Hey I have a 1985 rx7 with the 1.1 4bbl my problem is that I am getting hella backfiring from this old dog I have went through and changed out my sparkplugs wires and oil I apologize for my ignorance but this is the first time I have ever messed around with a rotary so please excuse my lack of knowledge on how these work. Anybody have any suggestions? I have also tried to advance the timing and mess with the idle speed control on the carb but nothing seems to work to even out the idle and eliminate the misfiring. Any suggested paths to resolve this issue?

 

An exhaust leak always seems to be the culprit with unctontrollable backfiring.

Marques

 

actually i found that improper ignition timing, and/or occasionally improper fuel/air mixture (only if the MAS cap has been removed) can be responsible for this...

 

you might be running too rich and extra gas is is not being burned and is entering your exhaust manifold and is detnating in there. that would cause back fires and fireballs. happens to me in my stang.

~Steve

 

backfires are thru the carb, not the exshaust

 

you're running too rich buddy.. simply mess around w/ your air/fuel ***** on the nikki carb. should be a simple task to do

 

Ok I tried to mess with the carb but all I have is an idle speed screw no mixture screw I have a vacuum line that leads out of where it should be I have tried to disconnect the hose to test for affect but it won't run without it so how do adjust mixture on this carb ???? I really want to take this thing out and play with it

 

Which screw can you get to, and which is covered by the hose?

Red = Mixture
Blue = Idle Speed



Brian

 

ok I see now the odd thing is the haynes manual I have lists th two screws stacked on top of eachother I can get to both of them then my problems goes further than I thought I have adjusted the mix screw and still get a serious lack of power it seems like it is still running to rich but I will take another look at that to see what is going on

 

Yeah, unfortunately the haynes manual is written mostly on the Series 1 79-80 model cars. For most items, this is no big deal. There are, however, "minor" descrepencies.

 

I am still not getting it down just right I am still lacking power in a major way and it sound like poop it sounds like a car with a bad o2 sensor but these things aren't equipped with that right ?

 

As far as I know, only the EFI 13B's have O2 sensors. What is it acting like? Is it sputtering at an idle? Or is it smooth at an idle, but bogging when you punch it? Let us know some more details now that you can adjust it fully. What RPM is it idling at? Things like that...

Brian

 

It is idling fairly smoothly at about 1k which seems high to me but I again am not familiar with this type of engine and yeah whenever I put a load on it it bogs down

 

those haynes manuals suck. they made me more confused than helped. thats why i go to you guys!

 

Idle should be the same as most piston engines, 750rpm.

 

sounds like you may need to adjust your a/f mixture, if it bogs when you stomp it your prolly running hella rich.

my truck does that till it's warmed up

 

I have tried to adjust the IDle mix but it is not doing any good and then I put a timing light on it and it shows it as being way out of whack what would cause that ?

 

Have you tried adjusting the timing? Have you checked the vacuum advance units to make sure they are working? To do this, pull the cap and rotor off the dizzy, and make sure both units inside move freely. Check the timing advance vacuum control valve solenoids as well. And check for vacuum leaks. If I think of anything else I'll let you know. Too tired right now, just woke up. 6 hours of sleep, after being awake for 35.5 hours...

Good Luck,
Brian

 

Thanks Brian I was starting to think that there was something wrong witht the vacuum I tried to move the advance units and it seemed as if they were frozen in place I kinda thought that might be the problem I will work on it more later thanks again you have been so much help I wish you lived closer I'd take you out for a beer bro

 

if u still have the air pump hooked up it could b the diverter valve

 

I took the air pump for the emissions off a few weeks back.

 

OK so I took another look at things and it seems as if my Idle is at about 1200 rpms and I have thinned out the mix as much as I can I took notice of the leading and trailing advance diaphrams and they seemed to move freely but the vacuum pressure to them seemed a bit weak now if this helps at all I did notice that when I ran it before it did hesitate a little when I jumped on it for like a second or two and then it seemed asif it caught up with itself this is before it went to pot on me I am kinda confused by all these vacuum lines and what not I am used to working of fuel injected vehicles I thought this would be less complicated boy was I wrong I have been considering taking it to the mazda dealer in my area would you recomend this course of action?