chiefnobum

so the rx-7 seems to be misfiring really bad when additional electronics are on e.g. (any combination of audio, defogger, high beams) or anything else to cause a load. With no electrical load it runs great. It has an FD alternator and a really big battery, so not quite sure what the problem is. Coudl the load be affecting the TPS or some other sensors? or maybe is it just a bad sensor?

Any help would be very useful!

86GXL

i'm having the same problem... only much more severe... And i'm on my stock S4 alternator

WAYNE88N/A

How's your grounds?

chiefnobum

I've regrounded everything a while back, but that was my dad posting the problem, I just took it out for a spin and it sputters something mean on and off when you just have the lights on...it feels like it's not getting enough fuel or there's no spark or something. I think there's something wrong with the electrical system because I was getting like 12 volts with the stereo and heat all the way on as well as the lights...so I don't know if the alternator belt is slipping or something else

another wierd thing was that it didn't seem to have the problem after the 5th and 6th ports open up...seemed smooth above there.

WAYNE88N/A

Are you SURE that the wiring at the back of the FD alt is correct?

We just had this problem with another guy a couple of days ago...

H4Inf

I had this sort of problem when my alternator wasnt charging as well as it was meant to. It was really quite violent. I'd be sitting at the lights and push down on the pedal and it would hop a few times until the revs got up then suddenly would take off and go smooth..... had to keep revs over 3000 for it to go smooth.. it was the only way it would drive.

New alternator, no problems.

I'd check the alternator and connections. Check brushes and clean the slip rings, check the wiring to the alt + ground (where the bolt goes thru).

Icemark

The simplest way to see if there is an issue is to see what the voltage is when the engine is running.

It should always be above 13.5 volts if the engine is running and typically around 14.5 volts in any RPM above 2000.

That is the bare minimums... if it is less than that, the Alt is wired wrong, burnt up, or you have radically bad grounds.

chiefnobum

so I took out my voltmeter and Im' getting 15.5 volts to the battery and other electronics when the car is running with no electronics, but once I put on like my lights and my heat all the way up and idling at like 750, I see like 13.5 and if I put on the defroster just above 12. And when Ihave the ligths on and the heater all the way it starts like hesistating and sputtering when you aren't accelerating...push the gas down and it'll smooth out...but if you like take off the heater, it's fine...so yeah...I have no clue what is going on...coudl the signal that's supposed to tell the alternator to pick up the slack when electronics come on not be working?

the battery is getting charged fine so that part of the alternator is working and we've been running it like this for forever...so I don't know what could've changed...

any suggestions would be great!

H4Inf

Sounds just like your altnerator.

1. You can take it apart and check how worn the brushes are, if they are worn replace them, and lightly sand the slip rings to clean off any gunk.

2. Replace the whole alternator.

Depends how much money and time you have

I had this exact problem. Brushes were worn out, I replaced them but the bearing seazed soon after so I replaced the whole thing

Paul.

Icemark

Bad alt... it should never drop under 13.5 if the car is running

WAYNE88N/A

I concur...That 15.5v is getting kinda scary, too...