Suddenly super lean while at cruise

[blageo23]

I PM'd ya. Im free sunday if you wanna use my logger. Let me know.
Mike

[Outlaw1]

As this happens, my tach jumps around spurradically. Not much, but if I'm decellerating, then accellerate, as I accellerate the tach will jump up 150-300 rpms.
A flickering tach is a tell tale sign of an ignition problem. Usually it's a bad wire but a bad coil will do the same thing. I'd swap another set of plug wires onto the car. I noticed the water sitting in the top of the strut tower. Was there water on the valve cover too? Look down in the spark plug holes and see if there's any sign of tracking on them. Not to say that's the only possibility, but that's where I'd start.

[scheides]

Thx for the advice! The water in the strut tower was b/c this pic was taken just before the all mitsu cookout, and I was doing a bit of cleaning under the hood (long before this all happened). The plug wires are almost brand new, 10mm taylors from elite. The #1 (shortest) plug wire actually had a minor manufacturing defect which I noticed after this was happening. The metal part that sticks into the coil for contact was only about half-way in (that's as far as it could go), and the tip of it was covered in carbon build-up. I adjusted the boot and it fits well now, but I did not clean off all of the carbon, as there was plenty of clean contact space left.

I swapped out to the original coils I had in the car w/ no change a few days ago.

I'll swap out the plug wire(s) & see if it helps.

btw, plug wells are dry.

[scheides]

Swapped out my nice 10mm taylor plug wires for my old magnacores, no luck. Checked out lots and lots of wiring, and everything seems to be ok, time for the multimeter...

I pulled the 'engine' link in the fuse box under the hood to reset the ecu, took it around the block. Seems to be worse, so I drove it a bit further to play w/ the afc & voila, car stumbles, stumbles, stumbles, and eventually dies. Now it won't start, and I'm officially happy to join the ranks of the undriveable dsm. It must miss it's native habitat on jackstands....

[scheides]

Who loves dsm's? I do!

After the car spent some time at LSE, it recieved a new CAS plug and fuel pressure regulator. Problem seemed to be resolved, and the car has run fine for two-three weeks. I'm finally planning on dumping money into more 'fun' stuff when voila! Back comes the problem!

I am thinking now that this has to be electrical some where, as the studdering a lot like running on 3 cylinders. Just to eliminate it, I swapped out the fuel pump for a brand-new Walbro 255HP today, no luck.

I am going to try and re-locate the coil-pack when I get back from vacation. With the coil pack near the hood like it is, I had one other incident where one of the boots of the wires coming off of one of the coils actually was burnt through in one spot, grounding out at idle.

Any other ideas? Anyone want to help? Cash reward for anyone who solves this for me. I've wasted too many hours and too much money already, and 70+ hour work weeks make me not want to do anything when I'm not working :( I'll be out of town until 11.29. If anyone can/wants to help me anytime after that, let me know. I'm serious about the cash.

[93sc]

How's your alternator doing? What does the voltage look like when the problem seems to surface?

[EclipseGST]

My car was doing the same thing this last week, took out the plugs, cleaned them up a bit and regapped them and it worked just fine. Now its doing it again so I am just going to swap them out. If that doesnt work then I will have to search farther.

Have you tried a new power transister or running a ground strap from it to the firewall? I remember I had a problem like this before where it would only run on the 2nd and 3rd cylinder and it was because the transister wasnt grounded good enough. I'd check that and also make sure its got a good connection with the harness. If you dont know what I am talking about, its the little black box located near your FPR and where the coil pack mounts on the intake manifold.

Hope it helps.

[scheides]

Good question. Voltage is rock solid during the condition ~14.1v.

Also, I've thought that maybe it was the CAS going bad (mentioned above) but while looking at my safc during the condition, it stays rock solid, as does my MAF--no major oscillations that would seem to cause this issue. I replaced the CAS anyways, to no avail.

Here's a trick, though: as I mentioned above, sometimes my tach seems to jump up and down a bit during the condition. However, if I look at the afc, it reads steady. The s-afc is spliced into the ecu harness, but I hardly see how this could be the cause (it seems more likely that the lead going to the ecu would be dead, not just consistantly messed up under specific conditions : 10-15% throttle at cruise, near 3000 rpm).

[scheides]

EclipseGST: thanks man, I'll try these too.

Remember though, this happens ONLY at partial throttle (10-15%) while cruising in any gear around 3000+ rpms. I can run through the gears to redline at full or part throttle (50% ++ or whatever) and the car drives great, no lean condition on wideband. no oil leaks, no fluid leaks.

[EclipseGST]

Have you messed with the TPS at all?