Getting the engine running better could increase your poewr slightly, make it run smooth which will allow the motor to pull the car out of this bouncing chug you are getting.

So since your trailing is working, you should look at some wiring diagrams to find out why your TACH is not working.

 

Connect the timing light to the battery, turn off all of your accesories, insert a wire into the check connector? It's in the fsm exactly what connector you need to jumper, let the car warm up completely. Put the clip on the timing light on the T1 spark plug wire, and aim it at the main pulley by where the pin sticks out of the front cover, pull the trigger and see whats up.

If you can pull your injectors and see if they're clean or not.

The only way you can adjust the mixture is by the screw near the AFM and it only does it for low RPM operation

 

Yes on top of the throttle body right where the intake pipe connects to it there is a bypass screw. My idle does not change when adjusting it, I can adjust my idle seperatly from the variable resistor screw.

As far as motor mounts, my garage (operating over 30 years ish) told me they pryed at all of them and inspected em visually.

 

what should i be looking for with the light exactly?

Um, im pretty certain the screw im tunring is allowing more/less air into the mixture as it clearly is a bypass screw (as indicated in the FSM) right on the TB after the intake piping,. Since turning it left (lean according to the FSM) alot of the fuel smell is gone and its more powerful.

I can adjust the A/F mixture as well from the variable resistor screw and this seems to directly and only effect the mixture @ idle.

This is what ive gathered from reading the FSM, searching the forums and my recent tinkering.

Correct me if i am wrong,
Cheers
Zip.

P.s. I will take a picture of the screw I am speaking of

 

pull the fuel pump and check the pump filter sock directly on the pump.

kevin.

 

A light flashes when there is spark and you see how far away the mark on the pulley is from the pin on the front cover. Then you turn the CAS to adjust the timing to get them perfectly lined up.

The variable resistor, which is by the MAP sensor and AFM, is what controls the A/F ratio, at idle. The screw that is on top of the throttle body, is the air bypass screw which raises the idle. Adjust the air mixture according to the FSM.

 

Bad wire(s)
Bad plug(s)
Bad trailing coil (probably un-related to the chug but as said its why your tach is shot. Three bolts, two plugs - easy to change)

I'd check those out and then move onto spec'ing the pressure sensor and AFM....has someone installed a cone filter on the car lately? Or is it still a factory air box?

And what is on the car for exhaust? Sounds close to stock to me. May there still be a cat in place on the system?

 

yeah thats a good one classic, his afm could be bad

 

Thats not right. You should NOT adjust the idle with the Variable resistor.

Since when do standard mechanic shops know that the hell they are doing on a rx7? I havn't seen one.

Use a timing light hooked up to Leading 1 spark wire and shine it at the main pulley while the engine is running and make sure the first notch on the right of the pulley lines up with the pin, you can even advance it a couple degrees.

At WOT, there is virtually no restriction in the throttle body so very little if any at all will flow through that tiny restricted hole. This will have no affect on your AFR.

Thats what the idle bypass screw is for, idle, to bypass more or less air by the throttle plates to allow the engine to idle. This will in no way effect your AFR during cruise or WOT.

Variable resistor is only for idle. Nothing else.

You will learn a lot more soon. As long as you are open to learning, you will get better responces.

Click on the link below to learn a little bit about idle adjustment and idle AFR adjusment
http://howto.globalvicinity.com/gv_w...i=61&co=1&vi=1

BTW, soft mounts will do this.

Also, when did this start? Does it chug when use light throttle to accelerate? Does the engine skip or chug when you are in neutral or park and quickly going to WOT?

 

Mine did something very similar to this.

On my car, the AFM had a tiny dent in the side that caught the flap and held it wide open at all times. Car chugged horribly at low rpms but the smoothed out towards the top end (sounded fairly wicked at idle with dual N1's though. More lope and bass than my '71 vette with 4-inch side pipes).

Anyways - my 2 cents says check out your AFM. Sticking flap causes all sorts of issues, and is an easy fix.

 

You mean Air Flow Meter right? like the MAF? I thought you ment air fuel mixture. :-PThis is a sensor is it not? How would i find/check this?

When i bought the car it wouldnt Idle, period. Now that ive got it to idle, it has this problem while driving. So im not sure when it started per say.

No If i give the LIGHTEST amount of throttle from a dead stop (i.e less than 1/4) then it will go smothely and very slowly, this is the only way i can drive it now. Once i ease into it and it gets into 2nd gear or even high 1st gear rpms I can floor it and it seems fine. It only is chugging from dead stop generally.

Nope, in neutral or park i can go WOT and it revs up like a bat out of hell. loves it.

As well I noticed something after you guys told me to check my aux port actuators We looked at them while the car was off, the 'arm' was sticking all the way out of the actuator. We put some grease, and drove it. After we turned the car off, we then went to look at the actuators again. And noticed that this time the 'arm' was 'closed' (not extended). This was odd. actuator is doing two different things. Now weve been constantly looking and its imposible to predict. Its either open or closed when the car shuts off, I know they are moving. I dont know if they are moving properly. Maybe this is my problem?

p.s. thank you guys very much for helping me understand about the idle bypass screw and variable resitor. I realise now where i was misunderstanding things. Thank God and thank you guys for making my rx-7 enthusiasm much more understandable!!!!!!!

Cheers,
Zip

 

Don't confuse Air Flow Meters (AFM) with Mass Air Flow Sensor (MAF). They are completley different animals. AFM measures air flow while MAF measures the air mass. The AFM needs to use the intake temp sensor located in the AFM to determin air density to calculate for Air Mass. The MAF does't need to do that since it measure mass directly.
You can read a little bit about a project in progress about converting AFM to MAF
http://howto.globalvicinity.com/gv_w...=120&co=1&vi=1

We have a AFM. Look in the Factory service manual below under Fuel and emmisions.
http://www.teamfc3s.org/main/factory_service_manual/

Im going to head in a different direction with this question, is your throttle very sensitive? if you go to 1/4 throttle pushing the pedal slowly does the engine jump in power, as if you floored the gas? Or can you accelerate the engine smoothly?

So you can rule out ignition and fuel problems.

This may hurt your performance if they don't open. You will also loose some low end if they don't shut. You can remove the actuators and push the arm in and out to make sure the actuator is not binding. Then try to turn the rod on the lower intake manifold (LIM) and make sure they tune easily. IF not, you may want to start learning how to remove the intake manifolds and start cleaning your port sleeves.

This will not cause your chugging. If they are open at low rpms, this could aggravate the main issue but is not the cause.

You Welcome. Everyone on this forum is more then happy to help out as long as you are interested in learning

 

I still think its a fuel issue, or ignition, one of the two.

 

ok guys, dont bite my head off, but turns out I checked the wrong coil, figures. Had an rx guy take a look at it, he says trailing coil isnt working . I only paid for him to find the problem going to try and fix it myself with a friend.

Never the less he said it is wierd that both of the trailings are not sparking and he thinks the coils might still be good. And dosent think that the 'chugging' is due to that either.

Going to search 'trailing coil' in the forums and see what I come up with.

p.s. is this bad for my car to run like this? as soon as he told me I drove home and stopped driving, Im scared.

Cheers
Zip

 

I think the trailing coils use one igniter for both. I can't be sure though. I would have to look at the FSM.

The trailing is like a clean up coil. The leading coils are the one you can not run the engine without. It wont start. You will loose power without trailing firing but thats about it.

At least im not the only one that knows the ignition is not the cause of the chugging

 

ok trying to understand the fsm, says i need an 'igniter checker', so confused here, dont wanna have to replace the coils if they arent broken. Not 100% sure how im supposed to check em. gotta work now, will do some readin there.