ck engine light won't flash

[cyclonecom]

I recently bought an '85 with a fresh 9.8:1 383, BBK intake, roller cam, headers, etc. Previous owner unfortunately passed away before he was finished doing his final tune using a Moates APU1. My first real drive with the car was about 16 miles, about 5 miles on a twisty 35 mph road; then 11 miles at 65-80mph. (Car ran fine, although she had stalled the previous day when put into drive.) At the end of this drive, was about a 3 miles steep downhill coast...no or minimal throttle.
At the first stop after this the engine started to lightly pop/backfire through the intake. The check engine light came on. I was within four blocks of home so went home and parked it.
I can jump the data port but the check engine light remains on steady. I'm using one of the plug in tools, not starting the engine, but can't get a code to flash. Any ideas on where to start or at least get it to reset?
Bob

 

[Schrade]

Welcome onto the boards there...

First thing I would do is see if there's any receipts for the build, INCLUDING baseline tune data. Even if the motor is tight as a drum, if it's not programmed right, it won't burn right, and it's gonna' foul with carbon in the intake manifold and the exhaust.

If you do have to get a chip burned, do it as soon as possible, while everything is clean and tight. It might cost a pretty penny too, but it should be done right...

Test for continuity on the circuits from ECM - ALDL interface in the meantime.

 

[cyclonecom]

I have all the specs on the engine as recorded by the previous owner...including the custom grind on the cam, head flow specs, etc., but no receipts. I also got one printout of the data tables...probably about 10 pages.
Checking the continuity sounds like a real good idea. I'll pull the chip and see if I can figure out how to read it with the APU1 and TunerRT software. I'm considering taking the easy way out and sending the specs to pcmforless to see if they can create a tune that works for now and then tweak it later.

 

[boomdriver]

I recently bought an '85 with a fresh 9.8:1 383, BBK intake, roller cam, headers, etc. Previous owner unfortunately passed away before he was finished doing his final tune using a Moates APU1. My first real drive with the car was about 16 miles, about 5 miles on a twisty 35 mph road; then 11 miles at 65-80mph. (Car ran fine, although she had stalled the previous day when put into drive.) At the end of this drive, was about a 3 miles steep downhill coast...no or minimal throttle.
At the first stop after this the engine started to lightly pop/backfire through the intake. The check engine light came on. I was within four blocks of home so went home and parked it.
I can jump the data port but the check engine light remains on steady. I'm using one of the plug in tools, not starting the engine, but can't get a code to flash. Any ideas on where to start or at least get it to reset?
Bob

if the SES lite will not flash or cycle into diagnostic mode, then thats not necessarily the prom but rather the ECM or plug ground.
I'd double check all the grounds, and the power source wires in the fusable links behind the battery.
The ECM has to ground at the ALCL plug in order to go to diagnostic, and from there it should be an automatic cycling that reads dischargable or erasable memory, not PROM.

If it were me, I'd run the thing a good 500 miles to loosen it up, THEN get a tune done,.

 

[Schrade]

Sounds like the guy has done his homework on the build and tune. That paperwork is VALUABLE. You should make a copy and store it SAFELY.

BUT, I think maybe DON'T drive a couple of hundred miles, because if it's hangin' in Open loop, you're gonna' get some carbon deposits that aren't necessary, from maxing injector pulsewidth the entire time...






edit:
I mean 'INCREASED' pulsewidth; not 'max' pulsewidth. (gotta' keep the resident tech nazi happy :W )

 

[cyclonecom]

So I tore into the engine bay and found that a lot of wiring was way to close to the headers. Found that: The #8 plug porcelain was cracked, #8 MSD plug boot looked intact but was actually completely cracked and detioriated, the O2 sensor wiring plug was melted...along with one of the white wires, the radio suppression capacitor wire was broken, the fan relay housing was cracked, and the chip emulator was not properly seated.
Removed the headers and wrapped them in fiberglass. Also wrapped and re-routed all the harnesses to the starter, O2 sensor, etc. with fiberglass, new tape, and tubing. New plug and boot. Replaced the plug and wiring to the O2. Removed and cleaned all the grounds that I came across. Voila, it runs great! Mileage readout is working, ck engine light is out, and I don't smell any melting wiring.
I had no idea how much that High Temp silicone paint on the header wrap would smoke until it cured...that was kind of scary. Along with the little bit of spilled coolant that they had soaked up I had quite a fog bank going for awhile. Anyway, took it on a 20 mile run last night and all seems OK. I should have a new chip installed later this week so the emulator can go away. Thanks for the help and advice, can't wait to see what breaks next.

 

[Hib Halverson]

When you say you can "jump the data port", between what pin and ground are you jumping?

 

[Schrade]

So I tore into the engine bay and found that a lot of wiring was way to close to the headers. Found that: The #8 plug porcelain was cracked, #8 MSD plug boot looked intact but was actually completely cracked and detioriated, the O2 sensor wiring plug was melted...along with one of the white wires, the radio suppression capacitor wire was broken, the fan relay housing was cracked, and the chip emulator was not properly seated.
Removed the headers and wrapped them in fiberglass. Also wrapped and re-routed all the harnesses to the starter, O2 sensor, etc. with fiberglass, new tape, and tubing. New plug and boot. Replaced the plug and wiring to the O2. Removed and cleaned all the grounds that I came across. Voila, it runs great! Mileage readout is working, ck engine light is out, and I don't smell any melting wiring.
I had no idea how much that High Temp silicone paint on the header wrap would smoke until it cured...that was kind of scary. Along with the little bit of spilled coolant that they had soaked up I had quite a fog bank going for awhile. Anyway, took it on a 20 mile run last night and all seems OK. I should have a new chip installed later this week so the emulator can go away. Thanks for the help and advice, can't wait to see what breaks next.

"What breaks next?"

This info makes it sound like someone ELSE has tampered with the car after the owner died - tried to get it motored up???

Normally, someone who does work, and the paperwork to go along with it like you described, pays attention to other details too, like securing wiring harnesses.

And the new chip there - you might want to see how it's being written, with the baseline parameters for the new motor written in... I would REALLY want to know that it's not an 'off-the-shelf' chip.

 

[geekinavette]

the chip emulator was not properly seated.

I think this is what caused the initial symptoms. When the ECM looses connection with the PROM it has no valid engine cal data and goes into "limp home" mode. This mode is designed to safely get the car to a repair facility, but also designed for a stock engine. Since yours is heavily modified the limp home calibration is very likely not going to supply enough fuel, thus the lean backfires.

The ECM does a PROM check when the ignition is turned on...if the PROM checks out you will get a single flash of the CEL. If it does not...some (older) ECMS will flash the CEL rapidly, some (later) ECMs simply turn the CEL on solid (no flash). The '85 ECM (1226870 I believe) kinda falls somewhere in between...I never had to test that particular model so I'm not sure, but either way I'd bet that it still does the "single flash PROM check". After the emulator was properly reseated it "should" have stored a code 51.