NCross

iTrader: (18)

On hot starts after sitting for more than 10 minutes or so the engine will stall out with the A/C on. It starts up strong, does it's little 2000 rpm rev up that all 2nd gens do, settle to about 900rpm then stalls. If I start it with just the blower going or no A/C at all it finds idle at 800rpm just fine with no stalling or dipping.

On a cold start it will always start up to around 2800rpm then quickly settles to around 1200rpm like normal with no stalling or dips.

Would the BAC be bad even though it seems to be working? It clicks when you ground the check plug and periodically bumps the idle up to 1100rpm or so when the compressor clutch kicks in.

If I try to remedy this by adjusting the idle to 900rpm it starts hunting for idle even though the tps is dead set.


Suggestions? Ohm tests?

satch

iTrader: (1)

If you started the car w/o the A/C on how long do you have to wait til you can turn it on w/o the car dying?

Poker Player

Oh, I'm gonna love this thread because I have the same problem.

Poker Player

I had drove my 89 n/a to the "expert" mazda shop after I finished rebuilding my engine. Just to make sure I did everything right. They adjusted the timing for me and said I did a pretty good job. As I drove home on the hot sunny day, using the a/c, (yup mine still works!) after I got off the freeway, as I reached the stop sign.... S..T..A..L..L... After flooding problems, I got it to restart. After I got home, I turned the A/C back on, and stall again... It's that little bit of extra horsepower that's needed to keep it running while on idle... So I've read the book, I know the idle is correct... Since I have to fix or replace fuel injectors, I'm not gonna mess with this problem yet. But I would sure like to know, what's up????

NCross

iTrader: (18)

I usually have to drive down the road for a few miles for it to hold idle with the A/C on after a hot start.

I have replaced the TPS with 3 spares, installed brand new Mazda o2 sensor, replaced fuel filter and air filter recently. Coolant temp sensor replaced recently. Plugs in January. Timing is good according to my light. Each plug lines up with the corresponding timing mark at 750rpm. BAC turns on and vibrates when 12v applied directly and when connected to the engine harness and check plug grounded. I took it out to inspect it.

My throttle body is factory sealed in the stock position as far as adjustment screws and all go. Appears to be no carbon build up on the plates. Appears to be no vacuum leaks.
I have to bump the idle up to at least 1500rpm to remedy the problem.
Could it be the ECU?

walken

iTrader: (6)

probably the bac or a vacuum leak.

satch

iTrader: (1)

Probably not , but is your Initial Set Coupler currently jumpered? And have you been able to check fuel pressure after a hot start? Might not make a difference, but the pressure is supposed to rise after a hot start for a short period of time before readjusting itself.

NCross

iTrader: (18)

Figured it out. I had the o2 sensor wire running straight to the ECU pin. So I reconnected the wire that is supposed to run to it and reconnected the original o2 wire near the tps plug. Problem solved. Also fixed my loss of power going uphill.

Any idea what other systems run off of the o2 wire on the ECU? Pin 2f I think...

superjeff

I just got the 1990 I bought running and it died with the AC on at stop signs too. But then the coolant light came on and I have quite a bit of pressure built up in the coolant system. I fear the coolant seal may be shot....any other ideas?

MIDNFauciUSN

iTrader: (8)

nothing, last time I checked. This is how I'm running, and it works fine.

I'll check the FSM again, but I'm pretty sure that wire goes straight to the ECU.

MIDNFauciUSN

iTrader: (8)

nevermind, on an N/A it goes to 2C, to the AFM, and CAS it looks like?