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05 automatic, cold it runs fine, hot - hunting, stalling
Burgie , 09-09-2019 06:57 PM 05 automatic, cold it runs fine, hot - not so goodThere'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 the engine idles just fine, but at some random time, the idle drops to ~500 rpm, then bounce back to~750, and this cycle continue 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 the 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 3600 miles after plugs/wires
Early June '19 after 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 nearly as noticable.
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, (so take my observation with a grain of salt) so the old cat looked fine to me, but I replaced it. (The fuel pump was the (incorrect) newer style (09 and later??), but I was unaware of any significant difference, I installed the replacement fuel pump and it ram fine - however it was replaced with the correct model later - wanna buy a new 09+ fuel pump). I also cleaned the SSV at this time.
Car ran okay, but not great, this was when I noticed the hunting/stalling, replaced MAF with new one.
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, after driving 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 to my 8, just don't think it's dying yet!
#52 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.
Burgie: 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?
#55 Burgie , 09-10-2019 05:00 PM 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.
#57 Burgie , 09-10-2019 07:40 PM
"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.
Had accident traffic on the way home today, stalled 6 times, twice while rolling slowly, so it doesn't always happen when stopped, once backing into my driveway.
Once home, I opened the hood, (in park and idling) and moved the air box around (stock air box) to see if the idle was affected, it wasn't.
Set the emergency brake, placed it in drive, repeated the same exercise, same result, nothing!
Pushed, prodded, wiggled vacuum lines - no engine response.
I replaced the air filter last night. No improvement.
I haven't done a compression check, the stealorship is 75 miles away, pretty much lose a day of work doing that, but it's on the list of things to consider.
The stalling is becoming more often, but only when hot, and only during low rpm, like stopped or slowing to a stop.
Tonight I got the P0171 code, "system too lean".
Other than the compression test, any recommendations?
The problem is it sounds like you are doing all these things and it could actually be the engine. Compression loss while hot is a symptom of low compression. It sounds like you have a lot of miles on her since the engine replacement. It's definitely worth your time to do it. Even if all you have is a normal compression tester it would be at least enough to know roughly where you stand on it. Search youtube for "Driven by Madness easy compression test". Unfortunately, it's not super easy...
First, thanks everyone who's helped me whether on this thread, or answered other people's questions, that I was able to get help over my 11 year ownership of my RX8.
I got the compression check completed yesterday, I'm no rotary expert, but I don't believe this is good.
I'd appreciate any suggestions, however, at 182k on there rest of the car, and little interest in pulling and rebuilding there engine, the advice from the stealorship was that it's dying a slow death.
I guess it's time to search for a new ride!
Thanks again, and any comments or suggestions would be appreciated.
First, thanks everyone who's helped me whether on this thread, or answered other people's questions, that I was able to get help over my 11 year ownership of my RX8.
I got the compression check completed yesterday, I'm no rotary expert, but I don't believe this is good.
I'd appreciate any suggestions, however, at 182k on there rest of the car, and little interest in pulling and rebuilding there engine, the advice from the stealorship was that it's dying a slow death.
I guess it's time to search for a new ride!
Thanks again, and any comments or suggestions would be appreciated.
Dave
Not terrible actually. You numbers are better than one of my RX8's and it still runs, makes good power and starts hot as well. Mazda minimum spec is 6.8 @250 rpm but I find anything over 6 can be reliable if you have a good ignition system. Check your starter, coils, plugs and wires. You can also do a Seafoam treatment on it as well as it could just be that the springs for your seals are slightly carbon locked.
Dont give up on it yet, those numbers are good enough to have a reliable car for another year at least.
I dont know if I should start a new thread or whatever but I also experience this same problem (05 AT rx8), the only key difference i see is that if I downshift before I come to a stop my engine won't stall. Also I have not seen it mentioned but for me its only if i come to a stop in 3rd gear, if I stay in 2nd gear i never have any issues, haven't tried 4th just cause i'm never goin that fast to feel justified cruising in 4th. Its not a perfect fix but its definitely gotten me from point A to point B on highway drives effectively. I guess it's not the worse thing since my car will start back up no problem.
09-11-2019, 09:18 AM
wannawankel , 09-09-2019 10:05 PM
Loki , 09-10-2019 08:02 AM
