2000 Grand Am SE

That sounds like an engine misfire. Did you replace the spark plug wires along with the plugs? Bad wires usually cause misfires.

GW

Two things could be wrong: Your engine is almost completely out of coolant OR a vac door is not working right because of a vac leak. However, I don't think your vehicle uses vac doors but I could be wrong. GM went to electric motors instead of vac on many of their vehicles. If is is a vac leak, the heat door should return in just a second or two when you let off of the accel (vac builds up)

I don't know what you mean.

Sounds like it's out of coolant - better check before the engine burns up.

What do you mean by "slipping"?

The CEL codes stay in memory. Have the codes read and post them here.

thank you for your prompt response "=?iso-8859-1?Q?=AB? I've had that heating or lack of air distribution since I purchased the veh at 50,000 km. It is very odd, the concern will never be while driving in town just at hwy speed. Another explanation is the heat will suddenly stop blowing out of the vents after driving at hwy 95-100 km/hr until I do a total stop. When the heat does stop it sounds like the heat is now going out inside the hood by the cowl. My coolant level is full, I had my intake manifold gasket replaced at 167,000 km in which I was lucky it was an external leak. The veh was indeed hooked on a obd after my service engine light came on but there was CEL codes in memory and even when I had the tranny checked for which I thinking is slipping and even the tranny shop did not have any codes. They did mentioned that it seemed that it might be a torque lock up in which is normal?? It was after I told them that I had to pass 4 big log trucks on the highway and that was when I noticed that it felt like it was slipping and they said it is the lock up of the torque converter. But the symptoms will be present also at a stop light when I go to accelerate and it seems to be more at 2000-2500 rpm and as soon that I let the accelerator and press it again it is ok. I also try if it would still have that slipping sensation on 3 as it does on D and does the same. The tranny level is perfect too and had no metal filings when the tranny shop pressured flushed and replaced the tranny fluid in Aug/04. They say it is not the tranny but it does feel like it is slipping but I don't have any trouble on acceleration and these symptoms started in May 04. I would of thought that there would of been a code when they hooked it up since the check engine light did flash and stayed illuminated but after a while of driving it shuts off. I would of thought if it is the tranny slipping it would of gotten worse and not able to accelerate right? Thank you again for your suggestion

Thank you for your prompt response GW. I'm hoping that it would only be a misfire and not the tranny.No I did not replace the ignition wires because they were checked with a (sorry don't know what the tool is called)for steady current and was advised that they were fine. But I can definitely try replacing them because it will not harm it. Wouldn't you think that it should be worse by now since I noticed these "slipping sensation" since May

2004 and do it more often or have trouble starting the veh.Another symptom I just remembered something, sometimes after hwy driving at 100 km/hr for a few hours I had to make a "pee stop" haha and I pulled in a side road and backed the veh in order to go forward afterwards and I put the veh in park and went outside and it was poorly idling, it was like it was gasping for air. I replace the air filter every second oil change so I know that it is not due to a dirty air filter. That idling concern happened maybe 3 times and it seems to be after driving for a while and stopping. If I do stop the car while it does that it starts right away and is idling ok. The check engine indicator does not come on either. The service engine indicator will only comes on while I don't let go the accelerator while it seems to be slipping and will flash about 5 times and stay on. It will shut off byitself or after a few days of driving.There is never a code in the memory, the first time that I thought that the tranny was slipping and took veh to tranny shop and they road test the veh and of course they claim there was nothing wrong with the tranny and they did hook their computer and there was no codes stored, they told me that they resetted the computer.I will try and replace the plug wires and hope that will resolve the issue. I did start the car last night to see if I can see sparks coming off the wires but there was no sparks. THank you very much for your suggestion Geoff

There is air in the system.

You mentioned this in your reply to Geoff:

" I pulled in a side road and backed the veh in order to go forward afterwards and I put the veh in park and went outside and it was poorly idling, it was like it was gasping for air. "

That sounds to me like EGR valve stuck open. That can happen after running at highway speeds with a hot engine / hot exhaust. Perhaps that is what you are interpreting as trans slipping?

There will be codes in the ecu mem unless they were cleared on purpose or the ecu is bad. A 2000 will store trans codes as well as engine codes. It's unlikely the trans is slipping. You will need to narrow it down.

thank you again, when you mention air in the system, is it for my air distribution concern and how can I remove the air? How else can I determine about the EGR valve being defective since no one can get any codes? I even paid 84$ for a diagnostic charge at the Pontiac dlr here In Toronto which they told me there is none.If the cat converter would start to be plugged up what symptoms would it came me?

A plugged cat tends to limit rpm. Noticible lack of power. Cats oftem plug due to raw fuel being dumped down the exhaust. Take the egr off and clean it and the passages out by hand.

In an earlier post you said: "The service engine indicator will flash and stay on at times after it feels it is slipping but i'll let go the accelerator and press it again and no problem."

If there are no stored codes then they have been cleared by the tech or the ecu is bad. obdii should retain them.

As to the air in the system, you will just have to work with it until it is all out. Sometimes there are other bleeders, or parking on a hill, or loosening a hose, adding coolant at a moderately high rpm, etc.

Geoff, your thoughts on this?

GM still uses vacuum doors for vent controls. Not sure why he thinks air is blowing outside the windshield. Newer electronic EGRs hard to test. Trans's either slip or don't, and they slip from a standing start, or have lazy ass shifts. If the Engine Light is flashing, there should be a code...if he can get the car to have the proble consistantly, a scan tool ready for Capture Mode should find why the light is flashing.

GW