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98 Grand Prix GT 3800 159k on it but engine LOPES

Fritcr

Fritcr

New member
I don't know how to explain it really but the engine lopes...idles up and down up and down. This usually happens when the car is warm. Like drive to town...then shut it off...go in Walmart...come out and then it does this and will do it all day as long as you have waited long enought but not so long that it completely cools down. I can't find a thing wrong with it. As a side note..I have the dreaded bank 1 to lean code off and on all the time and can't figure that out either. It does not seem to be related to when the light is on or off. It is now my daughters car so I have to get it fixed soon.
Thanks for any and all ideas on this! I'm stumped!
Rob
 


sounds more like a maf sensor gone bad but for the code most definatly a vacuum leak! like dsmuts said check the T's and the lines that goes from the back of the engine and to the left of the fuse box! i found mine was cut up badly in more than a few areas!
 
bank 1 lean is usually a vacuum leak check then line going into the throttle body
also check the maf
start the car unplug the maf and let us know if anything happens
 
unplug the maf before you start the car and see if the problem is still there. if you start it and then unplug it it will most likely fordure stall
 
RyanL said:
unplug the maf before you start the car and see if the problem is still there. if you start it and then unplug it it will most likely fordure stall
Click to expand...

^this works
but if you do it with the car running we kind find out if the car is running on the computers data tables or if the maf is reading properly
 


When my maf was bad on my car it just hesitated from a stop. It still idled fine and it threw a code for the maf low input. With the lean code it's almost always a vacuum leak.
 
Rob..

The two Bill's are here for you on P0171.
Check/replace and or seal the EGR to LIM tube. Typically it cracks over time and no testing will find the leak.
Check all other vacuum and TB gasket etc.
Clean maf sensor
Ensure fuel pressure is good
Check battery cables for any corrsion

That'll start you off.
 
Lol @ the two Bill's although I am flattered to be included in the same sentence. The battery cable thing perplexed me but that is what finally caused my P0171 to go away and there was no visible corosion on my cables either. Good Luck!
 
Ok here is what I have done so far with no difference.
I have put 2 new Maf's on it
New TB gasket and checked the tube from the egr. However...like you say..might not be able to tell?
How would I fix/seal that up?
I ordered new vac t for the front side of the engine. I think I also got a new one for the back of the intake too.
New PCV and made sure the O rings were on it.
Sprayed everything I can think of with carb cleaner and no change in idle.
No gas the line for the Fuel Presure regulator.
New fuel pump..for no reason I guess although the Stealer told me that is what was wrong.
cleaned battery ends and in fact put a new battery in it at the same time for no reason.
Cleaned the TB and IAC also

The only thing I didn't look hard at was the line going from the back along to along the fuse box that was mentioned. I will look at that. It is my daughters car now and she is always working when I'm not! lol I'll probalby just have to have her take mine and leave hers.
So you think the MAF would make it lope like that?
 
Sarasota did you replace the ends? I have not done that but I cut back the plastic and cleaned them really good.
 


He replaced the whole cables IIRC.

Another thing he found was that even though his EGR tube was good when he pulled back the retaining piece....he RTV'd it to the LIM. Not my usual suggestion, but it fixed a leak for him.
 
Yes the entire cable is what I replaced.

As far as the EGR leaking it was so stupid of me but I had sparyed enough carb and brake cleaner near the egr and various places to clean a fleet of taxis but it never hit the leak so it never changed the idle at all.
I had GTPSHAWTY on here come over and he was helping me and he was on the forum and somebody and I am not sure who (but thank you very much) suggested plain soapy water in a spray bottle since you can spray that in a tighter stream and beyond when the engine gets hot without fear of catching fire, it was only thru that method was the leak found. My egr tubes are now a nice golden color from the copper rtv that was slathered all over them. It is the little stuff that drives people crazy and even though it was a little leak in relation to say the brake booster or something I could not find it and replaced a lot of the same parts as you plus some in an effort to find what the soapy water wound up finding. Good luck!
 
Ok thanks for all of the suggestions. I will send her off in my car Saturday to work and I will take a closer look at these things. So you can put RTV silicone on that hot egr tube? I took it all off when I had the TB off to clean it and replace the gasket and it "looked" fine. I will also look those cables over again and that vac line from the back of the intake and aorund the fuse box area.
Thanks so much for all of the help!
Rob
 
I did not know if it was okay to use on the tubes but I looked at the heat ratings of all the different rtv's I have and the copper one was plenty high so it was slathered on. I figured if it didn't work then I would either replace the egr stuff or delete it since I am in Florida aka The Sunshine and Smoky Tailpipe State and we have zero emissions testing. It worked on mine so but yours could be different but good luck again
 


Haha we are in Missouri so we don't care about smog either! No emissions testing. Smokey tailpipes here too! LOL JK is it not to bad but don't have testing.
 
ok I got a new postive battery cable on the car this weekend and it is still kinda hard to start when warm and lopes! (no difference) Check Engine light already on and off again with the lean bank 1 code. I want to investage the EGR tube a little but I didn't have time this weekend. Plus...my daughter drives it all the time. Poor thang.
Rob
 
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