AAAAAAGH!! . . . . Backfire!

[VA VIPERAM]

I nailed it from an idle today and it spit back through the throttles. I've never had a multi-port injected engine do this. The drive train was warmed up and it was 42°F outside. If it were a carbureted engine, I'd be looking at timing and pump shot. I haven't put a meter on the TPS to see if it has "noise" on it yet. This is the first odd-fire engine I've had that fires sooner than 90° (90-54-90-54-90-etc.) Has anyone else seen this? It runs great other than this. I can make it do it almost any time I want by stomping it from an idle.

It would have been embarrassing if I hadn't been on a remote country road near my house.

BTW-My truck is COMPLETELY stock. Any ideas?:dontknow:

 

[Silverback]

I nailed it from an idle today and it spit back through the throttles. I've never had a multi-port injected engine do this. The drive train was warmed up and it was 42°F outside. If it were a carbureted engine, I'd be looking at timing and pump shot. I haven't put a meter on the TPS to see if it has "noise" on it yet. This is the first odd-fire engine I've had that fires sooner than 90° (90-54-90-54-90-etc.) Has anyone else seen this? It runs great other than this. I can make it do it almost any time I want by stomping it from an idle.

It would have been embarrassing if I hadn't been on a remote country road near my house.

BTW-My truck is COMPLETELY stock. Any ideas?:dontknow:

My guess it's either the crank sensor or the PCM.

 

[VA VIPERAM]

My guess it's either the crank sensor or the PCM.

I was affraid someone might say crank sensor, especially since the dealer just replaced my harmonic balancer. I was hoping if I didn't mention it, it wouldn't fail.

 

[FerrariTruck]

Well if it wasnt doing it before you got it serviced that is where you need to start. However this is no brainer but, your filling it with 91 or 93 right???

 

[VA VIPERAM]

Well if it wasnt doing it before you got it serviced that is where you need to start. However this is no brainer but, your filling it with 91 or 93 right???

Yeah, I'm just tryin' to avoid the dealer since they dragged it accross the lift!
I fill up with 93 at minimum. One shell dealer here sells 94, but he fills up from the same truck as the 93 stations, so obviously it's 93.

 

[VA VIPERAM]

The backfire is GONE!!

I drove it 60 miles today and after I got back home, I tried several times to make it do it by gagging it as fast as I could from an idle. It revs like it should now with no problem at all. Must have been some crappy gas or something.:dontknow:

 

[Silverback]

The backfire is GONE!!

I drove it 60 miles today and after I got back home, I tried several times to make it do it by gagging it as fast as I could from an idle. It revs like it should now with no problem at all. Must have been some crappy gas or something.:dontknow:

Personally I hate it when that happens. Just bugs the shit out of me knowing that it might start it again at any time.

Hope it was just some bad gas.