What's wrong with my 2.8?

[89Hatchback]

Was the symptom present before the ECM swap?

That mechanic claimed he saw the data disappear at times. I didn't notice any improvement in the car's behavior.

I took it in for hard starting. A problem that ultimately turned out to be a ruptured diaphragm in the fuel pressure regulator that caused flooding during starting.

[89Hatchback]

Was the symptom present before the ECM swap?

Maybe I'm misreading your question. My current problem popped up about 3 weeks ago. The ECM was replaced in November to try and fix another problem. While both problems could be described as "hard start", that one was excessive cranking before catching. This one catches normally but doesn't stay running.

[89Hatchback]

This is getting very discouraging. It's not the ECM. The one pattern that's emerging from the stalls is that it's hills/acceleration. It appears that it's related to the engine moving in it's mount rather than with pulling. When it was acting up, I put the front wheels to a high curb and gunned it. It seemed ok. But when I backed up, set the hand brake and gunned it (forcing the drive train to pull the car) it stalled. It's more prone to it after the car has been warmed up with a few short errands, but not required. But everything on the engine harness seems to pass the wiggle test while the car is idling. Perhaps my test was faulty since it really didn't want to jump the curb.

But that still leaves the occasional crank-catch-die symptom. That can happen hot or cold. Both appeared in the last few weeks.

I'm going to try and inspect a few things today, but I think I need to shop for a replacement car. I'm an apartment dweller with only one parking stall, so it's not like I can make this a project car. After 12 years and 100,000, I think I got good run out of a used car.

[86FieroSEv6]

Hmmmmmmmmmm, good puzzle. Maybe we're being fooled into thinking it's the physical movement of the driveline. We shouldn't forget that the circumstance also involves engine load and the way it is being reported to the ECM. I'd give a frosty bagel to ride along with a scanner plugged in, observing the LV8 (engine load) value during the failure regime.

[89Hatchback]

I'd give a frosty bagel to ride along with a scanner plugged in, observing the LV8 (engine load) value during the failure regime.

I'd give a case of them for some one who would do that.

Poking around, I found something. My prior mechanic put in Champion 3015 plugs some time ago. Now, Champion is a fine brand, but not what I'd choose to put in a GM product. But the 3015 is a single tip Platinum plug and this is a DIS system where half the plugs fire in reverse polarity.

If this was just generally poor performance, I'd change them. Or if I was planning on keeping the car, I'd change them. But to blame the current problem on them seems a stretch - I think....

[86FieroSEv6]

I have personally never seen an intermittent spark plug failure that present the symptoms you have. How about, backprobe the key+ wire at the ignition module and make sure there isn't something screwey with the subharness or relay? You can rig an extension wire to under the hood and set the test light on the dash for the test drive.

[89Hatchback]

I'm cautiously optimistic that we (my brother and I) found the problem: a bad (shorted) injector.

The car was disabled in the crank-catch-die mode. We used a timing light to show that the ignition seem to be working through the stall. We figured out a way to get some gas into the throttle body and got the car to run for a few seconds, showing that it was fuel delivery.

I measured the resistance of the two injector banks and saw a far amount of difference between the two. So I pulled the plenum to measure each one. Three 12 ohms, a couple of 10 ohms and one 4.8 (!) Left that one disconnected and the car fired right up.

I'm going to run it a day or two and see if the old problem is still there. If that's it, I know what to fix.

The next question is where to find injectors for a good price. RockAuto wants $100/ea for AC Delco. (gulp!)

[86FieroSEv6]

Did you inquire about reman' injectors? Since it ain't no race car, the reman's should work just fine.

[89Hatchback]

Yes, but some remans are better then others. But that's a question that's probably worthy of a new thread.

[pocket-rocket]

Maybe post in the For Sale section as a Wanted post. I'm sure someone around here has a set they will practically give away that would work for you.