Nvram battery life

[Tony B.]

I have 2 that are used regularly that are 15 years +

Well over the 10 years of rated battery life lol

[vlad01]

I've watched a youtube video where these was one of these exact NVRAMs in a lab digital bench multimeter (suitcase sized thing).

The NVRAM was still working at 27 years at the time of the video which was about 8-10 years ago now.

[vlad01]

Been having sporadic Code 55 error from ECM (ECM Failure - check grounds. If good, replace ECM)

Engine will either run poorly, or start, then stall immediately.
Usually check things. Find nothing obviously wrong. Things return to normal and engine runs again.
On weekend, it did the start/stall thing and had to get towed home.
Next morning it started and ran fine for the next few days.... until today.

ECM won't even flash a Code 12 (that it is working)

Has the NVRAM battery finally died?

Going back to this, I had the same thing happen a few days ago, but this time the cause was having a VR manual loom plugged into a VN car, the ECU would spit chips, code 55 and would not run, backfire and flood the car, however it would start but then die quickly most times or run extremely poorly for up to maybe 5-10 sec as most. So it was something to do with the wrong wires going to the wrong places as the plug above the ECU that goes into the main body under dash loom have most of the wiring pins in the wrong location between these two models. I removed all that was not needed and re-pinned the rest to the right spots, the ECU and car run fine now, no more 55 and weird TP dash data like inverted TPS. I also found bad battery grounds on the body and engine block later on, but those seemed to only make it act like a flat battery although it may have contributed, but for sure the wrong pin out made it act like the ECU died and went bat shit crazy. If I only supplied 12v on that plug and nothing else, it was fine and that's how I figured the mismatch was the issue.

So def double check stuff like this.

I am tuning a VN with a built VR v6 with crow stage 3 cam for abd old friend of mine, and it took me days to figure out the electrical and mechanical mishmash that was causing all sorts including a "faulty ECU" symptoms.

[immortality]

I just used my NVram board yesterday, it's from the early days and it still worked. Last time around it seemed dead so I bought a new one but I tried the old one first yesterday and it worked fine so now I'm thinking it was the GQ4 programmer playing up previously.

[Tony B.]

Going back to this, I had the same thing happen a few days ago, but this time the cause was having a VR manual loom plugged into a VN car, the ECU would spit chips, code 55 and would not run, backfire and flood the car, however it would start but then die quickly most times or run extremely poorly for up to maybe 5-10 sec as most. So it was something to do with the wrong wires going to the wrong places as the plug above the ECU that goes into the main body under dash loom have most of the wiring pins in the wrong location between these two models. I removed all that was not needed and re-pinned the rest to the right spots, the ECU and car run fine now, no more 55 and weird TP dash data like inverted TPS. I also found bad battery grounds on the body and engine block later on, but those seemed to only make it act like a flat battery although it may have contributed, but for sure the wrong pin out made it act like the ECU died and went bat shit crazy. If I only supplied 12v on that plug and nothing else, it was fine and that's how I figured the mismatch was the issue.

So def double check stuff like this.

Good advice for anyone doing a new install.

In my case, the car had been running fine on the NVRAM for about 10 years before the engine starting acting up throwing a Code 55.

My first thought was the NVRAM battery has finally crapped out, but swapping to another ECM "solved" the problem (for a short time).
The intermittent nature of bad one day/corrects itself the next had me blindly chasing Code 55 "check engine grounds" points throughout the car.

It wasn't until I noticed Service Engine Light WAS NOT ON with Key On whenever engine would start/stall, that I was able to find a diagnostic chart to systematically follow.
And yes, it was a ground issue, but in the multi-pin connection to the ECM itself. After weeks of frustration, problem was solved in 1 hour.

Five days on and engine still fires and runs properly every time <fingers crossed LOL>

[vlad01]

Yep! Those pesky grounds! I didn't checked if the CEL was doing anything or not on this car I am working on atm, but TP item list logged 55 and another code I can't recall the number but said unstable voltage. The unstable voltage I reckon in my case was the grounds, but the weird harness pin mismatch was what was causing the ECU to go mental and spit a 55, the TPS appeared faulty and sometimes inverted.