Hunting idle

[Rice car]

Hey guys

Some info on the car in question:

95 VS commodore, manual, l67 conversion + mods.

The issue:

Just wondering if anyone would have any idea on where or what to look at that would cause my car to hunt at idle. It is probably the reason my car also has a DTC 76.
I've searched for vacuum leaks but haven't found anything. I do plan on replacing every vacuum line anyway, so if anyone has a diagram for an l67 or even knows what size hoses are needed, that would be great.

Also, the car has a (what feels like) misfire when coasting at around 1500rpm, in any gear.

So far I've replaced the dfi module, CAS, o2 sensors, purge solenoid, IAC valve, PCV.

I've checked the spark plugs and leads (with a multimeter), injectors all work.

Not sure where else to go. Just need a little bit of guidance, I've searched a fair bit and I've fixed what I thought it could be, short of pulling the motor apart and replacing gaskets. I am looking at doing compression testing through the week and probably buy a diagnostics cable to see if I can get anymore info.

 

[BottleFedVS]

Try replacing your coils or crank angle sensor.
DTC 76 - Air/Fuel ratio variation between left and right banks
This may be a false code thrown up because of the miss. However you may also want to check that both oxygen sensors are ok and in reasonable condition.
I hope that helps.

 

[losh1971]

Try cleaning the MAF

 

[Deuce]

Throttle blade manual stop adjusted correctly for proper IAC steps?
This can effect hunting if you have been messing with it.
If it used to go fine and you've never touched thia, DO NOT TOUCH IT NOW. Or you'll create more issues for later

 

[Rice car]

Try replacing your coils or crank angle sensor.
DTC 76 - Air/Fuel ratio variation between left and right banks
This may be a false code thrown up because of the miss. However you may also want to check that both oxygen sensors are ok and in reasonable condition.
I hope that helps.

Already replaced the crank angle sensor and o2 sensors. I will look at buying some now coil packs because I have read that they can still be faulty even If tested ok (with a multimeter).

Try cleaning the MAF

have done so, no change

Throttle blade manual stop adjusted correctly for proper IAC steps?
This can effect hunting if you have been messing with it.
If it used to go fine and you've never touched thia, DO NOT TOUCH IT NOW. Or you'll create more issues for later

I haven't touched it, but I can't say if the previous owners haven't. It's been doing it on and off since I got it. But now it seems to do it every time i stop (lights/signs/ect)

 

[Rice car]

Im now leaning towards lack of tune. It has basically been rebuilt with modified parts; cam, lifters, rockers, flat top piston (the main reason I feel the tune may be be non-existent), bigger injectors, fuel pump, smaller pully, pushrods, valves springs, exhaust, ect.

Im probably better off putting in another motor and rebuilding this one, but I won't have time to for a few months.

But I'm open to any other ideas that people may have in the meantime that I could check in case it has been tuned.

 

[mikman42]

fuel pump could be dying

 

[Rice car]

fuel pump could be dying

Would it be intermittent though?

 

[t_lala92]

Did you ever find out why the car was hunting during idle? I've got the same issue ATM with my 09 VE wagon. My mechanic is scratching his head! It's been there for a month with majority of issues fixed but this one hunting issue! I need my car back! The car had 2 failed fuel injectors, all spark plugs had to be replaced. Misfires were happening in the cylinders but now fixed with the new fuel injectors.

 

[ephect]

Did you ever find out why the car was hunting during idle? I've got the same issue ATM with my 09 VE wagon. My mechanic is scratching his head! It's been there for a month with majority of issues fixed but this one hunting issue! I need my car back! The car had 2 failed fuel injectors, all spark plugs had to be replaced. Misfires were happening in the cylinders but now fixed with the new fuel injectors.

Totally different engine and components.

Best start a new thread in the ve section