SE ECM...

[Htown]

Can someone please verify (not just a website please, I need to hear from somebody who has actually installed one) that the GM 01228708 is the correct ECM for a N.A.S. 90SE? Mine is wagged. I have come across various mistakes on the EFF x-reference page regarding sensors etc.. and really don't want to make the same mistake with the ECM...

Thanks in advance..
Craig

[karmavore]

I have one on the way from GMPartsDirect... I'll let you know soon. BUT in talking with Sanj it would seem to be so.

Why do you think your ECM is shot?

[Htown]

One of the 'mounts' or nuts I guess you would call it, backed itself out of the ecm housing. She was flappin around pretty good, and the board is now banging around inside the housing...They're cheap enough just to pick one up and plug her in...having a serious miss in #2and3, and the car is getting 56dgrees of timing AT IDLE! has a new icm and coils, but the new icm isn't giving out it's 5volts...code 41. going to plug the old icm in with the new coils tomorrow before pulling the trigger on the ecm, just wanted to get my ducks in a row beforehand on the part number...

Thanks Luke,
Craig

[gixxer]

1228708 is the "service part number".
Yup,that be the one.
If you are in the U.S and are in a hurry, just sashay up to an "automotive recycler", and he should be able to get you one out of a Quad Four Oldsmobile, or whatever, in a couple days at most for about $100. They rarely go bad. All you have to do is pull the mem-cal out and pop the Lotus one in, and off you go.

[Htown]

thanks guys...

I pretty sure that's the culprit... most likely a problem within the primary injector driver within the ecm. It's basically only running on #1and #4 with good spark all-around. compression is 132 highest and 128 lowest. Leakdown test looks good. the wierd thing is that when I pull the connector off of the #2 injector, the car smooths out, but if I pull the connector off #3...NO CHANGE! If I pull #1 or #4 car the car dies ...resistance at injectors 1,3 and 4 is around 2.5-2.6 ohms, but #2 is down to 1.7 ohms. Going to move the #2 inj to another cylinder tomorrow to see if the problem follows to the new cylinder.

Correct me if I'm wrong, but isn't the primary injector driver(s) in the ecm board? and don't 2&3 share the same driver?

Craig

[inno]

You have the correct number, I got the number from Dr Hess' website.
I just replaced mine two weeks ago, paid $112. When the car got hot it would stall. When I checked it out on freescan I noticed that my water temp and tps were giving screwy readings, when cold the readings were fine. Just to be sure I applied heat from a hair dryer directly to the ECM, sure enough, all of a sudden the readings went crazy and the car died. I'm told that the D/A converters that read the sensors can go bad after a while. Car is running great now.

Pete
90 SE

[karmavore]

GMPartsDirect sells them for $80 (plus $90 core). They are remanufactured “weatherproof” units. I think it’d be best to buy one of these then one that’s been pulled out of a junker, but that’s certainly a quicker idea!

A compression PSI of 132-128 is kinda low, in’it?

Also, I recently discovered form Sanj that if your MEMAL is socketed that the EPROM should only be installed one way, other wise you will ruin it. Whoops. So that can go bad too.

[Squelch]

Code 41 typically is an Ignition module problem, not an ECM problem, the ECM is not getting the signal from the ignition module, this is why it hasn't triggered the ignition module to slave it's timing from the ECM. It could also be wiring...

Also 56 degrees at idle would NOT be the default timing if it was an ECM failure.

Are you using the correct Ignition module ?


John

[mikelr]

Squelch said:

Code 41 typically is an Ignition module problem, not an ECM problem, the ECM is not getting the signal from the ignition module, this is why it hasn't triggered the ignition module to slave it's timing from the ECM. It could also be wiring... Also 56 degrees at idle would NOT be the default timing if it was an ECM failure. Are you using the correct Ignition module ? John

To add to John's post,
I don't believe the ECM has anything to do with ignition timing at idle. This function is controlled by the DIS until a certain trigger point at which it follows direction from the ECM.

[Htown]

Switched the old icm back in and got rid of the code 41...now getting the required 5volts out of the icm.. and no code...

I agree that the compression is low, (that's another issue for another day) but more importantly it is consistent across the board..ie, there isn't a dramatic difference between cylinders...

WC eng installed my prom onto a new memcal for me about a year ago...no doubt in my mind regarding it's install or integrity...no socket, straight solder..

Lastly, I don't think the conventional way of checking timing applies here seeing as though the car uses a wasted spark system...ie, a spark on compressin stroke and exhaust stroke... other than verifying the timing marks at the pulleys,(good) what is the correct procedure? My 56degrees could be a bogus reading...

Hence...i'm leaning toward a problem with the primary injector driver in the ecm that controlls 2 and 3.

Thanks,
Craig

[lotusse89]

Craig,

Compression will be lower at our altitude correct? I think about 15% less for altitude density, compressing thinner air will yield less pressure.

Leakdown test is more helpful anyways.

I didn't read through everything mentioned, but a good check (assuming the code 41 was bogus) would be to switch around injectors to see if the problem follows the injector or the driver circuit...

I had injectors 2&3 fail in the middle of a drive about 70miles from home. Lew took his car apart and drove 140 miles round trip to bring me two injectors. Car ran fine after that.

I just pull the whole fuel rail, with injectors attached, and have them spray into a paper towell while I crank the engine. Look for the wet spots to see which injectors are firing rather than trying to see which cylinder is running...

Travis
Vulcan Grey 89SE
www.lotuscolorado.com/vulcangrey/



>> Edited by lotusse89 on Friday 22 July 00:38

[Squelch]

mikelr said:

To add to John's post, I don't believe the ECM has anything to do with ignition timing at idle. This function is controlled by the DIS until a certain trigger point at which it follows direction from the ECM.

That is close to being correct... here are the details:

The Ignition module controls timing on startup and up to 400 RPM. (this is a parameter in the ECM calibration)

When the ECM gets a speed signal from the ignition module that is above 400 RPM, the ECM triggers the IGM that it will take over control of the timing, it pulls a line high, then the IGM gets a pulse from the ECM as to when to fire the coils.
The ECM needs a valid RPM signal, and reference pulse from the IGM, or it will not take over timing.

There are several part numbers for IGM's floating around that are similar to the Lotus IGM and were used on other GM products, but many of them do not have the same signialing as the correct part.

John

[Htown]

lotusse89 said:

Craig, Compression will be lower at our altitude correct? I think about 15% less for altitude density, compressing thinner air will yield less pressure. Leakdown test is more helpful anyways. I didn't read through everything mentioned, but a good check (assuming the code 41 was bogus) would be to switch around injectors to see if the problem follows the injector or the driver circuit... I had injectors 2&3 fail in the middle of a drive about 70miles from home. Lew took his car apart and drove 140 miles round trip to bring me two injectors. Car ran fine after that. I just pull the whole fuel rail, with injectors attached, and have them spray into a paper towell while I crank the engine. Look for the wet spots to see which injectors are firing rather than trying to see which cylinder is running... Travis Vulcan Grey 89SE <a href="www.lotuscolorado.com/vulcangrey/">www.lotuscolorado.com/vulcangrey/</a> >> Edited by lotusse89 on Friday 22 July 00:38

Hey Travis...
Pulled the rail and gave her a few cranks...All are firing with a nice pattern, but I think that only tells part of the story...With the number 2 injector at a full ohm less than the other three...it makes me wonder... strangely enough, when I pull the #2 injector, number 3 kicks in...hence the smoother running... with number 2 connected number 3 is wagged.. going to move the injectors today to see if the problem follows...

Lastly... some loser Hawaiian dock worker stole my laptop and freescan cable when I moved there... Anyone in or around Denver care to help?

Thanks,
Craig

[lotusse89]

Htown said:

Hey Travis... Pulled the rail and gave her a few cranks...All are firing with a nice pattern, but I think that only tells part of the story...With the number 2 injector at a full ohm less than the other three...it makes me wonder... strangely enough, when I pull the #2 injector, number 3 kicks in...hence the smoother running... with number 2 connected number 3 is wagged.. going to move the injectors today to see if the problem follows... Lastly... some loser Hawaiian dock worker stole my laptop and freescan cable when I moved there... Anyone in or around Denver care to help? Thanks, Craig

I have a laptop with freescan and a cable.

I also have the EMH section of the manual that explains how to diagnose the injector driver circuit.

Travis

>> Edited by lotusse89 on Friday 22 July 20:40

[Htown]

lotusse89 said:

Htown said: I have a laptop with freescan and a cable. I also have the EMH section of the manual that explains how to diagnose the injector driver circuit. Travis >> Edited by lotusse89 on Friday 22 July 20:40

Have the EMH...what section are you refering to? Might be the curse of the incomplete JAE supplied manual...grrrrrr

>> Edited by Htown on Friday 22 July 22:23

[lotusse89]

Htown said:

lotusse89 said: Htown said: I have a laptop with freescan and a cable. I also have the EMH section of the manual that explains how to diagnose the injector driver circuit. Travis >> Edited by lotusse89 on Friday 22 July 20:40 Have the EMH...what section are you refering to? Might be the curse of the incomplete JAE supplied manual...grrrrrr >> Edited by Htown on Friday 22 July 22:23

In the electrical troubleshooting section, in the back of EMH... A bunch of flowcharts with steps to troubleshoot different symptoms. The injector driver check involves using a multi meter and test light on the plug at the coils and the plug for the injector harness.

Travis

[Htown]

Sweet...JAE strikes again...

not in my EMH.

Craig