Ok so heading home from my football game on sunday a teammate in a nissan titan tried to race me. When we came to a light he told me that my car was blowing black smoke and when i shifted it poped a fire ball. I have heard my car on a rare occasion pop real loud when i shift. Is this just because I am running to rich?

Also previously (few months ago) i had a CEL for system too rich. I have not had a CEL since then. Also when i had the CEL the car never backfired like that.

 

probably running rich like you suspect.

 

There arnt any bad side effects from this are there? Im guessing the obvious are worse gas mileage.

 

I'm not a genius on this issue, but wouldn't that backfire have something to do with your A/F ratio?? How's your air filter look....is it pretty dirty/clogged?

You might also wanna check your MAF sensor for damage or dirt as it sends the air flow information to the ECU for the proper Air/Fuel adjustments to be made.

 

What are your mods again?

I believe running to rich can decrease MPG's and result in a loss of power. I believe you want your A/F ratios around 13.1.

 

I think he's on ihe no tune. Correct me if I'm wrong.

 

14.7 is stoich.. anything higher is rich..anything lower is lean. richer is always better then being to lean.

downfalls are decreased MPG due to having more gas..duh lol

dowqnfall again is that those fireballs could explode your muffler. lmao...reminds me when my car was backfiring during shifts...one day it really backfired and a huge glow came under the car and you could feel the explosion in my chest. car sounded so dam awesome right after due to no muffler. the seams actually blew out of the muffler.

basically your car thinks it is lean and dumps more fuel to compensate. depending on how bad this black smoke is i wouldnt worry to much about it.

 

running rich is better than running lean.
yea you lose mpg, but its better than burning valves!

hey greg, my car pops an occasional fire ball also. but it doesnt smoke.
and when i downshift i get real loud backfires.
but the black smoke means your shooting out straight carbon. now if it was blue or white, i would be very worried. but still if your shootin any smoke i would keep an eye on it.

 

I think (I could be wrong because I can't quite remember at the moment), but I think you got that backward. The lower the number the richer the mix. At least on my AF gauge that is how it works. If your running 14 to 1 under power, your running too lean. The pop noise could be detentation which is the result of too lean a mixture because intake tempuratures get to high. You want to be running between 11.5 to 12.5 under power, around 12.6 to 12.8 under normal driving.

Also, if your using a lower octane fuel, that makes the situation worse. The lower the octane the faster the burn. The faster the burn, the more heat you build up, the more heat the more likely you are to have detenation problems, specially in hot temps.

I am not a mechanic, but AF is the current issue I am fighting with now and I do listen to what my race mechanics tell me, at least sometimes (they usually are talking over my head).

Good Luck

 

You are right he has it backwards.

 

if your hear detonation like that then there's a real problem there. for the most part detonation can not be heard unless you have a device that can amplify the sound.

11.5-12.5 is a good range for vehicles that are boosted. although me myself would keep it under 12:1

12.6-12.8 under normal driving conditions is rich...this is actually a good range for NA motors under WOT. 13:1 is a NORMAL AFR for tuning NA cars but it all depends on the setup.

under normal driving conditions you want to be at or as close to 14.7:1 which is stoich.

EDIT: and OP, in addition to bad MPG's you can foul plugs by running rich.

 

Ok thanks everyone for the replys. My car is running a I/H/E no tune or reflash. I had a buddy tail me and when i got on it in 1st and 2nd nothing happend no smoke but when i was in third he said a little and a little in 4th.

With a mixute of Hwy and city more city i get around 22-24 mpg. On long trips i average around 32-34. I run 93 octane fuel.

Not sure what my A/F reading is ill check on my dyno graph to see if its on there.

Also ill look at my intake today and check out the filter and the MAF and let you guys know.

 

x2.
but i would rather foul plugs than burn valves running lean.

 

you can do a lot more than burn valves running lean.

 

i know that.

 

We know you know that.