chris_g

iTrader: (29)

I know this has been covered many of times, over and over again. I did literally DAYS of research, checking many different options. I am still stumped.

My problems are these;

• It runs too rich (You can taste it in the exhaust fumes)
• It backfires upon deceleration
• When not fully warmed up, the choke still needs to be on
• Upon deceleration and clutch let out, it sometimes stalls
• The idle won't go below 1000
• The idle fluctuates between 1000 - 1200

Heres what I have -

• 84 GS
• Nikki
• No rats nest - (Previous owner took this out, I still need to figure out why some things are goofy on it)

Upon my research, I started to tear into the problems.

I started with a fresh rebuild of the carb. I replaced all the gaskets, the floats and needles. I adjusted the floats to 2" when down and 5/8" when up.

I put the carb back on and it started to run a little better.

I checked for vacuum leaks, EVERYWHERE. I checked this about 5 times or so hoping I missed it every other time. I used starter fluid to do this and no leaks were to be found.

I checked the shutter valve using this technique (http://www.mazdatrix.com/FAQ/SHUTTER.HTM). I find out by later research mine is not in use after the rats nest being taken apart.

I checked my jets, from this page (https://www.rx7club.com/showthread.p...light=jet+size) and YES, I did make sure the secondaries were both 160 and the primaries were 92

I changed my plugs to new NGKs. Wires are less than a year old. They all look and connect fine.

The vacuum I am getting is around 18psi. or whatever the abbreviation is.

Timing is dead on, I just set this and rechecked it.

When I put the carb back together, I will make 2 or 3 videos showing all of my problems. That should help diagnose something, I hope.

I also checked into this website - http://www.nellump.net/peri/epi/firs...gslseIdle.html - to help get the problems fixed.

See, I did some research, haha.

Thanks for the help,
Chris

chris_g

iTrader: (29)

Heres a video of the backfire;

http://www.youtube.com/watch?v=o8w-bhNwYSo

and here is a video of the idle. It only jumps around about 100 or so now at 1000rpms

http://www.youtube.com/watch?v=ELgMLRhHK6o

Sorry about the crappy vid. It was my phone as I couldn't find the camera.

lascelles

Check the plate they used to seal to air pump ports on the manifold.

If it thin, warped or they used cheap sealer …

Mine did not respond to Carb clearer, wd40 or starting fluid. But when I pulled it you could see the leak path

chris_g

iTrader: (29)

Where abouts are the air pump ports on the manifold.

Obviously on the manifold, but where are the ports, haha.

Sorry, I am getting so frustrated with all of this.

yetterben

the acv plate passenger side on the intake kinda trapezoid/rhombus looking deal!

lascelles

heres a picture

also could be your brake booster it plugs in at the rear of the manifold
disconect and cap the nipple

chris_g

iTrader: (29)

The air pump port still has the bypass on it. This was never removed.

Should that make a difference?

lascelles

try http://www.ten15.net/Maz.tutorials/ to help with rats nest

If it's pluged it should not matter. there is another elbow out the back going to the cat. the hose is a common leak point

it's in the tutorial

Jeff20B

iTrader: (13)

Under decel if it goes lean, it can cause an 'after fire'. If there are any exhaust leaks, it can cause 'after fire'. Those are two known causes that I'm familier with.

djjjr42

I saw the idle video and couldn't help but laugh. Seeing your tach is not gonna help us man.

As has been suggested already, go over that tutorial for the rats nest removal and make sure everything that is supposed to be plugged up, i.e. the shutter valve, the AAB valve, ports at the base of the carb, etc. are plugged. There's a lot of stuff and something small could've been missed when the PO did it. I'm guessing that there could be a vac leak somewhere and the PO just cranked up the idle to keep it from stalling out.

Did you pull the intake when you did the carb? You could have a leaking intake gasket. Is the catalytic converter still on? Without the air pump it doesn't fare very well.

djjjr42

To avoid confusion of terms, that's the air control valve that should have been removed from the manifold and uses a blockoff plate. The air pump runs on a belt at the front of the motor, and that should have been pulled off when the nest was.

Jeff20B

iTrader: (13)

I call it the ACV for short.

hanman

"It runs too rich (You can taste it in the exhaust fumes)
It backfires upon deceleration
When not fully warmed up, the choke still needs to be on
Upon deceleration and clutch let out, it sometimes stalls
The idle won't go below 1000
The idle fluctuates between 1000 - 1200"

Running too rich is kind of a subjective observation in these cars. Without the rats nest and emissions controls, it is going to smell "gassy". That doesn't necessarily mean that your car is not running "too" rich, just that in general they smell pretty bad without any emissions on them.

Backfires are usually caused by holes in the exhaust (even a pin hole can cause this) by allowing fresh oxygen in to the system. I would check this first. Timing can also be an issue.

Stalling until not fully warmed up.. Mine has always been that way. I need to use the choke (when I had one) until completely warmed up.

The idle won't go below 1000 rpm. You have an air leak somewhere.

chris_g

iTrader: (29)

Thanks for all the help guys!

It now seems to idle a lot better, still high, so I am going to check for the 6th time on vacuum leaks and just do the removal tutorial on my own.

I know the PO took out that little canister where the vacuum line goes to the oil fill neck, so I need to find another one of these.

As for the idle video, sorry about that. It was hard to get at the point in which I wanted to get at. Apparently the needle didn't move on video as much as it does in person. That is what I was trying to get at. Sorry.

The cats are still on, but I know there is a leak somewhere. It is just a tiny leak, but like HANMAN said, this could definitely be part of the backfiring problem.

I didn't take the intake off as I took it off when replacing the O rings a couple of months ago and I'm almost positive I changed the intake gasket while doing so. I think the kit I got from Atkins had the gasket and O rings.

chris_g

iTrader: (29)

Well, the trouble is still here.

The idle is near perfect. I have it set at 750, but it could be set lower id needed. I forgot what I did to fix the idle issue, but I know it was common sense and right in front of my eye.

Now this time, it runs crazy rich. I feel bad for the people behind me to be honest with everyone. It still backfires badly. But this could be due to the nature of the Rotary and a pinhole leak by the cats.

I just cant figure out why it runs so rich. I set the idle to 1000, set the fuel mixture screw til it stumbles, out 1/2 turn, and then set the idle to 750.

I replaced the muffler, thinking because I bought a cheap one it a. sounds like crap and b. wouldn't burn the fumes correctly. So I bought one of those Advanced Auto Parts Thrush Turbo mufflers. It sounds deeper, but didn't kill the backfire.

STILL, its insanely rich. What else could be the problem!? ahhh! It's getting so frustrating.

NCross

iTrader: (18)

Could your timing be off? Or your plugs be bad?