misfiring
 

ok now i am having a problem with my car and the engen light is on and i went and got it read and it say misfiring and I just got the motor rebuilt and it was fine but that was about 3 weeks a go. and now that dum light is on.. and it idel ruff and drives fine

tune up time.

The first thing I'll give advice on is grammar and spelling. I'm not being mean or busting on you, but many people will try to read your post and not bother replying because of the way you posted it.

On to your problem.

Please put your year and model (trim level) in your signature by clicking on the PROFILE link on the menu bar. I have no idea what car/engine/year you have.

Secondly, it would help us to know how old your plugs and wires are, and if they were put back in the car from the old engine, or the replacement engine's plugs and wires were installed into your car. Was it a used motor, or new?

Did you suffer from engine failure because of coolant in the oil from an UIM failure? Did the shop that installed your motor replace any gaskets before the install?

Are you running your original ICM and coils, or those from the 'new' motor? Have you checked your coil resistances according to the Techinfo article? Have you inspected your plugs?

What misfire code are you getting specifically? One or two cylinders? Or random multiple misfires? What's the code number?

We need ALOT more information.

is 1995 SSE AND I did the motor rebuilt my self and I did do Full tune up and High end wires and plugs and the coil is new about 4mo. ago and it a random misfies hope that all

Please check each plug wire for resistance and report the readings back here. Please also check your coils using the procedure in Techinfo, regardless of whether they're new or not.

Where did you buy the coils, and what brand are they?
Why did you buy them?
What plugs did you put in the engine?

I all ways by my stuff at napa and coils DEM pack, 4mo ago and becuse the old pack was giving out. that is when I redid the head gasket and plugs are acdelco stock that what go with Pontiac and wires are max profection

We're going to need to know more before going on here. Please be a specific as possible so we don't have to dig the information up.

Why did you have to rebuild the motor? UIM failure?
Did you replace the plugs with new plugs after the rebuild?
Have you checked your coils using the procedure in Techinfo?
Have you replaced your ICM? Or just the coils?
Have you checked the resistance of your plug wires?

(you need to answer/try all these things or we're wasting our time discussing your issues)

These questions have a direct bearing on your issues.

I rebuilt the motor becuse the head gaskit blown and i did cout it in time be for it over heated and when I rebuilt it and got the part to replace it. I got new wires, plugs and 1 new coil becuse it failed and replace it becuse the computer said it was bad. and I did get all the other coils tested too. that pass.. the wires have been replace 3 time becues i thout it was the problem. whit the same tip of plugs..

I can't understand everything you're trying to say.....but I'll lay BIG ODDS on this:

Your head gaskets didn't go. They rarely (if ever) do. In fact, I've never seen a documented case of head gasket failure in 5 years and over 7000 members here on this Forum.

Your UIM failed. And you put it right back on the rebuilt top end, causing coolant to foul your plugs. MANY people associate the UIM failure to head gasket failures. And they're all wrong.

Did you replace the UIM?

ok hope I get this out right.. I first was doing a full cheak up on my car one day as uslly and I decied to give it a oil change and as I did it. It was dark and green in it. so i quickly look at the rad and it was low so that day I went and got the parts and worked on my car new head gaskets and manifold and plugs, and spark wires... then after i got done with it.. I started it up and it ran great and no problems no light no nothing till now... did this clear it up alittle?

That helped alot.

Your head gaskets didn't blow. Your Upper Intake Manifold failed, and is still bad. You are fouling plugs with coolant, causing your misfire.

This should tell you everything you need to know:

http://www.bonnevilleclub.com/forum/...e=article&k=38

ok now it is back P0300 and I can not find the problem any idas It runs ruff wen i come to a stop and it feels like it want to move foward..

It is understood that you have a misfire code, but you have to understand that everything you need to know has already been posted here. Did you read everything in the link that willwren posted?

Check your coolant level, is it low?

Yes i did and It got fixed by a coil pack was bad and now its back and every thing is all right coolant is fine and the oil is great no leak in hoses

I don't think you understand. You still have the SAME UPPER INTAKE MANIFOLD on your car? Correct?

You are going to go either BOOM or POOF very soon. You didn't read what we were trying to tell you.

so sorry for not talking sooner but it is fixed and man you have no idea what it was and man you were off track.. it was a plug and a bad wire will post pic of it soon of plug

The very first thing suggested here was plugs and wires...of which you said you replaced.

You're missing the point entirely. Are you still running your old original UIM on the car or not? Do you know how dangerous this is? You are going to suffer from doom and gloom very soon if it is. Every stock OEM UIM on an L36 on this Forum and in the world is on borrowed time. Literally. This isn't an exaggeration.

Dogman... The Series 2 NA motor (the one you have) is known to suffer a failure with the upper intake manifold. While yours may seem to be holding up well, please see the following link in case you car does start to exhibit the symptoms which happen to be close to the ones you had with this thread.

http://www.bonnevilleclub.com/forum/...e=article&k=38