Part Throttle Exhaust Backfire
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Part Throttle Exhaust Backfire
I have a 2001 Ram 1500 4x4 with a gas 5.2
The problem is, when at part throttle (for instance, cruise control engaged and going down a hill where the throttle is being backed off), the engine backfires through the exhaust.
The kicker is that the engine runs superb under all other conditions! No codes and the plugs all look good. I've changed the coil (this was for a separate upgrade) but no other parts.
I can reproduce the backfire at will. It is very consistent. Nothing random.
Any ideas? Thanks!
The problem is, when at part throttle (for instance, cruise control engaged and going down a hill where the throttle is being backed off), the engine backfires through the exhaust.
The kicker is that the engine runs superb under all other conditions! No codes and the plugs all look good. I've changed the coil (this was for a separate upgrade) but no other parts.
I can reproduce the backfire at will. It is very consistent. Nothing random.
Any ideas? Thanks!
Last edited by bogwan09; Feb 17, 2016 at 01:40 PM. Reason: misspelled a word
I have a 2001 Ram 1500 4x4 with a gas 5.2
The problem is, when at part throttle (for instance, cruise control engaged and going down a hill where the throttle is being backed off), the engine backfires through the exhaust.
The kicker is that the engine runs superb under all other conditions! No codes and the plugs all look good. I've changed the coil (this was for a separate upgrade) but no other parts.
I can reproduce the backfire at will. It is very consistent. Nothing random.
Any ideas? Thanks!
The problem is, when at part throttle (for instance, cruise control engaged and going down a hill where the throttle is being backed off), the engine backfires through the exhaust.
The kicker is that the engine runs superb under all other conditions! No codes and the plugs all look good. I've changed the coil (this was for a separate upgrade) but no other parts.
I can reproduce the backfire at will. It is very consistent. Nothing random.
Any ideas? Thanks!
Grand Champion
Joined: Apr 2010
Posts: 5,011
Likes: 6
From: Meeker, CO
I've seen bad throttle position sensors do that. After a couple of seconds of closed throttle/high vacuum/speed over (I believe it's about) 30MPH the PCM wants to shut down the injectors -- if the TPS output is too high to signal a fully closed condition, you won't get injector shutdown and so will get final combustion when the unburnt fuel reaches the hot substrate of the cat.
If you've got just about any kind of scanner, even a cheesy Chinesey bluetooth OBD-II adapter, you can see what the PCM believes the throttle opening to be. It's normal to see it in the range of 7% to 8% at full closure, but if it's much higher than that the PCM will never see what it thinks is a closed throttle.
If you've got just about any kind of scanner, even a cheesy Chinesey bluetooth OBD-II adapter, you can see what the PCM believes the throttle opening to be. It's normal to see it in the range of 7% to 8% at full closure, but if it's much higher than that the PCM will never see what it thinks is a closed throttle.
