1990 RX-7 GXL Idle and Stalling Issues
 

Hi, I’ve had my RX-7 GXL for a little over a year now. It was bought out of a field in non running condition. It hasn’t hit the road yet, but lots of progress has been made. Currently, my roadblock consists of two issues. My first issue is that it appears as though it’s misfiring while idling, and my second issue is that it stalls while being driven after being warmed up. The fuel pump, fuel filter, spark plugs, and pedal assembly have all been replaced. Currently injectors and vacuum lines are on their way. I’ll leave a link at the bottom of this thread of the car idling to give you guys a better idea of what’s happening. Does anyone have any insight as to what my problem may be? Thanks in advance.

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I'm not sure if its the video, but it sounds like your only running on 1 rotor. Compression test, make sure you have spark at all 4 plugs, and if that all checks out, put the injectors and new vacuum lines on and it should help greatly

Yeah, does sound like it could be on one rotor. Do what lduley says. First, check that you have all of the spark wires in the right place and that you are getting spark at all of them. If that checks out, do a compression check. Pull one plug and make sure the pulses are even, then replace and the same on the other side, then take out one on each rotor and make sure they are roughly the same. If that checks out, move to the injectors. Not sure of an easy way to check it, but it sounds like you have new ones coming it.

Also, the video is too short to tell for sure, but it sounds like you have a hell of a vac leak somewhere.

its not running on one rotor, its doing the S5 idle dance, by retarding and cutting fuel in an attempt to get the idle to settle down at 1100 and below, usually unsuccessfully. this is caused by an idle thats set too high or a thermowax that isn't opening as it should.

Thanks a lot for the responses! I’ll definitely start by making sure I’m getting a spark at all 4 plugs and that they’re in the correct locations. While I don’t have access to a compression tester at the moment, I will check for even pulses from both rotors, and if need be, pick up a compression tester. For some extra information, the car does have a nasty exhaust leak, which is what’s causing a lot of the noise. Also, when going through it’s cold start procedure, the car seems to run perfectly. However, once the procedure ends and the idle drops, the issues surface. I’m thinking about checking the BAC valve and, after your comment, the thermowax to make sure those are in order. The TPS has already been adjusted, so I don’t think that’s the issue. Vacuum lines and injectors should be coming soon. Any extra opinions would be appreciated.

that would explain the dead rotor sound then, the retard is trying to retard itself more retarded :lol:

technically the leading spark plug wires can be switched, since it's a waste spark system and both leading plugs on both rotors fire at the same time.

but if the problem is worse for whatever reason, you can always switch the wires back and see if it goes back to the way it was.

your battery also sounds extremely weak, which isn't doing you any favors with starting issues.

your battery is toast, and likely your afm as well, or the car has some rather big vacuum leaks. try jumpering the fuel pump test connector and see if it stays on, but your battery needs a serious charge or to be dumped for a new one.

theres a yellow 2 pin connector by the right front strut tower off the engine harness. use a wire to bridge the 2 terminals. this will keep the fuel pump on whenever the key is turned on and omit the fuel pump relay and afm switch.

I just got around to jumping the fuel pump test connector. When jumped, I was able to hear the fuel coming through the fuel rail (should the car be started this way?). This leads me to believe this is either a vacuum leak or a MAF problem. I decided to tighten up the bolts/nuts on the throttle body and upper/lower intake manifold, as they were taken apart recently and are spots where vacuum leaks could occur. I wasn’t able to start the car because the battery is dead, but I should be able to get it charged tomorrow and see what happens.

yes the pump should be running with the key on while jumpered, that's normal. you can start it like that and see if it stays running, if it dies when you remove the jumper then the afm pump switch is bad.

Just got the battery charged and started the car. It started quickly and ran smoothly for a few seconds, holding perfectly at 3,000 RPM before it shut itself off. After this, I jumped the fuel pump test connector and started it again with the same exact results. There may have been a vacuum leak at the upper/lower intake manifold or the throttle body, because after tightening those up the car started running much better. Here’s the clip of it starting:

After some further reading, it seems as though the AFM could be the problem. Currently the car runs well during the cold start cycle, but dies after it ends. Since the car only starts to rely on the AFM after the cold start cycle ends, it would make sense that if the AFM was giving no reading, the car would cut air and fuel, shutting it off. Just my theory. I’ll probably do some testing on it tomorrow.

I'm having a similar issue as well, 89 s5 na. It' starts no problem, does the normal cold start but as it gets close to operating temperature idle will bog for about 15secs or so then idle like normal when it' fully warm. I changed fuel pump, got the injectors flow tested n cleaned, checked timing, changed uim and lim gaskets, replaced the t- wax valve, replaced old or cracking vacuum hoses, cleaned all engine grounds and adjusted the tps with the banzai racing tps adjuster. The only thing I can think of is the throttle diaphragm on the tb that has a vac line to the t-wax. I don' see that diaphragm move when engine is on, and moving it by hand doesn't effect the engine. Or my bad sensor is bad, afm (changed 3 times) or tps(changed 3 times as well)

have you done a ohm test on the afm?