sr20det barely runs. bad mafs?

[harleys]

ok, for starters here is all the info on my car:

redtop sr20det
tomei manifold/turbo outlet
s14 t28
SMIC

had the motor in my last car, a douche bag rearended me and totaled the car so i swapped the motor into a new car that i picked up. i've had it in for about a week now, everything has been fine. i put a new alternator on today, but other than that havent' done anything to it since i got it swapped. a few minutes ago, my g/f and I were going to rent a movie and the car is now acting all goofy. it's raining here and the roads are wet, so when i left the stoplight i got on it and got a little sideways, rpms weren't really high or anything, shifted to second still spinning and then it happened. sounded like i may have hit something, or maybe the car just backfired, not really sure. after that it would try to die if i gave it any gas. i pull over on the side of the road and start looking. it will idle, but idles like shit, sounds like i have cams or something. it also smokes and smells as if it is running rich. if i unplug my mafs, the idle speeds up a little bit and it seems to run alright. i revved it a little and it revved ok, didn't see any smoke. sooo, is my mafs bad? could it have just went bad just like that? if anyone could tell me how to check it, that would be great. i have a multimeter and i work with car audio/electronics all day, so shouldn't be a problem testing it. or if anyone has any sugestions, please please tell me. sorry for such a long post, just trying to give as much info as possible and i'm sure i'm still leaving something out.

thanks in advance, harley

[harleys]

anyone? please help?

[cavakilla]

sounds like you blew apart a charge pipe coupler...

[kevtrinh]

if you can't rev past 3000 then its your maf. Check your charge pipe...especially the hot side.

[tastycakeman]

your maf is loose. make sure your plug is on tight and secure and wont move around. take a ziptie tight around the top of the plug, and then take another ziptie through it and tie it down to something.


and go ahead and drive without your maf. you wont get past 20mph.

[Z U L8R]

the maf may not be bad necessarily. you may have just popped an intercooler pipe out of the coupler.

theory and operation:

with your maf plugged in, it's metering the air being ingested by your engine and giving that data to the ecu to process. if there is a leak after the maf, whether it be an intercooler pipe, stuck bov, vacuum line popped off or whatever, the engine's not going to be getting the same amount of air that the maf has communicated to the ecu, which will throw off your a/f ratio's aka your car runs like ass. when you unplug your maf, your ecu's getting no reference therefore it goes into open loop and it'll run however the ecu see's fit to keep the motor alive, whether it be by altering the timing, a/f ratios, both or whatever.

sorry if i'm getting long winded, but i want to help you understand how your car works, so in the future you'll be able to diagnose your issues as they arise.

first, check your intercooler pipes that they didn't pop out of place anywhere, and check your clamps that any aren't broken. if you can't find anything wrong, hook your maf up with a coupler right to your throttle body and see if it runs/revs perfectly. you also might want to check your intercooler that you didn't put a hole in it running over anything. good luck, keep us posted
Dave

[jaboyak]

Sounds like a MAF. Replace it. They're relatively cheap.

[GSXRJJordan]

^^^ Z U L8R said it all. Probably a coupler/clamp, so check those first. The way to check your MAF (as he said) is to position it right in front of the TB and try to run the car - runs the same as now = new maf.

[harleys]

the maf may not be bad necessarily. you may have just popped an intercooler pipe out of the coupler.

theory and operation:

with your maf plugged in, it's metering the air being ingested by your engine and giving that data to the ecu to process. if there is a leak after the maf, whether it be an intercooler pipe, stuck bov, vacuum line popped off or whatever, the engine's not going to be getting the same amount of air that the maf has communicated to the ecu, which will throw off your a/f ratio's aka your car runs like ass. when you unplug your maf, your ecu's getting no reference therefore it goes into open loop and it'll run however the ecu see's fit to keep the motor alive, whether it be by altering the timing, a/f ratios, both or whatever.

sorry if i'm getting long winded, but i want to help you understand how your car works, so in the future you'll be able to diagnose your issues as they arise.

first, check your intercooler pipes that they didn't pop out of place anywhere, and check your clamps that any aren't broken. if you can't find anything wrong, hook your maf up with a coupler right to your throttle body and see if it runs/revs perfectly. you also might want to check your intercooler that you didn't put a hole in it running over anything. good luck, keep us posted
Dave


thanks for such a detailed answer. i ened up figuring out that the plug i had for the stock bov on the smic blew off. so i plugged it again and problem is fixed. the car now has a miss though, so tomorrow i'm gonna change the plugs. i figure i fowled a plug when the car was running so rich. anyone have any suggestions on good plugs to run that i can find locally? thanks again.

harley

[GSXRJJordan]

NGK Iridium 9's are the standard, gapped to 28 thousanths (.028") IIRC. Should be able to get em at Autozone.

[Z U L8R]

9's is too cold

Part # 5690 = NGK BCPR7EIX

they come already gapped at .028 which is what you want if you run ~14psi, i have no problems with em at 22psi. if you don't want to spend $6-8 per plug, you can get the copper version which are part # 3330 = ngk bcpr7es, they come gapped at .030 , i recommend running .028 gap for 13+psi. good job on finding your problem =]

[GSXRJJordan]

I'd agree for a stock SR 9 would be too cold, but for the usual exhaust/t28/1bar setup, 9 is just what the doctor ordered... it's all good though ~ Z is right about the copper stuff, they're just as good (or better, arguably), just don't last as long.