Milage Info/Questions
#1
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Low MPG fix?
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.
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.
#4
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!
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!
Last edited by Rx-Appreci-8; 12-02-2003 at 05:48 PM.
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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
http://www.finishlineperformance.com...01-024-03.html
#8
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Re: Low MPG fix?
Originally posted by VelocityRedRX8
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!
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!
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
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
regards,
rx8cited
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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!
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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?
#11
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.
Very intrested in this possible fix, not usre it'll explain everyone spoor gas milage , but it might.
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Originally posted by RobDickinson
The 'learning' only works over the last 15miles or so anyhow, it wont take long to relearn to your style.
The 'learning' only works over the last 15miles or so anyhow, it wont take long to relearn to your style.
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Originally posted by Maniac
DTC P0128 is a coolant thermostat problem.
DTC P0456 is an EVAP system leak.
Neither of these are likely to manifest themselves as performance issues and are likely due to minor variations in manufacturing tolerances in the sensors.
This TSB is to install a new PCM code to mask this issue, not really a fix, per se.
DTC - Diagnostic Test Code
WDS - Worldwide Diagnostic System
ESI - Electronic Service Information (Mazda's Online Service)
PCM - Powertrain Control Module
DTC P0128 is a coolant thermostat problem.
DTC P0456 is an EVAP system leak.
Neither of these are likely to manifest themselves as performance issues and are likely due to minor variations in manufacturing tolerances in the sensors.
This TSB is to install a new PCM code to mask this issue, not really a fix, per se.
DTC - Diagnostic Test Code
WDS - Worldwide Diagnostic System
ESI - Electronic Service Information (Mazda's Online Service)
PCM - Powertrain Control Module
https://www.rx8club.com/showthread.p...threadid=14188
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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
Well, not my hops at least sinc eI have no issues there anyways :D
#15
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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.
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Originally posted by 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.
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.
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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
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
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Originally posted by balletsushigirl
... 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?
cheers,
balletsushigirl
... 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?
cheers,
balletsushigirl
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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
-BSG
#23
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Originally posted by Nubo
Did they test or replace the temperature sensor and associated wiring?
Did they test or replace the temperature sensor and associated wiring?
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Re: Re: Low MPG fix?
Originally posted by 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
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
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
regards,
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.
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Originally posted by 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.
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.
By raising a stink now, we can avoid problems for some poor owner in the future. "The engine you save might be your own."