I'm looking to pick up my first FC (10th anniv too) on Friday, but the owner told me it has a "cold start" problem. Until the engine is warm, the rpm are floatly and sometimes he has to give it more throttle so it doesn't die.

Should I be really worried about that? How can I fix it? BTW- no luck on search, so any help would be great.

 

i dont know what the problem is but it shouldnt do that. In fact in cold starts the rpm should go up to 3000 rpm for about 20 seconds or so and drop to about 1000 rpm and then to 750 rpm.

 

Unless he removed the cold start assist system, which is stupid and bad for the eninge over time.
It not idling well could be related to a vac leak, although I wouldn't think it would clear up when the car got warmer. Anyway, it doesn't sound like something that would be too bad, or hard to fix. Have you driven this car? Make sure you drive it and see this problem for yourself before you buy the car.

 

My 1991 TII does this. I've been too lazy to fix the all the "idle assist" systems for cold start. Essentially you need to remove all the valves, diaphrams, etc... from the LIM (lower intake manifold) and UIM (upper intake manifold), clean them, test that they work (download the workshop manual), rebuild them, make sure they work correctly.

Electrical grounding & compression issues can cause these symptoms, but that's most likely not the case here. The 1986-1991 RX-7s have several idle assist systems that prevent the RPMS from getting too low such as compensate for Air Conditioning Load, Cold Idle/High Idle, Accelerated Warmup (emissions), Electrical Load, deceleration, and cushioning RPM drops.

 

So would that cause it to start up, then die after a second until it gets warmed up if its really cold outside?

 

Yes, the "wax thermo valve" is probably shot in mine (all the wax is gone or gunked up). It's suppose to hold the idle open until the wax melts. There's a coolant line that runs to this and heats up the wax.

I have to keep my foot on the gas for 15-20sec to simulate what the wax-thermo valve does.

Note my "accelerated warmup" system still works, but I don't like my engine running that fast while cold. So I tap the accelerator to dis-engage it. Then the wax-thermo sub-system is suppose to take over & hold open the idle so it won't die.... that's when I hold the accelerator open at 1500rpms for 20sec.

 

Really, i bet thats what my problem is. I just gave up trying to figure it out. Mine had all the cold start assist crap removed by the previous owner. Would that have something to do with it, also?

 

I've edited my responce above with more details.

That's your problem right there. Go to a "pull-a-part" that has a 86-88 Turbo II and pull those parts you need. Or check the salvage yards such as www.mazmart.com or www.mazdarecycling.com , or use the RX-7 & FC3S e-mail lists and ask if anyone has those pieces. You can also check the forsale section on this website or try www.thepartstrader.com

 

Its an NA, but there are several in the area, at least one of which has a fairly complete engine bay. OK, I'm done, sorry for hijaking the thread.