Misfire

[qwertydog]

Yet another problem with this '01 LS that we bought less than a week ago.
This evening it developed a misfire, so I plugged the scan tool in and got "misfire detected cylinder #1"
I know the coils can break down, but when I increased the revs it seems more like a whole engine misfire rather than one cylinder. It idles smoothly and only does this when given a bit of throttle and then it seems to be cutting in and out, as if the ignition is being quickly turned off and on. Wondering why the code only mentions cylinder #1 ?
As always, any help would be most welcome.

[shorod]

Is your LS a V6 or V8?

-Rod

[joegr]

Your LS has a neutral rev limiter. If you try to rev the engine past 3000 RPM while in park or neutral, it kicks in and starts killing fuel to all the cylinders.

Coil problems are common with the LS and usually when one fails, the rest are already marginal. Most of us have found that the best course of action is to replace all the coils and all the plugs when this happens.

[qwertydog]

My bad, did not mention that it is the V8 engine.
Also, did not know about the rev limiter. That would produce those exact symptoms when I gave it some throttle. As for replacing all the coils, I agree that is the right way to go, but I just need it to run on all 8 cylinders for 2 hours. So I can get it back to the used car lot where we bought it. We have other issues ( see my thread on beeping ) Seems suspicious that both the "check engine' and "srs" lights do not work. Hmmmm? I phoned the guy who sold us this LS and he said to bring it back and he would get his mechanic to fix every thing. If he gets all the problems solved that will be fine. If not, then I will be holding out my hand for a full refund ! We have bought many, many, used cars over the years and once in a while there is the inevitable lemon, just hope this LS does not earn that title.
Will keep you informed as this sorry tale unfolds.

[shorod]

The V8 is quite a bit easier to access the plugs and coils than the V6. I'd suggest you pull all 8 coils at least and look for evidence of any oil seeping in to the plug wells or moisture getting in the coil covers. If you have either of these, you'll want to make sure the car lot fixes the issues by replacing seals rather than just fixing the immediate issue (such as a bad coil).

-Rod

[qwertydog]

Found the problem when I started to remove the coil cover !
The upper middle retaining screw was missing and there was a LOT of water in there. As the misfire developed on a day when it was pouring with rain I can only assume that the missing screw allowed the water to get in. It was definitely plain water, not antifreeze or oil. There were 3 new coils with #1 being what looked like an original, the mechanic who put the 3 in cut off the bolt head that holds #4 in place as the brass insert rotates in the plastic. Also he had removed the driver's side coil cover and left out the 3 lower retaining screws. So I removed all passenger side coils, dried everything and put his 3 coils in plus the one new one I had bought. The engine fired up on all 8 and ran smooth with no codes coming up on my scan tool. That was yesterday, today as it was sunny and all the roads were dry we drove it for 2 hours to the used car lot and got our money back ! Plus the cost of the coil I had bought. I am lucky, as the law stands here in Ontario, used car lots are under no obligation to refund a buyer's money, they are required to offer to fix the problems and that's it. But with a mechanic like that ?
Thanks guys for all your help, I have lost count on how many times this forum has stopped me from banging my head on the garage wall

[shorod]

I'm glad to hear you were able to get the car running well again, even if it was only enough for you to return the car to where you bought it and got a refund. I am impressed that you were able to get a refund!

-Rod