P0301 code on RA Rodeo with VZ alloytec ???

[Davew033]

Hi all, have had an issue for fourteen months on cold start up. Have a misfire on no.1 on first start of the day until the engine warms up a little and you turn it off and restart again, then it is okay for the rest of the day.
This engine is also dual fuel. If you do not turn off and restart, the miss will continue on both petrol or gas until such time you pull over and restart. The engine has had new lpg cyl.heads, new timing chains,guides and tensioners, new coils, new plugs, new ecu temp sender, ecu has been sent for testing 12 months ago and just been sent back for reco but to no avail. Has also had new no.1 injector fitted, been to local holden dealer for testing and local auto electrician and also had all earths and wire harnesses checked twice.
Intake manifold rear mounting bolt was a bit loose but tightening didn't make any difference.
Can anybody tell me what can cause a miss to no.1 with P0301 code and check engine light on at cold start only? Have also swapped plugs and coils from other cylinders to no.1 with no difference. Starting to run out of ideas, hoping someone may have had this same issue at some time?
Regards Dave

 

[99notout]

If your have a fault on one cylinder, and have replaced that injector (you can get a bad one out of the box, don't discount it, but they are easy to check), and also replaced the ECU (same issue), then you can probably discount the driver in the ECU, and injector, and that really only leaves the wiring. As it only happens when cold, then you have an ideal opportunity to check the injector is receiving the pulse from the ECU on first start up and go from there. Could be a stretched pin connector at the ECU for cyl 1, or a break in the wiring that touches when warm, but too many variables to guess over a forum. Tip, see if you get the pulse to cyl 1 when cold probe the brown with blue trace wire at the X102 connection and look for a pulse with an led wiring probe from supercheap or somewhere, just put a pin through the wire to pierce the insulation. If no signal, then you will have to check cold again at the wiring from the ECU (don't unplug it) either back probe it, or once again pierce the wire near the ECU. This is assuming the 5v reference is good to the injector cold? If you have a signal there, then there is a problem in the wiring, if no signal directly from the ECU, then it is getting a bit more complicated. I've attached the wiring diagram for the injectors, and the location of X102.

Also the ECU can intentionally shut down a cylinder if it detects no spark. This is to reduce unburnt fuel going out the exhaust, and or burning the cat. Just an after thought.

 

[Davew033]

Thanks 99notout,
Forgot to mention that once started cold and the miss happens i can drive for twenty klms or more on petrol or lpg and the miss will not stop until such time as i turn off and restart. Can also idle till temp comes up a bit then turn off and restart. What is it that resets once restarted ?? Will take miss away but check engine light remains. Racking my brains trying to determine what is causing the shutdown to no.1 only. Have again just been through coil by coil replacement, also ran another wire to no.1 injector from the other side of harness plug to eliminate injector harness. Had all sorts of problems trying to get the ecu revamped and have heard they may not do them anymore owing to the dramas they have had with the vz ecu?
Thanks again, your help is much appreciated.
Regards Dave

 

[greenacc]

Sounds like it would be worth changing spark plugs to rule them out.
We're new plugs fitted when the chains were done?

 

[Davew033]

Sounds like it would be worth changing spark plugs to rule them out.
We're new plugs fitted when the chains were done?

Thanks greenacc, plugs have been changed twice and also swapped to no.1 from other cylinders along with the coils.

 

[99notout]

I would bet that the ecu is actually disabling the coil and not the injector, changing coils around won't fix this as the signal to fire the coil is missing. Try and verify that it is actually the injector, even if you just buy a single noid light, and jumper it inline while the engine is missing. No matter what, all engines only need air, fuel, spark and compression to operate. You obviously have compression because it runs ok when warm, you must have air, so eliminate fuel and spark and prove which one it is first.

 

[Davew033]

I would bet that the ecu is actually disabling the coil and not the injector, changing coils around won't fix this as the signal to fire the coil is missing. Try and verify that it is actually the injector, even if you just buy a single noid light, and jumper it inline while the engine is missing. No matter what, all engines only need air, fuel, spark and compression to operate. You obviously have compression because it runs ok when warm, you must have air, so eliminate fuel and spark and prove which one it is first.

Will see if anyone i know has a noid light if not will grab one, being old school mechanical i don't have a lot of electronic testing equipment. Since the ecu revamp have now also found that if i disconnect the battery and reconnect it now makes the problem and check light disappear even though they assure me the ecu does not reset? Also still have power through one wire at the coils with battery disconnected?
Can you tell me where that comes from?