loss of acceleration

Hi all i got a 1994 Pontiac Grand AM GT Sport with a 3100 sfi and was wondering if anyone knew what was happening here cause i cant figure it out. if i floor the gas feed it runs decent BUT when I'm just cruising about 50 or 55 its losses power like i took my foot of the gas feed & my heat gauge shoots over to about 280 or so, then when it regains its normal acceleration the temp guage goes back to normal... .. Any help would be great thanks in advance... :confused:

welcome to the forum. I'm thinking you might have a clogged cat converter. Other guys will be able to help you out more.

welcome to the forum. I'm thinking you might have a clogged cat converter. Other guys will be able to help you out more.

Thanks for the suggestion will have to try to change or bypass the cat converter. but would a clogged cat make the temp gauge shoot up when it looses acceleration??? you'll probably hear a bunch of dumb question from me i'm more a computer geek then a mechanic... ..lol...thanks again any other suggestion you & anyone else has would be great... ..

LoL no problem. A clogged cat can cause overheating, yes - I'm not sure if it could to your extent, but it's possible. The heated exhaust gasses under acceleration would have a great enough velocity to get through the blockage, however when you let off the gas, the gasses under normal RPM's may not be fast enough to get through the blockage efficiently, causing them to build back up to the engine, raising the engine temperature, and causing the loss of power.

dont get a new cat convertor....

this just happened to me and it took me like 5 months to figure it out, went to the shop and said its most likely my cat convertot so i got a new one, no help...so then they said that its my tranny...

so i held off on getting one, just getting by, by putting it 2nd then 3rd then drive....then i just got it inspected...said i needed like 4 new fuses..and when i got my car back, it had all the power back, i was amazed.

I had the same EXACT problem as you, and it really is frustrating...so im probably like 90% sure that its your fuses that are causes this problem.

This is just a guess based on a previous post I saw, It maybe a temperature sensor going bad. It'll cause a similar situation, temp gauge jumping to high temps when driving, and the engine will bog down. Hopefully someone who knows about this can verify it.

First of all thanks for all the help & tips thus far!!!! this is a list of parts i have & have not changed yet. maybe this will help you automotive geniuses figure it out (sorry for the brief ass kissing but hell it was worth a try LOL) So let start this brain numming act begin...

Parts I've Changed:
Air Filter, Fuel Filter, Throttle Position Sensor TPS, Air Cleaner Temp Sensor, EGR Valve, MAP Sensor, Coil Pack, Air Idler Control Sensor AIC, PCV Valve, Fuel Pressure Regulator, Fuel Vapor Canister Valve, also looked over wiring cant visually find any shorts or skinned wires & Cleaned all grounds in the engine compartment, Checked all fuses in the fuse box all is good And Changed the ECM!!!!!!!!!!!!!!!

Now The Only Stuff I havent Changed YET!:
Fuel Pump, wanna hold off from dropping the tank unless i have no other choice...

ESC Knock Sensor, Will be done in the next day or two

Cam Position Sensor, Another one that Will be done in the next day or two

O2 Sensor, Dont think thats it cause no check engine light comming on

Cat Converter, Sorry Ridenour Being a little lazy but I will get to opening it up & trying to clean any clogs... ..

This is soo annoying Cause the Car Starts & idles Great but is not a big fan of keeping its acceleration constant... ..

BTW grfnkl i didnt change the temperature sensor but we unplugged it & the temp gauge didnt move but still lost acceleration but will change this sensor in the next few days.

P.S. here's a lil bit of info i forgot to mention in my original post when cruising down the road & the car loses its acceleration (does not stall)if i let up the gas feed & push it again the acceleration is back... ..just freeky!!!!!!

My 02 sensor was bad, and I never got a check engine light. Just thought I would pop that in there.

My 02 sensor was bad, and I never got a check engine light. Just thought I would pop that in there.

ok Thanks... .i'll change it anyhow... ..

welcome to the forum. I'm thinking you might have a clogged cat converter. Other guys will be able to help you out more.

you the man!!!! told my buddy clean out the cat & he finally did today!!!! lets just say it looked like someone was mixing cement inside of that knocked all the sh*t outta the cat & oh yeah running like she should... .. thanks everyone for the idea's

No problem - glad we could help. Just wondering though, don't you have a post-cat o2 sensor? If that is the case and you gutted your cat, you will need to get a simulated o2 sensor so you don't get any engine codes.

No problem - glad we could help. Just wondering though, don't you have a post-cat o2 sensor? If that is the case and you gutted your cat, you will need to get a simulated o2 sensor so you don't get any engine codes.
it must not cause i aint getting codes...but unfourtantally i spoke to soon after 1 day back to its old tricks... ..