johngammel

My stock California '88 automatic has recently started sometimes displaying "Service Engine Soon". As background I've also previously noticed some momentary hesitation when the car is restarted after sitting for over an hour after being at operating temperature but since it was momentary I didn't take any action. Local guys that had an OBD I code reader read out a code 42 this morning - which is the electronic spark timing (EST) circuit. I have a service manual but like most problems there is usually a normal suspect for each problem. Any quick things I can check?

I think I'm going to buy one of the 12 pin to USB adapters and then use a laptop so I don't have to go back and bum another code read while I'm working on it (and yes I know you can short pins but I don't like that solution). Any vendor better than any other for the cable (I have contacted the Green Bay guys but haven't heard back yet)? Thought I'd use the free TunerPro software since it's much later than winALDL and will likely work with a Windows 10 64 bit laptop. Thoughts on this?

hcbph

Don't know if this applies or not, but IIRC last year I was getting a 42 on occasion. Cold weather (near freezing) and within about 5 blocks from a cold start it would throw a SES and barely run. Limp home and let it set 20 min and it would run just fine. FSM lead me to the ECU but that didn't make sense, everything considered. I was tracking it down and planned on tracing the wiring and sensors but didn't finish it.

Happened one day and I kept coming back to the IAC (which I was planning on replacing but hadn't yet) and happened to have a plastic faced hammer with me. I rapped the IAC 4 or 5 times lightly. Low and behold the problem ceased happening.

Don't know if it's your problem or not, but it's worth a look-see, who knows?

johngammel

The idle air control - interesting. I'll give it a try. After I feel better I'll rattle all the wiring as well.

P.S. - your pic doesn't look like Minneapolis - before retiring and moving to FL I lived in Shoreview.

Kevova

Intermittent Code 42 for est has no for sures. Possible causes are ECM, ICM, connections, grounds, and emi do to spark plug wires running too close to distributor EST (4 wire) harness. Things to try with intermittent 42 make sure plug wires are at least 1 inch from 4 wire distributor harness. Harness connector terminals are clean, weather seal is in place, and is fully seated. Grounds are clean and tight. Loosen and retighten distributor hold down. If 42 is still occurring ICM because it's more effected by heat cycling last would be ECM. There are those who will replace both ECM & ICM for a 42. Remember to transfer prom if you replace ECM.

johngammel

Ouch - just about everything under the hood. I'm going to try the old night time test - with no lights late at night start the car and look for sparks. I'm also going to disconnect everything, look at the connectors and reconnect - this has fixed things on other cars.

I've not been able to get the OBD I cable vendor to contact me back. Anyone got some reasonable priced resource suggestion?

hcbph

Picture is from when I bought the car in New Mexico. It was prettier than the background around Minneapolis and a lot more expansive.

johngammel

After getting delayed working on the '61 I'm back to my '88. I did some investigating with an ohm meter in the ECM connectors and it looked like the ignition module was bad. Got a generic replacement which the store was very confident was a correct replacement. Also replaced the rotor and cap as they both were very old. While the Service Engine Soon went away for awhile it has come back. Disconnecting the battery clears it but after a restart or two it comes back.

On the MW2 get:
ALDL Mode (10k Ohms) - to be expected
DRP Occurred

On the MWAF1 get:
Closed loop flag
Rich Flag (comes and goes)
EECC Slow O2 Rich/Lean Flag (comes and goes)
BLM Enable Flag

Thoughts on my next step(s)? Pics are idling in park.

Cliff Harris

You should NOT be in ALDL mode (10K ohms). You should be in Diagnostic Mode (0 ohms).

10K mode sets the idle speed to 1000 RPM and advances the timing. It can also turn on the canister purge solenoid (you don't want that, as it can affect the mixture).

johngammel

Interesting - the vendor said to set the 10K mode - but it wouldn't be the first time a vendor was wrong. I'll give that a try and see what happens. I'll also try to get a screen grab and then push that across my network (if all else fails I'll use sneaker net).

Cliff Harris

Here's a fun fact: the 3.9K mode will put the ECM into "limp home" mode. I looked at the ECM program code and I don't think there's any other way to get into limp mode. I've heard people say that X failed or they disconnected Y and the ECM went into limp mode, but the code doesn't work that way.

johngammel

The car seems to run fine with the code Service Engine Soon light on caused by the 42. My focus is the '61 and my zinc plating/chromating development so I work on this as time permits.

Cliff Harris

Error code 42 is an open connection between the ICM (Ignition Control Module) and the ECM. Usually it's caused by opening the EST (Electronic Spark Timing) connector to set the timing.

johngammel

After even more time I bought a reman ECM that one of the Florida guys had. After miles and starts no more codes. If you're got this problem and the wiring looks good I recommend just getting an ECM box, putting your PROM in it and giving it a try. Would have saved me lots of time and reduced my expenses.

hcbph

Good to hear you got it solved. Congrats.

johngammel

Ahh - MN my home for more than 60 years. And I had the '88 there as well.

Now I just need another replacement climate control and things will be reasonably good.

HAD2HAV2

Talk to batee.com. Bryan works on those as well.