eastbay77

'91 L98 A4 convt. All stock

I had a power from an aftermarket amp come loose and arc on the metal amp housing.

After that happens the car will barely start and run rough until it dies.

I check the codes and C41 comes up.

How do I go about fixing the issue?

Per my own search c41 comes us memcal issues or cylinder select error circuit?

Diesel_Jerry

I found this on google in a old post from this forum. pC41 = Cylinder Select Error Check wiring at ECM. Possible PROM failure, or incorrectly seated PROM.

Reseat PROM. Possible ECM failure. before you try reseating the prom try taking the negative wire off the battery cycle the key to the on position a few times to get any residual power out.

Put the negative wire back on, say a quick prayer to your favorite deity that you didn't fry something and see if it starts.

eastbay77

Thanks I will try that before I start changing out parts. Good news is if I do have to change the chip/prom or ecm I located a TPI enthusiast off eBay that restores/ reprogramms ecm and proms. His rates and prices seem fair.

WVZR-1

You're sure that the CODE 41 you're seeing is actually the ECM.
Regardless of the eBay information or what seems to be an "enthusiast" (your description) you want to be very careful about giving up either your PROM or ECM for diagnostics.

Do you have a FSM for this car? What year is this car?

Never mind - I went back and the CCM thread mentions '91 so maybe you do much more regarding diagnostics.

Did you notice that the PROM was original with the labels from GM on it or was it maybe an add-on that had another component attached?

You've got threads regarding CCM - tune up parts and this CODE 41. In what sequence did the "runs poorly - CODE 41" occur? Has it always run poorly and the CODE 41 there before your other attempts at removing things and then you mention the CODE 41? In your other thread you seem to hint since the other attempt but your error code seems odd/unusual through that effort. Anything is certainly possible but .......

eastbay77

I just edited my post to clear up what I left out.

The car is a base model '91 convt. A4 all stock.

Has factory chip and computer.

The car was running fine until the wire arced. After starting the car it runs like it is really rough then will die.

I tried the method suggested above to reset the ecm but it did not work.

As far as the eBay guy. Of course I will do my do diligence before any transaction happens or I throw parts at it.

At this point I'm stump. Are there any fusible links or fuses that could have shorted out?

eastbay77

I got the car running.

After reading numerous posts and websites dedicated to C4s I came up with the dime store idea the ecm needed to reset to factory baseline.

So unplugged the negative lead on the battery. I left the key in the on position over night.

This morning plugged the negative cable back. Started car and kept throttle at around 1500 for 2 minutes or so.

I let off the gas and it started to idle on its own.

I took it for a quick drive and no codes no stalling.

Hopefully it fixed it. Thanks for all the help

eastbay77

No dice. Car went right back to not being able to idle unless I give it throttle.

Pulled another code 41.

I ran the jumper AB test to check if ecm is bad. It checked out OK.

While I'm waiting to my FSM Manuals to show I have been reading as many posts and related post to my issue.

From what I read could be a bad prom since the ecm passed OK.

What vendors can I get a replacement EPROM from?

raya123_2000

I'm got a ECM C41, also after changing the EPROM on the Memcal. The EPROM was failing so I copied it an programed a new chip. Removed the old chip from the carrier and replaced it with a new chip(National Semi NM27C256Q-100) The numbers on the original chip were (014-045915-AD8947B).
The car runs perfect, haven't taken it for a long drive yet. Before I changed the Chip, I went to a junk yard and got a few memcal's but only off of 6cycliners. but I programed one with the original chip code(Erased with a ultraviolet light eraser), the car ran great and I didn't have the ECM C41.
Any idear's???

eastbay77

I didn't change the prom yet. But my troubleshooting is going in that direction. I do not have the tools to burn proms. Maybe in the future but at this point I will need to buy on allready done. To get car runninb .

I'm leaning toward PCM NC they have been used by many members with excellent results. They are also priced fairly.

My FIL is master diagnostic tech and has hopped aboard to walk me through obd troubleshooting. I should be able to sort it out soon . My fsm should be here tomorrow that will be a big help.

raya123_2000

I just brought a ECM on Ebay for $27.80 and it seems to work.

Here is the URL: :http://www.ebay.com/itm/262809222991

eastbay77

After troubleshooting with the FSM , all test pointed to the ecm. I was able to score a used AC Delco reman off eBay for under $40.

Plugged it in an all is good!

Car runs as it should.