I decided to start a new thread, trying to address the problem with my 20k mile 1986 coupe. I started out with a fairly minor idle & driveability problem and now have a car that will barley run. Right now I would be afraid to take it out of the driveway. I was advised to get a scanner to help diagnosis the problem. I have now purchased an Equus Innova 3140b scanner. Keep in mind that when I scan for codes using the OBD I connector, & short terminals a & b, the only SES code that flashes is the 12, 12 , 12, code. Imagine my surprise when, after some difficulty, I retrieved the following codes with the new scanner. Some of thes codes are not even listed in my 1986 FSM. Codes: 41, 46, 51, 52, 54, 63. Would a remanufactured later model ECM, produce additional trouble codes? And why only a 12 code with the SES light? I am hoping that some of the major contributors in the last thread ie: Aklim, MrWillys, SunCR, Jseremba, Cliff Harris, and others, would chime in on this thread.
Here is a list of parts replaced and procedures pefrormed.
Battery, ECM, oil, air, gas filters, fuel pump sock, pcv, thermostat, engine oil, coolant, misc, gaskets, vacuum & fuel hoses. drained or diluted old fuel and added Seafoam addative,
Removed & cleaned, or tested or adjusted the (3) air injection valves, EGR and IAC valves, MAF sensor, throttle body, & plenum, ignition timing, fuel pressure & bleed down, blew out fuel, vapor & return lines, engine to frame ground, checked for ignition "fireflies' after dark. pulled & inspected spark plugs. Last adjustment I made was the idle, IAC & TPS adjustment. There are probably more items to list, but you get the idea. Things still on my "to do list" are a more thorough cleaning or replacement of the fuel injectors. All suggestions are appreciated. Thanks in advance!

 

I think there's a compatibility issue with your scanner. Does the scanner allow you to monitor sensors?

Unfortunately, it looks like you've spent a lot of money on this scanner. A much cheaper solution would have been to use a laptop with an ALDL to USB cable ($65) and TunerPro RT software (Free Download). TunerPro would have allowed you to data log as well.

 

OK. Lets dance. You have no codes. GOOD. What do you mean "it will barely run"? When you are on the throttle, is it running ok or do you mean it won't keep running when you are at idle?

 

Actually as scanners go, it was not that expensive, $189 from Amazon. If you looked at the Equus Innova website they want $482 for the 3140b. Amazon is shipping the improved 3140b for the same price as the old 3140. Plus I've used it on two other vehicles and have more than recovered the price all ready. I wanted a scanner that would scan OBD I & II & CAM, this one does. Moving on, I'm new to C-4's and scanners, so much of what you just said will be something for me to learn in the future. Regarding monitoring sensors, I'm not sure of all of the capabilities but it has "Freeze Frame", "Live Data Graphing" View, Record, Playback, but some capabilities do not work in ODB I mode, here's a link to their site innova.com, Thanks for commenting.

 

No codes! Are you saying the scanner is no good? six codes! 41, 46, 51, 52, 54, 63. Won't keep running. If I stay on the throttle until it warms up it will stay running, but not very well, it gurgles and pops and will not rev properly. The other day when I flushed out the cooling system I was able to keep it running, but it was fully warmed up. I'm wondering if there is something wrong with the rebuilt ECM I just bought?

 

My bad. I thought you got 3 sets of 12.

DTC - 41 Ignition control error

DTC - 41 MEM-CAL error

DTC - 41 C³I Cam Sensor Signal error

DTC - 46 Pass-Key II (VATS) system error - circuit out of freq range

DTC - 47 UART (serial data) circuit error

DTC - 51 PROM error

DTC - 51 Incorrect MEM-CAL

DTC - 52 Fuel cal-pak incorrect or missing

DTC - 54 Fuel pump circuit low voltage

DTC - 54 Digital EGR Valve solenoid 2 error

DTC - 63 Right bank O2 sensor circuit error

Clear all the codes and see if they repeat. Try that also with the OLD ECM. Before going to replace ECMs, make sure all the connections are tight.

 

Okay, here's what you have:

http://www.chevythunder.com/code_41.htm
http://www.chevythunder.com/code_46_vats.htm
http://www.chevythunder.com/codes_5152_55.htm
http://www.chevythunder.com/fuel_pump_code_54.htm

Code 63 is not a TPI error code, and is most likely why Cumbercr said it must be a scanner issue. Clearly if it did work you have a bad memcal, or ECM. Can you give us the service number from the ECM, and pull the cover to give us the BCC from the silver sticker on the memcal. IE: an 87 could be HDA, or ABTR?

 

These are not 91 an older codes.

 

No 47! I have disconnected the battery so there should be no codes. The old ECM was turned in when I got the reman'ed one, but I kept the old MemCal. Just to be clear I should try to start it to create more codes! Right?

 

yes

 

They are 95 and older from http://www.gmtuners.com/OBD1_DTC.htm

 

I ask if the scanner will read sensors (I believe yours will) because that is how you are going to find problems. If sensors are faulty, they will provide the wrong inputs to the ECM. You'll need to get familiar with the important ones such as Mass Air Flow (MAF), Throttle Position (TPS), Idle Air Control (IAC) and Coolant Temperature (CTS).

Check out your "Live Data Graphing" and record and playback. Try to get the car to idle and do a freeze frame. Then post the readings.

 

1227165 is the number of the ECM that I removed & traded in last month. I'll have to remove the re-maned ECM tomorrow and check the ECM & MemCal numbers. When I saw the extra problem codes not associated with the 86 C-4, I wondered if a later C-4 ECM may have been substituted for the original configuration. The receipt I have from Autozone shows the ECM number as 777165, but I don't know if this helps any?

 

I've cleaned and/or adjusted three of the four sensors that you mentioned above, but not the CTS. I hope it will read sensors, but it doesn't do some of the more elaborate checks in the OBD I mode. Right now it won't start and the scanner won't re-connect. I think the ECM or connections are bad or wrong.

 

Too much Chevy Thunder information to comment on all at once. Most of that showed up in the scanner with the trouble codes. But thanks for posting it.
An old receipt from 1990 shows a dealership invoice for replacement of parts of the VATS system and new keys. There is one of the three ignition keys that won't work, ie the resistor is wrong, probably one of the original keys. I may have tried to use that key and set the error code, but, I have reset the ECM by disconnecting the NEG battery cable so many times I doubt the code would still be there.
When working on low voltage equipment "In my former life" I used to use Deoxit the purple juice to coat circuit board connections and connector pins. I've been out of it for a couple of years now. It used to cure a lot of gremlins in equipment. Any reason not to use it on the ECM connector or other electrical components? If not I'll reorder some.

 

If I had gotten 4 codes that said the memcal was bad I would assume that may be the cause of the VATS code. Your memcal is most suspect, and it could be as simple as a bent pin, or?

 

The fact you have cleaned or adjusted sensors does not necessarily mean they are functioning properly. A case in point, for some time, I have had an idle issue that I wrote off as part of a new engine and custom tune. Recently I started getting intermittent codes regarding the throttle position sensor. I checked the adjustment and it was right on. So I replaced the TPS with a known good sensor. The problem was solved.

If you had the wrong ECM, I doubt your car would even start and it should definitely not flash a normal Code 12. Code 12 is supposed to indicate a good ECM. And as far as all the codes go, I suspect a setup problem with the scanner. You should not be getting a bunch of erroneous codes for different year vehicles. If the scanner won't connect, that should be a clue that the setup is wrong or the scanner is not compatible.

Backtrack your steps to when the car last ran.

 

It does sound like the scanner configuration is not matched to your ECM.

The error codes are bit mapped. That means that each error code byte that comes out of the ECM is reporting 8 error codes (or not), one bit per code. It will send something like $08 (the $ sign is Motorola's way of denoting a hexadecimal number), which is 00001000 in binary. That means that there is one error (where the "1" is). The scanner needs to know which error that 1 represents. The meaning of the various error code bits changed over the years so the scanner has to be configured correctly to interpret the error codes correctly.

 

Here' are the numbers on the ECM # 7-7165 DC Code 1107ST. There is a paper UPC sticker on the electrical receptical 07716500072770059 REMFG. Another UPC sticker is underneath the one listed above 310038201389045. On the MedCal through the top holes in the blue plastic are Delco BUA 1728 and through the other hole is 16055376. on the side of the brown base is #68767 8718. There does not appear to be any bent pins. I plan on applying Deoxit spray to all the pins and recepticals. Then re-assemble and see if there is any improvement.

 

Would this mean inputting a different year and/or eighth VIN digit when I first set up the scanner? For example input to the scanner, 86, then try 87, then try 88, and so on, until one configuration works? Also, I didn't hear a response back on the main fan running all the time the ignition is on, I don't think this is normal, is it?