Discussion
I've been getting about 18mpg from my Chim400 and always assumed that is about right for urban driving. This has recently gone down to around 15mpg. Even if I don't welly it I only get 15mpg.
I guess it could be running rich - It's just been to TVR Bodyshop for a service and they adjusted the timing, but not the mixture. Can any garage set up the mixture?
Failing that, any other suggestions for the cause of bad economy?
I guess it could be running rich - It's just been to TVR Bodyshop for a service and they adjusted the timing, but not the mixture. Can any garage set up the mixture?
Failing that, any other suggestions for the cause of bad economy?
meeko said:
I guess it could be running rich - ............ Can any garage set up the mixture?
Failing that, any other suggestions for the cause of bad economy?
Hi Meeko, I'm not wishing to sound condescending but you are talking as if it were running carbs. Diagnosis and investigation of fuel injection maladies (if there are any) need to be carried out by people with appropriate and extensive knowledge and experience (plenty of good sources on here). It can be very difficult to know if an engine is actually running rich without doing a proper rolling road session with exhaust gas analysis, as its the on-load mixture that you are trying to get sorted, the idle mixture or no-load mixture will not confirm correct on-load settings.
Basically unless there is a component failure or wiring problem a FI system should never need "adjustment" and most problems arise from other components.
The first question is: "how is it running?" - noticed any change in behaviour, starting, idling, acceleration , misfire, (more) overrun pops / bangs and so on?
The first thing to look at IF the economy is GENUINELY deteriorating (which can be very difficult to objectively measure) is routine service items, plugs, air filter, HT components, dizzy cap etc,
then things like; air flow meter, throttle pot, air leaks (would cause lean running), injectors (leaking / sticking injector could cause rich running), fuel pressure, camshaft, just to mention the first things to come to mind.
So really there is no meaningful definitive answer but just a load of questions. Dont know if thats any help??
Hopefully there will be a bunch of well qualified people to comment shortly.
Many thanks for the information. I am based in Bath - Can anyone recommend somewhere nearby who may be able to diagnose?
The car's performance hasn't really changed. It does smell quite rich and I have noticed a lot of "sooting up" of the exhaust pipes, with a thin trail of soot on the underside of the pipes. Economy is definitely down, as I do the same run every week to work, use the same fuel etc and it does do about 3-4 mpg less now.
I guess I need to test what I can and see if any sensors are faulty. I'll do some reading in this forum and see what I can test myself.
The car's performance hasn't really changed. It does smell quite rich and I have noticed a lot of "sooting up" of the exhaust pipes, with a thin trail of soot on the underside of the pipes. Economy is definitely down, as I do the same run every week to work, use the same fuel etc and it does do about 3-4 mpg less now.
I guess I need to test what I can and see if any sensors are faulty. I'll do some reading in this forum and see what I can test myself.
Just had a similar problem on the 450, fuel consumption up, power felt down and MOT fail on the emissions (high CO, HC and lambda on the low side). Turned out to be the HT leads on there way out. A new set fitted and it feels like a different car (the grim is back!).
As previous posts indicate though it could be any number of things that give these symptoms. Get it to someone who knows their stuff.
As previous posts indicate though it could be any number of things that give these symptoms. Get it to someone who knows their stuff.
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