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About ready to throw the whole car in the bin

5ltrlady

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Vt S1 5ltr auto
Hey all. I'm suffering a misfire gremlin and im at my wit's end. Please chuck some suggestions at me.

Car is a 1999 VT commodore S1 with the 5ltr conversion. Auto. Engine is stock.

Consistent misfire through entire rev range. From idle to 4000. Doesn't change in any gears, forward or reverse and doesn't change with heat. Replacing the dizzy didn't make any difference, it was timed properly with a timing light, all leads connected in correct order and place and new dizzy was installed exactly the same as the removal of the old one.

So far I've changed

Spark plugs
Leads
Coil
Dizzy (complete)
Ignition module
Done the wire reroute to avoid noise from coil to ICM.
Dropped the cats and it made no difference.
Fuel pump
Fuel reg
Fuel injectors serviced and no leaks.
Fuel filter
Compression tested. Results are in psi
Passenger side
136
137
140
135
Drivers side
140
155
136
137
Checked all earth's, cleaned and reassembled.
Ignition ring replaced as car was having trouble starting. Misfire started before this. This solved the starting issue.
Pcv checked and new hose fitted due to age deterioration (passenger side)
Maf swapped with known working
IAC and TPS swapped with known working.
No air leaks at all.
Rockers checked for twists or imbalance due to 155psi compression reading on cyl 5. This was not the issue. Thinking valve? But don't want to pull the head if I'm missing something.
All fuses checked and replaced if old/burned to ensure clean connection, all relays replaced with known working. Have pulled pcm fuse to reset. Made no difference. Battery has been disconnected. Made no difference.
Oxy sensors replaced with known working.


Codes: 22,23,32,35,48. Only code that sticks around after reset is 48. I'm aware I have a HES that acts as crankshaft sensor.
 
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lout

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remove one injector lead at a time and go for a drive
if it is worse move onto next lead
until you find the lead that makes little difference
then swap injector from that cylinder and see if fault follows injector,
then swap plug lead from that cylinder and see if fault follows lead
then swap spark plugr from that cylinder and see if fault follows plug
i dont like the 155psi, cyl 3? as second in your list, or is it 5 counting from back
check if rockers seem to be moving equal amounts
 

Trevor loves holden.

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Its telling you the signal to cam sensor isn't there, not a cheap one is it? seen a lot of post lately having issues after replacing dizzy, you should check all your wiring and connections.
 

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5ltrlady

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Vt S1 5ltr auto
Must be very strong, and your bin must be big..
I'll build a bloody bin big enough!

It's definitely cylinder 5. As in 1,3,5,7. Second from the firewall on drivers side. I don't like it either, it has me worried. I wrote them as they sit from firewall forward. Thinking about it though, I can understand the confusion. Should of flipped that list.

Thinking injector.

Dizzy is fine, leads are all in order. 48 is crankshaft not cam. Same sensor though. Nooo not a cheap one. Arm, leg, first born child type thing haha
 

BlackVXGTS

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When you say "Car is a 1999 VT commodore S1 with the 5ltr conversion", do you mean the 5ltr option, or do you mean that it was a V6 that was converted into a V8 via an engine swap?

With that number of sensor-based error codes, I'd be suspecting the PCM. First step would be to remove the PCM connectors, spray them with circuit board and contact cleaner (available from Supercheap, Repco, Autobarn etc.) and replace them a couple of times.
 

immortality

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If the misfire is consistent on one cylinder after swapping injector, leads etc than I too would suggest swapping out the PCM next. The VT 5lt is full sequential injection which means each injector is fired individually so a faulty injector driver could cause a misfire, if not a faulty driver than possibly a wiring harness issue. A Noid light might reveal more too.
 

5ltrlady

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Vt S1 5ltr auto
When you say "Car is a 1999 VT commodore S1 with the 5ltr conversion", do you mean the 5ltr option, or do you mean that it was a V6 that was converted into a V8 via an engine swap?

With that number of sensor-based error codes, I'd be suspecting the PCM. First step would be to remove the PCM connectors, spray them with circuit board and contact cleaner (available from Supercheap, Repco, Autobarn etc.) and replace them a couple of times.
It was a v6. Converters into 5lt. Thinking pcm needs to be replaced soon. Too many ongoing problems.

I've found a non functioning injector, don't know how it would be blocked as it was fine on a priming test however not fine when plug pulled. Replacing said injector has helped but It's still not running right but it's better. Thinking combination of pcm and maybe just fault in pcm connection to injectors?
 

_R_J_K_

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It was a v6. Converters into 5lt. Thinking pcm needs to be replaced soon. Too many ongoing problems.
When you had the car converted, did you have the ECU linked to the car? Did you just put it in the car and it started? 5L engine, ECU, and loom all from a VT or something else?

When you took the rocker cover off to look at cylinder 5 you didn't check to see if the valve springs on that cylinder were shorter (snapped) or try to compress them with your hands? Sounds weird but this has been a thing before. Maybe also look at something like a bent push rod.

Also, part number of the spark plug you're using.
 
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