error code 12 help

[Glanza Gaz]

Hey guys, recently after a trip in the lakes my car has started to mis-fire on load/boost > 0.7 bar. I've just done a diagnostic check and got error code 12, which after a little bit of research is 'no rpm signal'. Any help in diagnosing the cause of this would be greatly appreciated, of course rep will be dished out to you helpful lot
cheers, Gaz

 

[Glanza Gaz]

late night bump

 

[Glanza Gaz]

cmon, someones gotta know or have had experience with this code!
apparantly this code occurs, if the 'G' or 'Ne' signal from the distributor is not picked up by the ecu within the first 5 - 10 seconds of cranking. Anyone know what could cause this, how to check it or even what the hell 'G' and 'Ne' mean/represent haha!
At the moment I have ordered a new dizzy cap in the hope this will solve it, but any info/experience on the fault would be greatly appreciated,
cheers, Gaz

 

[Texx]

It's possible there's a break in the wire harness that connects the distributor to the ECU which only becomes apparent when the engine moves under load. The wiring diagram shows the distributor circuit as having a grounded shield around the wiring, I'd think the outer shield would also be used to ground the Ne and G sensors, so if it's the outer shield that has the break it'll effect both pickups. Have you tried wiggling the wire harness that connects to the distributor to see if the mis-fire appears? Just be careful you don't get hit by a bolt of lightning from one of the HT leads in the process.

 

[Glanza Gaz]

It's possible there's a break in the wire harness that connects the distributor to the ECU which only becomes apparent when the engine moves under load. The wiring diagram shows the distributor circuit as having a grounded shield around the wiring, I'd think the outer shield would also be used to ground the Ne and G sensors, so if it's the outer shield that has the break it'll effect both pickups. Have you tried wiggling the wire harness that connects to the distributor to see if the mis-fire appears? Just be careful you don't get hit by a bolt of lightning from one of the HT leads in the process.

Nice one I'll have a look tomorrow. After a little more research it appears 'Ne' is an engine speed sensor (24 tooth reluctor) and 'G' or if Im correct 'G1' and 'G2' on the 4efte are crankshaft positional sensors within the distributor that fire off at 360' crank rotation intervals 10' BTDC. Like you said both 'G' and 'NE' share the same ground 'G-'. Although I'd of thought that if it were a break in the earth bonding, I would also get error code 13: 'No 'NE' signal when engine speed above 1k rpm' unless the fault is only on 'G' as error 12 states ' no signal to ECU from 'NE' OR 'G' suggesting that either one of them could trigger error 12 individually. hmmmm too much to ponder at this time at night hahaha :homer:
Anyway during my search of the web I came across this article which I thought you might want to have a look at if your interested or for future reference:
http://www.autoshop101.com/forms/h23.pdf
dunno if it's already been listed on here but what the hell
cheers,
Gaz

 

[scrappygit]

Pm'd for advice