I know there's a lot of us with this problem. So far I've grounded the **** out of everything. Changed all my vacuum hoses. Set the TPS with an ohm meter, and LEDs from ECU plug.
Changed/cleaned/tested the BAC, Yesteday I took the belt off the alternator, and hooked the car up to a battery charger, and ran it. That seemed to work, but I haven't re-checked it yet. I hooked the alternator back up, and checked it with the car running. I was thinking maybe there was an AC component in the voltage that was causing problems. I read 15 volts AC on the battery with the car running. I started my Chevy truck, and checked it....same thing. The alternator keeps the battery hot, so I hate buying a new one. I guess to check it right you would need an oscilloscope to see if it's putting out some transient spikes, or whatever.
When it does this it's when you have the clutch in, and it's dropping to idle from higher RPM's. It will hit 500 RPM try to bounce back up (sometimes it does) struggle for a second, and die. I also have a new pilot bearing. I just put my transmission in last week. It's quiet, and shifts/disengages well, so I don't think that's an issue. I put the seal in also, and packed the bearing with Mobil 1 synthetic. When my pilot bearing was bad, you could hear it. Without the A/C on, it runs great. It's an 88 vert-N/A, and no; I don't want to just put the top down and forget about it. Have you ever been to Houston in July?

 

More later, I'm going to check it again with no alternator.

 

mine seems to have the same problem same car 88 vert mine is like brand new it only has like 50k miles on it and when i have the ac on it does the same thing but mine usually never stalls it drops down to 500 rpms but it always recovers...i wonder if they do this right from the factory that would be stupid but i dont know what it could be good luck and let me know if u figure it out

 

probly have a vacume leak

 

Just a idea of things to check to solve this issue that have worked for me in the past.

IF you have already done all the grounding mods and your electrical seems ok, and the idle system doesn't seem to be able to adjust it out...there are only a few other items that can cause this type of issue.

Vacuum lines or intake could have a leak....but from your description, I don't think so.
Fuel pressure could be low due to the FPR or the pump....need to check that if you didn't yet.
Idle fuel mixture could be too rich...I know TII's have a potentiometer to adjust it, but I can't remember on the NA's...I have never owned a vert.

OR the one I think it is in your case....check your timing..your timing may be backed off a bit.

Have you tried to read out any codes from the ECU yet? That would be the first thing to try.

Hope that helps...

 

Also....spark plugs fouled out can do this....or bad spark plug wires/ignition.....

You have an idle issue...not an electrical issue....more than likely...

ALL gens of RX7's suffer from this problem...believe me.....I am on my night 7 and ALL of them have had to be tweaked to solve the issue....

 

My wires have 15k miles on them, plugs maybe a thousand. I've checked the ECU with the little LED thing I made for adjusting the TPS. I had an O2 sensor code, until I rev'd it up. Thats all. I'll check into the timing, and fuel pressure. I'll have to read up on that. Thanks

 

Try the BAC. Sounds like its not compensating for the additional load to the motor.

 

damn j-rat beat me to it.

BAC helps stabilize the idle with diff accessories on/off.

I've had bad idle from intake leaks, and possibly from a very bad exhaust leak too. Not positive.

 

When are you gonna learn?!?! I am EVERYWHERE!

 

raise you idle a little, what are you idling at right now when fully warm?

 

750 rpm, I tried raising it. It didn't seem to help.

 

I already cleaned, changed, and checked the bac. Thanks

 

This morning on the way to work I noticed that at redlights, when I push in the clutch, and the RPM's drop; my dash lights dim significantly. I'm starting to lean towards changing my battery. I've had the car 2 years, and the battery wasn't new when I got it, so it's probably about time anyway. My voltage drops to exactly 12 at idle. I would think a good battery would hold that 13.5-14 volts for a little while, and gradually drop. It starts the car OK, but I'm thinking that it might have a cell going bad. I'd like to hear any thoughts you might have, even if they suck. fred

 

Sounds more like the alternator to me. Have the alternator and battery tested under load.

 

With some RPM's the alternator takes the voltage over 14, but the battery doesn't hold it very well. It drops off pretty fast. I don't know if an auto parts store would pick up anything strange on an alternator. If it charges, they'll probably say it's OK. I guess I could disconnect the battery with the car running,turn some stuff on with it idling, and see if it stalls?

 

Idle and 12vdc?.....revs and gets 14vdc? Well...Do you have a stock alternator pulley or aftermarket? What about the main pulley? You may not get charging voltage (13+vdc) if your pullies are spinning slower than stock at idle. These are the symptoms of an aftermarket pulley....or possibly a bad voltage regulator on the alternator....

IF you hold the rpms up past 2k does the voltage on the batt STAY at 14vdc? It should....
Go to a local parts store with a load tester and have them check your charging system. They can check the alt and batt while still on the car. (depends if they have a tester or not).

There are a lot of assumptions to troubleshooting on a forum. Need to have more details...

By the way....the BAC valve design sucks...can't compensate for much of anything IMHO. A good electrical charging system and battery is a must, so do that first. Second...make sure ignition and spark are good. Next...check timing. IF all this fails to solve the issue.....check the fuel system and pressure...

Hope that helps...and hope my writing doesn't suck too bad at this late hour.....I am tired...

 

solution: rip the ac out

 

If I lived in Conneticut I would (rip the A/C out). Apparently you've never spent a summer in Houston. A/C is as necessary here, as heat is up there.

 

Sez the guy with a limited world view.


If all you have is a hammer, every problem looks like a nail.

 

I don't think it's a good idea to disconnect the battery with the car running because the battery acts like a big capacitor and filters the output of the alternator. Electronics hate dirty power. I've done it myself, but that was back in the 70's before there was much electronics in cars. But I know it's frustrating trying to figure this stuff out and you reach the point where you just want to try anything!

 

Mine did that as well, with AC off, turned out to be a precursor to apex seal going out, I believe it had lost a little compression right before the seal went. Might check compression.

 

I was thinking about that (checking compression) I have a block in my garage with 40k miles on it, I was thinking about throwing that in. My only concern about that block is that it was sitting in a car that had a fuel fire for a year. I'm concerned about corrosion inside th engine. It sure sounds good when you spin it over though. I wish I could look inside with fibre optics or something. I don't feel like taking it apart. Right now the car runs pretty good. I can get about 107 mph out of it. I know a new one would do better, but it seems pretty peppy, especially at 3-5k RPM.