Engine Missfire

[Tiny78]

Guys,

I've got a 99 Speed Six that's got an engine misfire.

From 3,800 to 4,200 rpm in all gears the misfire is quite obvious.

I've changed the coil pack, ht leads and spark plugs and it hasnt made any difference.

Any advise would be greatly appreciated.

Cheers,

Rich

[bionicjim]

I could be a million and one things
But it's good to see you have started checking the easy stuff
I would guess that's its a set up thing or poss throttle body balance or maybe both

[FUBAR]

If its not the coil packs or leads then start looking at throttle pots and lambda sensors (guess who's been through this recently)

[awhite2199]

Hope it's not but could be worn throttle bodies.

A

[anonymous-user]

FUBAR said:

If its not the coil packs or leads then start looking at throttle pots and lambda sensors (guess who's been through this recently)

M3John?

[ukkid35]

djstevec said:

M3John?

[Tiny78]

The car was set up on Austec's rolling road when the miss was found.

That was when the coil pack, leads and plugs were changed, and they thought the problem had been cured, but as soon as I drove the car the miss returned.

Unfortunately Austec are a good three hours away from me and I've not had the chance to go back.

Can i assume that throttle bodies are the worst case scenario?

How much could they set me back?

[FUBAR]

LoL not yet...just ordered the coil packs today

[ukkid35]

Tiny78 said:

The car was set up on Austec's rolling road when the miss was found.

That was when the coil pack, leads and plugs were changed, and they thought the problem had been cured, but as soon as I drove the car the miss returned.

I would connect the diagnostics and look for noise from the throttle pot (I presume there's only one on a SpeedSix?)

Since it was found on the rolling road, that could suggest it's throttle position related rather than RPM related - does that make sense?

[N1CERB]

Did you try fuel pressure regulator?

[Tiny78]

Thanks for all the ideas.

I'll put the car into the garage and see what's happens,

Cheers,

Rich

[N1CERB]

See my pic on loose wire inside coil pack connector plug. Possibly the same on a Six??