Rough Idle
 

Hello everyone, I am new to this board, and I was wondering if someone could help me with my problem. My mustang seems to have a rough idle after I had equal length headers, offroad H pipe, flowmasters and dumps added. When the work was being done, they also removed the air pump. The thing is that I think they didn't remove it properly. They didn't cap the heads first of all(I did it myself).

Does anyone know what mightr be wrong?
Any help would be greatly appreciated. Thanks

After the mods you did, you might try resetting your car's computer, disconnect the - terminal for 20 minutes.

reconnect, start it, and let it relearn it's idle, also, you might try replacing your 02's, but that would throw a code if they were bad.
good luck, and welcome to a cool site.

Thanks for the reply coupe50

I tried resetting the computer, and all that did was help it idle smooth(around 800rpm) for about a minute or so. I was wondering if anyone removed the air pump themselves? Is the vaccum system connect to it in anyway?

Thanks for your guys help

Also I replaced one of the 02 sensors( because it broke). The other one seamed fine.

I know its probl a newbie question, but what are dumps?
What do they do for your car hp/lb wise?

Thanks

Dumps is just the term for an exhaust that "dumps" right after the muffler. So basically after the muffler there is just maybe 3" of pipe and it just points down.

Oh...

I just put a deposit on a 89 that has dumps, so I was curious.
(Cold Air, Long Headers, H Pipe, dumps)
Does that style change the noise, or is it purely for looks?

You cant really see dumps and they are usually a fair bit louder than normal full exhaust. Just because it resonates since its right under the car instead of behind the car.

At a lower RPM "dumps" sometimes create alot of vibrations inside the car. My dumps at the rear axle(helps to stop a exhaust smell inside the car)

There is a vacum connection that went to a valve in the hoses coming outta the air pump. If that was not pluged, then you have a vacum leak, causing the rough idle.

Thanks for the reply RPM427

I think I found it. I blocked it off with electrical tape. Do you think that is good enough? Also is their any electrical connections on a smog pump?

Thanks for the help

When I removed my smog pump, I used a lighter and "welded" the hard plastic vacum hose shut at its orgin with a small piece of plastic used as a plug. I don't remeber any eletrical connections though. Bad idle problems are ussaully cuased by vacum leaks, so check all your vacum hoses.

How did you plug the heads? Did you just crimp the pipe? or did you accually plug the heads? If you pluged them, how did you access the back of the heads? Thanks.

When I plugged the back of the heads I took the metal pipe off and used two bolts(I believe 5/8). Took awile to get them in.

Also, how can you check to see if a head gasket is blown(compression check?). Because the night I got it back I got in a little race and I think I might have "overreved" it. It doesn't burn or leak oil from the head, nor does it burn or leak coolant either. So can the head gasket be blown in a spot were none of thee above would happen?

Thanks for your help RPM427

Usually if you blow a head gasket youll notice some smoke or something from the pipes. But if not you can do a compression check. Look for either one cylinder thats a lot lower than the others or a pair of cylinders that are both the same and also lower than the rest.