Running on 5 cylinders.

[J_D]

G'day all.

My VN has started to feel like its running on 5 cylinders at idle. It started about a week ago. It feels fine when cruising or with the throttle down with only a slight vibration but is crap at idle. So far ive done a power balance test(pull each injector plug and listen for rpm drop) initially number 2 cylinder wasnt dropping the idle so I pulled the injectors and cleaned them up and swapped the number 1 and 2 injectors around(to test for dodgy injector) but now the 1 and 2 cylinders both drop revs when the injector plug is pulled but I still have the problem. Im thinking something to do with ignition. I will be getting new plugs and leads as they are probably due for replacement anyway. If anyone has any better ideas or have had the same problem any help would be appreciated.

thanks.

[SweetWagon]

well the coil setups used on the v6's utilise each coil (3 coils total) sharing 2 cylnders each. so if 1 coil dies then so does those 2 cylinders.... you have a s1 so chances are you have s1 coils which cannot be replaced individually unlike the better s2 setup. hope it helps

[88GreenVN]

Have you changed plugs. Leeds normally play up under load - eg when going up a hill you get a miss fire where the car feels like its being tugged at from behind and then let go. so leeds may not fix the issue.

[Tasmaniak]

didn't the VN S1 coil packs have an issue with being faulty so a lot of people simply swapped them over to VP or VRs?

[J_D]

Mine have already been swapped over to VR coils. I know its probably not the leads or plugs but they need to be done anyway. So how do you test the coils?

[samuels]

G'day all.

My VN has started to feel like its running on 5 cylinders at idle. It started about a week ago. It feels fine when cruising or with the throttle down with only a slight vibration but is crap at idle. So far ive done a power balance test(pull each injector plug and listen for rpm drop) initially number 2 cylinder wasnt dropping the idle so I pulled the injectors and cleaned them up and swapped the number 1 and 2 injectors around(to test for dodgy injector) but now the 1 and 2 cylinders both drop revs when the injector plug is pulled but I still have the problem. Im thinking something to do with ignition. I will be getting new plugs and leads as they are probably due for replacement anyway. If anyone has any better ideas or have had the same problem any help would be appreciated.

thanks.

if it's now doing it to # 1 and 2 injector,after swapping them around,i'd be looking at the washers or seals first,once again,the problem you are describing can be an array of things,like people are saying....plugs or leads right through to a crook sensor and worst of all a burnt out valve(s)
can you compression test it? thats a tell tale sign of anything internally,if it is low on compression

[Not_An_Abba_Fan]

I thought he said that #'s 1 and 2 are OK now because both drop revs. I'd be trying a different coil pack and DFI module if you can get hold of them to see if it improves.

[samuels]

I thought he said that #'s 1 and 2 are OK now because both drop revs. I'd be trying a different coil pack and DFI module if you can get hold of them to see if it improves.

so he did...my apoligies

[J_D]

I thought he said that #'s 1 and 2 are OK now because both drop revs. I'd be trying a different coil pack and DFI module if you can get hold of them to see if it improves.

I will get a coil pack and then the DFI from the wreckers then. What models have the same DFI as the S1 VN, incase i cant get one off a S1 VN?

[PaRaDoX]

checked leads? mine did the same thing turned out to be fouled leads

[Not_An_Abba_Fan]

A lot of people change them to the later model because each pair is individual unlike the S1 which is a one piece coil pack.

[J_D]

Update.

Well ive done the plugs and leads, tested the coil resistances (all OK) and replaced the o2 sensor but the problem is still there. The computer seems to be compensating for it to some extent because now the idle isnt that bad when in gear although it does have a vibration at idle but when you put it into park or neutral the revs flare up to about 1100rpm and settle back to about 1000rpm which is a lot higher than it used to be and when its in neutral/park you can feel the engine imbalance a lot worse. It hammers when I put the boot in now with new plugs and leads and the o2 sensor seems to of improved initial throttle response. I also got all new suspension over the weekend so now I just need to solve this problem and then the car will be sweet.

[J_D]

OK, so far ive replaced the following.

Spark plugs (new)
Spark plug leads (new)
o2 sensor (new)
IAC valve (new)
Coil packs (second hand)
DFI module (second hand)

and ive still got this problem. Does anyone have anymore ideas? I was thinking maybe the torque converter. I dont think its a mechanical problem because it only does it down the bottom of the rev band, (idle to 1500rpm) if it was a mechanical problem I would expect it to affect the engine all the time (or at least at different temperatures).

Problem fixed. It was a dodgy injector. Bought a set of injectors from the wreckers for 20 bucks, runs smoother than it ever has.