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[Andy H]

Basically, the car when correctly identified as a manual drives fine until 4K under load. In first gear, or de-clutched it will rev right round, smooth as anything.

If you rev to 4k you loose 2cyls, if you can struggle to 4k again you loose another two!!

I see why TB is curious about the mass flow readings now. Whatever it is seems to be related to the apparent load. Cut two cylinders and the apparent load will increase because 1/3 of the air passing through the mass flow sensor is being pumped through the dead cylinders.

I assume you checked for fuel starvation last time this issue occurred.........

Posted by: AndyStobbs Yesterday at 20:57:16 »
Just to throw another variable into the mix (though I don't set much store by it) does the operation of the multiram system differ between auto and manual differ?

Rear multiram opening occurs at about 4K IIRC. Can't see why auto should be different to manual but I wonder if the solenoid is faulty or a trapped wire is shorted somewhere

[Kevin Wood]

You can see multiram operation in the datalog (Intake valve 1/2) and they do operate normally a few times before the fault occurs. 

[AndyStobbs]

Shouldn't kill cylinders no matter how bad the wire is. We haven't got to the bottom of how the cylinders are failing yet though. That log file is missing all the useful sensor data.

[Andy H]

Shouldn't kill cylinders no matter how bad the wire is. We haven't got to the bottom of how the cylinders are failing yet though. That log file is missing all the useful sensor data.

The rev-limiter on the V6 ECUs works by cutting cylinders - normally somewhere above 6500 rpm

If there is a current fault code then the rev limit drops to 4000 rpm so we are working on the assumption that the ECU is cutting cylinders.

My naff code reader isn't discussed on here because it isn't legally available in the UK (only pirate copies) and we don't want any lawyers trying to shut the site down.

[Entwood]

Going by what Andy has just posted ..... rev limiter .. is that "adjustable" via Tech2 program If it is ... is there a "chance" that the Rev limiter has been set at a "wrong" value ??

Or are the manual  ECU's "missing" a rev signal and "assuming" its reached the rev limiter at 4000 rpm ?

[jtypecav]

Will look out the laptop tomorrow to see if it has any of the files still.

As for limiter.. I wouldn't mind a rev limiter, or something that felt like one. This properly goes permanent misfire like when a coil pack goes!

[Andy H]

Will look out the laptop tomorrow to see if it has any of the files still.

As for limiter.. I wouldn't mind a rev limiter, or something that felt like one. This properly goes permanent misfire like when a coil pack goes!

So once it loses two cylinders they don't start firing again?
Do they come back immediately if you stop & restart the engine?

[jtypecav]

Once they are gone they are gone. They don't come back till you ign off and start again.

The bizarre behaviour is above 4k loose 2 cyls, then struggle up to 4k again (whilst running only on 4) and you loose 2 more (and it's trying to run on 2 cyls!)

Off and on again and it's back on 6, no matter what circumstances - happy as larry till you dare rev it again. Or as an auto it pulls strongly to the redline!



*edit* I say 4K - it's pretty much there, but couldn't say whether it's just reaching some threshhold or actually rev related, but it has a 100% reproduction rate.

[Andy H]

Once they are gone they are gone. They don't come back till you ign off and start again.

*edit* I say 4K - it's pretty much there, but couldn't say whether it's just reaching some threshhold or actually rev related, but it has a 100% reproduction rate.

The fact that that it resets after cycling the ignition points very strongly to a software/firmware issue in the ECU. Something unexpected triggers the stage 1 rev limiter but nothing 'untriggers' it afterwards. Do it again and stage 2 is triggered.

We don't have access to the source code for the ECU so we cannot check for 'unexpected' triggers, it might be a properly useful piece of protective code but it does appear to be a bug that is only exposed when the ECU is coded for manual transmission.

Have you checked the battery/alternator voltage when things are getting weird?

[jtypecav]

Hi Andy, that's the long and winding path my limited reasoning took originally. I hadn't checked the voltage at the same time. I think that both ecu's are good, so I binned a "broken one"..  months back.

Were there ever any critical software updates for that engine? It was running factory version apparently. I bought her with 60k on, although it would be crazy if the old boy had never got it to 4k!!

[Kevin Wood]

IIRC, Taxi Al had a very similar issue to this.. on a Manual 3.2.

Can't remember what fixed it in the end.

[jtypecav]

Kevin - don't tempt me to spent hours searching the forum!!

Here are two original live data captures from start till EML blinking taken when I first experience the same problem 18months ago.

6 >> 4 cylinders: https://dl.dropboxusercontent.com/u/2011453/ECU_Good_to_Bad_Livedata_2001_Omega-B_Engine__Y%2026%20SE_201206261444.xlsx

4 >> 2 cylinders(!):
https://dl.dropboxusercontent.com/u/2011453/Bad_to_Terrible_Livedata_2001_Omega-B_Engine__Y%2026%20SE_201206261450.xlsx

[05omegav6]

IIRC, Taxi Al had a very similar issue to this.. on a Manual 3.2.

Can't remember what fixed it in the end.

Two coil packs, two engine looms and alot of head scratching

Alot of bits were swapped in the process, only significant item was a year old pattern MAF was replaced with the original one (which is still fitted)...

[AndyStobbs]

Has anyone with a scope looked into this yey? Or has it all been done on live data?

[jtypecav]

Just live data, the injector testing was done by a friend who was a Vauxhall mechanic for years, same chap who donated 3.2 parts to this temporarily.

Fully open to a trek for a days diagnosis now!