chocolate_supra

I've been having issues with my 93. The thing runs great, but it's now the worst of summer and I've finally gotten to turning my A/C on. When I do, it idles so low that it nearly stalls when you take off. I tried adjusting my idle so that it idles at the proper 850 or so with the A/C on, but then with the A/C off it tries to idle at about 1500 and bounces back and forth roughly between that and 1000 unless I readjust the idle back down.

Thing is, I notice there are multiple adjustment screws, and after all the research I've been doing, I'm not quite sure which one adjusts what. I've posted a picture with the adjustment screws circled and numbered. Can someone tell me which screw adjusts what, and under what condition (cold, warm, etc)? Many thanks!

catch-22

iTrader: (2)

number 1. you still on the stock ecu?

oo7arkman

iTrader: (2)

Actually if your car was idling fine before you should not use any of those screws to adjust the idle. The front set of screws (1&2) adjust the plates inside the throttle body to be fully closed and wide open at proper throttle application. Number 3 I believe has to do with the warm idle adjustment, I don't know, I have never touched that one. Where you should be adjusting the idle is with the Air Adjusting Screw that is located underneath the elbow in the lower, center area of the throttle body. If the other screws as well as your TPS are set correctly a good starting place for the air adjusting screw is all the way in then out 1/4 turn and adjust acordingly from there.

Are you on the stock ecu? If not and you have a pfc it sounds that the setting for your idle under load (ac on) is set too low.

If not, then check the TPS and make sure it is within spec.

If all that checks out pull the Idle control valve and see if it is any good. It is in the FSM what the ohms should be if it is good.

**edit** here is a good thread talking about idles with a great shot from the fsm on the TB. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/2k-rpm-idle-still-854524/

chocolate_supra

Thanks for the advice, catch-22. I closed the Air Adjusting Screw all the way and reset it between 1/4 and 1/2 turn, then readjusted what I had done with the other screws and the idling sounded about right.

I'm still having one issue, though: I've noticed after all this playing around that when the A/C comes on, my revs decrease, although I've read that the revs are supposed to be about 100rpm higher with the A/C on. In order to keep the car from stalling under A/C conditions, I've been setting it at 850rpm or so with the A/C on, but then when I turn the A/C off the revs come up over 1100, and then the weird rev-bouncing happens. Is there a particular module I can check that's supposed to sense when the A/C is putting a load on the engine, then raise the revs?

By the way, I'm on the stock ECU.

arghx

iTrader: (3)

remove ISC valve and clean it

gracer7-rx7

iTrader: (16)

Whenever I have had idle issues, I usually wind up adjusting those three as well as the one at the bottom of the throttle body (need to remove the intake elbow) and the fast idle cam. The FSM has the procedure for adjusting and there is a thread in the Archives as well as some links in the FAQ thread - both of which are stickied in this forum.

Monsterbox

iTrader: (6)

I might be wrong.

But, I believe Number 1 is the preload on the throttle cable. Its literally like pushing the pedal in but keeping the ecu in idle mode. You get bouncing because ecu doesn't control the fuel.

When I adjusted my idle higher, I removed the actual elbow and there was a screw that I turned with a screwdriver that litterally opens the throttle plates. I cracked the plates out a little more which raised the idle perfectly. I've learned to never touch Number 1 as it bounces the idle. Number 2 and the one underneith are related to the cold start I think.

arghx

iTrader: (3)

how to check the magnet which moves the plunger inside the valve:






You have the factory ECU. The first thing you need to try is troubleshooting the problem the way that the factory intended for you to troubleshoot it. Much of the advice on idle issues (including a lot of advice I myself have given) is for a car with a Power FC. Setting the idle on a stock ECU is not the exact same as setting the idle on a Power FC because of the way the ISC valve is controlled, so don't necessarily do what PFC users are doing. Verify no vacuum leaks, then remove, inspect/test and clean the ISC valve. You can clean it by spraying carb cleaner in it and applying 12V to the terminals multiple times. Reinstall the valve and try setting the idle according to the factory procedure. Then verify that the TPS voltage is in spec after that.

When you jumper the diagnostic connector, the ignition timing is fixed at 5 degrees ATDC leading and 20 degrees ATDC trailing (no A/C or electrical load), while the ISC valve duty cycle is fixed at 38%



if the connector is not jumpered, the ECU will start responding to the changes you make in the throttlebody and you will not be able to set the idle correctly. The Power FC does not work the same way. When the unit is reset it sets an operational range for ignition timing and ISC duty cycle through a self-learning procedure. Often the TB needs to be adjusted before this procedure is performed. Then the PFC controls the ISC behavior during deceleration mostly through the fuel cut settings.

catch-22

iTrader: (2)

still have an air pump

Kim

This sounds interesting.
* I'm running the stock ECU, I can't adjust the idle at all - tried the AAS in every posible setting with no luck.

* Engine has zero miles on the fresh rebuild, but is a real bitch to start, I have to tickle the throttle to get her going.

* When cold, it would idle.

Would cleaning/replacing the ISC probably fix my idle ?

Thanks
kim

oo7arkman

iTrader: (2)

I would check out your ISC but there is something else going on if the aas has no effect on the idle. You should check the tps once the car is warm if you can get it to idle.

Kim

TPS is in spec, except the lower wire is a tiny bit off at WOT.
2nd wire is .82Volts and 4.9x at WOT

Just went and cleaned the ISC, will check if it worked tomorrow, don't wanna **** off the neighbors(midnight over here)

arghx

iTrader: (3)

did you follow the FSM idle set procedure exactly? The one I posted? Did you check the resistance on the ISC valve per the FSM procedure?

Kim

She idles like a kitten now, isc and tps are in spec.
Only now the bitch stalls with electrical load on.
I've tried swapping different isc valves, all within fsm spec, to no use.

I changed the front wireing loom because of a meltdown, now I'm thinking it could have shorted something in its path.

Anyone have a picture of the Electrical Load Unit ?

Just for kicks.
This is the problemchild.

gracer7-rx7

iTrader: (16)

Follow the steps above in the pages arghx uploaded. Your mechanical settings are probably off for it to stall with E/L. Here's a hint - check the AAS and pay attention to how many turns out it is from fully closed.

Kim

Sorry to OP for kindda hijacking this thread.

So far ISC is at 11.8ohm @20C
TPS is also within spec in the entire spectrum
Idle is a steady 800-900, even with the heater and AC running.
But as soon as I turn the lights on, engine stalls immidiately even if i try to keep the revs to lets say 3000 manually.

*EDIT* I wired the headlights via relays if thats any help, will try and redo it to stock.

Kim

Going back to stock did'nt help.
Tried another ECU too - no luck

Kim

Alternator puts out a healthy 14Volts.
Damn this little issue is killing me.

arghx

iTrader: (3)

you need to make sure the ELD signal is getting to the ECU. Bypassing the factory wiring was a pretty bad call.

Kim

Mkay the ELU should be behind the ECU right?
There's a small black box, with no where near the amount of wires in your diagram.
Not sure if thát is it, this is a Jap car,

http://i25.tinypic.com/280qpfn.jpg

Also I noticed a funny clicking sound from under the uim when using the LEFT turn signal WITH the headlights on.
http://www.youtube.com/watch?v=956gW9NVcHM

Thanks for helping out - hope You dont mind me being a noob. - i'm new to the FD wireing hell :cheers:

arghx

iTrader: (3)

That might be the ELD computer. I've unplugged it before but I've never unbolted it and dropped it down, nor have I ever worked on a J-spec car. When you flip the lights on, does the ELD indicator come on or not?

Kim

Fixed.
It was bad grounds on the front wiring loom.

Pheew

Tak for the help, i've gotten a little smarter on Fds now

Peruvianrx7

iTrader: (25)

I have the same problem where is the front wiring loom?

blkops

#2. That's what I've had to play with on both of my single turbo FD's. After a while the idle just got too low and the car would stall. Literally just turned that screw/locking nut less then 1/4 turn. Maybe like 1/8. Pita. Also if you have the nipples on the UIM blocked off the high heat can crack the rubber covers and cause a higher idle. Just for reference for anyone else who might have a modded car. Feel free to correct me.

SA3R

Two questions. What/where is the ELD and this ELU you guys are speaking of??
I've never noticed it in my literature nor when working on my Jap-Spec car?