warm/hot start HIGH rev idle/ sticking throttle??3800

**rschap1** · 03-20-2012, 03:05 AM

Since our recent heat wave here in Michigan...my 2000 Grand Prix GT 3800 with 200,000 miles has been acting strange

I drive 60 miles after work each afternoon to the gym I hit on the way home.
Trip is all highway from work to gym.
I park the car, work out, and return to start the car and head home about an hour later.
When I start the car to head home. It starts hard, takes a bit longer than usual to fire, chugs, bogs, then idles slowly for 5-10 seconds. Stumbling clears then engine REVS way too high. Gets up to 3,000 rpms. I try to give a little throttle and RPMs just increase and stay there.
The more I add throttle the higher it reves and stays/sticks.
Shut down 2 or 3 times and slowly starts to get better and return to normal.
???
Air temps have recently went from 30s and 40s to 80s this time of day.
I am GUESSING that fuel/timing maps/curves maybe out of wack with air temps and going from an hour at 80mph to a cold/warm start situation...???? I guess.
I was formerly informed that the backside of the throttle blade usually gets a carbon build up.
I have had a sticky gas pedal for a few years. 1st time you step on the gas it took alot of effort then was OK. So...last weekend I pulled the throttle body and did clean a TON of build up off the inside of the bore, off the blade, and pulled what I am calling an idle by pass valve (I guess too). I had hopes that cleaning this mess would help the starting revving after the gym, but no luck...
Wondering if any help, advice, or similar situations that may be passed along.
APPRECIATE IT !!!

BTW...car does run well the rest of time...only after the long highway drive and restart hour later.
???THANKS

**FinZ28** · 03-20-2012, 04:27 AM

I had an odd problem like that with my '94 Camaro 3.4L. It mainly did it when it was cold, though. It plagued me for a year or so. Did all sorts of stuff to it including plugs and wires, cleaning the EGR and some other things. Ran a can of Sea Foam through the engine and it never acted up again. Not saying that will fix it but because your problem could be any number of things. Start off simple though. When is the last time the car had a tune-up? Any codes present?

**rschap1** · 03-20-2012, 10:24 AM

The SES light is not lit...I do not have a scanner to know much more than that regarding codes.
It has been a little while since I have done much as far as tune up.
Pulled plugs a few weeks ago, they all still look good, so left 'em.
Regular oil change about 300-400 miles ago.
Blew out the air filter element and cleaned up the air box and ductwork when I pulled the throttle body...

THANKS for the tip

**chris1974** · 03-20-2012, 12:32 PM

It just started out of the blue one day? It didn't start after a tune up or a trip to the shop or somethiing?

**Smittro** · 03-20-2012, 07:05 PM

What are you using to "clean" your electronic parts (sensors) with??
@ 200K the car likely needs 02 sensors amoung many other things..

Also,, you said you pulled the plugs and they "looked" ok.
When was the last time you put on a set of plugs and wires?

Are you still on the Stock catalytic converter?

Stock intake gaskets?
Any smoke durring these odd times?
If so what color does it seem to be?

**GTP231** · 03-20-2012, 08:06 PM

Without seeing the car I'm thinking IAC with either tps and or crank sensor issues as possibilities

**rschap1** · 03-21-2012, 01:26 AM

Yesterday it did fine

Stumbled just for second, I let it idle longer and NO STICKING high REV

This did just start happening last week. Our weather here went from 40s and 50s to 80s during the time of day this occurred.
Car has 02 sensors that are just a little over a year old. Did those prior to replacing my ACT with a MagnaFlow. It was lighting the SES then. I do still have stock intake gaskets, I have been pretty religious about the coolant, always hoping that would help them survive. No smoke at all. Plugs are probably a little over a year old also, but I used platinums and same gap, no deposits, just re-installed them. Wires are probably 2 years old. Car got a recall notice a couple years ago for their looms. Dealer suggested new then, so I did 'em after they re-routed. And I used a can of CRC brand MAF sensor cleaner when I was working on the throttle body.

Like I said, it acted good yesterday, fingers crossed it keeps on.
Only other time the car did anything like this was last fall. Sat with motor running/idling for nearly an hour. It probably got hot then too. Talking with neighbor. When I went to leave it revved HIGH and stuck. Shut car off and on aagain a couple times and it seemed to regain it's senses. Seems to be high temp related. When it does it the temp gage is a lil' higher but not overheating or anything. Like just under 200....
VERY much appreciate the HELP

**Smittro** · 03-21-2012, 06:48 AM

Well then lol looks like you covered all the bases..

There could be a slight head gasket issue starting.

That's a sh&t ton of mileage on stockers.

Idle will jump up when it starts to go, and it may not seem to smoke @ first.

Coolant temps will rise also.. It should NEVER over heat just idleing even if you idle a full tank of fuel away..

Have you done a thermostat lately? Prolly have

but just asking..?

**rschap1** · 03-21-2012, 08:02 AM

I have always been leary of the intake and head gaskets after hearing so much about the DexCool issues.
Tried to keep fresh stuff in this all the time hoping to avoid so many troubles.
I was not thinking along those lines in this case, but I will take a closer look at the cooling systema nd coolant now that you mention it.
Stat is probably a year and a half or two years old.
I have been through a few of them.
When the wife drove this she would see 190-195 temps once or twice on the hottest day of summer, park the car and call me saying she was afraid of melting it down and me having to yell at her. So I have been forced to stay on top of stats

THANKS for the coolant tip.
Does the coolant burning cause the high revs?? Or does it's burning screw up a sensor or something if it does have a little leak at high temp?

AGAIN Thanks!!

**rschap1** · 03-22-2012, 01:42 AM

Well it got even worse yesterday.
Previous little stumble and high rev as I left the gym again. Let it "search", waited, shut off and re-started a couple times then was able to drive home.
Drive went OK and ran well.
When I got home and pulled into the drive 20 minutes, 15 miles later...car stalled and died as I parked.
Chugged and stumbled as I restarted. High rev and temp gauge rose to 195-198.
Checked coolant and it looked like same level as usual.
Radiator full, looked good, bottle at hot level and seemed good.
I added about a pint of water just to be sure.
???
Autozone says that they won't scan w/o a SES light on.
I am sure a scan would help, but I have been too cheap to buy a scanner.
See how things go today...
Fingers crossed, THANKS again!!

**GTP231** · 03-23-2012, 05:44 AM

Take some 2+2 and spray around for vacuum leaks. Its either that or sounds like the IAC is going or there is a wiring issue

**rschap1** · 03-26-2012, 05:29 AM

Temps here dropped back to normal Michigan range for March.
Now that we have went back to 50s and 60 instead of mid 80s the car has been fine.

It seems to be high temp related.
Maybe I will start looking closer at stat or water pump maybe...?
An known issues or method to check flow on a water pump w/o tear off?
Or any other ideas I may be missing??
Thanks for the help this far.
I have checked for vac. leaks recently and previously for some other issues. That and wiring seems OK...
Is the IAC the "plunger" mechanism right in the throttle body? It was caked with carbon, now clean.
Thanks!

**GTP231** · 03-26-2012, 06:46 AM

Unless its locked up a water pump will not affect idle speed. Replacing it now is just a gain of piece of mind with it having 200K. You're car isn't actually overheating and frlom your description everything sounds normal. The car is designed to run 210 range for fuel economy.
You need to get a scanner and see what's going on when its acting up. At least one that will read set and pending codes. One with a data stream would be ideal. I'd still do a resistance check on the temp sensors and IAC with the car warmed up.

**flybird** · 03-26-2012, 07:33 AM

Could be fuel related... ? Just pointing it out there.

**rschap1** · 03-26-2012, 10:50 AM

Originally Posted by GTP231

Unless its locked up a water pump will not affect idle speed. Replacing it now is just a gain of piece of mind with it having 200K. You're car isn't actually overheating and frlom your description everything sounds normal. The car is designed to run 210 range for fuel economy.
You need to get a scanner and see what's going on when its acting up. At least one that will read set and pending codes. One with a data stream would be ideal. I'd still do a resistance check on the temp sensors and IAC with the car warmed up.

Getting to the edge and beyond my knowledge and know how...
I am sure I could shop for a scanner and see if the specs list set and pending codes or one with streaming data. Guessing that a data stream is a more real time display set up.
Guessing again that an ohm meter would be the resistance check for the IAC and temp sensor, any idea where I could locate specs for those?
THANKS big time.
Like I mentioned with cooler weather here now, I am thinking I will be OK for a time, but figure it is going to heat up sooner or later and I will be getting this issue again then.

**rschap1** · 03-26-2012, 10:51 AM

Originally Posted by flybird

Could be fuel related... ? Just pointing it out there.

You thinking the fuel itself? Good vs. bad gas situation...
Or fuel system? pressure? stick injector or regulator or something along those lines?

Again, THANKS

**flybird** · 03-26-2012, 03:36 PM

Regulator or injectors, filter, pump, ect.

I could be wrong, just trying to point out all possibilities!

**rschap1** · 03-29-2012, 02:30 AM

With the lower temps here, I noticed the car not even getting as warm as it should now.
Running less than 180 while driving and then gets a lil' warmer when setting at a light or just idling.
Think the stat may be doing a lousy job.
Going to see about replacing that soon.
I am wondering if it was overheating before and getting a real rich mix???
Anyone know if these motors do the extra fuel wash down cylinders when temps get too high?
I didn't think that was the case according to the gage before, but maybe just too hot and going into a limp/safe or some kinda extra rich mode ? ? ? THANKS again!!!

**rschap1** · 04-03-2012, 03:56 AM

Car had seemed to be running cooler than normal when air temps cooled now.
Too hot when air temps are wam, too cool when air temps are cold.
Figured thermostat...put in a new one (195 degrees).
Been running OK since.
Drove it hard to Detroit and home this past weekend, 300 mile round trip w/o any trouble.
But air temps were still mid 50s, guess I will have to wait until temps warm up to know for sure now.
Fingers crossed.