Running rich or lean?

[MJCRO]

I actually ordered a cheap fuel pressure gauge on eBay, I'm guessing if it's not a fuel delivery problem, then I blame my MAF for sure. I'll let you guys know.

[Baxter Auburn]

Ive been thinking it was my maf since install, since before that i was having no issues with the engine stuttering or losing power. What maf are you using?

[MJCRO]

I'm still using the original one that came on it from factory. I also tried a an 85' eta MAF from the junkyard and cleaned both but it made no difference. But there is a lot more to the MAF than just the external sensor. A lot of interior components are known to go bad that cause this exact problem of sputtering when moderate throttle is given. Once I check my FPR, I'll be able to know for sure what is the issue.

[mrgraphics]

I haven't been working on this issue due to the holiday. Back at it now.

I have two more sensors on their way as a final check. Talking with a mechanic friend, he suggested (as previously mentioned) to verify the wires between the ECU plug and the sensor plug. He explained that if there is increased resistance or a short, then the computer will see the wrong readings (possibly higher ohms) and it will run just like we describe. If I do have a short, I'm simply going to run new wires and splice them into the ECU connector.

[MJCRO]

Checked my fuel pressure from both the pump and the regulator. There all good. Really at ends here and thinking about going the swap route...

[Baxter Auburn]

Yesterday i ended up resetting my ecu and pulling my maf off and then reinstalling after cleaning, after the initial rough idle from resetting my ecu it balanced back out and didnt take away the hesitation fully but it did reduce it greatly, i know this wont help you two long term but it works as a short term solution before finding the actual root problem.

[mrgraphics]

Checked the wiring - it's good. I have zero resistance to ground on the brown wire of the connector, and the Brown/red wire to the ECU has .3 resistance on a scale of 0-200 ohms. So that is not enough to throw off the reading of the sensor.

Yet another new sensor in and it still behaves badly.

It idles fine, and runs ok, but there is just no power and it sometimes feels like the transmission is slipping, and the discussed power bogging. Yet, I know the transmission is good because it runs strong without the sensor.

Looking at the wiring schematics, I see that there is also a brown/red wire that goes to the idle speed control unit. Could this be what is causing the issue . . . not the DME, but this box?

[MJCRO]

I actually had swapped my ICM with a new one and it made no difference. I'm actually gonna start gutting my car tomorrow so if anyone needs any parts, let me know. Going to make a part out thread probably sometime this week.

[mrgraphics]

That isn't really an option for me.

Yesterday I drove it around and it was behaving fine. This was on a reset DME. Then when I went to start it in the evening, it couldn't find an idle. Chugging, choking, sputtering, then dying. Start it then yank the coolant temp plug, smoothed out.

I'm going to see if I can find anyone locally who has a known good ICM and DME to completely rule them out.

[liquidgroove]

Hope you guys find a solution soon.

My car died last night suddenly while driving around town. Engine got spark, fuel delivery, but would not start. Pulled couple spark plugs and found they were wet. Engine was getting too much fuel and flood the engine.

We had to choke the fuel line while starting the engine (unchoke after engine starts). Engine ran very rich afterward. It would not start unless we choke the fuel line. After swapping out FPR, DME, my mechanic pulled the temp sender plug and plug it back in and everything worked.

Guess the temp sender connector had poor contact with sensor and causing very high resistance?

[MJCRO]

Hope you guys find a solution soon.

My car died last night suddenly while driving around town. Engine got spark, fuel delivery, but would not start. Pulled couple spark plugs and found they were wet. Engine was getting too much fuel and flood the engine.

We had to choke the fuel line while starting the engine (unchoke after engine starts). Engine ran very rich afterward. It would not start unless we choke the fuel line. After swapping out FPR, DME, my mechanic pulled the temp sender plug and plug it back in and everything worked.

Guess the temp sender connector had poor contact with sensor and causing very high resistance?

Have you checked for vacuum leaks?

[liquidgroove]

Have you checked for vacuum leaks?

yes, checked. No leak we could detect. Anyway, my car is back to normal now after re-seating the temp sender plug. I will spray some contact cleaner tonight and hope problem won't come back.

[mrgraphics]

I am feeling pretty defeated. Nothing I do seems to fix this issue. It's almost to the point where I may have to sell it. Over a year of working on this thing, and it's still not reliable. And I'm starting to not have any fun now.

Latest thing I did: Complete swap of yet another DME, ICM, yet another coolant temp sensor.

Symptoms: Start from cold, ran beautiful, almost purring. Came up to temp, was running well. Drove from San Francisco to Salsalito and back with no problems. Park at Trader Joes, shop for 20 minutes, and go to start it and it's sputtering, choking, dyes, loss of power so much it'll barely more forward.

At this point I am stumped.

[jlevie]

I see where you had a smoke test run, found a big leak at oil return tube and presumably fixed that. I don't see where you repeated the smoke test after the repairs. In the case where a large leak was found the smoke test should be repeated after repairs. The work could have introduced a new leak or the size of the leak could have prevented sufficient smoke pressure to be attained to find other smaller leaks.

As far as the fuel system is concerned. When you checked the rail pressure was the engine misbehaving? The problem now seems to intermittent, meaning that you need to see the pressure when an event occurs.

[mrgraphics]

There was such a significant improvement after I fixed the tube that I am nearly 100% positive that it fixed the issue (before I fixed it, the car would bog when trying to start to move. Now it moves without the slightest of hesitation.) And the leak at the tube wasn't huge - about as much smoke left it as an extinguished match. I was able to fix the leak without disrupting any of the other engine components (intake gaskets, etc) using the trick you told me . . . pressing the tube down and slipping the o-ring over the top.

I'll have to T the fuel pressure guage back in. My only idea is the FPR, but then I keep coming around to the fact that in open loop there is no issue with fuel and power. If it was fuel pressure (or vacuum related), then wouldn't the same issue present itself regardless of open or closed loop operation?