I apologise if this was asked already, but I'm loosing my mind over it. My '88 NA VERT has a pain in the *** backfire when shifting gears at any RPM over 3K, its mild unless you get over 5k... Then its just real annoying. I swapped the ACV off of 88 engine with 50,000 miles on it (Mine has 170,000) and that stopped the backfire for a few months, but it came back about 1/2 yr later. I have heard it might be the ERG valve... Any guesses would be appreciated.


Thx in advance!

 

uhmm... wow.. this is the first time I've heard this question, normally it's the exact opposite ("how do I shoot flames?")

so, ahh, somebody who doesn't just regurgitate stuff they picked up earlier had better answer this one... lol...

 

I noticed that backfires can go away by setting your TPS

 

Good call, I'm gonna check the TPS cause the car occasionally stals when you start it and immediatly turn the AC on MAX.

 

you must not have any cats for it to backfire THAT MUCH, If you do then you defenetly have a prob.

 

Actually I have the STOCK, yeah STOCK exhaust on right now with all (3) cats on.... And it does backfire that noticably!! But there is no power loss and this has been a problem for well over 1 1/2 yr! If I should be really scared please let me know.

 

My friends 90' GTU backfires and his mufflers light up at redline

 

Oh yeah, he has n1 dual's and bonez midpipe

 

I'd ditch the stock cats soon. They clog & begin shortining engine life after 85K - 100K miles.

Most rx-7s will ignite the ritch exhaust fumes when you high rev the car. I prefer this, but if you want a muted car with no exaust note you'll need to run at least 2 catalytic converters (pre & main) and good mufflers (ie sucks power).

Make sure both catalytic converters are rated for the rotary engine's heat output.

 

Upon replacing the ACV, did you check or replace the valve under there? It's small and round, and I believe would effect this.

 

No, I didn't change the small circle like valve under the ACV. I hear that could be a possible reason for the backfire. I had a Bonez dual cat midpipe but i fail emmisions (due to Jerseys new restrictions) so I threw the stock cats on there just to get my sticker. But it backfired with the other cats also....... ugh

 

EGR Valve could be suspect. Check to see If It's holding vacuum. I have a Brand New one for sell If you need one. PM me for details

Also a faulty TPS Is usually accomadated with buckling at higher rpms load usually with a heavy load.

 

Bad EGR won't cause backfires, but a bad ACV certainly will. Also, adjust TPS and make sure your airpump (and related hoses) are in good condition.

Sounds like you're running too rich, which could be the things above, as well as (commonly) dirty injectors.

 

A bad EGR Valve could be attributed to back fire and a bad Idle.

Without the EGR Valve, your exhaust Is being expelled In the purest form. i.e lack of O2. That coupled with a faulty ACV or misadjusted TPS could all be considered suspect on having back fire. Or In my case running a Header straight pipe and a hi-flow exhaust.

 

Not true.

S5 cars ditched the EGR valve altogether, and they don't backfire...

 

The car gets total **** gas mileage (200 miles a tank) if that is another symtom of the problem. Is there a vaccum test I can do on the ACV to see if the smaller valve is no good.... Doing some pondering on the ACV swap, I'm not sure how good the gasket on the "newer" ACV unit is. What are the odds its dirty injectors, cause that goes past my technical limits to remove them and get them cleaned. I have been told it could be the ERG, but at the same time people swear that the EGR doesnt affect backfires.

 

Sorry. I was refering to the s4. With the s5, that a whole different beast altogether as far as the EGR Valve Is concerned.

FWIW, do the 3rd gens have EGR Valves?

 

I have a ACV bypass plate, I was thinking of removing and disabling the ACV for test purposes. BUT BEFORE I DID THIS! I wanted to ask you guys (more experienced) if this could harm anything. Or if I'd be wasting my time, I'm not worried about emissions legality anymore so if you have experience or thoughts on the subject lemme know!

 

I would like to see other post in regards to this matter....lets here it.