Thread: loss of power under load,start stall,and more

2001 gp 3800 non sc with 116000 also has k&n filter

this car belongs to my buddy who is in a wheelchair so i am helping him fix it.

the problem started as a lose of power while under load he drove me around to show me the problem and there was a noticeable sluggishness to the car it did not rev like a slipping trans and before we left i started and reved the motor it sounded fine.

there are no codes and the only engine light is an srs.

That night i filled all the fluids and added chevron to a full tank of gas.
we cleaned the air filter an oiled it and placed it back on.

i was going to test drive it the following day myself as to get a better feel as to what was going on but he drove it to a rewards dinner and broke down on the way home, and it now is in my driveway.

it would start and stall within a few seconds , i have read multiple threads with like symptoms for both low power and start stall and started to look into what was going on.

i have cleaned the mas and inspected wires to other sensors i did find oil in the air intake tube and the mas was dirty.
after cleaning it still would stall after start

i then was able to keep it running with some pedal but noticed that it did not seem to have any exhaust sound from the rear , it used to sound very throaty when he first got the car so i thought that the cat was clogged and cut the pipe just in front of it with hopes of being able to drive it to a shop for a new cat.

but now it still stalls with the mas plugged in and with it unplugged it will start and rev on its own hitting the rev limiter untill i turn it off.

i will be getting a battery charger,fuel pressure gauge ,and code reader tonight to help trouble shoot but any help or direction on where to start would be great.

looks like another lost weekend.

thanks

it cranked over about ten times before the battery gave out but did not fire at all i am going to charge the battery tonight.

thanks for the reply and any more to help me get started in the morn will be great.

I am outside on gravel with a dead bat at this point so prob not going to get much further tonight.

Scottyd i tried that and no luck plus i did not hear the pump prime at all ?

current condition is i have the exhaust pipe cut right before the cat and a new maf i also removed the iac and found it was covered with a hard black substance like melted plastic prob carbon build up i assume , i cleaned it and replaced it.

with the maf plugged in i get start stall, unpluged i get start and it continues to bounce off the rev limiter.

ALSO WITH CAR IN PARK AND KEY TURNED ON I GET 50 PSI ON THE FUEL GAGE.

(HELP)

thanks that is just my luck

Update I have replaced the IAC,FPR,and the MAF at this point and no go.

The exhaust is cut before the cat because at on point i was sure that was the problem, and was to dumb to just remove the o2. ( not happy with myself for jumping ahead so quickly)

I still have the start stall problem and if i unplug the maf it starts but repeatedly bonces of the rev limit.

I have a lighter,know where the filler neck is, and have a long piece of rope.

Might want to check for vacuum leaks. Grab a can of carb cleaner and spray down all the points that vacuum could be (hoses, fittings, injectors,etc). The car will have to be running for this to work. If you find a spot that smooths the engine out for a second then that's a leak.

Never heard of one bouncing off the rev limiter with the MAF unplugged. That's kinda odd. Usually what will happen is that it will take a bit to start and it will run rough until the programming catches up and runs off the tables in the ECU bypassing the MAF function.

thanks ford man but i can not keep it running in order to do this, or i would. the reving is a mystery to me to.

I hate that i threw parts at it and none helped but we where desperate, he is off Tuesday and is going to look for another car, I hate that as well, he is a good friend and i kinda fell like i have failed him, i will continue to dig for a solution.

My thoughts at this point are to remove and clean the TB , and then maybe the CSP any thoughts on that or am i at least heading in the right direction.

What is the wost you have seen an IAC the one i took out was no doubt not functioning correctly , i wish i had a pic of it before i cleaned it, but the amount of solid carbon on it is what has me thinking that everything else in there is frozen in place.

direction is what i need the most , and if i am in the wrong place for this please say so or move it.

So the IAC is new now? I'd lean towards cleaning the TB as well. There is a gasket between the TB and upper manifold that may need replaced as well. Would not think the crank position sensor would cause this one. Clean the TB till it shines and reinstall and see what you get. Hopefully then at least you can keep it running long enough to check for any vac leaks w/o it bouncing off the limiter.

good call i will try that, it may be a few days or later this week before i get to it because we are about to get hit with a storm and i am out side. Thanks for the reply .

well tonight i removed the throttle body to clean it and found more of the melted plastic i spoke of on the IAC.
I have been unable to find anyone else with this same problem.
The UIM has a hole burned through it just behind th IAC ( I can fit my finger through it).
I will post pics if i am able, as i took alot of my findings, now i am wondering what caused this.
Clogged cat?

That's odd. I just took a look at an old UIM that I have laying around and the only thing that I can see that could cause this would be the EGR stovepipe in the LIM, as the hole for it is directly behind where the TB attaches to the UIM. Sounds like you need a new UIM.
That would explain why the engine can't idle right since there is a huge vacuum leak in the UIM, lol...

While you're in that far may as well save the guy the trouble and change the LIM gaskets, VC gaskets and grommets and plug up the coolant passage on the LIM and call it done for a long time. Do a search for LIM gasket replacement on here as it's a common issue on these years, and is not a matter of if, it's when. We all go through it at one point in time due to the nature of the gasket material.

If you need help on finding the info on what all is needed for this try a quick search, then ask if any lingering questions remain. All you need is simple hand tools and a torque wrench and a day to do the work.

Good deal. See, it's not as bad as you thought. Just a matter of tracking it down and now some new parts and that thing will run for another 116K.

have others had this problem i have yet to see anyone where the egr pipe has blown a hole in the uim, and why would it do this ?

I want to make sure i fix the whole problem so i don't ruin the new uim.

so i replaced plenum with the hole in it today and she fired right up, i still have the exhaust cut because i plan to have it replaced, and think it played a part in this problem and may have caused the egr to stick open ( i checked and it moves freely) how ever it was white, leading me to think it had been very hot or white hot.

Ultra if you know of any threads of this i would like more info on what caused it, i know what i think caused it, but would like to be sure.