M12 GTO-3 Misfire
Discussion
Hi all,
This is the second time I've had this happen. Both times under exactly the same circumstances :
Wash car (hose-pipe, soap, hose-pipe), then go to local Shell garage to fill up with some nice Optimax then almost exactly the same place on both occasions I get a misfire on the way home. The first time, a few months ago, it sort of worked itself out over a period of about 6 miles going home. This time, today, it was wery poorly. Sounded as if it was running on only 2 or 3 cylinders and the smell of un-burnt Optimax was very obvious.
This time I limped home - thankfully no traffic-light hold-ups or I'm sure it would have died not to be started. This time I left it 5 minutes (to let the fuel smell go away !) and then set at the engine with WD40. Did the spark/coil connectors on all 6 Cylinders, plus the throttle body plug, and about 4 or 5 others .. all the ones I couls see. Took about 10 minutes then fired it up and it was perfect. A quick blast round the block.... 0.7 bar and going like a good 'un.
Both times it's happened, it goes like this : I'd washed the car and gone down to the same garage (10 miles away) immediately after, giving it a sort of blow-dry run. Fine until I got to the garage and re-fueled then within about a mile after leaving it started to misfire both times.
OK - what do people recon... damp/water in the connectors, water being let in through the filler cap during re-fuel after the hose-down, ECU throwing a wobbly (re-programmed about 8 months ago) or perhaps my local garage do a nice special Optimax/Diesel/water blend just for me ??
Why did it do it only on return from the garage and not on the way ?
I generally do this process every week or 2 and like I said, it's the second time it's happened, and the only fuel I ever put in is Optimax from 2 or 3 different garages during the week.
Thks
PAul
This is the second time I've had this happen. Both times under exactly the same circumstances :
Wash car (hose-pipe, soap, hose-pipe), then go to local Shell garage to fill up with some nice Optimax then almost exactly the same place on both occasions I get a misfire on the way home. The first time, a few months ago, it sort of worked itself out over a period of about 6 miles going home. This time, today, it was wery poorly. Sounded as if it was running on only 2 or 3 cylinders and the smell of un-burnt Optimax was very obvious.
This time I limped home - thankfully no traffic-light hold-ups or I'm sure it would have died not to be started. This time I left it 5 minutes (to let the fuel smell go away !) and then set at the engine with WD40. Did the spark/coil connectors on all 6 Cylinders, plus the throttle body plug, and about 4 or 5 others .. all the ones I couls see. Took about 10 minutes then fired it up and it was perfect. A quick blast round the block.... 0.7 bar and going like a good 'un.
Both times it's happened, it goes like this : I'd washed the car and gone down to the same garage (10 miles away) immediately after, giving it a sort of blow-dry run. Fine until I got to the garage and re-fueled then within about a mile after leaving it started to misfire both times.
OK - what do people recon... damp/water in the connectors, water being let in through the filler cap during re-fuel after the hose-down, ECU throwing a wobbly (re-programmed about 8 months ago) or perhaps my local garage do a nice special Optimax/Diesel/water blend just for me ??
Why did it do it only on return from the garage and not on the way ?
I generally do this process every week or 2 and like I said, it's the second time it's happened, and the only fuel I ever put in is Optimax from 2 or 3 different garages during the week.
Thks
PAul
Sounds like you are creating steam by running the engine for a short time off things like the exhaust, and then it's condensing due to the engine bay not being fully warm as you stop down.
As the electrics will be "cool" they will become a magnet for water vapour - hence your WD40 trick will fix it.
Either leave the engine running for a good 5 minutes after it's got up to temp, or just take it out for a longer drive!
Also, whilst the engine is fine with the grills in normal conditions, it's generally not a good idea to fire water straight into them.
Hope that helps.
J
As the electrics will be "cool" they will become a magnet for water vapour - hence your WD40 trick will fix it.
Either leave the engine running for a good 5 minutes after it's got up to temp, or just take it out for a longer drive!
Also, whilst the engine is fine with the grills in normal conditions, it's generally not a good idea to fire water straight into them.
Hope that helps.
J
When my Mums car was around 2 weeks old we took it out just after washing it, and whilst driving we got caught in one of the heaviest down-pours I've ever seen.
On returning the car cut out twice and then developed a really bad missfire (it sounded just like a 4-stroke go-kart). It felt like one of the banks was not working at all, therefore down to 3 cylinders.
My best guess is that one of the timing sensors got wet and confused, meaning the sparks on one bank were either not present or firing at completely the wrong time.
Anyway, I told my Dad who was driving to pull up somewhere, switch off for a minute, and try again. After doing this we got home without a problem. It seemed that the sensor had re-synchronised with the engine by swtiching off and then on again.
This event did re-occur once again. As before it was after washing, (although no rain present).
Turns out that whenever my brother washed the car he would literally pour the water into the vents above the engine, and a closer inspection revealed that pools of water would be left sitting in the recesses above the spark plugs!
We are all really carefull about rinsing the car now - keeping the water through the vents to a minimum, and the problem has never rematerialized.
On returning the car cut out twice and then developed a really bad missfire (it sounded just like a 4-stroke go-kart). It felt like one of the banks was not working at all, therefore down to 3 cylinders.
My best guess is that one of the timing sensors got wet and confused, meaning the sparks on one bank were either not present or firing at completely the wrong time.
Anyway, I told my Dad who was driving to pull up somewhere, switch off for a minute, and try again. After doing this we got home without a problem. It seemed that the sensor had re-synchronised with the engine by swtiching off and then on again.
This event did re-occur once again. As before it was after washing, (although no rain present).
Turns out that whenever my brother washed the car he would literally pour the water into the vents above the engine, and a closer inspection revealed that pools of water would be left sitting in the recesses above the spark plugs!
We are all really carefull about rinsing the car now - keeping the water through the vents to a minimum, and the problem has never rematerialized.
Thanks Guys.
Joust - you mentioned about possible condensation. I know you're talking logical physics and it is a potential cause, but I don't think this was the case. The engine had been running for about 20 minutes in total before it went tilt including a good 5 minutes or so stuck in traffic. When I did lift the engine cover to have a look it was baking hot. There were a few connector blocks I couldn't WD40 as they were so hot from the engine heat. Certainly no obvious traces of water/moisture/condensation to be seen anywhere. It was like an oven in there.
I'm thinking LaurenceFrost might have something in his description of the ECU loosing the plot. It's a damn shame I didn't try to restart the engine immediately after I got home without WD40'ing the connectors. Perhaps it would have been OK (after resetting the ECU).
One thing I do remember whilst driving home is the strange Tacho readings - wildly fluctuating between 2 and 4k revs in 4th gear (1 or 2 times a second). Now I'm guessing that the 2k difference in 4th is about 50mph and all I was experiencing was a misfire and not the car jumping from 20 to 70 mph and back all the time. I suppose it depends on where the tacho gets its reading from - an ECU derived value or from any one of the 6 feeds to a plug(coil). An ECU derived feed might point to an ECU wobbly (or a sensor giving duff information due to water), whilst a spark plug feed might just point to that plug being one of the ones that was not firing correctly.
Next time (if there is a next time, no problems since) I'll definitely try just a key off/on test to see if that fixes it before getting the WD40 out. I'll also watch out when I get the hope-pipe on the car, though it's left out on the drive in all-weathers (including 4 inches of snow over this winter just gone) and never had a problem.
One final thing, any body know if the ECU records sensor errors that can be downloaded during service time ? Perhaps that might throw some light onto what happened.
Again, thanks for your time.
Joust - you mentioned about possible condensation. I know you're talking logical physics and it is a potential cause, but I don't think this was the case. The engine had been running for about 20 minutes in total before it went tilt including a good 5 minutes or so stuck in traffic. When I did lift the engine cover to have a look it was baking hot. There were a few connector blocks I couldn't WD40 as they were so hot from the engine heat. Certainly no obvious traces of water/moisture/condensation to be seen anywhere. It was like an oven in there.
I'm thinking LaurenceFrost might have something in his description of the ECU loosing the plot. It's a damn shame I didn't try to restart the engine immediately after I got home without WD40'ing the connectors. Perhaps it would have been OK (after resetting the ECU).
One thing I do remember whilst driving home is the strange Tacho readings - wildly fluctuating between 2 and 4k revs in 4th gear (1 or 2 times a second). Now I'm guessing that the 2k difference in 4th is about 50mph and all I was experiencing was a misfire and not the car jumping from 20 to 70 mph and back all the time. I suppose it depends on where the tacho gets its reading from - an ECU derived value or from any one of the 6 feeds to a plug(coil). An ECU derived feed might point to an ECU wobbly (or a sensor giving duff information due to water), whilst a spark plug feed might just point to that plug being one of the ones that was not firing correctly.
Next time (if there is a next time, no problems since) I'll definitely try just a key off/on test to see if that fixes it before getting the WD40 out. I'll also watch out when I get the hope-pipe on the car, though it's left out on the drive in all-weathers (including 4 inches of snow over this winter just gone) and never had a problem.
One final thing, any body know if the ECU records sensor errors that can be downloaded during service time ? Perhaps that might throw some light onto what happened.
Again, thanks for your time.
micknall said:
Just a quick reminder that all our cars are callibrated to run on 95RON unleaded, so using Optimax won't improve performance (though it won't hurt it either).
Simon Hucknall
Press Officer
Noble Automotive Ltd.
Simon,
Does that include the 2.5? I'd always put 97 in it, as I use it everyday, going to 95 would make quite an impact on my fuel bills, would there be any consequences of going back down to 95 having used 97 for the last 10k miles?
Cheers,
Tony
joust said:
2.5's run on 95 as well - the manual is "incorrect".
But, remember that Optimax has significantly better detergents in it than normal. Given an engine costs >£10k, does 4p more per litre really matter?
J
Thanks, £10K -4p, put like that, I guess the answer is No! Handy to know 95 is OK though, as not always near 97 ron fuel in some of the remoter parts of N.Yorks.
Mr Noble said:
Am I right in saying that the MPG is higher using 98 ron than 95 ron, giving a "similar" cost when all is said and done.
I used to alternate in my 330ci. I would get 350 miles off a tank of 95ron and about 390 miles off a tank of 98 ron. The resultant costs were identical in mpg.
GN
I've heard people say that in Elises too, and I can't see how it would work?
DanH said:
Am I right in saying that the MPG is higher using 98 ron than 95 ron, giving a "similar" cost when all is said and done.
I used to alternate in my 330ci. I would get 350 miles off a tank of 95ron and about 390 miles off a tank of 98 ron. The resultant costs were identical in mpg.
GN
I've heard people say that in Elises too, and I can't see how it would work?
Simple I think. 98 has a higher burn rate and gives more power per engine cycle and therefore uses less fuel to get the same distance.
Over to you Joust!!
gn
The BMW will do that as it has a knock sensor. It will therefore 'sense' the 98 RON (it doesn't work that way, but it'll keep it easier) and improve the engine performance to take advantage of it.
If it therefore takes "X" power to propell the car along 350 miles, the average power required per mile is X/350.
If the power available from 1 gallon of 95 fuel is Y, then the power per gallon per mile is Y/(X/350).
If the power available from 1 gallon of 98 fuel is Y+m, then the pwer per gallon per mile is now (Y+m)/(X/350).
Conseuqently you will get a range increase proportional to "m" assuming you drive the car in a manner that requires the same power.
Simple maths really - although of course things are a lot more complex.
Interestingly most BMWs are able to operate from 100 to 88 RON - it's a game played in many european countries of how much cheaper it is per l for 92 compared to 95 or 98 against how much further you get from 98.
Of course, if you just drive your car with a throttle that is either "on" or "off" then the above doesn't apply!
I think.......
J
>> Edited by joust on Friday 20th May 12:03
If it therefore takes "X" power to propell the car along 350 miles, the average power required per mile is X/350.
If the power available from 1 gallon of 95 fuel is Y, then the power per gallon per mile is Y/(X/350).
If the power available from 1 gallon of 98 fuel is Y+m, then the pwer per gallon per mile is now (Y+m)/(X/350).
Conseuqently you will get a range increase proportional to "m" assuming you drive the car in a manner that requires the same power.
Simple maths really - although of course things are a lot more complex.
Interestingly most BMWs are able to operate from 100 to 88 RON - it's a game played in many european countries of how much cheaper it is per l for 92 compared to 95 or 98 against how much further you get from 98.
Of course, if you just drive your car with a throttle that is either "on" or "off" then the above doesn't apply!
I think.......
J
>> Edited by joust on Friday 20th May 12:03
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