Stalling and Code 42

[90RedBurb]

Hey guys this is kind of a long post and hopefully i dont lose too many people. I have been having an intermittent code 42 problem that until this morning I thought that I may have fixed however it showed its ugly head this morning on the way to work. So while driving it will intermittently hiccup and set a code 42 and SES, while the SES light is on the vehicle will run crappy as if the timing is retarded (which I believe it is). If this happens on the highway it will stay on for a random length of time ( could be a couple seconds, could be 20 miles or anywhere in between). If it happens at low speed it may or may not cause the engine to stall. I was lead to believe it was the ICM however I replaced the distributor with no change. Following is the vehicle info and what has been changed over the last year or so. Some of this was hunting the code 42 and some was just maintenance items and or potential future problem points.

1990 V1500 suburban 5.7/700r

Parts replaced/ diagnosis attempts:

New distributor with ICM

Another new ICM that I had in case the new one in distributor was faulty

New AC Delco CTS

New vacuum lines where needed

Cleaned IAC valve then replaced IAC valve

Thoroughly cleaned and rebuilt throttle body

New AC Delco CR43TS plugs

New Plug Wires

Checked timing (set to 0 with EST connector unhooked)

New Injector Pigtails (old ones where in rough shape, partially melted assuming from backfire of some sort before purchase of vehicle)

Tested knock sensor/ESC module

Changed computer

In the last week I have plugged in my auto xray 7000 and watched live data and everything appears normal ( i think, integrator and BLM started at 128 and dropped to 108 and 114 but i did find a leaky injector oring and repaired that, have not plugged scanner back in to see if that changed) however I have not had it on the system while the code 42 was set and SES light on. I ran through the code 42 Flow chart multiple times and land at different points each time depending on the intermittent problem. However I went to the junk yard and picked up another computer and put my Calpack/Prom in it. Problem persisted. Checked est wiring and found no problems with it. Then I tried to change proms and this is where im starting to get very confused.

From what I found online:

ASDZ – 1989 LO5 5.7 MD8(700r) auto GU2 axle code

ARJT – 1991 L05 5.7 MD8(700r) auto No axle code info found

Junkyard computer and my Calpack/Prom(ASDZ) – No change in symptoms

My Computer with junkyard Calpack/Prom(ARJT) – popping and missing for first 30 seconds on cold start evertime, no SES or 42 for 2 days of driving then problem came back this morning.

Im not sure what to do or where to go from here on diagnosis. I don’t have another ASDZ prom to try to know if the prom is really the problem or what. Also not sure why the junkyard calpack/prom causes popping and missing on cold start.

If anyone can possibly give any insight on possible places to go from here it would be greatly appreciated as im rapidly becoming discouraged. I really thought after the prom swap and no SES for 2 days that I may have been on to the problem but now I don’t know. I have been reading posts like mad trying to come up with a solution and havent yet. I was just reading a newer post in the suburban section here about a member with a similar issue and it was advised to check the section of engine harness behind the distributor so i will pull the distributor tonight and see if i can find a problem ( ive checked it before but maybe not thoroughly enough). Any other advice would be helpful. If you made it all the way through this and didnt give up on me thanks! Also i was going to post this in the 73-91 suburban section but maybe because im new or dont have the premium membership yet i cant? im not sure

 

[Wes Harden]

We have had a few 89-91 ecm related drivability issues lately. It sounds like you hit all the normal bases. 1 solution that was mentioned in a thread was the loom going over the bell housing being compromised and shorting wiring. Your problem is intermittent and doesn't happen static running. Give that part of loom a close inspection.

the only dist worth buying any more is an AC Delco, even they are made in china now. Get new, not rebuilt.

 

[90RedBurb]

Thanks for the reply. I plan to inspect that section of the harness more thoroughly tonight. I guess I didn’t mention but will update my post above that if I leave the rig running in park long enough sometimes it will stumble and set the code as well without moving. I do have another new dui distributor I might try swapping in as well to see if I notice a change after I inspect the harness in that area. I put the dui in my ol lady’s 91 obs and it has been going strong for a few years now however the current distributor is a Napa unit.

 

[90RedBurb]

Also these pictures were of my scan tool with the vehicle running in park and at temp prior to me fixing the leaky injector. Other than the integrator and blm numbers being a little off does anything else here raise concern with anyone? O2 counts and voltage were climbing then starting over as I believe they are supported to but I may be wrong on that. Also for some reason when I plug the scan tool in and enter live data mode the idle raises up to around 1000 normally idles lower.

 

[Wes Harden]

Cross counts on O2 are a little slow, that tells me the O2 sensor is old. This is not causing the issue you have though.

 

[90RedBurb]

The o2 mv and cross counts start low then both rise together to a point (can’t recall exactly where though) then both drop down and start over doing the same thing. Is that normal? I thought it was but I’m fairly new to the Tbi/fuel injection thing

 

[90RedBurb]

I may try hooking the scanner up and getting a video of it while it’s running

 

[Wes Harden]

the cross counts, are how many times the 02 switches, above and below .5v. It should this regularly and the more the better t mean the o2 is responsive to air/fuel mixture changes the computer is making.

 

[bradshawtech]

I’m the guy who brought up the wiring harness crossing over the bellhousing, here’s hoping you find something there, it’d be a first of someone besides me with the issue. Mine caused a hard stall and engine shut down until I manipulated the harness.

 

[90RedBurb]

I could shake the harness around with no change however I found a couple things while I was just back there. There is a white wire in the loom that splits into 2 white wires with a non insulated crimp just behind the distributor. It was very poorly wrapped up and was coated in oil from what I believe was a leaky distributor base gasket. I fixed that. Next is there is a tan wire and I think dark blue that exit the loom behind the passenger head and run somewhere (trans maybe) the tan wire feels broke within the sheathing but it was getting dark and I needed to get the distributor back in and get it timed so I can drive to work in the morning as I’m out of town for work and doing this at the air Bnb. The new dui distributor is in and it’s timed. Driving it now about 10 miles on so far and no lights or codes. Going to eat something and drive back to the place. Oh also I switched the computer back to the computer with my original prom and cal pack. I’ll post back here when I know more. Thanks for the ideas and help guys

 

[90RedBurb]

Also side note on the distributor I took out when I turned the shaft it would turn freely about 180 degrees then had resistance turning it the other 180 leading me to believe the shaft is bent within the housing. Doubt it made any difference to my problem but probably less then ideal to have a bent distributor.

 

[90RedBurb]

Well I made it back to where I’m staying (about 20 miles total) without issue. Well, without a ses light or code, however while out I popped the hood to have a look around and apparently my radiator cap decided it didn’t want to play anymore and was leaking. So I got a new cap and will throw it on in the morning when it’s cool. I’m going to look at some diagrams tomorrow and see if I can figure out what the tan wire is I found and see about fixing it tomorrow. I’ll update if anything changes. Thanks again guys

 

[Wes Harden]

if the tan wire has a plug in the middle it is the EST (electronic Spark Timing) disable for base timing.

 

[90RedBurb]

No it’s not the est line. It’s a tan wire that comes out of the loom behind the passenger head and runs down behind the head somewhere. I will look into it more tonight

 

[ktmoutfront]

One thing I will recommend when chasing a ghost like this is, make one change at a time. I know the goal is to "just get it fixed", but if you change 3 things, which one fixed it. For future reference if it happens again.

 

[90RedBurb]

I know I don’t like doing it that way but being on limited time with only a few hours of daylight after work and it’s supposed to start raining tomorrow and rain for the next week straight I needed to get as much done at once as possible.

 

[90RedBurb]

Well I hate to jinx myself or speak to soon but since the changes made Wednesday evening I have put on about 50 miles of driving and have yet to have an issue or set a code so that’s a plus. I do still have a cold start issue that has been an issue for quite some time that I’m trying to get figured out. First start of the day and starting after a 10-12 hour work day it will start then die. However if I give it a quarter throttle and crank it it will start right up but will blow a little black smoke and smell like fuel (rich). I remember replacing the iac when I rebuilt the throttle body. I tried to reset the iac and min air last night but it made no change to this mornings start. Starts great when warm. Will try looking into it further this evening

 

[Wes Harden]

try turning the key to the on position then off, then on for a sec, then to start. If this helps, your fuel system is not staying primed, injector dripping, check valve bo. Or the carbon on the intake valves is absorbing all the gas, not to common on tbi, more so port inj.

 

[90RedBurb]

I tried that a while back and it seemed like it worked but I’ve tried it on the last couple cold starts and it didn’t seem to make a difference. I can hear the fuel pump run for a second or 2 when the ignition is turned on. I replaced the pump last year

 

[Wes Harden]

ok. When you replaced the IAC did you run a wire pipe cleaner in the passage portion of the TBI ? I know it was rebuilt I expect it would have been clean then but one bcan never assume.

Still might have drippy injectors, evidence is cracking throttle, needing more air, and black smoke, rich mixture.