Trekt43

Hey guys,

I have a JB4 on and thing is awesome. I've noticed though every once in a while when I'm flooring it, I'll get an exhaust pop (like mid gear, not during the change or when letting off the gas).

Anyone else have this "issue"? Is it dangerous for the engine? I imagine it'll add some backpressure. What's the cause of this? Too low AFR? Timing issue?

Thanks

RichardCranium3

Think methodically about what's going on when this occurs and try to repeat it while logging. I'd put my money on misfire/knock, but if it's as loud as an exhaust backfire....ehh, idk

MatthewJ

Log it and post it please. What map and what fuel are you using?
Is it in a higher gear or lower gear? If low are you seeing wheel spin when it happens?
My guess is the car see's too much boost for the fuel/temp/elevation and is pulling back significant throttle even though you are all the way on it. But its just a guess without seeing a log.

Trekt43

Map 2 with 4 gallons E85 (California) and the rest 91 octane. I was using ****ty 76 gas though for the 91 octane and some of my buddies swear its crap.

I was thinking misfire but I imagine that would throw a code. JB4 can read DTS codes as well as fault codes correct? As far as knock, the ignition timings look OK (not fantastic).

Both times I believe it was second gear, shortly after shift change (change had been completed), pedal completely floored. Didn't notice any traction issues, and its happened with traction on and completely off (not sport).

I will post a log that looks unremarkable in my opinion of when it happened the first time (0-60 pull).

I also have some slightly weird behavior from shift change 3-4 where the engine seems to begin to rev up again after shifting, then drops revs, then starts reving again. This seems to be improving though and I think its just the ECU adapting to the new parameters. I included this info for completeness.

I plan on getting another log of it this evening and hopefully some video.

Thanks for the help guys.

jim04clk

Sounds to me like to much boost for the gas your running. Can’t tune these cars to tight. Especially on a map that might be designed for 93. Even good 93. The car just might not like it. Looks like tuners are pushing these cars to highest possible increase at the best possible conditions. AT least that’s what they are selling us.

Trekt43

It should be ok boost wise as long as the 91 is actually 91 and the E85 is reasonable close to E85. I've done several runs this evening and cannot get it to reproduce. It did it every one yesterday, none today. Log timings also look much healthier today. My guess is it was the ECU adjusting for the new map and the new fuel blend. Did both at the same time.

If any ones wondering, the map makes fantastic power. Running about 0.7/0.8 seconds faster 0-60 without break boost. Everythings stock. Might add DP's at some point if I get some advice on how to tune for them.

If it happens again/I get a log of it I'll post.