Burgie

There's a ton of info on here, and I've read a lot, but I'm not finding the answer I need.

The short story is that once there car is hot (15 miles or so) and I stop at a traffic signal or park after my 30 mile commute, at first there engine idles just fine, but at some random time, the idle drops to ~500 rpm, then bounce back to~750, and continue this a few times, then the rpm jumps up past 1000, then settles to 750 and the cycle continues, usually somewhere after a number of cycles it just stalls. It really doesn't happen there same way every time. Once stalled, it starts immediately, just like starting it cold.

History:
2005 automatic 182k (owned since 08 and 38k miles)
Rebuilt Mazda stealorship warranty replace at 88k
Mar '19 replaced radiator, original had very small leak
Mar '19 brake pads, rotors, plugs, wires replaced
May '19 coil packs replaced
Early June '19 on a hot 70 mile drive, car was extremely weak at traffic lights, nearly stalls, had to keep rpms up, made to my destination of only a mile away, the radiator fan ran for a much longer period of time than usual. Return trip home, car started and ran fine, I did notice the power loss near the end of the return trip, but not as bad.

I researched RX8Club, identified the fuel pump or cat as the likely culprits, I ordered both, and two weeks later I replaced them both, I'm an electrician by trade, not a mechanic, (with a grain of salt) so the old cat looked fine to me, but I replaced it. (The fuel pump was the newer style (09 and later??), but I was unaware of any significant difference - however it was replaced with the correct model later - wanna buy a new 09+ fuel pump). I also cleaned the SSV.

Car ran okay, but not great, replaced MAF.

Few days later I replaced the ECC sensor, (cleaning didn't help the performance). Somewhere along the way I got a SEL, read the codes, rear O2 sensor, removed it, cleaned, drove a week, no improvements, replaced the O2 sensor in August, within a few days the light extinguished.

New battery in August also.

So, I have this "hot idle issue/stalling" issue, I have always tracked my gas mileage (I realize that is old school, just can't break the habit) and the mileage is around 22, normally it's 24, so that may be a useful clue?

I purchased a diagnostic dongle and played with it and an app, but, without some guidance, it's interesting, but I'm unsure of what I'm looking at or for.

I sprayed some carb cleaner on the vacuum lines, but I think I did that when it was cold, so, that test could have been a waste of time.

I appreciate you taking the time to read this post, the car was the fulfillment of a 1982 promise to myself I'd one day own a RX7, my buddy only let me drive his once, something about the squealing wheels, an intersection, high highway speeds, he was a city boy. I'm not stupid attached, just don't think it's dying yet!

Thanks, Dave

wannawankel

Mine did that when I first bought it used at 36K - replaced the engine air filter (was dirty but not oil filled) and cleaned the MAF. It never came back.

Loki

iTrader: (1)

Can you guys start your own threads? This is going to be a disaster to troubleshoot with 2different cars in the same ancient thread. You can use the new members section.

RedRotor: what are the fuel trim and airflow values on a warm idle? You can read them via OBD2. Knowing this will help determine if there is new air being introduced or not. Also try running with the MAF unplugged and report change of behavior if any.

Budgie: have you had the spark plugs replaced along with the coil packs? When the car ran poorly that first time did you take note of the temperature? Possible it overheated? Is the car consuming coolant? Is it consuming oil at the normal rate?

TheRedRotor

Sure thing I can start one later today and transfer over the info, I believe I have the values recorded on my phone from a few weeks ago. Also running with the MAF unplugged the car died immediately but I'll go into detail in the thread when I create it

Burgie

From Loki
Budgie: have you had the spark plugs replaced along with the coil packs? When the car ran poorly that first time did you take note of the temperature? Possible it overheated? Is the car consuming coolant? Is it consuming oil at the normal rate?

I believe the coil packs, wires, plugs were all done within a few weeks, although I'll verify that.
When the car first performed weak on that hot day 70 mile drive, I do not recall the temp gauge being out if the ordinary.
There is no coolant consumption.
Oil consumption hasn't changed notably.

Burgie

Loki,

Plugs and wires, 3/27
Coil packs, 5/26, 3600 miles later

Burgie

"wannawankel , 09-09-2019 10:05 PM
Mine did that when I first bought it used at 36K - replaced the engine air filter (was dirty but not oil filled) and cleaned the MAF. It never came back."


Changed the air filter tonight, cleaned the MAF, checked everything back together, checked (2 month old) battery connections tight, rotated the larger vacuum line spring connectors about a quarter turn (kept the hose in place, released the spring pressure, turned the spring connector a quarter turn).


The biggest revelation was on the accordion tube, I visually inspected it while flexing it, there is cracking, however, when inspecting the inner lining, and flexing it, it doesn't appear that the cracking has migrated all three way through. But maybe just a little is enough to bring on the hot idle issues and stalling.

Slight cracking