Tuneup gone wrong...

[brooksbronco17]

Hi guys, my 98 dohc taurus was running fine but thought the mileage (190,000) warranted giving a little tlc so I ordered plugs, wires and a new coil for the beast. When I took the upper intake manifold off I saw the gasket was flattened a little and figured to be safe replace it and the lower gasket as well. Ordered those from rockauto and while I was waiting for them I soaked the injectors in seafoam and also blew them out with throttle body cleaner. I also scraped ALOT of carbon from the lower manifold that was stuck on the sides and put brake clean in the IAC valve.

Put it back together, torque wrench only goes down to 120 in/pounds but figured that was close enough, and couldn't get it to start. Found I got some dielectric grease on some of the plugs so took them all out and cleaned the plugs and wire boots. Now it starts but revs up high to 2000 rpms and slowly falls back down and at about 900 rpm you can hear a misfire. It keeps falling till the car dies. Does this sound like an air leak? Did I tightin the manifold too tight and crack a gasket or something? Could the IAC be stuck? but that wouldn't cause a misfire would it?

[willyum]

Next time, if it ain't broke, don't fix it

[behlinla]

You probably need a new IAC. Check for strong spark at the coil and read the misfire thread. My inclination would be that you have more than a vacuum leaks causing your problems.

[Breeves002]

My guess is IAC as well since you used blake cleaner on it. You should only use throttle body and MAF cleaners on it.

Any codes?

I think its good to do tune ups like that every once in a while.

[sheila]

^ A few weeks ago I was performing the the same tasks as you on a 99tec. As part of my preventive maintenance, I also spray-cleaned the the iac, buttoned everything back up and car wouldn't idle. Checked carefully for vacuum leaks and only thing I found was I'd forgotten to snug up the big corrugated air tube clamps. Car still wouldn't idle and stay running. Swapped out the iac with one I had from a parts car and things were back to normal. Funny thing, every time I've performed engine work, I've always spray-cleaned the iac, egr valve, passageway, c-channel, throttle body, intake, maf with maf cleaner and never encountered a problem. I've always elevated the electrical end of the iac while soaking.

[brooksbronco17]

my cousin has a taurus so i'll see if i can swap with his and c what it does. His is a 97 vulcan, would it be the same?

Thanks for the input, I'll get her back on the road somehow

[behlinla]

No, Duratec and vulcan use a different IAC I believe.

[Lgbpop]

Is your intake manifold plastic or metal? From what you said about the torque wrench if it's plastic you could have cracked it.

[sheila]

^ His 98 tec uim is metal.

[brooksbronco17]

Ok, replaced IAC and still runs like junk. I'm thinking that either the carbon I loosened up fouled some plugs or the cleaning I gave the injectors screwed something up in them. Still got the old plugs and wires so I'll try a quick switch with the fronts and see if it atleast changes some
.