SR20 running a bit lean...tried all the normal stuff...please read

[dj_lennon_franz]

well my SR is running a bit lean right now...i get these annoying little pops and backfires when i let off the throttle at different RPMs...i have checked the timing...its set 15 TDC (where SRs should be)...checked the sparked plugs...theyre fine (no abnormal build up of carbon or oil)...checked all the vacuum lines on the throttle, wastegate, and BOV...everything is fine...checked the oil...didnt notice a weird smell to it or ne thing...its level is right where it should be...i did notice however that one of my fuel injectors looks like it was knocked (prolly happenend during the motor swap) the plug is a bit outta shape...however i held a screw driver to fuel injectors 1-4 while the car was on...they all sound like theyre working fine...BUT fuel injector 4 (on cyl 4) sounded a slight bit different than the rest...not sure what that is...but this popping thing is driving me nuts...the cars gas millage has also gone to SHIET!!!! (im missing about 80-100km to the tank...thats about 50-65 miles...and for me...thats quite a bit)

ne suggestions???

[Onizuka]

Are you sure its running lean? Pops and backfires generally occure when there is extra unburnt fuel that makes it past the combustion chamber and ignites in the exaust stream. Poor gas milage can result in anything from bad alignment, to underinflated tires, to leaky injectors.

[llamabeta]

Sounds like your running a bit rich.

[dj_lennon_franz]

well the exhaust doesnt reek of gas...most of the rich exhaust smells ive smelled before have a HEAVY gas smell to them...mine does not

[Onizuka]

To be honest, my car does the same thing, and I still got 30mpg on the highway after my alignment.

[dj_lennon_franz]

well an alignment is on my list very soon...waiting for new parts to come in...so well see if it changes at all after that

[Onizuka]

I'm going in for tuning on the 10th, so I'll see if its a lean or rich condition (not that it will help your situation much).

[crazyfast]

maybe check your coil packs for crack?? that was what happen to my car.

[dj_lennon_franz]

ok...went out...got some electric cleaner...sprayed down the MAFS...seemed to help a little..not a whole lot though...so im pretty stumped on what it could be

[180fan]

Check the o2 yet?

[dj_lennon_franz]

yeup...02 is working fine....according to my smog test i had done it runs lean every 10 seconds or so after 2500 rpms

[ETTInnov04]

As for the popping... do you have a aftermarket BOV? If so, I know when I loosen my GReddy Type-S a bit my car pops backfires and runs pretty rich, hence the pops and backfire. That could be your cause fo the pops. I doubt your lean though because you should've seen it on your plugs.

[dj_lennon_franz]

im going off what i was told from a good friend of mine who is a mechanic and a guy who has been doing smog checks for the last 15 years and its an experienced domestic tuner

and now that ive researched it a bit...the plugs were a bit white...which indicates its running lean

[ETTInnov04]

Is your car popping or is it missing? Did you upgrade your fuel pump? Are you still on the stock turbo? 2500rpms is almost/about where full boost is on a T25, could be an issue of not being able to keep up with the fuel demands.

[2Fass240us]

Have you thought about getting a SAFCII and having it tuned?

-Andy

[dj_lennon_franz]

im not sure if its missing...i do know the motor has always revved a bit strange between 2000-3000rpms (ive had it goin on 3 years now) like it jumps a little bit in those rpms at random...my buddies RB did this as well so i thought it was just a nissan turbo motor thing...yes ive upgraded my fuel pump...its a Walbro low flow 255....and i dont reach full boost on my T25 till close to 3800-4000rpms (im on stock boost as well)...and i found out tonite that a few other SRs in town are having the same problems as me...VERY bad fuel millage...car runs very lean after 2500 rpms...and there are NO signs of fuel leakage whatsoever

and i dont have the money right now to pop for a SAFC...its not really worth it given i dont have anything worth tuning on the car...its a stock motor with a FMIC and 5zigen catback

[ETTInnov04]

3800rpms??? Wow. Are you on stock boost? I'm running 10-12psi and it comes in right around 3k. Hmm do you have a fuel pressure regulater or a fuel pressure gauge? You could try and pull the codes from the ECU and see if its giving you anything.

[dj_lennon_franz]

ok...once again...I AM RUNNING STOCK BOOST...lol...i have a stock FPR...this is no longer an issolated incident...4 other SRs are having the EXACT problems here in town...im thinking it MIGHT be the gas changing from oxyginated to non oxyginated for summer

[93180sxredtop]

check your injectors im having this problem and it was a leaky injector!

[dj_lennon_franz]

well see thats the thing...i dont smell ANY gas coming from the engine bay...i mean if ur injectors are leaking...wouldnt that cause a gas smell to come from the intake side of the motor??

[dj_lennon_franz]

well i checked the ECU and its not throwing ne codes...i think im just gonna pop for a damned SAFC2...bah

[chezicrator]

i get the same thing on my car. have u noticed which rpms it normally does this at?

i'm changing my plugs and getting an afc w/ a fuel pump so we'll see if that fixes it.

I notice whenever i let out a large backfire it smells a little funky. Anybody know what that is?

[dj_lennon_franz]

it pops right between 2500 and 3000 rpms on the dot

[Nicksemianiw]

Just because it pops doesent mean its runing lean, are you running a catlitic converter? if not that might be your problem with your poping.

Nick

[BlkTp]

I'm running a hollow cat and i hear little pops when engage the clutch and shift.

[SRMatt]

Im having the same problem as he is, backfiring around 2500 to 3000 rpm. I still dont know what the heck that is from.

[chezicrator]

do all of u have ur exhaust done?

i have 3' dp and exhaust and i just assumed since i don't have an afc yet that air was getting trapped in there or something. it helps when u totally ease off the clutch and make sure not to give it any gas before it goes into gear. i still get a little pocket of air stuck inbetween shifts and it scares the **** out of people sometimes lol.

i'm getting my afc installed next week along with some other goodies and i really hope this will fix this cause it gets kind of embarrassing.

btw i don't have a cat but would i still be able to fix that with the afc, fuel pump and such?

[creophus]

This is happening to me also. My DSM buddies are general mechanics, but my SR20 guru says that its a sudden rich condition from the atmospheric BOV. He checked the plugs and said they looked "perfect". I don't like backfires because they can be very loud.

I have an aftermarket (i.e. generic) catback exhaust. My cat is present, but I think it's hollowed out?

[dj_lennon_franz]

again...my plugs are white...this is an indication that its running lean...my smog test showed that it leaned out heavily after about 10 seconds after 2500 rpms...im going to check the fuel lines today to make sure im not leaking ne gas...my gas millage SUCKS right now HARDKORE

im running a stock down pipe..2.5 inch straight pipe and 5Zigen exhaust...BOV is NOT venting astmospherically...i know what happens when u do vent into the atmosphere...it causes a rich condition when the RPMs die down to idle