TBI diagnosing, stumped

[dusterbd13]

Truck is a 1995 c1500. 5.7 TBI, recent 4l80e swap using BJDR bin burned onto a memcal using the moates software and prom adapter. Stock everything else with 166k on it.



Since ove pwned the truck (9 months or so) its been dead nuts reliable. Until the 4l60e died.



The 4l80e swap was uneventful. 1000 miles since the swap. While we were in asheville, started acting up. Would kick the check engine light (paperclip trick only showed one long flash), and shift hard. Shifted extremely late 1-2, and it acted like first was slipping (not pulling in first like it normally does. Like converter was a really loose one suddenly). Would go away after a key cycle, and go back to normal. Couldn't figure out a reason for it, or a precursor to the CEL and behavior that seemed to be consistent. I guessed that the TPS was the culprit, and put tunerpro on it. Noted consistent and linear TPS readings from the computer end. So I replaced the connector, as it was pretty crusty looking and no longer had the weather seal on it. This was done after the first instance of the CEL and shifting, before asheville. Happened three times after replacement of the connector.



Yesterday, after fixing the air conditioning, and extended idle times, things got worse/weird. No CEL, second gear only, idle at 2000rpm.i shut it off, hoping the trick that we learned in the mountains would fit it again. very difficult restart. As in, extended crank times, no start. Finally did, and got it home. Hooked up tunerpro, and other than noting IAC order being at 90, and TPS voltage being high, nothing odd in the data and no codes set. Tried unhooking the TPS and no change.



Today, we tried to start it to move it. No start. Noted that there was no prime pulse form the injectors. However, fired right up on ether and revved good. Got it moved, second gear only other than reverse. So I know we have spark, and fuel when its running. Tried swapping ECM with another (reusing my burned chip setup) with same results.



Got no idea here, and don't want to start shotgunning parts at it. Has to be something im not thinking of.



Far as diagnostics go, Im not even sure where to start, as there's no codes or obviously strange data to lead me in any particular direction.



What diagnostics/where to start?

 

[PlayingWithTBI]

Since you have TP what are your other sensors showing like, CTS, O2 cross counts, Injector DC, etc? What's your fuel pressure? How old is your ICM? If you're not getting fuel while cranking it sounds like you're not getting the signal from the ICM. I'd try to figure out why TPS and IAC are high.

Here's a guide that may help.
https://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/distributor-mounted-icm-tests-1

BTW, how about trying BNKM .bin in your 95 truck? You have a 16197427 right? FWIU .bin BJDR is for a 94 with a 16169395 or 16168625 PCM.

 

[dusterbd13]

You may be onto something with the icm, judging by the symptom list. At least a partial failure. Ive only ever had them fail to no spark at all.

As far as the high counts, no other odd data. Cts is reading realistic values, in a linear fashion. No high blm counts, and voltage sensor reads reasonably close with an alternating value.

Could the high courts be associated with limp mode? Even without cel?

 

[PlayingWithTBI]

Would kick the check engine light (paperclip trick only showed one long flash)

If you don't get the usual 12 with the paper clip trick, something's wrong with the PCM or chip. Did you look in TP to see if you have any codes? Go to Acquisition/Show Data Lists/Error Codes to see.

Could the high courts be associated with limp mode? Even without cel?

That's possible.

 

[dusterbd13]

If you don't get the usual 12 with the paper clip trick, something's wrong with the PCM or chip. Did you look in TP to see if you have any codes? Go to Acquisition/Show Data Lists/Error Codes to see.


That's possible.

When the light was lit, my laptop was hundreds of miles away. So unfortunately was unable to check.
And im seriously wondering about the ecm. Its got a napa reman sticker on it. Before i condemn it, any good test procedures?

 

[PlayingWithTBI]

And im seriously wondering about the ecm. Its got a napa reman sticker on it. Before i condemn it, any good test procedures?

One sure way to tell if it's bad is to run a log for a while then look at your Error Codes. If you have code 55 you're pretty well screwed.

 

[PlayingWithTBI]

Another check, is to turn on the key (don't start it) and see if the CES light flashes and then stays on steady.

 

[dusterbd13]

Another check, is to turn on the key (don't start it) and see if the CES light flashes and then stays on steady.

It does. And today it starts just fine, but cel on immediately. Didn't have time to hook up the laptop and tunerpro, so maybe tomorrow

 

[dusterbd13]

So, swapped pcm with another i had on the shelf Saturday afternoon. No change in behavior, except now has cel after running. Had to ise ether, as no prime pulse. Swapped the known good fuel pump relayfrom the other truck. No change.
Today, git the laptopout and hooked up, spun the key. Fired right up, cel on.

Cel is for tps voltage high. Pegged at 5v according to tunerpro.

Swapped in old ecu, fired right up like normal, cel on for tps voltage.

Went for drive, other than shifting super hard, seem to be back to normal.

My thoughts:
1. Replace tps, see wht happens. Have a spare used laying around.
2. Leave the original reman ecu in place after replacing tps, put some miles on it.
3. Replace ignition control module with new to correct prine pulse, as i think its starting to die.

Y'all's thoughts?

 

[PlayingWithTBI]

My thoughts:
1. Replace tps, see wht happens. Have a spare used laying around.
2. Leave the original reman ecu in place after replacing tps, put some miles on it.
3. Replace ignition control module with new to correct prine pulse, as i think its starting to die.

Y'all's thoughts?

Sounds good.
1. While changing the TPS check your wiring. When calibrating the TPS you may have to oval out the mounting holes so you can rotate it to get your proper voltages.
2. Usually the ECM doesn't go bad but, they can.
3. Your symptoms may suggest the ICM is going out. If so, your coil can be too.