GSL-SE going nuts at IDLE!!
 

My car started idling really high out of nowhere a few months ago. It would usually start doing it after a WOT run. It will usually rev up to 2.5-3k and oscilate up and down slightly. It makes an unusual sound like a sticking shutter valve or something is holding the idle way open against its will. I know my SE doesn't have a shutter valve:)

So today I started on cleaning everything up.

Cleaned intake manifolds
Blocked OMP
Removed nest
Blocked ACV

After reassembling it is acting weird as ever.
Upon startup it imediatly reved to 4k and stayed. I played with a few things and got some ideas. I had a friend plug the tube coming from the top of the plenum and going to the BAC valve. It immediatly dropped the idle down to around 1.5k but it still oscilated. I also beleive that the thermowax system could have something to do with it as well. I am open to ideas and opinions.

Thanks

Your problem is most likley a vacuum leak of somesort like the one you plugged... I own an 84 se and have been around the block with this damn thing lots of times. One thing you must understand before trying to correct any idle problem is that once rpm's reach over about 1050 the computer starts issuing timing advance, that makes the idle go up to about 1200 or so then the computer sensing that its too high and still at idle cuts timing then it drops back down, sometime it stays below a grand, sometimes it just keeps bouncing.. condition of ign system will too effect idle, so will a sluggish 02 sensor/tps sensor... in short just convert it to a carb!:evilgrin:

Explain which nest you removed.
If it was the whole rats nest and you are still running the stock FI system, then no wonder you car isn't running right.
You can't run a stock SE FI system without the nest.

:werd:

check the tps.

Going to a carb (unless Weber 51IDA, or Dellorto) will not fix your problem with this SE.

The ignition system is vacuum advance, so the likelihood that the ECU is adding to the problem is pretty remote. More than likely, by removing the 'rats nest' you've disabled just about all the vacuum assisted controls on the intake side, which is going to cause all kinds of problems with the butterfly valve positions, secondary valve positions, and the vacuum advance on ignition - if you also removed the black barrels to the left of the vacuum system 'tree'.

As pointed out above, a stock SE RE-EGI engine will not run without these controls in place, and you're better off trying to fix one problem at a time, than removing the rats nest and causing a bunch more that will need to get fixed.

There are 2 camps on the EFI system on the SE's; 1) chuck it and get a carb - usually stated by 12A drivers who have never experienced 13B EFI performance, and 2) stick with factory design and clean/lube everything to get it back to 'new' running condition. I am of the latter...

Along that line, I'd suggest reinstalling the rat's nest using the hose diagram on the inside of your hood. Once you have this hooked up, you can likely fix the 'surging' problem (revs to 4000, then, once warmed up, surges from 1500-3000 every second...) by removing the Throttle Body and cleaning everything out thoroughly. Surging is usually brought about by cold weather and the 'thermowax pellet' that you eluded to in your first post - this pellet is used to function as a choke for the EFI engines to reduce air intake and provide a rich mixture to keep the engine running when cold out. Oil the throttle body shafts for the butterfly valves (primary and secondary), and you should be good to go.

As a last resort, I'd check the Throttle Position Sensor setting to ensure that it's set correctly, and then start it up. All the factory systems, when clean and functioning properly, keep the idle at 800-900 rpm, rock steady, rain or shine, day or night, hot or cold - if yours doesn't, you just need to track down what's causing it to miss a beat. Good luck, and I hope you stay with EFI...

Well I fixed the unusual reving. The thermowax was sticking causing it to rev like crazy. I adjusted the TPS, and checked for vacum leaks. The car doesn't want to idle and runs kind of rough in lower Rpm. I didn't realize I needed the "nest". When I bypass the BAC valve it seems to run fine and idle fine with the idle screw all the way out. I will try playing with it some more and see what I can produce. I am thinking of blocking off the BAC valve it proves successful......I am going carb I just don't have the cash right now.

THanks guys

Longduck - why is your PM disabled? I have a question for you that I wanted to ask outside this thread.

I don't check PM here very often, since I'm in and out of the forums. If you want to get ahold of me, send me an e-mail to LongduckNOSPAM@mindspring.com (remove NOSPAM to reach me).

Thanks, and good luck with bypassing the BACV. I chose to stick with mine, after getting it to run correctly after disassembly and cleaning.

There are many threads concernng the SE's idle "hunting and surging". Generally speaking, it's either the secondary throttle valves sticking or the vent solenoid valve is bad. Mine was the VSV. Check out page 240 of the '84 RX7 Mitchel Manual (http://www.iluvmyrx7.com/index.htm) for the Tech Service Bulletin covering it.

you nailed it longduck.

It seems that keeping the BAC is the best idea. After looking at the diagram, I discovered the 2 black silinoids and the BAC are a seperate system from the othere two.
I reassembled the 2 black silinoids from the diagram. I just ran my own lines. I beleive my problem is one of the 2, VSV or the other one. My BAC valve is in perfect condition, I cleaned and tested it. My lines were correct in placement, so logically it would have to be one of the silinoids. Because the only thing that controls the BAC is one of the 2 black silinoids, telling it to close or open with vacuum. My car is running rough at all rpm ranges, it makes good power but surges and lurches at light throttle. So if it was a silinoid, the wrong amount of air introduced all the time would cause it to run like crap.

Let me know what you guys think. Testing silinoids tomarrow:)

Keep the BAC as it adjusts air to hold the idle properly. Ttest the solenoids and see what happens. If they are on the fritz, I have a spare set I can sell ya for fairly cheap.

Do a search for GSL-SE idle problems. It's probably in the first gen archive. If not I know it's on the mazspeed website. It's a good read and should be read regardless.

Well, I tested both valves and they are both working properly. I thought for sure it would be one of those valves. However, I did find one of my vacuum caps missing and it almost wants to idle. From my diagnosis I have come to this conclusion.

The BAC and two controling silinoids are clean and work properly, TPS working and adjusted. So, the thing should be idling......unless its loosing vacuum by a leak.

Thanks guys

This thing is killing ME!!! Butterflys are clean and move freely, TPS adjusted, BAC valve working, Both controling silinoids working, hard to look for vacuum leaks when it won't idle but I can't seem to find the problem.........suggestions!!!?????????????????

I started having that problem a few months ago too. The funny thing is that I would notice my car all the sudden have a grip of balls, and when I let the car idle, it would be at 2k rpm's and surge up and down to 3k. I would honestly just rev up to close to 7k and the problem would go away. I dont know why. It came back a few times and would do the same thing and it would go away. It hapened a good 10 times. But it hasn't done it for about 6 months now. I dont know what I did or what...

that post was from 03' RoX7an