rx7_lover

ever since i passed CA smog test after failing pre tests many times due to very high HC value, ive been trying to pinpoint what cause this rich condition without any success.

some symptoms...

-at idle, if i give very slight gas (from idle to ~1300rpm), it makes small pops like 7 times.
-driving at low speed, it pops multiple times.
-mostly highway mpg (crusing w/o boosting) gets about 11~15mpg at best.

during deceleration in any gear, PFC shows inj. duty of 0.0% aka 'clean burning.' however i found out very recently that when i came down a hill (~15mph) in either 1st or 2nd gear with no gas, it pops too.

does this mean that some degree of uncontrolled fuel injection was going on when it was not supposed to? i think this relates to overall very rich condiiton in normal driving as well.

any ideas what might causing this problem?

mods...
-PFC (base map), but same rich condition remains with stock ECU too
-Downpipe
-Highflow Cat
-AVC-R
-ColdAir Intake
-BOV

saburo

iTrader: (1)

my car is all stock but has 3" catback and it pops often. Not sure if that helps. I also get pis poor fuel economy on highway when im not boosting much.

rx7_lover

yes but does it pop like 7~10 times continuously in neutral with very small gas? i used to have 3" straight until CHP wrote me up for it. i still have the greddy catback system but am not planning to put it back on until i fix the richness problem.

BLKTOPTRVL

I think you may have a leak in the exhaust system. It allows air to mix with the unburned fuel, then the heat ignites it.

rx7_lover

possible but just by looking at HC numbers from smog station, HC level was way to high to start with.

i was curioius if faulty FPR, or fuel pump might cause the problem. something related to fuel system. like i mentioned above the car pops during decelerating at low speed as well. i dont think any fuel is injected during deceleration meaning no popping is possible during decelerating unless fuel was still injected during that period.

birdy01

all i have is a DP and Apex GT, in the morning I run really rich and wen my car warms up, i get pops sometimes too wen i gently give it a lil gas

i get poor gas mileage too but oh well, i love my car

rx7_lover

i love my car too.

well, my car pops continuously for 2-3 sec, not just a single pop. and about MPG, i get 7~9 mpg on city driving with occational light boost.

moehler

iTrader: (12)

I used to have a LOT of poping and small backfires. This weekend I removed my airpump and disabled the 02 feedback control loop in the pfc and not one pop since . I don't know if its from the missing airpump or the just turning off the o2 feedback, but it worked like a charm.

fd3s_rx7

iTrader: (13)

I'm in your same shoes too bro...
I get pop every time I'm on 1st and 2nd when let off the gas for a while. Also it's weird how now I always get some loud *** pop when I WOT and shift near redline...

gas mileage is 9 mpg... It's runnin' real rich too. However my car has always been runnin' rich, because I have a Pettit ECU. When me and my buddy took it out and install his stock ECU back on, the result came out clean. The car is not rich anymore, and no more crazy poppin..
Maybe just your PFC not actin' up correctly??

rx713bt

iTrader: (4)

ACV or air control valve failure would cause a high HC level.

lopedl

iTrader: (1)

maybe your tps needs adjustment.

damian had a write up:
https://www.rx7club.com/showthread.p...&highlight=tps.

Let us know what you figured out. Mine runs a little rich but I think its due to a bad injector.

Androidmj

mine pops alot on deceleration in low gears, high rpm shifts, or if i throw the car in neutral when its at high rpms. It also pops occasionally during idle. I checked my TPS and its fine.

littlemilla3

iTrader: (1)

There IS a reason you paid 400$ more for the power fc over a chipped ecu isn't there? IT's ADJUSTABLE, TUNE THE STUPID THING. If it's so rich, why don't you lean out all the vacuum cells until you have about a 15:1 AFR. I swear this will make drivability way better, double your gas milage, and stop all that popping.

1QWIK7

iTrader: (33)

well during the winter months, my car would pop while warming up if i had to move it from one side to the other in my driveway without it being fully warmed up..

but then i found out that one of my injectors were leaking??? or something like that.

but i thought that our cars run rich during warmup anyway.

i need to get my car checked, my injector is probably still leaking..

rzograbian

i also have the popping but i know i have an exhaust leak on the cat...

i like the popping sound....

rx7_lover

thanks for the tips guys.

few clearifications...

-TPS has been tested and all the values were in the range.
-ACV cant explain very poor gas milege, and it has been checked out ok.
-injectors were cleaned and balanced by RC engineering.


continuous popping would occur at any time of the operation, both when cold & fully warmed up.

rx7_lover

i dont mind getting it tuned by XS, however, this extremely rich condition stays even with stock ECU. i think it is somewhat mechanical problem.

also i dont think making adjustments via PFC to lighten the problem helps much IF the problem is caused by a hardware.

FD_dave

this may sound real stupid, but here goes. might there be a leak in your boost gauge tubing? if no boost gauge, then the rubber cap to the nipple where boost gauge tubing goes. this'd cause the car to run a bit rich and lots of popping sound

rx7_lover

ill double check the vaccum lines for the BOV and the boost gauge tonight. thanks.

2a+RoN

any updates? I've been having very similar problems with my car. It seems as though it started one day while I was driving home from school, and it started running so rich it would stall out if left in neutral. I parked it then came back to it and it seemed to run normal again. But just lately it started up again and has stayed running that way for the past week. Under 2k it seems quite hesitant and the boost gauge is seems very jittery.

Kento

Have you checked the O2 sensor?

Zyon13B

And the MAP sensor?

2a+RoN

How do you test the MAP? I just did my TPS. It was a little off, but it still runs pretty much the same...

CANRX7GX

iTrader: (1)

What base map are you running on your pfc??? I supposed the second factory map setting that supports full exhaust, intercooler and intake?? Maybe you are running too rich because of that?? I know I was
When I had a stock ecu with my mods it ran super rich as well.
Good luck with figuring it out
Edwin

2a+RoN

I'm actually running a remapped ecu, not a pfc like the other guy.