idle missfire

[CJ-IROCZ]

The maro has developed a mis fire on idle. I dont notice it mising when driving but thats not to say it isn't there.

I'm going to check the obviuos things tonight like plug leads ect but I could do with some suggestions from you guys.

The idle rev's seem low and there is also a slight exhaust leak but Thsi is a definate missfire.

[Gator]

plug lead i reckon is the rev counter a bit twitchy

[55starchief]

Check your vacuum line on the advance of the dizzy

[Gator]

is it vacuum advance though

what engine is it craig

[CJ-IROCZ]

L98 mate, the rev counter is a little twitchy at low revs

I'm going to have an inspection at dinner time.

I hate little problems like this

[55starchief]

is it HEI as it might be the coil pack on the way out as the rev counter takes its feed from that

[CJ-IROCZ]

I have just checked the leads and dizzy cap/rotor arm and they all look good , as they should as they were only replaced about 500 miles ago.

I'm going to take it up a friend of mine who's a mechanic and knows a bit about V8's. hopefully its something simple but something tells me this could be a pain.

[CJ-IROCZ]

Stupid question but can you pull the spark leads off the dizzy whilst its running ? just to see if there is an obvious problem on one or more cylinders

[55starchief]

Quoting: CJ-IROCZ

Stupid question but can you pull the spark leads off the dizzy whilst its running ? just to see if there is an obvious problem on one or more cylinders

YUP

Just make sure you use a pair of insulated pliers as a 40,000v shock isnt nice

[F Body]

Quoting: 55starchief

YUP

Just make sure you use a pair of insulated pliers as a 40,000v shock isnt nice

As I was going to post " You can but it hurts ! "

[Gator]

how old is the dizzy

[55starchief]

Quoting: F Body

As I was going to post " You can but it hurts ! "

no thats what happens when you put your hand on top of a coil pack used on a hart 1500cc turbo, that was about a 100,000 shock. The guy lost feeling in his arm for almost 5 mins

[CJ-IROCZ]

My mate reckons its either vacuum leak or a plug, there isn't a huge difference when you pull one of the leads off.

I've had a good look but there are no noticable leaks. there is 2 pipes that run under the plenum one goes to a cannister in the front right bumper area and one goes to some sort of valve directly below the plenum. Both then finish at a plastic junction under the distributor but there are no pipes coming out of the other side of the junction

th plugs are not very old but the car has been stood since fitting them + they are champions and my mate reckons they are shite

Might just order a set of good ones , anyone recommend some.

[CJ-IROCZ]

Looks like the 2 vacuum lines that run under the plenum go to the EGR solenoid.

[CJ-IROCZ]

would injectors give the problems i'm experiencing ?? andanyone know how to check injectors

[55starchief]

Quoting: CJ-IROCZ

would injectors give the problems i'm experiencing ?? andanyone know how to check injectors

Possible, you need a set of noid lights to check injectors, but if it was those i would expect to see the SES light on

[CJ-IROCZ]

noid lights ???

No SES lights though

[Gator]

you can do injectors with multimeter

[55starchief]

Quoting: CJ-IROCZ

noid lights ???

they plug in where the injector would and flash mate

Have you pulled the vacuum line of the egr to see if it makes a difference?

[CJ-IROCZ]

No, I think thats my next step. I'm going to pull the plugs and check them and then pull the vacumm lines whilst its running to seem if there is any difference.

I'll post what happens tomorrow.

[Gator]

it could also be the idle air valve if its low on revs it could need a clean or might be buggered

[art b]

it just needs a feckin raggin a brisk run, craggy....

[CJ-IROCZ]

tried that Art but stil no joy

Steve IAC is on my list, is it the electrical connection on the lower left hand side of the TB ?

[Gator]

yep the square one under the throttle position sensor

[Pod]

You could put a vacuum gauge on it and actually see what's going on....