JesterFD

I will start off with the run down...
My issue is that, at roughly 6psi, when the secondary turbo should be firing, a long chain of backfires rips out.

Here is the scoop on my car when I bought it...
- 3 month old used car, though she is new in my heart :P
- twin turbo touring 1994 rx-7
- removed cat
- installed downpipe and racing beat cat-back
- replaced stock twins w/ Efini '99 spec turbos
- (added Fluidyne radiator and Pettit Alluminum AST since)

Car ran like a champ from what I can tell when I first got it.
Changed the oil every 1,800 - 2,000 miles...

Put in some monitoring gauges (better temp., better oil press., and air->fuel)

Air to fuel seems to be fine.
Pressure seems to bounce up and down fine.
Temp ranges between 190* F -> 210* F.

Had a turbo gasket leak.
-fixed...

~Installed right after were
-fluidyne radiator
-petit alluminum ast

But ever since a little before the leak issue and after when I step on it so that the secondary turbo kicks in, pow-pow-pow-pow...
Every, oh I'd say, 1 in 20 times, I'll see (*and feal*) it hit 10 psi like when I bought it... but most of the time it's just death...

I know something is wrong.

I thought maybe the oil was an issue now so I switched to Royal Purple. Though the temperature of everything went down, the problem continued. Waited.... Changed the oil again... putting Royal Purple back in, thinking that maybe it didn't like possible non-synthetic oil remnants throughout the system.... NOPE....

And now I am at a loss for words.

Any help would be great...
It's just a pain, because the only place that I trust to work on my car is an hour and a 1/2 away... and I would like to think it is something I can fix versus having to have them tear into my car... :: heh-heh

...and on that note I will sleep.
<3 6:00 AM work (wish I was rich and could just toy around with this money pit all day)

~Travis

Madmax670

replace the spark plugs, it works wonders, seriously

JesterFD

I will try it... I have held off because I thought it was something more. I was "told" that they had been done before I got the car. I'll check it out and let you know. Thanks bro.

~Travis

dgeesaman

iTrader: (7)

And also do the plug wires if it's been a while.

Dave

BoostFrenzy

Sounds like a boost leak to me...

Also, you're still running the main cat I hope? Boost creep is a no no on the factory ECU

dgeesaman

iTrader: (7)

I don't think boost leaks cause backfires.

Dave

Madmax670

Yea, I watched the guy put new spark plugs in my car, ran horribly, bucking, hesitation, replaced them the other day, runs perfectly.

alberto_mg

Did I read this right. Are you are running a full open exhaust w/o any kind of boost control or ecu?

What do you mean you fixed a turbo exhaust gasket leak? Which gasket?

JesterFD

Well for starters.... it was the spark plugs... whoever replaced them last put in Trailing in all 4... dumb@#*'z

~> Thanks Mad Max

Secondly, I changed the oil and installed the Pettit grounding upgrade... Now if my ac is on, it won't stall at a stop like just cause... w00t

Thirdly, my cables prolly need to be changed out. In due time I sure will dgeesaman...

The mid-pipe is stock I do believe.... that would leave me to believe I am not running a fully open exhaust... though the Power FC is 3rd to buy on my "need to do" list.... 1st being the suspension, because my back right side hates its life, and 2nd being the transmission, because sometimes it hates 5th gear :-X... One question for you though alberto If I had a complete exhaust system, what would buying just a boost control due for my car (other than being to control boost) I am pretty sure if I had huge pipes from front to back the ECU would be what needed an upgrade...

Lastly, to answer your question, the exhaust gasket on one of the turbos had "heated up and cooled down to many times improperly" leading me to believe that after running the car hot and hard, the previous owner would drive home quick aswell and just shut it off... If not that, then it's beside me. I just think it was due to that because Mazda of MASS. (though I live in NH, talk about a drive for a rotary mechanic) fixed it for free because they fixed it for the old dude already within the last year :P

Car seems to be running like a champ again... <3

Thanks all, happy hunting!

BobfisH

ok, the boost control thing people are referring to is caused when running a fully open exhaust. What happens is that because of the less restriction in the exhaust, the turbos spin faster and the wastegates cannot vent enough boost to keep it in check at 10psi...On long throttle runs (i.e 3rd gear up flooring it) as the car cannot vent enough boost, the boost climbs and climbs (sometimes up to 15psi or so)

This is a fast track to a new engine. The only rememdy for this is to have the wastegates ported, which requires removal of the turbos themselves. A boost controller and ECU will not sort this out, as the problem is that the car physically cannot get rid of all the boost its producing.

HOWEVER

A) I believe the 99 spec turbos have a larger wastegate, so do not suffer from this problem. Dont take my word for gospel though.

B) if you do get a new ECU (Apexi PFC or similar) and a boost controller, you can then run higher boost (13 - 14 -15 psi or whatever) and boost creep will go away, because the car is using the extra boost it produces and tuned for it...

Glad you got the spark plug problem sorted! I had the EXACT same problem on my car.

JesterFD

Interesting... even more for me to think about : )
I love this car, everyday that goes by I learn something new, because some new issue pops up :-P

riptor

glad to hear u got it sorted dude...my friend had a similar prob with his...jus tthat when he changed the plugs he only cahnged the back ones and not the front ones lol.....so he fould the new ones pretty quick and they were iridiumj plugs...!!! so lesson learned im sure..and yes happy hunting...