Intermittent Stumble + Code 8

[James Matteu]

At the end of May 2013, I noticed that every once in a while my car would stumble a little. It was nothing serious. No CEL and no other noticeable symptoms. Each time the stumble or hesitation would get worse. I didn't notice any particular time it would happen.

 

 

 

 

 

 

On June 15, 2013, I finally got a CEL with the stumble. Code 8 TDC Sensor Error. After pulling the codes, I cleared the ECU by pulling the 7.5A fuse and leaving it out for about 10minutes. I reinserted the fuse and turned the car back on; the CEL came back on immediately. I didn't pull codes a second time; I assumed it was code 8 again though recall no abnormal idle or stumbling.

 

 

 

June 22, 2013, i decided to dig into this problem. The CEL light was on and stayed on since the 15th. I don't have my datalogger setup so I don't know if it was the intermittent code8 or the non-intermittent (?) Code 8.

 

 

 

 

 

This time, before clearing the code, I performed the diagnostic ruberic in the Helms Supplemental Manual for V6s, pages 11-83 and 11-84.

 

 

 

I found the TDC sensor on spec, so I idled the car for a while and rechecked.

 

 

 

 

 

 

 

I also checked the CYP sensor too, it was on spec.

 

To sum it up...

 

At C109 the TDC sensor has:

2.284 kilo-Ohms at 90°F

2.608 kilo-Ohms at 137°F

 

At the ECU the resistance is the same which means no permanent opens Iin the wiring; spec is 1.5 to 3.0 kilo-Ohms. I checked for connectivity to chassis with the ECU B-connection disconnected and found none which meams no permanent shorts. Those checks done at the ECU where done after the warm up so hopefully they represent operating conditions.

 

 

After performing the checks i took it for a drive to see if the error would resurface then.

 

 

 

 

 

 

The possibility of a transient error in the wiring, sensor, or ECU still remains a possibility.

 

There is another possibility that's been persisting in my thoughts: internal ECU failure. This due to the other intermittent errors that have popped up in the past 3 years: a couple of misfires and a TPS signal error.

 

 

 

So, I'll just leave this here in case the issue returns.

 

 

 

Car: 1997 Honda Accord EX V6 stock C27A4 (2.7 liter 24 valve PGM-Fi V6) and stock MPZA (4 speed auto)

[James Matteu]

As of today, I've driven roughly 100 miles and haven't had any stumbling acceleration nor any CELs.

[Xeryon]

Having spent a considerable amount of time working on circuit boards for my current job has the thought of a cold solder joint in the ECU popped up at any point? Have you noticed the symptom occurring in rhythm to any environmental variables?

[James Matteu]

Nope. Not that such a correlation doesn't exist, I've just not been paying attention or i did notice and forgot the next time something happened. This thread is the first step, now I have somewhere to record observations.

 

I have a backup ECU, or I'm using the backup. I'm not sure which is in my car, but the other is in the garage in a plastic bin so needing another ECU to remedy these random errors isn't the end of the world for me.

 

 

Arr you going to tell me to stick it in the oven?

[Xeryon]

Maybe... lol

 

With something 'bigger' like the ecu I don't think I would reflow the whole board, rather do a visual inspection to see if I could see any of the failing joints. Get out the magnifying glass and go over it from top to bottom to be sure.

[James Matteu]

Okay, will do!*

 

*you don't mind if I be lazy and wait until I get another CEL light before removing the ECU and checking it over with my magnifying glass do you?

[Xeryon]

Check the one that is out of the car. Possibility that it may have a similar issue if such an issue is present. I can see them from 5 feet away but it's what I do daily. Others need a workbench with a high power light and magnifying glass.