Very rough idle with high boost missfire

[whtv6turbo]

Just bought car. Can not stay in throttle or it starts to misfire under high boost. I started with a new O2 sensor, as the prior owner told me that it was throwing code 44. No luck. Then I checked all plugs, wires and injectors by pulling them off one at a time. Just bought car yesterday, no scantool YET. All seemed to be in working order. Any ideas?? Maybe a good TB mechanic in the Phoenix area?? Thanks

 

[TurboBob]

is the car stock or modified?

The stock boost gauges don't work well. They don't go high enough when they do work, and as they age they get unreliable. So you need to know how much boost you are running.

If its not running cleanly at full throttle, do not push it until the issues are resolved or you will break something (most likely head gaskets)

There is a "Y" shaped hose on the passenger side of the engine that connects the turbo to the wastegate, and ties into the boost contrrol solenoid.
check the condition of this hose because if it fails, you boost will climb out of control.


The stock fuel pump was barely enough to fuel these engines when the cars were new. Age or modifications make the stock fuel pump inadequate. So if the
previous owner did not upgrade the fuel supply, you should plan to.

Are you hearing detonation (spark knock)? or just missing?

What kind of fuel are you running, and do you know what kind of chip is in the ECM?


Welcome aboard.

Bob

 

[whtv6turbo]

Bob,

Appreciate the response. It is stock as far as i know and looks to be. I owned a GN in 89 and at 16,000 miles that is exactly what happened, stayed in it even though I heard it detonating and next thing I knew rod was through block. Of course I was 19 at the time and racing a buddy. I was not letting up. The GN I had idled fine, as it was almost new at the time, but had same problem when I got into higher boost. At 16k the dealer put a long block in under warranty and never had another problem. And yes I hear detonation and am not going to push the car until I have it running correctly. I replaced all lof the vacuum lines and think that "Y" shaped lines looked fine. I will double check in the morning. 91 octane fuel and stock chip. Just getting started...........


Thanks again,

Jason

 

[RmvBfrFlght]

Double check the fuel pressure. Code 44 is O2 lean, which can be caused by a failing fuel pump.

RemoveBeforeFlight

 

[whtv6turbo]

Fuel pressure was 22 or so. I was told to change filter and get new pump. I got the filter changed and it certainly feels a little better. I also got my brand new O2 sensor double checked on scan tool. Faulty. Never a Bosch O2 sensor for me again. I will replace it tomorrow in hopes of fixing the knock. Still unable to hold the pedal down once boost builds without it pinging-detonating. Maybe the O2 sensor being dead is causing it??? I will find out soon. Found great TB guy here in Phoenix also to work with.

 

[KL Mallender]

Always check fuel pressure when running, stock regulators opened at 36 psi, plus 1 lb per lb of boost, if it ever falls below 36 under light throttle(no boost) your pump is dead, get it replaced before it really hurts you.
Good luck,

Kevin.