Severe Engine Miss

[lennyrebel]

Okay--tech jargon 9472 OBD2 CODE PO300 [9999] missfire happens at 65 kil/hour [35mph] most collected on cyls 5+7 Replaced 5&7 sparkplugs and clear DTC. So thats the verdict, first time it was one sparkplug at about 500 miles. This time 9400 kms about 5500 miles. No other info from dealer, anyone else have any strange occurences like this? Regards The Rebel

[lennyrebel]

I'm Wondering -are they platinum plugs in the 6 litre engine? I've never experienced this problem with my Avalanche that I drove 4 years. Service engine light never came on. Yukon before that I drove 9 years and only saw light twice. Any advice? Regards The Rebel

[ssgharkness020147]

Does the H2 have a EDIS system?

[f5fstop]

That many spark plugs in 5500 miles, makes me think something else is wrong. If it happens again, recommend to the dealer to a compression check on all affected cylnders for a start.

ssgharkness020147
What's EDIS? It does have an electronic ignition system if that is what you are asking.

[ssgharkness020147]

EDIS stands for Electronic Distributorless Ignition System. It can also be called a direct coil system.

[f5fstop]

Originally Posted by ssgharkness020147

EDIS stands for Electronic Distributorless Ignition System. It can also be called a direct coil system.

Wow, we have not called it that for years in house....

[ssgharkness020147]

You should use it more often, especially around people that know very little about cars. People will think that you are really really smart.

Either way your right. The term is like sooo 90's

Originally Posted by f5fstop

Wow, we have not called it that for years in house....

[lennyrebel]

Originally Posted by f5fstop

That many spark plugs in 5500 miles, makes me think something else is wrong. If it happens again, recommend to the dealer to a compression check on all affected cylnders for a start.

ssgharkness020147
What's EDIS? It does have an electronic ignition system if that is what you are asking.

A friend just told me samething. He said he ws getting missfire one cylinder, the compression test showed one cylinder 30 pounds low--discovered broken top ring. Separate coil for each plug with crankpulley inductive pickup. regards The Rebel.

[f5fstop]

Originally Posted by lennyrebel

A friend just told me samething. He said he ws getting missfire one cylinder, the compression test showed one cylinder 30 pounds low--discovered broken top ring. Separate coil for each plug with crankpulley inductive pickup. regards The Rebel.

If the same cylinder's plugs are being replaced, then I would suspect a mechanical problem. If different plugs are being replaced, I would suspect an ignition problem. So, if it happens again, make sure to compare the cylinders where the problem is.

[lennyrebel]

Originally Posted by f5fstop

If the same cylinder's plugs are being replaced, then I would suspect a mechanical problem. If different plugs are being replaced, I would suspect an ignition problem. So, if it happens again, make sure to compare the cylinders where the problem is.

Did happen again. Last Saturday as a matter of fact. Did compression test myself all cylinders at 210 Psi. Dealer told me first time it was #5 plug second time #5 + #7. Third time I wiped a little soot off plugs ,5+7 blew them out and service engine light went out and miss disappeared. Dealer service manager returned my call on Monday considering cylinder leak down test but are presently as stumped as I am. Regards The Rebel