VX L67 Series 1 - PCM or Com Problems?

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
Red_Six
Posts: 10
Joined: Wed Jun 23, 2021 1:18 am
cars: VX, LC, HQ

VX L67 Series 1 - PCM or Com Problems?

Post by Red_Six »

Hi Everyone,
I'm new to the forums & tuning the Holden PCMs but have had some experience with a few aftermarket ECUs.

I've been trying to troubleshoot a problem with my car for a while now. The car has an intermittent misfire or stumble that happens at all loads & speeds. The ignition module died and was replaced but that was a symptom of another problem with the leads (also replaced). I have also replaced the AFM, sparkplugs, cam sensor and tested other sensors.

I thought I had trouble connecting to the ECU with the ALDL cable (from Envyousy Customs, tested working on a VX N/A 3.8 before) that I had because I was unsure if the tune had been previously modified. There was a plain MEMCAL and a MEMCAL with "HSV XU6 (Enhanced)" label on it. I tried a few adx files but still had the problem of the gauges displayed values jumping all over the place.
I bought an NVRAM module so I could do live tuning, thanks Gareth, and can connect but still have the same problem. This happens whether the engine is running or not.

The battery and alternator are good but the displayed voltage is all over the place.

I have read through the FAQs but didn't find an answer to this problem, unless I missed something.

Could this be a problem with the PCM? Or is it a problem with the wiring? Or just with me? :wall:

The numbers on the PCM are:
Service No. 16233396
3.8L Auto PCM
16269068
*869068S502135039*
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'quipt4it
Posts: 675
Joined: Sun Oct 28, 2012 12:57 pm

Re: VX L67 Series 1 - PCM or Com Problems?

Post by 'quipt4it »

Hi Red_Six,
It could be the ADC (Analogue to Digital Converter) in your computer gone bad.
Also check all PCM earths.
Can you swap in that other PCM to rule this in/ out.
Also check the TPS output just to be sure it's OK.
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: VX L67 Series 1 - PCM or Com Problems?

Post by immortality »

Another user recently had connection issues and he discovered damaged wiring going to the OBD2 port.
Red_Six
Posts: 10
Joined: Wed Jun 23, 2021 1:18 am
cars: VX, LC, HQ

Re: VX L67 Series 1 - PCM or Com Problems?

Post by Red_Six »

Thanks for the tips.

I'll try checking the earths and the OBD2 wiring.
I think it could be one of the earths as it seems to be making the engine run erratic and not just affecting the coms.

Hi quipt4it, unfortuneately I don't have a spare PCM at the moment. It's quite frustrating being my daily driver.
The ADCs would be in the micro-controller, going by other ECUs I've worked on. Not an item anyone has had a go at replacing on the board.
'quipt4it
Posts: 675
Joined: Sun Oct 28, 2012 12:57 pm

Re: VX L67 Series 1 - PCM or Com Problems?

Post by 'quipt4it »

Red_Six wrote:...It's quite frustrating being my daily driver...
I'm hearing you lol.
Just fixed up my old VZ SV6 daily.
Found an open circuit injector (0280 156 131). Had to replace it ASAP. Paid overs for a fake copy lol.
Funny thing is, it's never run better :lol: :driving:
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delcowizzid
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Re: VX L67 Series 1 - PCM or Com Problems?

Post by delcowizzid »

Click the rs232 echo setting in the adx and see if it stops jumping
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
Red_Six
Posts: 10
Joined: Wed Jun 23, 2021 1:18 am
cars: VX, LC, HQ

Re: VX L67 Series 1 - PCM or Com Problems?

Post by Red_Six »

Thanks for all the tips and pointers.

Yesterday I finally got a few minutes to work on the car.

All the grounds tested okay. The hot battery voltage at the PCM was the same as the battery voltage at the terminals. The board looks okay and couldn't find anything else when inspecting.
I connected the laptop with TunerPro RT and was able to get a stable connection & readings. I think I must not have loaded the .adx file correctly previously :oops:

The stumble/misfire is still there but at least with the laptop able to communicate I should be able to change to the upgraded injectors now, once I read up on how to change the settings for that. :study:
Red_Six
Posts: 10
Joined: Wed Jun 23, 2021 1:18 am
cars: VX, LC, HQ

Re: VX L67 Series 1 - PCM or Com Problems?

Post by Red_Six »

Finally have a spare moment for a quick update.

I was able to install the new injectors... still no change.

I ordered a delfi ignition module and that has now fixed most of the problems. I will try the new coil packs to see if that helps the occasional misfire/stumble. It probable needs a bit of time tuning to clean up a few parts in the mapping with the bigger injectors, when i can get to it...
Red_Six
Posts: 10
Joined: Wed Jun 23, 2021 1:18 am
cars: VX, LC, HQ

Re: VX L67 Series 1 - PCM or Com Problems?

Post by Red_Six »

Well I am a bit baffled.

I swapped in the new NGK coils (3x) on top of the Delphi ignition module, and tested again. It would fire up momentarily but would not idle or even run on the new standard coils. I had to swap back to the old MSD coil packs again.
Not sure why. The leads still look in good condition. May have to try a new set of plugs again.
upyas
Posts: 76
Joined: Wed Mar 29, 2017 11:51 pm
cars: vy s

Re: VX L67 Series 1 - PCM or Com Problems?

Post by upyas »

does it jump to max then back and then back and back etc etc?

if it does that happens to me alot, just disconnect and reconnect until it starts working. Usually happens with l67's for me. sometimes it works after the 5th time sometimes 10 times but usually always starts to work.
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