missfire/running bad after engine is warm.
Thread Starter
Instructor
Joined: Feb 2014
Posts: 121
Likes: 4
From: Atlanta GA
missfire/running bad after engine is warm.
Guys, have any of you seen anything like this? When I crank my car when it's cold it runs great, once it hits about 190* it starts missfireing underload, has a rough idle, pops and just runs like $hit. I can turn it off while its hot and it will crank right back up with a bump of the key. No starting issues. I can let it cool down and it will drive good again until 190*.
Things I have done and replaced.
New Coil and coil wire
New ICM
New Coolant temp sensor on the Fuel pump
New Intake Air temp sensor
New Fuel filter.
I've unplugged the MAF to force open loop and it still does it once it gets to 190*. It only takes longer because both fans are running.
I have an appointment at a vette shop to troubleshoot it this saturday, and the first thing they asked is if I've checked the Fuel injectors. My question, Will Fuel injectors fail once they get hot and be okay at lower temps?
I would like to avoid $110 an hour if I can?
Things I have done and replaced.
New Coil and coil wire
New ICM
New Coolant temp sensor on the Fuel pump
New Intake Air temp sensor
New Fuel filter.
I've unplugged the MAF to force open loop and it still does it once it gets to 190*. It only takes longer because both fans are running.
I have an appointment at a vette shop to troubleshoot it this saturday, and the first thing they asked is if I've checked the Fuel injectors. My question, Will Fuel injectors fail once they get hot and be okay at lower temps?
I would like to avoid $110 an hour if I can?
Burning Brakes
Joined: Apr 2012
Posts: 888
Likes: 4
From: Ridgecrest Ca
You didn't state which engine. Generally ignition fault due to heat would shut it down completely.
You didn't mention if you tested the fuel pressure when hot. I know but this is a Ford story.... My Ranger ran great cold but had no power hot. It was a bad fuel pump.
You didn't mention if you tested the fuel pressure when hot. I know but this is a Ford story.... My Ranger ran great cold but had no power hot. It was a bad fuel pump.
Burning Brakes
Joined: Apr 2012
Posts: 888
Likes: 4
From: Ridgecrest Ca
Then it being an LT1 you may have an OPTI problem. I've heard those can cause those symtoms. I have an L98 so I have a regular distributor. The electronics on mine typically will cause the engine to just stop running when the module gets hot.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I had the same symptoms (OK when cold, major suckiness when hot). It turned out to be a bad spark plug wire. You might have a loose spark plug boot (not completely on).
