Running rich or lean?

[Earendil]

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?

You could have a stacked set of problems, but my guess is that it's not the FPR that is causing intermittent huge loss of power. Unless you know for sure your fuel pressure is good when the car has problems, you might want to check the Fuel Pump connection. My Car had an intermittent problem for a year where it would go back and forth between about 168hp and 100hp at WOT. It turned out the ground wire for the fuel pump was bad. However, the pump its self was grounded JUST enough to continue operating, just with far less current as the resistance to ground was a lot higher. In my case, simply wiggling the connection made the pump change pitch. When I stuck a volt meter on the partially pulled plug, while the pump was running, I saw that the voltage difference was something like 8v, instead of the car's natural 13.2v

The above is not a common problem, as I've only ever seen it on this board one other time. Though it's a long shot, it looks like you're down to long shots.

If your pump isn't grounded as well as mine, you might find that your pump functions, but only BARELY. You could see this in the fuel pressure. To me, this sounds like a more likely intermittent fuel supply story than the FPR, a purely mechanical unit, not working and then suddenly working again.

[jlevie]

In open loop mode the DME defaults to a rich mixture. That can compensate for minor intake leaks or low fuel pressure.

The other think that you need to do is to check the IAT, AFM, and ECT signals at the DME when the engine is misbehaving and compare those to when it is running right. If there is no difference in those signals, the DME or even the ICM is suspect. If the signals are different you might have a bad engine harness.

[Earendil]

Also, have you checked the injector harness? Unplug it, clean it up a little, and plug it back in. I've seen one of those go wonky and the car bucked, kicked, and made all manor of terrible sounds as it barely limped back off the track. Unplugged it, cleaned it up, and car fired up and ran fine.

Edit: Injector plug is the vertical one underneath the throttle body. Circular twisty style plug.

[mrgraphics]

I'll check the fuel pump voltage, but I doubt this is it since it runs fine with plenty of power in open loop. In my case when I installed the TrePerformance intank pump, I soldered the pump's ground to the assembly. ETA fuel pump assemblies have a metal bar that attached to the pump for ground, so I simply emulated this configuration.

It's possible that the injector connector is mussed. I did have to move it when I rebuilt the engine.

Googling "e30 loss of power" I come across numerous posts with ETAs behaving just like mine. None ever post a solution.

How would I test signals when the engine is running? To get a test pin in there I'd need to disconnect the harness. Or are you suggesting simple resistance tests on wires when working and when acting up?

Recovering from surgery now. I'll have to dig into this once healed.

[jlevie]

To accomplish the tests I suggested above, you remove the back shell from the DME connector to expose the back side of the the connections.

[mrgraphics]

Earendil: I thought of that . . . the C191 plug. But unless I am completely wrong, that plug only exists on 88 and above e30's. Although you are right, my symptoms are in line with a bad C191.

I'm not really digging the idea of pealing off the back of my ECU connector. I'm afraid the more I mess with the wiring, the more problems I'll introduce.

I do remember when I was pulling the injector / coolant wires through the hole in the intake I heard a loud "crack", but I though that was simply the hardened casing that surrounded the wires. I guess it is possible that some of the wires cracked and I have an intermittent short.

[mrgraphics]

Scored Pick-n-Pull gold today. An 85 ETA that looked like it smashed into a wall. So odds are everything was working at the time.

Picked up MAF (unadulterated - still had the plastic plug), coil, ICV (looked brand new), spark plug wires (they were brand new). All at 50% off. If swapping these out has no effect, then I'm chasing harness wires, because everything that affects the car running will have been swapped.

I grabbed the coil because it is within the relm of possibility that I have a weak or failing coil. When the engine starts to lean out for emissions, it would make it harder for a weak coil to jump the gap for spark - and it was $5. I'll install next weekend. This little jaunt took everything out of me.

[mrgraphics]

The new MAF made a huge difference. More power, no sudden drop offs on a hill. When testing the old and new MAF on a steep steep hill by my house, the old MAF wouldn't even make it up (I got stuck in the middle). Walked home and back, installed the new one and she climbed right up the hill. My alternator voltage regulator brushes were almost gone. Now there is a new regulator with nice long brushes (installed before said test).

But my symptoms are backwards now! The car only runs with the coolant temp sensor plugged in. Unplug it or the MAF and the car dies. Start up cold and it chokes and sputters till its warm and then it's fine. When cold starting the engine doesn't go into high idle mode either. Aaaand . . . My econo guage on the tach now never goes higher than 25. Even if I am idling and rolling down a hill at 50mph. Makes no sense. I have essentially a new MAF, spark plug wires, and more reliable electricity. Everything else is as it was. Idle warm is pretty smooth - not perfect but darn near it.

[mrgraphics]

Here's a video of what it is doing: http://youtu.be/o0sz19Ofzxo

[mrgraphics]

Returned that MAF, and picked up another from a "fresh" in the yard '86 like mine (untampered). Now it's back to where it was: unplugged C Temp Sensor, runs strong. Plug it in, idles smooth, but will only move at about 5-10 mph.

I checked my TPS - works fine.

I removed the hose that goes to the FPR so that it had no vacuum assist, plugged up the hose (so that the intake didn't have a leak) and it ran about 10-20% stronger. What does that indicate?

[mrgraphics]

PROBLEM SOLVED!

Let this be a lesson in our own hubris: Just because you engineered it, doesn't mean it's right and shouldn't be checked again.

When I installed my Tre fuel pump, I used the appropriate fuel line that can be submerged in gas. But, I over-clamped and stretched the hose. This caused a small tear right at the clamp. Under pressure this would open up and lose just enough pressure that the car would bog. Over time it got worse.

I re-engineered the pump so that there is no hose intermediary, and she ran SOOO strong, with everything hooked up (coolant temp sensor).

The new MAF is better than my old one, and I now have spare parts for life.

[Earendil]

PROBLEM SOLVED!

Let this be a lesson in our own hubris: Just because you engineered it, doesn't mean it's right and shouldn't be checked again.

When I installed my Tre fuel pump, I used the appropriate fuel line that can be submerged in gas. But, I over-clamped and stretched the hose. This caused a small tear right at the clamp. Under pressure this would open up and lose just enough pressure that the car would bog. Over time it got worse.

I re-engineered the pump so that there is no hose intermediary, and she ran SOOO strong, with everything hooked up (coolant temp sensor).

The new MAF is better than my old one, and I now have spare parts for life.

:up:

It continually surprises me how our cars can be both simultaneously stupidly simple in operation, and yet complex when it comes to fringe cases like the one you mentioned.