VelocityRedRX8

Greetings all,

I took my RX8 into the dealer yesterday to have my CD player replaced since it began skipping seriously upon minor bumps. While there I told them the history of my lousy gas mileage (last two tanks around 11MPG, overall average 15 MPG over 183 gallons, 2762 miles). So, they ran some tests and found code P0128. According to the tech this indicated that the car thought it was in a perpetual cold state, and stayed completely rich all the time! He reset the code and reflashed the PCM to the latest update. While they were at it they put it a new set of higher temperature plugs. I am hopeful that this will help my consumption. I filled up the tank to give it a go, and will report back after this tank.

brothervoodoo

Look forward to the update...

itsallaboutgary

me too.. i wonder if i have this problem too

Rx-Appreci-8

That makes sense.

The trouble code P0128 is the "Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)" code. Apparently it was a "pending" troublecode, otherwise the check engine light - CEL (a.k.a. Malfunction Indicator Light - MIL) would have come on too.

Looking forward to your future posts regarding gas mileage!

wakeech

yes, this is extremely interesting... i'll sticky it if your findings are significant

Nubo

Did they test or replace the temperature sensor and associated wiring?

brothervoodoo

Here's a service bulletin about the "P0128" error code. The procedure is to reprogram the PCM as you indicated. Unfortunately, the bulletin is rather cryptic in describing what the problem is and more importantly what it suppossedly fixes after the reprogram is done.

http://www.finishlineperformance.com...01-024-03.html

rx8cited

Hi VelocityRedRX8,

Thanks for the info.

Do you notice any difference in the way the car idles or accelerates now?

When the car was running rich all the time, did it idle higher then it does now after the engine has warmed up?

I'd be interested in hearing all the changes you notice since the fix. I hope you get better gas mileage now .

regards,
rx8cited

8_wannabe

Amazing what a technician can do if he actually believes you and looks for the problem. The only thing anyone else has gotten is "EPA numbers are estimates only under extremely controlled conditions." Nice to him to actually investigate and find something!

8_wannabe

Interesting note on the bulletin: It says after the reprogramming, a road test is necessary so the ECU can relearn. THe problem is, it is relearning according to the garage mechanics driving habits, not the owners; who knows how that knucklehead will drive. Has anyone ever talked a dealership into letting the owner conduct the road test, with a technician in the right seat?

RobDickinson

The 'learning' only works over the last 15miles or so anyhow, it wont take long to relearn to your style.

Very intrested in this possible fix, not usre it'll explain everyone spoor gas milage , but it might.

8_wannabe

I'm not quite sure what this means. Are you saying every 15 miles the ECU "relearns" your style? That's a pretty short-term memory and I'm not sure how useful it would be. I would have thought it would remember my driving style over some period of time and adjust engine settings accordingly. If it's only a 15-minute memory this would be of limited use.

brothervoodoo

The above is quoted by maniac, as to the P0128 error code. Taken from:
https://www.rx8club.com/showthread.p...threadid=14188

Genom

But hope is not dashed, as they arent likely to cause any performance issue, but that doesnt mean they arent :D

Well, not my hops at least sinc eI have no issues there anyways :D

Rx8Freehk

Well, ive started hot, started cold, drove in city, and on Highways, (last trip was little Rock to Atlanta VPC) and gas miliage seems totally random. I was getting 18.8mpg on Highway @90mph and She can drink a quarter of a tank in 20 miles if i lean on her.

mikeb

I already had the dealer flash my ecu for cel problem.
My cel never came on after that.

My dealer shouldn't give me any problem if I want this done too right?

brothervoodoo

LEARNING COMPUTER

JoeRX8ter

LOL, I was looking for that wav yesterday but couldn't find it.

balletsushigirl

i too am anxiously awaiting hearing back as to whether or not there was improvement with MPG. my car is about 6 weeks old. i'm averaging around 13-15 MPG (city/freeway). i knew i wasn't buying a super fuel effiecient car ... but 13-15 is a far cry from 18-24. i have reported my concerns to the dealership mechanic. he claims that the poor fuel economy is to be expected in the RX models. i think the issue deserves more attention than that.

also ... just wondering if you find this strange. today i picked up my spacepug from the mechanic (oil light sensor issue fixed with new oil pan). check it out. they brought my car around and shut the engine off cold. given that this is a mazda dealership, should we be able to trust that they know how to care for the rotary engine? should i complain or let it go?

thanks for all your help. your postings are very informative!

cheers,
balletsushigirl

brothervoodoo

New car, new rotary which hasn't been around for 10 years of so. I'm not surprised dealership mechanics or shop helpers, etc are unaware of the issue. If you are concerned you should let the receiving tech know the start/stop procedure to avoid a possible flood. From what I've read since I've never flooded mine, is that the occurrence seems to happen on a cold engine that was then shutdown right away. If the engine is warm from riding around I don't think it’s much of an issue.

zoom44

when my car was brought around after service yesterday it was complely warmed up. yours should have been too.

balletsushigirl

it absolutely WAS NOT warmed up. the guy started it up, moved it like 20 feet, shut off the engine. i was pissed off. more so, because when i dropped it off, i asked specifically that this NOT be done.

-BSG

VelocityRedRX8

To my knowledge there was no replacement, only a clearing of the code end PCM re-flash

VelocityRedRX8

Hi rx8cited,

The difference I have noticed is that the car DOES seem stronger at > 6000 RPM. However, initial back-of-the-envelope calculations suggest no more than 15mpg. But - I will fill up the tank tonight in preparation for a 475 mile round trip to Cleveland tomorrow. Stay tuned. I'll post the MPG figures upon my return.

8_wannabe

I think you have a right to be pissed. We should expect Mazda mechanics know this problem better than anyone. I realize there is a learning curve, but if we all make a point of it when visiting dealerships, pretty soon each joe ragman will understand. The alternative is the occasional flooded engine, and we all know now what a huge pain in the butt that can be.

By raising a stink now, we can avoid problems for some poor owner in the future. "The engine you save might be your own."