Tbi engine backfire

[Jims86]

Hey Jim86 I haven't been able to get to my garage to check the distributor on the truck. Is there any advice you can give me on how to test the sensors on the bracket next to the throttle body?

Those would be the knock module(ESC) and the EGR solenoid. You can un plug the egr vacuum, plug the line and see if it clears up, but if it was that, the whole engine would shudder, and it would set an EGR code. the ESC would set a code as well, and very rarely fail.

The code 44 you already got from the ecm points to a fueling/Intake issue, and the o2 sensor is seeing too much o2. Possible header leak?
what is the Idle RPM when it gets warmed up? A vac leak on a TBI engine would run the rpms up, and pretty smooth at that....totally opposite of a Carb, or Mass Airflow EFI system.

 

[89Suburban]

I swore up and down my valve backlash was not right even thought I red did them 50 times. Turned out I had bad spark plug wires leaking spark and making it run like ****. Does the backfire sound like just one cylinder is doing it? Do you have a vacuum guage to run some diagnotstics?

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[Jims86]

Well, he does have headers, which makes it easy to figure out what cylinder is misfiring using a spray bottle of water....But he got a lean code, which is engine wide.

 

[72chevy2door]

I don't have any check engine codes. It just runs like crap lol. I'm thinking the distributor or coil is bad. I haven't had time to go work on it or had the money to just buy new stuff so I'm hoping I can do it cheaply lol

 

[xmuertex80]

I would look at an exhaust leak. Even with TBI, most SBC engines have a bit of unburnt fuel present in the exhaust. If the exhaust pops especially on deceleration, you are getting cold air into the exhaust stream and it may reignite the unspent fuel. The popping would be close to the headers or manifolds. Look at collector gaskets or if you have a clamp together exhaust, check your connection points for carbon. That would be a good indicator. I would disregard ignition timing, and if you have just installed a new cam and timing set, the chance of lobe degradation on only one head would be minimal unless it's only one cylinder backfiring. If you hear multiple cylinders backfiring, it's probably not the case.

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[Jims86]

I don't have any check engine codes. It just runs like crap lol. I'm thinking the distributor or coil is bad. I haven't had time to go work on it or had the money to just buy new stuff so I'm hoping I can do it cheaply lol

I thought you pulled a code 44.

 

[72chevy2door]

No sir. I haven't had any codes that's why it's so confusing on to what could be causing my problem. I have gotten so aggravated with it that I'm ready to swap it to carbureted simply because I know how them systems work better. But I have no money to do the swap that's why I'm trying to fix what I have hopefully.

 

[badgas87]

ive had the same problem. I went thru and redid all my valve lash a couple times. what kinda plugs are you running? check for an intake leak at the intake manifold. and when your trucks idling does it seem like its searching for idle. you have the same set up as me and I have to run a stage 2 chip from tbi chips and the 3 wire o2sensor.

 

[72chevy2door]

ive had the same problem. I went thru and redid all my valve lash a couple times. what kinda plugs are you running? check for an intake leak at the intake manifold. and when your trucks idling does it seem like its searching for idle. you have the same set up as me and I have to run a stage 2 chip from tbi chips and the 3 wire o2sensor.

Sorry bud I didn't notice someone asked me something on here. I have t been on in a little while. I did get her figured out most of the way. My distributor was acting a fool. I got my brothers old one from his truck and now she is doing fine. I am running Accel header plugs by the way. She still idles rough every now and then and she don't have the torque like she should. I'm going to try to set timing again and readjust my tv cable cause I just bought a new one. And I noticed today the passenger caliper is locking up. If it ain't one thing it's another. Lol. I don't want to have to run any chips and if it get to where is have to it's going carbureted. I'm not wasting any more time or money on this tbi crap. I loved it cause it's nice and reliable when it works but I can set and tune a carburetor just as good. But it was worth a shot I suppose. Thank you for asking by the way