hi everyone new to forum and rotaries but knowledgeable about cars. wanted to say hi. quest is i just bought a 93 FD Red rx7 5 speed. completely stock except previous owner made it NON sequential twins. downpipe and cat back but stil stock cats. he has the air pump disconnected... so i reconnected to b/c i was told it's highly reccomended to keep it on. but if i free revs to like 2.5-3k rpms it'll pop... not too sure if it's a backfire or back pressure... but i didn't like it since i know these engines are fragile so i disconnected it again. wonderign if anyone can enlighten me if this is normal or not. i think it'sa pro 1 DP and Catback. stock intakes turbos etc as said. i was told the cat can fry if air pump is not connected so i'm wondering if my cat is friend already and causing the backpressure/backfire.. thanks for any help! btw i did search about it. and i found nothing just discussion about a/p. thanks!!

Carlos
1993 red FD3S N/S TT

 

If you do a search on Air pump you should come up with lots of posts. I personally do not run an air pump, since it was mostly to help with emmissions. Some people say that it might change your idle a little, but it should not effect your driveabilty. Do you have emmissions in your part of texas???

Not only that, but did you connect the piping from the airpump to the main cat when you put the pump back in??

 

the pump was always there and a belt conencted. but the electrical connector was unplugged that's all. i'm pretty sure like 90% that the hose to the cat is still connected. i was still at the house when i heard the back fires so i just unplugged it again before i damaged anything since i dont' know. i did find 1 post on the a/p backfiring but i just wanna make sure i'm not hurting the motor or turbo's witht he back fire. i DO have emmisions here in texas especially houston. so i would like it connected. is the backfiring normal on rx7's? i have the DP and cat back thanks for the quick reply

Carlos

 

my car backfires quite alot, often when i ease up the revs and let off.

Think it might be a fuelling problem on mine TBH...sorry for the useless post! lol. My airpump is still connected AFAIK

 

Carlos,

The best thing I ever did before I got my FD was find a competent mechanic that knows these things inside and out. Considering how finicky these cars are and the fact that you are new to rotaries, I'd recommend you get an experienced rotary specialist to have a look at it. You have a few good ones out in TX - Gotham Racing, Rotary Performance and a few others.

It is pretty weird to go non-sequential on a car running cats. Most people don't do that as you don't really get any benefit. Something doesn't sound right there and you shouldn't be getting any backfiring when you reconnect the air pump.

 

Crap that'swhat i'm afraid of. i have an idea of rotaries but i won't say i'm any kind of expert. i was reading a quite a few ppl backfire. i wonder if they put in a "chip" or anything?? not sure. i was told all stock the non sequential and DP and catback. i dont' see any exhaust leaks. and idle gets a little steddier with air pump on... i heard the cat will fry if A/P is disconnected... so i'm wondering if my cat already toasted wince the airpump wasn't on... causing the backpressure and fires.... grrr. thanks for the help guys. love my fd though =-)

Carlos

 

I'm new too and I don't know ****. I bought an FD with a blown motor and I just put a remanufactured motor in it. The engine isn't broken in yet, in fact I've put 2 miles on it going around the block just checking it out. When I give it a little gas then let off, it backfires. With the air pump disconnected it doesn't do it. My mechanic friend next door says it's fuel rich air combusting in the exhaust. My car is stock except for a downpipe and Apexi intake. I'd prefer to keep the A/P connected for environmental PC.
It sounds like we have a similar problem, so if anyone else has any idea on correcting the problem I'd like to hear it.

 

well the weird thing is. i connected again the a/p on my fd... ti would back fire right? after about a mile driving it stopped doin it. runs fine if not better. only thing is my idle has gone up from 750-800 to about 1100.. sometimes it'll stick around 13-1400 but if i tap the gas it'll come down to 1100. could it be since i cleaned up the cat a bit with the a/p connect.. and now i have more air idling the idle went up? should i just adjust the idle screw by the T/B and bring it back down? or should i check for leaks? can you spray T/B cleaner on the hoses like you would on a piston engine? sorry for the newb questions. thanks for the help!


Carlos
93 FD3s

 

Take a look at this..

https://www.rx7club.com/showthread.p...dle+adjustment

Btw, the factory manual is on the net. Just search this forum for it's location.
My backfire problem seems better after tighting up my exhaust connections...

 

sweet thanks. i love this forum. answers in minutes.. haha. hey after lets say 20 min drive, i let the motor idle for a min or 2. then do the rev up and turn off so it dosn't flood trick that rx7.com suggests. when i pop the hood to let it cool off... i sometimes hear like a sizzle like behind/under the alternator.. like at the middle top of engine... this normal? just expansion or something? just wanna know. thanks!

Carlos.

 

All I can say is if there are modifacations.....it's no longer "STOCK" Generally these cars don't backfire if the main cat is not gutted. It acts completely diferent if it's clogged up. They usually go non-sequential when they can't figure out whats wrong with the turbo control system, yours may or may not be easily reverseable depending on how it was made non-sequential. I personelly don't run a main cat and have just had my A/P disconnected for quite sometime. I just recently removed it completely. These cars tend to load up the exhaust with unburned fuel quite easily and without the cat's will backfire and throw somewhat large flames out the tail pipe. Most of the experianced owners recomend no more than threee mods before upgrading the ECU. You have two allready "the down pipe & catback" if the previous owner also changed out the stock filter for a K&N replacement this would be three and you can hurt the motor if your running higher than stock boost levels. It does have a boost gauge ? ? ? ? Read the FAQ and use the search. Congradulations on the purchase and hang on for the wildest ride of your life.

 

no k&n filter. just DP and catback. with the non seq setup. i have a autometer boost gauge but i'm gonna sell it with my miata turbo kit and get me a good Apex-i boost gauge and get the water and oil gaugews replaced. they did give me the mid pipe to replace cat completely. but the previous owners never put it on b/c they didnt' have a new comp. i will be saving for a PFC. can i remove cat on stock ecu... or don't even attemp until i get my pfc and retune? thanks!


Carlos
btw. it dosn't backfire anymore. after i drove about 3 blocks it never did it again. i can only think that maybe the cat was clogged a bit. and with the air pump i kinda cleaned it up. i want to remove the air pump when i put the mid pipe. though. eventually =-)

 

I vote for 'don't even attempt it until you get an ECU and a retune.' These turbos lose efficiency above factory boost levels, and the stock ECU doesn't support increased boost beyond a couple of psi.


-s-

 

the car is tuned rich from the factory the backfire is not a big deal, the downpipe is contributing to some of the backfiring because the precat has been eliminated.
enjoy the car and all its quirks.

 

Your motor is blown!















































just kiddin! :P It's normal

 

^ ooo that was a low blow :-P

 

That was so wrong.... haha.rx7's are nice just finecky. i was reading that more mods Can be done with stock ecu as long as the stock boost level is maintained. so if i'm correct i can put the mid pipe IF i get a boost controller right? intake and intercooler upgrade as well... or am i getting it wrong. not tryign to start a flame or big argument. just wondering from the ppl that have done this if it worked out for them. regardless. i'm gonna try to go full Apex-i. i'm saving for a Apex AVC-R Apex Turbo Timer and Apex PFC. probably change exhaust and downpipe for a Apex N1 or GT version. thanks for all the help guys. i appreciate it.!!


Carlos

 

My car backfires too. Infact it backfires everytime i let go the gas. It would eventually gone after I drive it for a while. But then it would backfire again in low-speed manouver (e.g. parking).
My mods are air pods, catback, centre muffler and MINE's ecu chip.
As far as i know, the car is running rich which wouldn't do any harm to the car apart from getting bad gas milleage and smelly exhaust. Correct me if I'm wrong here.

 

Carlos-
Don't tempt fate unless you have the cash lying around for a reman/rebuild, and since you said that you were saving for a PFC, you obviously don't. save your MP until you get a PFC, and install them together, and then get a tune. I think Steve Kan (correctly if i'm wrong) is based in texas, and he's arguably the best rotary tuner in the USA. If your car already has a DP and CB, save your money for stuff that will make your car more reliable (like an upgraded IC, an aluminum AST, silicon/viton hose job w/ check valves, etc). The autometer boost gauge is a decent piece, so wait until you get everything else done before you go replacing all the stuff that's on your car already. take pictures of the turbo manifold and stuff around there and post them, and people will be able to tell you if you have the poor man's non-sequential job, or if you have the full on, non-reversable non-sequential.

btw-how many miles do you have on the motor?

-Jim

 

There seems to be some belief that if you stay at stock boost levels you'll be ok.....it's your motor and the ECU can only compensate for so much air to fuel change.....that's how they found you could usually be safe with three mods. DP, CB, and better flowing intake= 3 any combination of three that increase air flow and stock boost .... remember even if the boost is stock pressure you've still increased the amount of air that flows through the engine. Your new to this so use your best judgement, and good luck.

 

i shall thanks for the tips!! Extremely helpful. i'llhold off on the MP. till i get the PFC and AVC-R. but FIRST on list is AST Radiator and oil coolers. i want it to have no reason for bad cooling =-). this week i gotta fix an exhaust leak i just developed tonight... i'll take pix of the turbo underside and top side with vac linesw etc for ya'll.

also about the back fire i noticed. the only time i'm backfiring now is during engine warmup parameters.. like if tomorrow mornin i turn it on, let it do ti's rev cycle. about a min or 2 later if i start driving or rev it'll pop.. but once it warms up ti won't backfire anymore... once.... in a looooooong while it might pop a tiny bit if i shift early. hehe. thanks guys. i really appreciate this forum. you guys are great.


Carlos
btw it has 63, 300... miles.

 

is there anything wrong with your oil cooler(s)? if there isn't, and you don't plan on tracking your car (road course, not drag strip), there is no reason to upgrade your oil cooler(s). the stock one(s) are sufficient for street driving/drag racing. get the Radiator, AST, PFC, install your MP along with an upgraded IC, and get it tuned. then worry about the oil cooler(s) if everything else is running correctly.