sr20. rough idle LOUD backfire

[2.0-TURBOcoupe]

89 base model coupe

redtop sr20
s14 t28
255 walbro
z32 maf (blo through)
stock fuel injectors
brand new plugs.

ok i was driving the car a couple of nights ago and it was kind of chilly out so i turned on the heat(which works great) but it was the first time i have ever used it. afterwards i puled up to a redlight and took of driving normally and the car let out one of the loudest backfires. now, during a shift or decel of RPM the car will backfire. i was driving back to my house and i fouled a plug. i replaced the plugs but its still idling rough and when i rev it up it will back fire very very loudly. checked fuel presure. cleaned iacv. throttle body. unplugged maf(no change in idle). im at a loss. the car has never given me any sort of problem before. if anyone has any suggestions let me know

[rightcoastimports]

check your timing...

[xxsptcuztomsxx]

where in tn do you live? if your close you could bring the car by and i could take a look at it...

[Jordan-S13-Silvia]

i suggest you not use blow through in all the cases ive seen it never works properly.

just try putting the maf back to its traditonal spot and see how it runs then

[flip3d]

check your timing...

+1

check that shit d00d. get a cheap timing light from autozone. you'll be glad you have one.

[2.0-TURBOcoupe]

i can never figure out how to time the motor properly. i have tried to set the CAS timing before with a light and i end up just having to do it by ear. when i hook up the timing light by the loop or by bridging the coil pack it looks like the pully is just rolling around. i need help bad.

[singlecamslam]

did you line up the CAS correctly? there should be a mark where you line it up. Make sure that is lined up properly.

[2.0-TURBOcoupe]

yes i did. i followed the timing procedure exactly like the fsm tells you too.

[2.0-TURBOcoupe]

morning bump can anyone help

[rps13drift]

One of my fuel injectors i think was either leaking or stuck open and it would shoot no joke a 2 foot flame just from decelerating and letting the rpms go down every single time pretty much on command! I used to scare the shit out of people on the side of the road all the time! LOL! So check those pups out or it could even be a slight boost leak! Pretty much anything that will cause your car to run hella rich will make you backfire/pop especialy if your not running a cat!

[sonomadrifter]

I am having almost identical issues with my SR as well (with similar set up), there are too many things that can cause this. I've replaced the coolant temperature sensor with no noticable gains next Im looking at injectors and timing. How is your start up? What is your fuel pressure exactly? (should be 43ish?) Did you notice any fuel on your plugs?

I wish I could help more, keep us updated.

[2.0-TURBOcoupe]

number four plug was a little wet after i let it set overnight. number four also seems to be the blackest in color too.

[2.0-TURBOcoupe]

anybody anybody

[Jordan-S13-Silvia]

hmm this kinda sounds similar to how my SR is acting.

[downshift_sideways]

It could be a lot of problems.

I'd suggest to check your coolant temp sensor...only because it happened after you turned up the heater. A bad coolant temp can foul your plugs.

I'm assuming your running rich?

[2.0-TURBOcoupe]

i wouldnt really say rich. its not smoking at idle or while driving the car just in between shifts w the backfire and then it goes away and only the number 4 plug is wet or black

[sonomadrifter]

Mine only sometimes smoked durring start up (in which it acted flooded) if not at all yet I could smell gas and my backfire's occurred deceleration and shifting as well.

*UPDATE*- Car is running perfectly now, I believe my number two injector was stuck or leaking but it is now fixed (fingers crossed).

[TurboNinja]

So is backfiring in general normal with these vehicles if your not running a cat?

[WoolyS14DET]

Sounds like a timing issue. Correct timing adjustment is as follows, Unplug and plug in the TPS 3 times and on the 4th time leave it unplugged. (this puts it into timing mode.) make you adjustment via the CAS. After adjusting then plug the TPS back in and see what happens. If the timing light goes crazy while your doing it you could have and issue where one of the cams jumped a tooth or may have a bad pulley. (the outer ring is slipping on the pulley) Try that and see what happens !