a controller what kind of controller do you mean?

I think he means a form of fuel management.
Can you? Yes.
Should you? Probably not. You will most likely be running rich.

 

[Razorbac23]

OK thks.

Why do you think the engine is stumbling at high boost???

 

[rcarbajal4]

OK thks.

Why do you think the engine is stumbling at high boost???

Answered before I did .
Does it feel like you just hit a wall?

 

[Razorbac23]

Not really it starts to loose RPM until I let off the gas. If I stay on the gas it dies.

Maybe my stock turbo is over boosting, my stock (I know I have a real boost gauge on order) is almost pegging out.

 

[nfernotalon]

Might want to check the fuel pump too. My car started doing the same thing lst weekend felt like a huge boost leak as soon as it started to hit boost it would buck and go no where.

I checked all day for boost leaks or a miss fire in the plugs, checked the turbo and nothing.

Took my walbro out put in the stock pump and ran great no problems. I hooked up the pump straight to the battery and it was spitting out fuel not spraying. Just another thought.

 

[Razorbac23]

Thats something, I've had my Walbro about 6 months with no problem.. Ill pull it out again.


What do you think about fuel pressure regulator??? possibility??

 

[2gGst98]

Is it a t25? what are your mods?

And no I would not upgrade my fuel until I have Link, or SAFC at the least. You said you have a 255? I would think you are already running rich. I thought a 190 is as big as you shuld go without a way to tune. correct me if im wrong anyone.

sorry "nfernotalon" didnt see your post. I type too slow

 

[Razorbac23]

I have a 255.... It was given to me so me being a guy I installed it...

I have an exhaust manifold, injec intake, manual boost controller, upgraded o2 housing, fuel pump re-wire, 255lph fuel pump, full 3" exhaust, and upper I/C piping with a Greedy BOV.


Like said this just starting happening when I fixed my boost leaks..

 

[nfernotalon]

Thats something, I've had my Walbro about 6 months with no problem.. Ill pull it out again.


What do you think about fuel pressure regulator??? possibility??

Ive had my walbro for about 4 years with no problems then I guess it decided to go last weekend. Doubt its the FPR theres guys running dual inline pumps on the stock FPR.

 

[razrman8]

Having a manual boost controller installed in your car is pretty much a no no without having a boost gauge to monitor it. I know that you said that you have one on the way, I am merely throwing it out there. So, I think that your problem lies, your are hitting fuel cut. Over boosting way over the limit that you should since you done have any fuel modifications on your car, as far as I am understanding.

As far as the pump, you're going to have people tell you that it is okay, but I am not going to. You should be adding that much fuel without being able to cut back some of it. I could maybe understand installing a 190 without a tuning method, but I would not do a 255. But like I said, you'll get the people that say they have done it and have had no problems at all. But to me, if you can't reduce the fuel, you don't need to add it.

 

[Razorbac23]

Ok i jumped the gun on the fuel pump.. learning experience....


I've had the boost controller on for a while , but I guess since I fixed the boost leaks I'm getting more boost.

I turned it all the way down with no change, Ill try to hook bk up the stock boost controller and see if anything changes.


thanks alot guys...

 

[nfernotalon]

Ok i jumped the gun on the fuel pump.. learning experience....


I've had the boost controller on for a while , but I guess since I fixed the boost leaks I'm getting more boost.

I turned it all the way down with no change, Ill try to hook bk up the stock boost controller and see if anything changes.


thanks alot guys...

If you turned down the boost controller and it didn't change you boost it sounds like it's hooked up backwards or your wastegate is stuck closed. Youll be fine running the 255.

 

[Tiki2777]

I had a stuttering problem in higher boost/rpm. It turned out to be bad spark plugs. I replaced em, and no more stuttering. (it was NOT a boost leak) Try that or you may even need better spark plug wires.

 

[ricktb]

I had a the same symptoms, I also thought it was fuel cut but it was not. It turned out to be an incorrect spark plug gap.. Pull your plugs, clean them off from any sort of carbon deposits, and re-gap to spec I think .028 Then hit the highway, and feel the power again

Oh yeah also I read you need a fuel regulator for the walbro 255, maintain stock fuel psi, and boost pressure until you have the rest of the parts needed to tune.

 

[bart taylor]

I had a similar problem on my old talon and thought it was plug wires/ign issue. turned out to be the o2 sensor.... having a similar issue in my current car thats why I found this thread