stuttering after boost

[Duke901]

well i got the new trubo ecu and started the car. the only thing i havent hooked up was the green and white wire from the mass to pin 6 on the ecu. and i have the bov line hooked to the P on the throttle body.i have a check engine light on i think from the wire not being hooked up to the ecu yet. well i took the car down the road and after it gets into boost and in the upper rpm range i have a really bad stutter. can it be caused by not having the turbo pump, and using the non turbo fuel regulater. and not haveing the green and white wire hooked up. other then that upper rpm problem it runs great.

 

[absolute_DSM]

So you turboed the 92 NT, is that what Im understanding?

the only thing i havent hooked up was the green and white wire from the mass to pin 6 on the ecu. .

Fix it.

i have the bov line hooked to the P on the throttle body.

Dont do that, its not the same. Find a line to designate from the intake manifold to the BOV.

i have a check engine light on i think from the wire not being hooked up to the ecu yet.

Pull the code and ye shall find out.

well i took the car down the road and after it gets into boost and in the upper rpm range i have a really bad stutter.

Sounds like a fuel problem.

can it be caused by not having the turbo pump, and using the non turbo fuel regulater.

Whats a turbo pump? And yes, try using a turbo FPR or even better, an aftermarket FPR.



What your boost set at? Do you have a boost gauge?

Any boost leaks? Good plugs, wires?

 

[Duke901]

where should i hook the bov up to. i dont the have the turbo intake so it doesnt have the extra nipple for vacuum. the boost is set to 10 psi stock wastegate psi. im running the non turbo plugs, and the wires are new. no boost leaks that i can tell of. do you think the non turbo pump isnt giving the car enough fuel

 

[Duke901]

well i changed the plugs over to turbo plugs, and drove the car, if i gradually get into the throttle it will rev out fine. but if i give it to much gas and have it boost fast it will sputter. the plugs are still white. i have heard that the non turbo pump would be fine. do you think the problem is the pimp or something else. i tried doing a boost leak test but my compressor wouldn't even move my boost gauge.

 

[Duke901]

well i took the car out again, and i hooked the voltmeter up to the o2 wire that is in the kick panel. when im driving it will go from .2 volts to .8 then when getting on it and into boost it will read over 1.0 volts. even if im sitting at a light and i keep the gas reved to about 2grand the volts will change and you can even tell a difference in the exhaust note. by the web site i read it says anything closer to 1 volt is rich. if thats true then how could i being running that rich and making it stutter when my plugs are white. also when boosting, if i keep my foot at about 70% throttle where im only boosting about 5-7 psi it wont stutter. hope some can help

 

[absolute_DSM]

Sounds like you arent getting enough fuel. The plugs are white because youre lean.

 

[Talesin]

Also, here's hoping you got the turbo intake, with the BOV/CBV recirculation fitting, and you aren't just running vented on the stock Karmann MAS. That'd be a pretty damn stupid move.

Yes, not having signal from the MAS, or having a partial/defective signal will generally trip a DTC. Boosting without fully functioning air metering is another stupid move. Unless you're planning to just buy a turbo engine and swap it in when the one you have becomes smoking toast.

Do you have any kind of actual tuning solution/fuel system mods/compensation, or is this a salvaged slap-on-jimmy-bob type of affair?

 

[Mikelb]

the turbo pump he was referring to is the turbo fuel pump. You're going to need something much better than a N/T fuel pump. That's one of the reasons you're running lean.

Change that quick... I'd say go with the 190lph, and get the turbo FPR... I don't know that they're different, but fuel is your safety net, why risk it

Before you keep driving the car and toast your motor, CHANGE THAT FUEL PUMP...

 

[Duke901]

well, just to restate, i have everything for it to be turboed on the car. i have the turbo ecu working and wired right. the injector resister pack and the turbo mas. the only thing i don't have on the car is the turbo fuel pressure regulater and the turbo fuel pump. people have said the non turbo fuel regulator will be fine because it is a rising rate. when i get some time i will change the pump. as how now i haven't been driving the car. i just don't get how the plugs are white but the o2 wire said it was reading over 1 volt on the voltmeter indicating its rich when it gets into boost and when it stutters.
thanks again mike

 

[Mikelb]

the only thing i don't have on the car is the turbo fuel pressure regulater and the turbo fuel pump. people have said the non turbo fuel regulator will be fine because it is a rising rate.

I'm not for certain on the FPR, though they look similar, IIRC.

when i get some time i will change the pump. as how now i haven't been driving the car. i just don't get how the plugs are white but the o2 wire said it was reading over 1 volt on the voltmeter indicating its rich when it gets into boost and when it stutters.
thanks again mike

I'm not going into a long spill, (this has been covered many times) but the stock O2 sensor (narrowband) should not be used for tuning.

Now, with that said, maybe at idle you are seeing too little fuel, yet under boost you're seeing too much fuel When I have some time to logically think this one through, I'll try and get back to you. For now, I'm puzzled. Though I might suggest you invest in some sort of datalogger. That will help you have a better idea of what's going on.

 

[Duke901]

ya it has me puzzled also. wonder if it could be a boost leak ?

 

[Mikelb]

you could possibly have a leak, therefore the A/F mixture will run rich, so much so that you could be hitting fuel cut?!?

I'm sry, I have been fighting with the ex (over custody) and my sugar dropped several times yesterday, I'm not really in a good frame of mind.

 

[Duke901]

dang man that sucks, hope everything goes alright. ya with the car im just so confused. how can the plugs look lean and then the o2 reading is way rich when getting on it. and it starts to stutter.

 

[absolute_DSM]

where should i hook the bov up to.

Tap your intake manifold. It needs its own line and not at the TB.

Also, here's hoping you got the turbo intake, with the BOV/CBV recirculation fitting, and you aren't just running vented on the stock Karmann MAS. That'd be a pretty damn stupid move.

So the question is, do you Duke?

My votes for you to get a logger, When you see the knocks coming up top, you may be convinced youre not getting the fuel. Im still gonna say the FPR/pump combo isnt enough.

Boost leak check that thing too.

 

[Duke901]

well i boost leaked it, i had a major leak at the intercooler and bov. so i swaped my buddys bov in and tested it again. all i got was a small pin hole leak in the intercooler. I also swapped in a turbo fuel regulater.when i drove the car is spooled faster but full throttle was still a no. it still stutters, my voltmeter is pegged at one volt when it is doing this.

 

[Duke901]

update i put the gap on my plugs smaller to 28, and i fixed my bov. it still stutters when you floor it. im thinking the NA pump can handle about 7 psi but when it hits 10psi at full throttle the pump cant keep up. the only weird thing about that though is that the volt meter still reads that it is rich, when stuttering.

 

[Mikelb]

Glad you're getting stuff straightened out. I really suggest getting a logger at this point. You should NOT use the stock (narrowband) O2 sensor to tune. The reason it is showing 1V is because at WOT, the ECU turns the O2 trims to 100% (it ignores the O2 sensor, which is why it's important to have a good tune).

 

[Duke901]

ya, today im getting the turbo fuel pump installed. Let you know how that changes things.

 

[Duke901]

Well, i got the car back today. When i left the shop, it was great. The car boosted 10 pounds with no stutter. Well, i drove the car tonight and it started to stutter again. What can this problem be? It makes no sense to me.

 

[Mikelb]

Ok, you never directly said this, so I'm going to ask again: Is your BOV vented to atmosphere or recirculated into the intake? (your car can stutter if it's vented and you run the stock Karman intake sensor)

Also, could this "stutter" be the wastegate opening?

 

[Talesin]

Trying to remember what size injectors came on the N/Ts stock... it's possible that you hit 10psi while it was warm out, and were just barely under fuel cut.. then when it got cold, too much air was being flowed, and boom, cut.

I'm also trying to remember what the stock fuel pressure is for the N/T.. my suspicions would be the N/T injectors, and the N/T FPR. I really doubt that they're the same units as the turbo models. And boost leak test it again. Never know what the shop did other than what you asked... some will 'helpfully' check for other problems, and cause more issues than they realize.

 

[Duke901]

I don't have non turbo injectors, My stutter was caused from a bad fuel injector o ring. Sense installing the turbo fuel pump and the o ring, everything is good. Thanks for the helps guys.

 

[absolute_DSM]

Turbo fuel pump for the win! Its magically what more gas can do.