Poor Fuel consumpion ....Still
Discussion
Can anyone (Mark Adams, Steve Heath ?) offer any sensible suggestions as to what could be causing my drop in MPG.
For my usual work run I used to get 17 - 18 MPG and for long runs it was more like 23 - 24 MPG.
About 15 months ago I noticed that this had dropped to more like 12 - 13 MPG and 17 - 19 MPG respectively. The following service dis not resolve the problem, not the one after that. Furnhurst plugged in their fault diagnostic tool and it showed that both banks were running rich. This was confirmed by a rolling road session at Surry Rolling road as the air fuel mix is really rich. However, the car runs fine in all other respects ...maybe a little hot is anything but then its always done that. Even the emissions are good.
So far I have changed the oxygen sensors, the cold start temp sensor, swapped the air flow meter for a known good 2nd hand unit from ACT.
I have just bitten the bullet and had the injectors checked and cleaned as 2 separate TVR garages suggested that leaking injectors would be the most likely causes. The injectors and seals were all OK.
Not sure what else could be the problem.
Any help here would be much appreciated.
For my usual work run I used to get 17 - 18 MPG and for long runs it was more like 23 - 24 MPG.
About 15 months ago I noticed that this had dropped to more like 12 - 13 MPG and 17 - 19 MPG respectively. The following service dis not resolve the problem, not the one after that. Furnhurst plugged in their fault diagnostic tool and it showed that both banks were running rich. This was confirmed by a rolling road session at Surry Rolling road as the air fuel mix is really rich. However, the car runs fine in all other respects ...maybe a little hot is anything but then its always done that. Even the emissions are good.
So far I have changed the oxygen sensors, the cold start temp sensor, swapped the air flow meter for a known good 2nd hand unit from ACT.
I have just bitten the bullet and had the injectors checked and cleaned as 2 separate TVR garages suggested that leaking injectors would be the most likely causes. The injectors and seals were all OK.
Not sure what else could be the problem.
Any help here would be much appreciated.
yep, I'd skirted round the TVR recommended option and replaced just about all of the other cheaper part I could think of , but no improvements.
I was still getting different opinions as to whether or not the car would run rough if the injectors were leaking.
Now that the price of petrol is rocketing it seemed worth solving + I have to keep stopping to tank up + its bugging the hell out of me.
Since the emissions and performance are OK I assume that the ECU is working OK. I just wondered if the wiring from one of the components I have changed (or something else) is buggered somewhere and so the correct signal is not getting to the ECU and it is therefore adjusting the fueling accordingly.
I have always thought that my engine bay gets much hotter than may other chimaeras, so maybe this finally got to the wiring.
>> Edited by philr on Wednesday 5th October 12:53
I was still getting different opinions as to whether or not the car would run rough if the injectors were leaking.
Now that the price of petrol is rocketing it seemed worth solving + I have to keep stopping to tank up + its bugging the hell out of me.
Since the emissions and performance are OK I assume that the ECU is working OK. I just wondered if the wiring from one of the components I have changed (or something else) is buggered somewhere and so the correct signal is not getting to the ECU and it is therefore adjusting the fueling accordingly.
I have always thought that my engine bay gets much hotter than may other chimaeras, so maybe this finally got to the wiring.
>> Edited by philr on Wednesday 5th October 12:53
i posted the thread last week re bad fuel consumption....(60 miles on £50 NOT AN EXAGGERATION!!!)and the emmisions last night were at 10% instead of 1%!!!
Had it down to a local performance car tuners who said there is no way amy car should have and adjuster on the airflow meter and lambda censors...told me the timing was out but did not want to adjust it as it looked like a pig of a job (North East garages are great!!!)...have ran out of ideas to the point where the car is going to Falcon Performance in middlesborogh...anyone heard of them???
So far i have replaced
lambda sensors
airflow meter
Temp sensors
ht leads, plugs, dizzy cap and rotor.
Have put cable ties round the stepper motor as that has been out and cleaned soooo many times!!!
Had three different garages look at it and not been able to come up with a solution.
If and when i get a fix i shall post it on here!!!
Had it down to a local performance car tuners who said there is no way amy car should have and adjuster on the airflow meter and lambda censors...told me the timing was out but did not want to adjust it as it looked like a pig of a job (North East garages are great!!!)...have ran out of ideas to the point where the car is going to Falcon Performance in middlesborogh...anyone heard of them???
So far i have replaced
lambda sensors
airflow meter
Temp sensors
ht leads, plugs, dizzy cap and rotor.
Have put cable ties round the stepper motor as that has been out and cleaned soooo many times!!!
Had three different garages look at it and not been able to come up with a solution.
If and when i get a fix i shall post it on here!!!
Thanks MM.
I think that the fuel presure regulator was checked when the injectors were cleaned. I will check back with the guys who did this work.
I know that the fuel pressure getting to the injector rail is OK (35 psi ?) as Furnhust checked this for me. However I think that the fuel pressure regulator comes into play after that point, so it is a possible candidate.
The vacuum pipe from this was split (according to the injection guys) and this was what he felt the problem was as he couldn't find a fault with the injectors. I think that he ran a series of tests after cutting back the pipe to make sure that the emissions were OK at various revs. However, I wonder if the actual pressure was checked...assuming it can be checked at this point.
I think that the fuel presure regulator was checked when the injectors were cleaned. I will check back with the guys who did this work.
I know that the fuel pressure getting to the injector rail is OK (35 psi ?) as Furnhust checked this for me. However I think that the fuel pressure regulator comes into play after that point, so it is a possible candidate.
The vacuum pipe from this was split (according to the injection guys) and this was what he felt the problem was as he couldn't find a fault with the injectors. I think that he ran a series of tests after cutting back the pipe to make sure that the emissions were OK at various revs. However, I wonder if the actual pressure was checked...assuming it can be checked at this point.
Last night I found a hole in the thin vacuum pipe from the pipe between the plenum chamber and the distributor vacuum. It looks like this has been nicked by a screwdriver or something at some time and produced quite a hole relative to the size of the pipe.
The bible says that this is used to control the advance of the ignition.
Can anyone tell me if this is likely to have been a contributing factor to my poor MPG and rich running problems......or was this just something else unrelated that needed to be fixed.
Cheers
Phil
The bible says that this is used to control the advance of the ignition.
Can anyone tell me if this is likely to have been a contributing factor to my poor MPG and rich running problems......or was this just something else unrelated that needed to be fixed.
Cheers
Phil
Hi Phil,
If you look at my profile you will see the thread i started a few weeks ago re very poor MPG...no exaggeration my car used to do 20+ mpg but then dropped suddenly to about 6 mpg...running very rich...strong smell of petrol when the car was running...my girlfriend followed me in her car and when i parked mine up and got into hers it smelt like someone had poured peetrol into hers the fumes from mine were that bad...any way i had lots of sound advice from the likes of Podie, GreenV8s etc...all of which is well worth trying as your fault might be different from mine.
In the end i Dave Beer(Mod Wise) leant me an ECU with a 5ltr chip (mine is a 4ltr) and it ran a lot better...so i took the chip out of mine and tried it and now it is a flying machine....sideways at roundabouts and corners....in fact the back wheels are turning more times than the front!!!
Fuel Consumption has improved dramatically as well...from empty i have put 30 ltrs in and have covered approx 110 miles and there is still quite a bit left...and i have not been taking it easy...
Hope this helps!!!
Andy
If you look at my profile you will see the thread i started a few weeks ago re very poor MPG...no exaggeration my car used to do 20+ mpg but then dropped suddenly to about 6 mpg...running very rich...strong smell of petrol when the car was running...my girlfriend followed me in her car and when i parked mine up and got into hers it smelt like someone had poured peetrol into hers the fumes from mine were that bad...any way i had lots of sound advice from the likes of Podie, GreenV8s etc...all of which is well worth trying as your fault might be different from mine.
In the end i Dave Beer(Mod Wise) leant me an ECU with a 5ltr chip (mine is a 4ltr) and it ran a lot better...so i took the chip out of mine and tried it and now it is a flying machine....sideways at roundabouts and corners....in fact the back wheels are turning more times than the front!!!
Fuel Consumption has improved dramatically as well...from empty i have put 30 ltrs in and have covered approx 110 miles and there is still quite a bit left...and i have not been taking it easy...
Hope this helps!!!
Andy
philr said:
Last night I found a hole in the thin vacuum pipe from the pipe between the plenum chamber and the distributor vacuum. It looks like this has been nicked by a screwdriver or something at some time and produced quite a hole relative to the size of the pipe.
The bible says that this is used to control the advance of the ignition.
Can anyone tell me if this is likely to have been a contributing factor to my poor MPG and rich running problems......or was this just something else unrelated that needed to be fixed.
Cheers
Phil
Would affect crusing fuel economy - if your vacuum module was actually working and not seized/leaking too.
Has anyone checked your timing? It's not at all difficult and if too far retarded would lead to bad economy - although most likely a feeling of being down on power.
Thing I don't understand is how your engine can be (detected as) running rich and yet your emissions are OK?
>> Edited by griffter on Thursday 20th October 12:27
>> Edited by griffter on Thursday 20th October 12:28
Thank Griffter.
I don't think that I am retarded but others may disagree
.
If the timing was retarded then surely the performance would be off...which is doesn't seem to be.
Crusing consumption seemed to be the big drop off point. On the Rolling road all was OK until 2400 rpm onwards. thats where the fule/air mix curve differed from what it should be.
The injection guy who found the previous vacuum pipe was split suggested that this would cause more air in the mix and so the ECU would provide more fuel to compensate. If the resultant fuel/air mix was then correct then the emissions would be OK and I would just be usingmore fuel. This sounds reasonable enough, but the plugs were baddly sooted up, so may be there is more to it. I will check the plugs again (well the easy ones anyway) and see what the state is like now that I have run for a few weeks.
Phil
>> Edited by philr on Thursday 20th October 12:59
I don't think that I am retarded but others may disagree
. If the timing was retarded then surely the performance would be off...which is doesn't seem to be.
Crusing consumption seemed to be the big drop off point. On the Rolling road all was OK until 2400 rpm onwards. thats where the fule/air mix curve differed from what it should be.
The injection guy who found the previous vacuum pipe was split suggested that this would cause more air in the mix and so the ECU would provide more fuel to compensate. If the resultant fuel/air mix was then correct then the emissions would be OK and I would just be usingmore fuel. This sounds reasonable enough, but the plugs were baddly sooted up, so may be there is more to it. I will check the plugs again (well the easy ones anyway) and see what the state is like now that I have run for a few weeks.
Phil
>> Edited by philr on Thursday 20th October 12:59
andy-w,
I have been following your problem. Great to hear that you finally have it sorted. I guess you don't want to think how much you've spent trying to get it sorted !
How much was the new ECU by the way.
It may be that if I can find someone willing to swap ECUs for a bit I will try this also.
Unlike your case, my performance is fine ..its just the MPG and the rich running.
I have been following your problem. Great to hear that you finally have it sorted. I guess you don't want to think how much you've spent trying to get it sorted !
How much was the new ECU by the way.
It may be that if I can find someone willing to swap ECUs for a bit I will try this also.
Unlike your case, my performance is fine ..its just the MPG and the rich running.
The performance was still reasonable with the old ecu...accelerated quick and top end as far as i could tell was ok...it was just a bit...spluttery (Technical term!!!).
The ecu change has made it run so much better and there is no soot forming on the rear bumper anymore.
The ECU i have is on loan from David Beer who managed to pick it up for £50!!! So far i have been quoted anything from £150 - £700(brand new)
But am checking local breakers tomorrow.
The ecu change has made it run so much better and there is no soot forming on the rear bumper anymore.
The ECU i have is on loan from David Beer who managed to pick it up for £50!!! So far i have been quoted anything from £150 - £700(brand new)
But am checking local breakers tomorrow.
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