90' Buick Running Bad

[nobody05]

1990 Buick 3.8l series 1. Fuel pressure running at 35psi-idle 42psi-WOT. Seem to running rough on WOT to the point of Power loss and engine misfire 4500 RPM is all you can get floored from a red light. Is that PSI in the ballpark where it should be? Does not fall so fuel filter is out of question. Ignition as far as plug wires/plugs/coilpak/coilpak moduel are all new. Any help would be fantastic. MAF sensor has been cleaned also. Ideas? its a head scratcher

[Eric Wettschreck]

Is check engine light on and giving you a code?

[nobody05]

there is a code but I repleced the crank sensor which is what the code was

[nobody05]

error 42 shows up right after clear… EST circuit Electic Spart Timing

[Eric Wettschreck]

Just taking a stab here but that makes me think of a cam position or throttle position sensor.

Iffin I remember correctly, the computer gets inputs from the crank, cam, and throttle position sensors and adjusts timing accordingly. If you're replaced the crank sensor correctly I'm thinking either cam or throttle.

I'm not going to claim to be an expert so hopefully some the the actual techs can chime in on this one.

[Jeremy airjer W]

Code 42 is nearly impossible to resolve. From what I know the ignition module translates the info from the crank / cam sensors and sends a signal to the computer. The computer takes that signal and further processes it based on other factors such as throttle, temp, air flow, O2, etc. then sends the recalculated spark timing back to the module. The module then fires the coils.

The problem is trying to figure out if the problem is the module, the computer, or the wiring. In the past I have run and EST jumper wire between the module and the computer to eliminate the wiring. If the code still persists than the module is the cheapest thing to replace. If that doesn't solve it the computer is next.

Believe me there are plenty of bald GM techs just from this one issue.

I have run into modules causing some pretty funky drive ability problems in the past, most of the time they just stop working all together. On rare occasions they will do some stupid stuff. The last one I ran into the car would run fine for hours on end and then all of a sudden it would barely run. Almost like it was running to lean or the cat was plugged. Boggy throttle response, and light backfiring. Then the next minute ran like brand new. After checking exhaust back pressure, fuel pressure, and verifying signals from MAF. MAP, O2, CRANK, CAM, and TPS I finally narrowed it down to the ignition module or the ECM. I'll admit I got a little lazy at this point and fired an ignition module at it and problem solved. The old module had been replaced within the last year and was still under warranty which made the decision to try it a little easier.

[nobody05]

that exactly where I'm at. engine always starts and runs but then gets these surging spells of terrible running. missing cylinders ect... most noticeably under load at high rpm. my next symptom is dash flashing. does that in anyway shape or form persuade your opinion? by dash flashing would be rpm will say 0 when the engine is obviously running. then everything will default... the dash and climate control

[Jeremy airjer W]

Well that's odd.

I wonder what the charging voltage is when this happens. Maybe check the A/C voltage as well. a/c oscillation from the alternator can confuse a d/c system and cause it to do some weird stuff as well.