fejjj

Found this thread and they are suggesting "broken valve springs" for the 5200RPM cut.

What do you think about this? Note: Mine does not do this off load.


http://https://rennlist.com/forums/924-931-944-951-968-forum/324722-wierd-stumble-backfire-at-5k.html

fejjj

Do you guys know the best way to test the fuel injectors for gunk/blockage?

JacRyann

Pretty easy to do quick test. Pull the rail with injectors still attached. Place little paper cups under each one. Crank engine for 5-10sec and see how matched the fuel volume in each cup is.

Let's also return to basics:

1. Intake-manifold vacuum. What is it when warmed up?

2. Use vacuum-T and measure vacuum at FPR. Does it match #1?

3. Use vacuum-T and measure vacuum at fuel-dampener. Does it match #1?

4. Measure actual fuel pressure at end of rail. What is pressure with vaccum-hose to FPR disconnected? What is pressure with vacuum-hose connected at warmed-up idle?

5. Do you have system configured for 80# injectors?

fejjj

"5. Do you have system configured for 80# injectors?"

Yes I have the Rogue M tune and his injectors.

pcleary1210

I'd start looking for loose electrical connectors. The key clue here is the fact that you parked it running fine, then had an issue on startup. Whatever is causing the problem came on quickly.

Alternatively, grab a can of brake parts cleaner or otherwise and start hunting for a vacuum leak (I know that's easier said than done on our cars).

The coolant temp sensor is a good one. These 80's cars rely a lot on that sensor and they start doing wacky things without it.

Not sure I'd point my finger at fuel injectors. Dirty injectors are a slow-onset type of problem. You won't stop your car, then start it and suddenly have bad injectors. If you did, it would only be one and you'd be experiencing a miss, not a rich code.

Even if the AFM plugs are tight, you might still have a break in the wire somewhere, or just a bad AFM. Easy enough to test out. An easy way to see if this is your problem is to quite simply unplug the AFM and see how the car does without it. If it drives the same, I'd say you found your problem.

fejjj

Thank you for your input.

No AFM.

Rogue M tune MAF.

This wasn't really a sudden onset as the car did the same thing the day I pulled it out of winter storage 1 month ago. Also last fall it sometimes would not start until after multiple attempts.

The new problem is the super rich condition. The only time I see a somewhat normal AFR (14.2) is at warm idle.

gruhsy

200.00 for the logger from Rogue

fejjj

Coming soon.

Not sure how this is going to help me now though as I already know the car is running pig rich (Innovate Wideband), starts and stalls and has a 5200RPM engine cut.

gruhsy

Maybe Joshua could clarify but I believe you would be able to see if a sensor is acting funny by the readings. I just re-read his description on his site. Could not hurt anyhow.

Sorry your having the issues you are having. Maybe a glitch in the software?

raleighBahn

Fejjj, what have you tested so far (in order to rule things out)? There is a troubleshooting plan in the turbo manual where the mutltimeter will tell you a lot for free (especially for sensors). Also easy ways to test your spark and fuel and make sure it's not something basic (air, fuel, fire).

fejjj

I am taking the car to my mechanic today. What would be your first steps?

fejjj

Ok.

After driving 25 mins today in 75 degrees, my gauge is at 1/8.

Do you think this could be a lot of my problem? Bad coolant temp sensor?

pcleary1210

TOOOOOOOOOOOOOOTALLY

fejjj

Ok.

1. New plugs: NGK BPR7ES gapped to .026

2. New Coolant Temp Sensor

3. New 3 Bar FPR

4. New Fuel Pressure Dampener

Car still running Pig rich!

Idle 14.2
Cruising 12.5
Part throttle 11.5
WOT 10.0

Car is still has hard cut at 5200 RPM under load.

What next?

pcleary1210

Sell it to me and get a new one?