'86 Calais 2.5l misfires/stumbles/bucks when warm...

I don't see any broken vacuum line though, that's the problem. It acts almost as though a ported vacuum line is leaking in that it stumbles most at part throttle under load (when ported vacuum is highest).

The problem is definitely related to something that was broken or damaged when I removed the air cleaner housing to change the spark plugs. The car ran very well before that and right after I put it all back together it ran like crap. It would be quite a coincidence for a problem with the gas to show up then, after I had already driven the car 300+ miles and immediately after taking part of it apart to change the plugs. I'll still look into any problems with gas, but I doubt that is the problem. I already ran some SynPower through it which is pretty strong stuff. It's a CFI engine... No carb or float bowl, just an electric pump that puts pressure in the line for the injector.

I seriously doubt it's the fuel pump as the car can go beyond the 85 MPH the speedometer reads with no trouble and can sustain 4,500-5,000 RPM silky smooth. Also, it's an electric pump.

I just can't wait until summer when I put a new short block in my '68 Galaxie. Then I'll have a nice reliable car again that at the rare times it does break I can easily figure out what is wrong.

Anyway... Do you know how to pull trouble codes from the computer? Maybe that could give me some insights?

Cory

-----Original Message----- From: Rick Colombo Sent: Thursday, December 25, 2003 2:26 AM To: Cory Dunkle Cc: Rick Colombo Subject: Re: '86 Calais 2.5l misfires/stumbles/bucks when warm...

Well at the very least, plug the broken vacuum line that you see. If

the line is coming from the engine, this leak will cause problems. If

it's on the side of the device that requires vacuum, well then that

device simply won't work.

As for sitting for two years, I would guess that there is bad gas in the

tank/system. I would drop the tank and drain it (I hope you replaced

the gas filter once or twice by now) or put in some "Heet" to take up

any water in the gas and/or add some gas stabilizer to help dissolve any

old gas. I don't know this engine (throttle body?), but if it has

anything like a float-bowl then you should drain it.

I had this sort of problem with an old MGB that sat for a few years. I

drained everything related to gas, eventually I bought a new gas tank

because I could see it had rust inside. Just filling the tank with

fresh gas doesn't get old gas out, but if you add gas stabilizer (which

I mentioned earlier), this might help to dissolve the old gas. I should

mention that I never tried this method myself (so I can't promise it

will work), because I remove the tank and drain it. It was then that I

saw the rust inside so I bought a new gas tank.

I thought of something else. I had another vehicle that ran fine around

town, but I couldn't get it up to highway speed. That turned out to be

a bad gas pump (the mechanical kind mounted to the engine vs. the

electrical unit that is mounted in the gas tank or along the frame.

-HTH PapaRick

--------------------------------------------------------------------

Cory Dunkle wrote:

If it ran fine before you changed the plug wires, did you per chance get the wires crossed?

immediately

I changed only two spark plugs and after that it ran like crap. I changed the plugs back to the old ones and it ran slightly better but still very poorly. When the engine started to run poorly I did not change the plug wires. In any case, the plug wires should be on the proper plugs... I doubt if the plug wires are even long enough for me to mix them up as they are sized to the length needed for each cylinder.

When it misfires it will misfire a bit then for a split second it will pull strong and smooth like it should, then repeat.

Cory

Dont know if this is a problem similar to what happened to my car. I had to do some work on the engine and disconnected the battery. After I started driving again the engine ran terribly. Would stop when I slowed down, no power. My mechanic told me that the computer lost all its memory and just to tough it for a few weeks, till the computer learned my driving habits again. You know, he was right. Car runs 100% now. So, if you disconnected the battery, maybe your engine will straighten itself out. Season's Gerrtings.

Case.

Did you ckeck the plugs for the correct gap or did you use them right out of the box? If you unplugged the computer, it will only take about ten miles of driving to re-program it. You should do the reprogramming at lower speeds with no jack-rabbit starts (just drive like you were taught for ten miles). Could be that you damaged a wire or vacuum connection while working on it. Sometimes, the plastic vacuum T's and Y's, etc. will crack at the junction. Make sure that you don't have a cracked insulator on the plugs also.

Nah, I didn't disconnect the battery, though it was dead when I got the car

600-800 miles ago. In any case, there is something mechanically wrong with teh car. It's not a matter of the engine not running optimally because the computer isn't operating the engine management controls optimally. No car would run like this from the factory and actually sell.

What I'm thinking is taht when the engine warms up the computer allows vacuum (most liekly ported vacuum) to flow into some line that it doesn't when the engine is cold. This line must have a leak. The engine runs great when cold, only after a minute or two of driving/running will it run like crap. Now that I think of it maybe the EGR is disabled when the engine is cold? I'm going to try plugging the vacuum line to the EGR from it's course. If anyone has any ideas as to what the problem may be, please let me know.

Cory

I gapped them to the gap specified on the emissions label. I then tried gapping them to what the old ones were set to, which was slightly less than teh emissions label. At the moment the old plugs are in the engine gapped at what they were at when I got the car (though I have new wires cap and rotor on the engine).

I'll have to thoroughly go over all vacuum lines and connections... I only briefly looked them over the other day, but I found nothing obviously leaking. I will check that and the plugs.

Cory

I have changed the plug wires, cap, and rotor... They are all new.

Cory