Hey everyone,

A few weeks ago when I was cleaning my throttle body, I noticed my gasket was broken on one corner so I probably had a vacuum leak. Since I didn't have a gasket with me, I went ahead and put it back on like that. It helped my idle, but I've always been in the situation where when I turned on the car, it would hit about 4000 rpm for a split second then fall down to 1100 or so for about 30 seconds, then down to about 650-700. I assumed this was the process of "warming up".

So I changed the gasket today, and when I turned on the car it immediately went to 500'ish. I found this to be pretty strange, since it no longer does the split second high idle then drops. Just straight to 500, which I consider low. So I put a mile or so on the car in case the computer had to compensate, and when I parked it the car was idling at about 600-650'ish. I turned off the car, then turned it back on and it instantly went to about 600.

My question is, should I be concerned that it immediately went to 500 when I first started it up? Or was it just compensating, like I assumed? Was I in better shape before, or do I need to take the TB back off and check all the connections and seals?

I'm going to give it a couple of hours to completely cool down and I'll give it another try. Hopefully it won't start up to 500.

On an unrelated note, my new gasket didn't fit quite right. I had to carve out a little around the holes to make it fit, but I don't think it should hurt anything. It definitely would not fit as stock. I thought they gave me the wrong part, but I compared it to the old gasket and it was the exact same. The torn away corner was probably done so in order to make it fit (done so by the previous owner, not me). Does this mean I have a non-stock throttle body or did they in fact give me the wrong part?

Thanks.


[Modified by Tourney3p0, 5:59 PM 11/3/2002]

 

What holes did you carve, the TB bores or the bolt holes?

When you first start the engine it usually goes to a fast idle, especially when very cold, then settles back to normal idle. If not, suspect the IAC needs service.

 

I carved the bolt holes themselves. I knew better than to carve the rest of it! :)

I went ahead and gave it another try and for a brief second it hit about a thousand, then dropped down to 600-650 again. Then again, it was warm when I did this. I suppose it wouldn't hurt to go ahead and inspect everything again, but I thought I did a pretty good job when I was piecing everything back together.

 

Would someone mind explaining this in a bit more detail? That's what my problem is exactly. I didn't mind it so much until this morning when I started the car, it died on me twice due to low rpm and cold weather. Usually it idles around 1000-1100 until it warms up. Then it would drop down to 650-700. Now I'm getting about 500 upon starting the car and it'll go to about 650 once it's warm.

Also if I rev it a little bit when cold, it'll die when it comes down. If I let the car get up to operating temperature then rev it, the car comes back down strong and doesn't even remotely hesitate. Could this be indicative of a dying IAC valve? I suppose it could be related to the TB gasket I replaced, but I can't really see how.


[Modified by Tourney3p0, 6:16 PM 11/4/2002]

 

You said it would hit 4000 RPM when first started before? :eek:

Did you reset the IAC?

 

I haven't reset the IAC yet. I was going to disassemble everything I did yesterday and check for anything at all out of the ordinary. I can't think of a way that I would have reset it without meaning to. I was hoping there was something easy I could do to get it to remember how it's supposed to be. Just to be sure I disconnected the negative battery terminal for a few minutes, but no change there. I just want it to idle over 400-500 when it's cold.

 

Alright, problem fixed. I feel like an idiot (even moreso than usual).

As I stated before, I had to cut around the holes for the bolts before to make it fit. This worried me greatly, but as I said it matched up to my old gasket.

Apparently the previous owner was some sort of master of making things work that shouldn't work, because he was able to cut it exactly as it needed to be cut in order to not restrict airflow. Due to the way mine was angled because of the cutting, it was restricting airflow to the point where I was losing many valuable RPMs. I feel dumb for doing that, but now I know.

My next task is figuring out why these gaskets are not fitting my throttle body, but I can figure that one out by myself.

For the record, I bought my gasket at Advance Auto Parts, and the label it gave was "305 350 Pontiac Chevrolet TPI Gasket", or something along those lines. I'd appreciate it if you would let me know if you've ever bought this part from them (I can look up the part number if necessary) and run into the same problem as me. I'm going to go to a different source to buy my gasket.