engelz_7

not sure if its been asked. can't get the search thing to work. but i've had my 7 for about 2 years now, and it started to back fire about 5 months ago. been told it was runing to lean or the air control value went out. but can't seem to figure out why its back firing. so if anyone has any advice i'd greatly appericate it. like to keep my limited on the road.

Rx-7Doctor

iTrader: (13)

What year?

VPTUNING

hey doc mine does the same thing 85 rx7 gsl. but i noticed it when i straight piped it and added exhaust it does it alot more. it it normal????

engelz_7

83 limited. just got it over 140K

engelz_7

thats weird...wasn't showing it till i reposted it..

trochoid

iTrader: (6)

First thing to check for would be exhaust leaks. If none are found, we can go from there. Also list any mods/maintainance you've done to the intake, carb, exhaust and emissions.

engelz_7

well a year ago i had the carb rebuilt and a new shutter value put on. previous owner wired it shut for some reason. before i bought it they had a hole new exhaust put on. still in great shape, since i try to avoid bottomin it out. its still just a plain stock engine, intake, carbs, etc. haven't had the funds to mod it. and of course the seasonal tune up.

Yellow '79

is the air filter on tight b/c the samethign happend to my dad where he replaces the cleaner and didnt tighten it and it caused the car to backfire

engelz_7

air filter or the whole housing? cuz it's on there pretty good.

Yellow '79

i think the whole thing or mabye just the cover

engelz_7

the whole thing is on pretty tight. takes a little effort to get the wing nut to break. could there be a house that i should check? i've heard that if it back fires a lot. it could cause the engine to need rebuilt. and i diffently don't have the money for that.

Yellow '79

i might be mistaken but i think that it would backfire more if it was running rich and not lean. im the hayns manual (if oyu have one) it should tell you where to adjust the carb so it runs more lean/rich. but im not sure why it didnt start backfireing as soon as you rebuilt the carb. did you have the thing tuned when you rebuilt it?

engelz_7

yeah, the guy that does the work on my car did it. he used to work at mazda back when 1st gen came out. i was referred to him by all the mazda dealerships that i went to. that i
haven't done and don't have anyone to teach me. still learnin the trade of do it your own.
i've messed with the mixture screw to see whether it was running lean/rich. i tweaked with it. i'm sitting about 1 and half turns out. it was at 2 and a half. it only seems to back fire when i'm high in rpms and let of the gas to shift up or down. if any of that helps.

Yellow '79

sorry but im otu of ideas, when rx7doctor or trochoid come on line they will beable to help you out

engelz_7

its cool. thx for the info.

Siraniko

iTrader: (13)

bad coil/igniter will make it backfire as well

engelz_7

explain...not quite sure what that is. does it deal with the plugs and wires?

Siraniko

iTrader: (13)

if leading aint firing, it will run rough and during deceleration, you will notice a constnat backfire.

engelz_7

that sounds like i need to check to see if the coils are getting fire. or just little own firin right?

Rx-7Doctor

iTrader: (13)

If the leading side is not operational the engine will have very little power.
Is the idle poor and is their stumbling on or hesitation on acceleration?

engelz_7

nah. the acceleration is fine. haven't had a problem with that. but i have been havin the idle stick at about 12k instead of 800.

Rx-7Doctor

iTrader: (13)

I'm sure you meant to state 1200 rpm. It sounds like there is a vacuum leak. Check to the small hose that comes off of the bottom of the air cleaner on the driverside and make sure it is attached to the rats nest.

engelz_7

yeah sorry.
catch all my hoses to make sure theres no cracks or just isnt hocked up?
do you think it the coil/igniter could be going out?

Siraniko

iTrader: (13)

In the manifold, there is a butterfly but I cant remember the name. If this goes bad, you will end up with very high idle and you cant lower it either.

Rx-7Doctor

iTrader: (13)

If you had a problem with the trailing ignitor then the tach would not be working.
If you had a problem with the leading ignitor as stated before the engine would have very little power.

As far as the hoses go, check to make sure they are not cracked and are attached properly to their respective homes.

Wacky,
Are you refeering to the shutter valve?