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99 grand prix power loss

M

maggz810

New member
Had this car 3 years and I've since replaced UIM & LIM gaskets, valve cover gaskets, water pump, ps pump, rack & pinion, coolant elbows and couple other things. It's currently not throwing any codes but from take off it's like I have no power at all until I get to about 40 mph. Takes maybe 10 seconds to get that fast. I'm sick of messing w thid car but at this point would be stupid to give up on it. Please point me in right direction...
 


One morning after driving 30 miles to work I shut car off to go into store, came back out and tried to start it and it sounded like it backfired. Later found out the vac line from brake booster that goes into UIM was blown out. Prior to that it was throwing an egr code and had some power loss. Replaced egr..no codes then this. Also since blowing out vac line from UIM I've heard what sounds like a pressure release or a hissing of sorts in area of egr but cannot locate one
 
As of now there are no codes but there is unusual acceleration and power loss until approximately 42-45 miles an hour
 
If you had a blow out did you check for vacuum leaks? Who knows what that pressure did to other lines or gaskets.

A tiny leak can cause acceleration hesitation

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maggz810 said:
One morning after driving 30 miles to work I shut car off to go into store, came back out and tried to start it and it sounded like it backfired. Later found out the vac line from brake booster that goes into UIM was blown out. Prior to that it was throwing an egr code and had some power loss. Replaced egr..no codes then this. Also since blowing out vac line from UIM I've heard what sounds like a pressure release or a hissing of sorts in area of egr but cannot locate one
Click to expand...

I ain't worth a crap troubleshooting but keep hunting for vacuum leaks because there are SO many places they can happen.

What you are experiencing sounds like what happens to me when I switch from driving my 99 GTP to my other, same car but a GT. Floor it and wait. Ha.

I quoted this post because, maybe, I can ease your mind about part of this. When cars were carbureted, on warm restarts, quickest cranking time was with the throttle held slightly open. See any owner's manual. This was due to the 'wet runner" intake design. Having an injector in each runner only decreases the amount that this is a factor. Fuel that was vaporized at shutdown falls out of the air, and with the throttle open slightly the warm engine clears that and gets a fresh vape hit when you twist the key but it takes a little longer with throttle closed. So, if by random chance occasionally you let off the key before it starts due to that... and you catch just the right spot during the engine's cycle when doing so...

You may hear the engine exhale into the airbox or buck wierdly, only for a sec, when you fail to start the engine on a warm restart. Just due to how engine works, it may buck you if you don't finish a compression stroke. Thats how lots of folks got broken arms back when a crank on the crankshaft tip was the starter. This concludes the history lesson. The moral being crack the throttle after running in the store, you'll crank up quicker.
 
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