2000 D2 with approx 150 K's

Ok, so... a couple weeks back I was driving and the CEL came on flashing and truck was sputtering. Pulled over and discovered that I was misfiring on my entire right bank only. It lasted a few minutes, cleared the codes and then it went away.

Took it to my mechanic and (after a 4 hour diagnostic) He told me I had a short in my ECU which was sending the wrong signals to my front O2's . This in tern eventually caused the multiple misfires.

I've had a front sensor right bank issue for over a year but never fixed it as it didn't seem to effect milage or anything else. It was and still is there. P0154.
I'm essentially getting no signal from that sensor. It's been changed twice with no different results.

I bought a new ECU and I've had no luck getting it to work with my truck. Tried security code learn with nanocom didn't work got (learn security code function terminated).

Put the old ECU back in the truck and it's been running fine for the last week. Drove it for 2 hours and no issues aside from a bit of a ruff idle. This is making me wonder if it is the ECU.

Any ideas out there people?

I've checked and cleaned the MAF
the plugs wires and coil packs were all replaced back in the summer.
purchased a new crank sensor but haven't put it in yet.

This misfire issue has happened twice. Once at low speed in traffic and the other time was HWY driving passing up a hill. Lost power, CEL flash, pull over idle for a minute clear codes and it seems to be fine.

ECU?
crank position sensor?
What could cause random multiple misfires that go away?

Thanks for any help.

 

That's... weird.

A short in the ECU definitely sounds like a possibility. Sounds like it could just be touching sometimes and not touching other times to me. Other than that... jeez, I just don't know. Also strange that the new ECU wouldn't learn the security codes. Were you able to return it as defective?

 

In live data mode, watch the o2 in question. Then wiggle the connector at the ECU. If no change start to twist on the harness bundle. I have had 2 occasions where the wires were messed up in the harness. Just went ahead and bypassed the harness and wired direct from sensor to ECU.

 

Thanks for those suggestions. I haven't been able to find any info on the "learn security code function terminated" issues i'm having with my nanocom. I've spoken with the guy I bought the ECU from, he pulled it from a working D2.
I was able to plug the new unit in and have the truck recognize it but it won't start. Turns over but won't start.
Also when I tried to "sync ECU with odometer" it tells me that it's already synced.
From what I've read I thought the ECU swap was gonna be easy with the nanocom but there must me something I'm missing.
Nanocom experts please chime in.

 

Ok, problem fixed. I just wanted to close this thread off as I hate it when I'm searching and people never follow up after problems have been solved.

In this case it was a short in my ECU that was sending bad...or no signal at all to my O2 sensors up front.

After a long period if time they would cause misfires and ruff idol, bad milage.

I purchased a used ECU and installed it, problem solved. Ruff idol gone, codes gone and new ECU is running great.

I could not get the ECU to sync up with my nanocom so I had to bite the bullet and get a shop to do it. Took them 5 minutes.