MichelleJD

Checked the vaccuum, grounds, MAF, IC hoses; no help. ISV vibrates, so it's not stuck. The car idles rough and you can smell raw gas exiting the tailpipe. It will eventually start backfiring while idling (burning the raw fuel I assume). I've changed DME's and gone from a stock chip to a GURU chip to a Maxhp chip. No change. Boost gauge (Zeitronix) shows b/t -13 and -15 psi. AFR is all over the map. It acts and sounds like a vaccuum leak, but I certainly can't find one. I will blow compressed air (around 15 psi) through the vac lines tomorrow. Any ideas?

DDP

Start with pressurizing the system. What injectors are you running and do you have chips mapped for them?

MichelleJD

55# injectors with a Maxhp chip mapped for the injectors and turbo.

blown 944

check your FPR vacuum line if there is fuel it is bad

also check the temp sensor

MichelleJD

FPR is new. I'll check the temp sensor.

Ski

Michelle, do you still have the factory O2 sensor?

If you can unplug one injector at a time, try this and see if you have any changes, noting which one, or if you have no change at all.

Rob

Check the vac line going to the damper for gas as well. I think it can go bad in the same manner as the fuel pressure regulator

Van

Have you, while it's idling, removed one injector plug at a time to see if the RMPs drop or if the engine runs roughly? I know you recently replaced plugs and wires and all... but if you can determine if this rough running is attributed to a lack of ONE cylinder properly combusting fuel, then it gives you a direction to start looking.

It could be a bad spark plug, a stuck injector, broken wire, or lots of other things - but some simple and thorough diagnostics should help narrow down things it's NOT.

lee101315

Is this still related to the clutch job you recently performed? You say that you checked the grounds, but make sure all of the contacts are super clean, especially on the bellhousing.

In my experience, assuming everything else checks okay, there is something wrong with the reference sensors. Either:

A. You read the clearance in inches and gapped it in millimeters, or vice versa

B. You damaged the reference sensor, the plug, or the harness while pulling the bellhousing out

C. The pin on the flywheel was somehow damaged, have someone turn the engine slowly with the reference sensors out, and look for the pin.

MichelleJD

This was my first assumption, so I regapped the sensors. I think I'll do the clark's test to see if the sensors are reading correctly, maybe one of them. although new, is damaged. This is the only major thing I touched doing the clutch job.

MichelleJD

Yeah, we did this and there was no single cylinder that was any worse than the other. Number 3 was the closest to being no change, but I think it was b/c that plug was a little more fouled than the rest. They all look like hell after a few minutes, so we pull them and clean them with carb cleaner.

I do still have the factory O2 sensor, as well as the wideband.


I have a Linsey fuel rail and it's brand new.

BTW - I'm running 33 psi from the AFPR. Anyone know what I should be running for 55# injectors?

Tom M'Guinn

Depends on your chips. If you still have factory injectors and chips handy, and a stock FPR/rail, you might toss those in, make sure you are getting about .5vdc to Pin 7 of the DME (AFM signal), and see how it runs. I would be a shame to chase after a bunch of parts just to learn you have a tuning issue with your chips/injectors, etc.

Jeremy Himsel

I run 41 psi with the vacuum line disconnected with 55lb injectors. If the chips are mapped correctly that's about where you should be.....+/- a couple psi to dial in the afr's at idle. I idle @ 15:1

951Porschiste

You know Michelle, Jeremy might be on to something here. Maybe the fuel pressure is too low. When I ran the Lindsey fuel rail, I had the hardest time getting the proper fuel pressure and the engine did not run very well. I finally gave up and went back to OEM fuel rail with 3.0 bar FPR and everything ran fine after that.

Hope we're not confusing the issue even more. Again, good luck!

MichelleJD

Wasn't the fuel pressure and we ran all the vaccuum lines and blew compressed air to see if there was a leak. Everything checks out. I'm lost.