I have a 1986 7 13b n/a and past 3800 my a/f is back and forth from full rich to full lean and so much so it makes my car jerk. Fyi i have a aem wideband.

 

Does it happen at 3800 rpm then go away? The secondary injectors turn on at 3800 rpm and if there's a problem during the transition it can cause hesitation.

To fix that you can clean up all your engines grounds and re-tighten them, its a known problem that I had myself on my old na.


Rotary >Pistons

 

sometimes it goes away other times is will jump till i get to the 5500-6000 rpm range. I will check all grounds as you said, now can a tps out of adjustment cause this issue also?

 

It does sound like a bad case of the "3800 RPM hesitation". The primary ground to inspect/clean is on the top of the rear rotor housing. In many cases, the wiring itself will have built up a lot of resistance over the years, so re-grounding the ECU ground wires to the floor of the car can be a cure. Pins 2C, 2R, 3A & 3G are grounds.

NA ECU Pin outs on 4A-30 to 4A-32
http://www.rotaryheads.com/PDF/2nd_g...systems_na.pdf

 

Thanks, i go ahead and clean up all the grounds then report back

 

Just got out of the studio (work) going to head home, grab a beer and clean some grounds so ill reply in the morning as im heading to the studio tomorrow to fix my exhaust since there are no model s's on the lifts. If the prob is still there im going to make some new heavy grounds.

 

I used sandpaper on mine to clean them up.

Rotary >Pistons

 

doing the sand/clean method for the grounds did not fix the issue so im going to make all new grounds and add a few extra as it wont hurt.

 

Yep, check grounds!

 

Well I did all the grounds (made nice new ones and added extras) and the issue is still present. What I have noticed is that the throttle position makes a big deal as to how bad the a/f jumps, so if im pedal to the floor or just crusing with a little throttle the jumping is little to none but if im half throttle getting on the freeway or round town the issue is bad.. Soooo tps?

 

anyone? can anything else cause the issue that im having?

 

Here is a good way to test a Tps.

http://fc3spro.com/TECH/HOWTO/TPS/tps.html

Also here is a good write up on grounds.

http://www.aaroncake.net/rx-7/grounding.htm

 

Thank you, after reading the ground topic and doing what i did im sure its a tps issue.