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Still getting hesitant acceleration

P

Pauley

New member
Ok folks here it goes. 1997 Pontiac Grand Prix, GT N/A 160,000....About three months ago, I started getting a misfire intermediately on my number one cylinder and started getting hesitant acceleration. Here is what I have replaced so far. New aftermarket Cat. New AC/Delco 41-401 Iridium spark plugs with AC/Delco wires. Cleaned all my sensors with the appropriate cleaner, checked my fuel pressure and was within specs. Had my coil packs tested and well within range. Cleaned my throttle body, "was clean to begin with". Unplugged my MAF and problem persists. Replaced PCV valve and air filter. I don't know where to turn next besides have my local dealership take a look at it. Yesterday I sea foamed my air intake and that seemed to straighten it out for a while but today the hesitant acceleration persists. Idle is strong and when I get to cruising speed it runs like brand new. The only thing else I can think of is maybe a stuck TCC? RPM's are where they're supposed to be with no problem with overdrive. I did take it to a local trans shop and they mentioned the TCC was sticking but according to my Tach, it has not been happening lately... Any ideas? Much appreciated!
 


Make sure fuel pressure is within spec when PCM is commanding higher injector duty cycle during acceleration.

If that's good then move injector for #1 cylinder to another cylinder and see if misfire follows.
 
Not getting an engine light after the plug and wires were replaced. Fuel injectors make sense but how to test these without a misfire check engine light?
 
Please..don't think in terms of engine light. That isn't going to fix this issue. You need a scanner to watch the data and see if you have a misfire.
 


Ok, I do have an OBD II scanner but pretty sure I can't watch the data. Sorry If have started two posts on the same issue...I can't recall posting here with this problem...Old Age.....
 
i thought the obII's read the data? or maybe you need an attatchment or something.. did u try switching #1 injector to any where else? or maybe check the ohms on it it with a multimeter, or both lol
 
Ok I did throw a code this afternoon. PO121 TPS code....This certainly makes sense....Will Swap out and let everyone know how it goes!
 


To say the least....I replaced this TPS about five years ago from Autozone...Ya think? I ordered an OEM Replacement
 
I'll take a check engine light when I can, have found with misfires that they are best found scanning while driving. I wasn't expecting a tps. Was thinking more along the lines of ignition system, which is common to our platform.
 
Installed new sensor Friday and has solved my acceleration problem. Thanks everybody for their input! Grand Prix owners are the best!
 


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