Well...Need Help

[RedCar]

The problem is the car will shoot to like 3000RPM when I start it up cold and then it tries to level the idle out. Sometimes the car dies, and sometimes it stays around 1600 and then it gets to around 900-1000RPM after 20 sec. and idles really rough. When i finally put into gear and acclerate it hesitates until it hits about 3000RPM and then it goes just fine after that. It seems to straighten itself out a little bit after i drive a while, but still idles rough and smells kinda gassy at the exhaust. There are no SES lights on at all. Any help would be greatly appreciated.
(1995 Pontiac GTP 130,000miles)

I have done the following: new plug wires, new ICM, plugs, new coils.

[RollinonZ34]

Mine does the same exact thing! I think this might be due to a leak in the lower intake gasket. I replaced the upper Plemun gasket last week hoping that would do it, but no help. It could also be the IAC going out. I have all parts ordered to change out the upper & lower intake manifold gaskets, and a new IAC as well. I will also be changing timing belt & all pullies associated with that. I will let you know if it helps, but it might take a week or so to get all of the parts together, so check back. Heads up on the Coolent Temp Sensor, as if you pull your Plemum, it is a good time to change it...It's the only way you can get to it...with Plenum off, & if you got that many miles, it wouldn't hurt to change it.

[93Oldsdroptop]

Check for leaks at the intake gasket by spraying Clean-R-Carb around the gasket edges at the ports. If Idle changes, there's your problem!

[LQ1]

It is more than likely the lower intake gasket leaking. Clean or replace the IAC and the CTS is only a few bucks. Note, when cleaning the IAC, do not use any type of cleaning solution, just whipe it off with a rag. Might also look into replacing your injector orings, unless you disconnect the lines from the fuel rail when pulling the lower, then you dont have to worry about it. Wouldnt hurt i guess, they are cheap.


Go ahead and try the spray thing first to check

[RedCar]

Thanks for alll the replies I'll try the carb cleaner trick. RollinonZ34 let me know what happens when you get it done I'm really interested. I forgot to mentioned the IAC was the first thing that I changed and made zero difference.

[RollinonZ34]

Thanks for alll the replies I'll try the carb cleaner trick. RollinonZ34 let me know what happens when you get it done I'm really interested. I forgot to mentioned the IAC was the first thing that I changed and made zero difference.

Well RedCar, My problem did turn out to be the Lower Intake Manifold...i am pretty sure, but i did change the Timing Belt also, so the timing being off might also have caused some of the problem. Sorry i can't be more specific and say that 100% it was the Gasket, but i do think that was it. Car runs like new now. Also, when you change the Lower Intake Gasket, it is pretty thick and the bolts that hold it down are not going to want to line up! You must find the 2 holes on it (around the middle of it) and use 2 bolts about 2 or 3 inches long, to pull the intake down before the bolts on the sides that mount it on will line up! The 2 bolts are the same size and thread as the intake bolts...just need to be a little bit longer, and use a couple of stacks of washers to adjust length as the 2 holes do bottom out.

I wish i could tell you the exact length, but i used the 2 bolts from my Cam Flat Tool, and used some washers and put the bolt through a couple of small sockets to make up for them being too long. Worked great, but you just need to be careful not to bottom out these 2 bolts. As you tighten down on the 2 bolts, you will see the holes start to line up for the bolts on the side of manifold. Just tighten up until these go in easily. Get them all in and then pull out the 2 that you used to pull it down and then put the last 2 in (the 2 you used to pull it down are in the way of these, so now you can get them in) Hope this makes sense, as i had to learn the hard way and almost crossthreaded a couple before i realized that i had to pull it down with the 2 bolts first. Also, if you go this far, you have everything out of the way to fix that "DAM Distributor less PLUG" that leaks oil!!! There are some nice comments on this site to fix it. I just lifted it up as much as i could and cleaned under it with thin strips of cloth and paint thinner and put a Chevy small block distributor gasket (u got to cut it) and some RTV Black silicone (as much as i could get under there) spin it around, and let it dry for a few, and then put the hold down clamp back on. Also, make sure when you go to change the Manifold Gasket that you clean all surfaces really good...i used Paint Thinner...cleans great & does not leave residue...hope this helps...Paul