Check Engine Light code help please
 

I have a 1991 Accord EX wagon with automatic transmission, 2.2L engine, non-VTEC that I recently acquired.

It has a peculiar problem and peculiar to me CEL codes.

The car starts, runs, shifts and drives fine below 3200 RPM. When I accelerate to the point of the engine reaching 3200 RPM the engine stutters and cuts out (for lack of better terms) and will not shift until the RPMs drop below 3000 and then it will up shift and run fine as long as you don't accelerate to the 3200 RPM mark again. It will shift fine at the lower engine speed as well.

The CEL is on. When I attempted to retrieve the codes there are none displayed by the CEL itself but the 'S' light beside the gear position indicator returns a code 14.

If someone will help me out with this I'll be very grateful.

I suspect that perhaps the catalytic converter may be clogged and that's causing the stuttering and erratic behavior of the engine at and above 3200 RPM.

The history of the car is that it was owned by an older couple who sold or gave it to a grandson who then drove it. It has 122K miles on it and it very clean on the interior. Paint needs serious restoration though.

A transmission code 14 means there is trouble with the transmission computer communicating with the engine computer. The symptom is harsh shifts according to the shop manual.

Since your cel is on and you are not getting codes, the engine computer (ECU) is likely the culprit, but it could also be the transmission computer (TCU).

If this were my car, I'd go to a u-pull-it junkyard and buy both the ECU and TCU. Ebay is another source.

You have to get the part from a 1991 wagon that is an EX or SE. No other models have the same part number. A 90-93 ECU from a 5-door may work, but there has to be some differences.

Your ECU part number is 37820-PT6-A50. (or 37820-PT6-L50 if it has California emissions, your ECU should have a sticker with this part number on it)

Your TCU part number is 28100-PX0-A03.

Thank you for your response PAHonda. I greatly appreciate the information that you provided.

In your opinion you believe that the ECU has failed and that is the reason for the acceleration issue as well as the FAS-Wire fault from the TCU?

I found a like ECU on Ebay last night. It is the only one that I have found. I am going to buy it today.

I tried an ECU from a different car. It is the A51 version but I don't believe that should make a difference since the difference in the A50 and A51 is a software revision or model year. The A50 being from my 1991 and the A51 being from a 1992 or 1993.

I still have all of the same symptoms and codes.

CEL light on with no codes displayed and "S" light flashing a 14.

I realize now that the engine stuttering or cutting out is the is actually the REV limiter activating at the 3200 RPM mark.

I have a source for a TCU with a different number that I may try to see if that is the issue. Seems a little funny to me that the TCU would cause the REV limiter to activate but maybe not.

I tested the ECU witout actually remounting it to the floor board. I'm not sure if that would affect it or not. The negative battery cable was removed during the removal of the original ECU and installation of the replacement.

Any comments or ideas?

Is the CEL still turning on while driving and giving no codes?

Yes. The CEL is on constantly and returns no codes at all when the diagnostic plug is crossed.

The only flashing light is the "S" light which returns 14.

You may want to check some fuses. The 7.5 amp backup/radio fuse in the engine bay fuse box. There is an ECU fuse that is 10 amps as well.

There is also an important ground on or under the thermostat housing. Make sure that ground is clean and secure. That grounds the ECU/TCU and a bunch of other items.

I read somewhere in another post (don't remember which forum) that the backup fuse can cause an issue with the ECM having a steady on CEL and not returning any codes. I am going to look at that when I get home tonight if I have time and energy. I have some honey-doos that I have to do as well.

Thank you for your continued help!

I visually checked both the 7.5a backup fuse and the 10a ECU fuse and neither appear to be blown. Forgot to check the ground. I'll do that.

Still puzzling over this.