fuel consumption??
Discussion
1994 4.0 HC 61,000 miles pre serp.
Hi All,
I've recently noticed my Chimaera is literally drinking the stuff whilst driving normally.
eg: put in 20 litres = 4.54 gallon........Distance travelled = 60km (37.5 miles).........20km freeway and 40ish urban.......petrol gauge is below previous fill point........37.5 miles / 4.54 gallon = 8.25 mpg!!!
Ok, these figures may be out a little either way but they are not wildly out. That is ridiculous mpg. Non of my previous V8s were anything like that, including my AJP Cerbera. The car is sleeved & fully decatted so does smell of fuel but the petrol gauge falls like a stone.
Obviously, I think there must be some engine issue. eg: when I block off the small breather pipe just before the stepper motor and adjust the idle screw - nothing happens to the idle at any point all the way top to bottom or when I release the pipe clamp. The idle is very speed dependant, 1200ish when rolling and slowly comes down to 1000 at standstill. It does not like it below 1000 revs. I do get shunting sometimes when backing off the throttle. Cleaned the stepper motor. I'm thinking a massive air leak somewhere but a local RV8 mechanic stated there were no vacuum leaks and he thought the engine was "worn" and was not "breathing" properly. Recent new plugs, leads, rotor, diz cap, distributor checked, MAF replaced and engine checked with a known good one, and original returned, new oil pressure switch.
Any further thoughts gents as that is ridiculous mileage whilst poodling around? I cannot wait to use Rover Gauge but must make do without at the moment.
Hi All,
I've recently noticed my Chimaera is literally drinking the stuff whilst driving normally.
eg: put in 20 litres = 4.54 gallon........Distance travelled = 60km (37.5 miles).........20km freeway and 40ish urban.......petrol gauge is below previous fill point........37.5 miles / 4.54 gallon = 8.25 mpg!!!
Ok, these figures may be out a little either way but they are not wildly out. That is ridiculous mpg. Non of my previous V8s were anything like that, including my AJP Cerbera. The car is sleeved & fully decatted so does smell of fuel but the petrol gauge falls like a stone.
Obviously, I think there must be some engine issue. eg: when I block off the small breather pipe just before the stepper motor and adjust the idle screw - nothing happens to the idle at any point all the way top to bottom or when I release the pipe clamp. The idle is very speed dependant, 1200ish when rolling and slowly comes down to 1000 at standstill. It does not like it below 1000 revs. I do get shunting sometimes when backing off the throttle. Cleaned the stepper motor. I'm thinking a massive air leak somewhere but a local RV8 mechanic stated there were no vacuum leaks and he thought the engine was "worn" and was not "breathing" properly. Recent new plugs, leads, rotor, diz cap, distributor checked, MAF replaced and engine checked with a known good one, and original returned, new oil pressure switch.
Any further thoughts gents as that is ridiculous mileage whilst poodling around? I cannot wait to use Rover Gauge but must make do without at the moment.
Are your spark plugs black? That's the simplest indicator of rich mixture. If it is really doing sub 10mpg then you should also look at the detector surface of the Lambda sensors, the surface should be completely clear of sooty deposits. If they soot up they'll give incorrect O2 readings to the ECU which can result in rich running
Is it using that amount of fue,l or is the fuel gauge the usual TVR rubbish that swings from full to empty and back, every time you go round a gentle bend, and then shows totally empty, but you can only get 2 litres of fuel in, at the petrol station?
Have you brimmed the car, then driven a few miles, then brimmed it again and calculated the consumption?
Have you brimmed the car, then driven a few miles, then brimmed it again and calculated the consumption?
“That’s f
king fked mate” only joking.
Open injector, could be loads of things.
You’ll be glad when you can use RG I reckon.
If your figures are correct I’d be looking at timing too a hole in the tank
Basically do a lot of checks. My 4.6 managed 7 mpg but on a runway doing 150mph so there’s a reference.
My car should do 20 round town stop / start and about 27 at motorway speeds 70-80 mph.
king fked mate” only joking. Open injector, could be loads of things.
You’ll be glad when you can use RG I reckon.
If your figures are correct I’d be looking at timing too a hole in the tank
Basically do a lot of checks. My 4.6 managed 7 mpg but on a runway doing 150mph so there’s a reference.
My car should do 20 round town stop / start and about 27 at motorway speeds 70-80 mph.
Jeez, I wish that I could be so certain it won’t explode if I was to go to some of those speeds! I’ve cancelled my track day as a result.
My lambdas were black - cleaned with wire brush and picked in holes. These are some of the plugs, I have regapped/ cleaned them all as less than 9mm.
They have only done about 1k miles max.
Drove to work this morning, smoother and now trying to idle below 1000. Gets really lumpy with whole car shaking at the lights - gives impression of MASSIVE engine but I know it is not the case!!
My lambdas were black - cleaned with wire brush and picked in holes. These are some of the plugs, I have regapped/ cleaned them all as less than 9mm.
They have only done about 1k miles max.
Drove to work this morning, smoother and now trying to idle below 1000. Gets really lumpy with whole car shaking at the lights - gives impression of MASSIVE engine but I know it is not the case!!
Wolvesboy said:
................ The idle is very speed dependant, 1200ish when rolling and slowly comes down to 1000 at standstill..............
There are likely other issues you are working on but for clarity.Normal idle should be around 900 and 1200 when rolling to a standstill is a design feature. a sort of anti-stall.
Steve
Well........I am prepared to "eat my hat" so to speak.
I filled up to the brim, drove 235 miles (odometer), refilled to the brim = 44 litres
My man maths: 44 litres = 9.48 gallon. 235 miles/ 9.48 = 24.78 mpg!
I am really pleased with that as some urban driving mixed with freeway and one or two "squirts" along the way for fun.
She still idles like a rocking horse. still has the idle screw anywhere without any effect but returns 24 mpg! Happy as! I am just going to drive her as she seems to run so much better the more she is driven.
My 450 Chimaera - totally standard - best MPG on a relaxed long drive = 24 mpg, worst (city driving) 13.5 mpg Average = 18.4 to date.
It used to be a bit "lumpy" and suffered from shunting but then my mechanic retarded the ignition a bit, cleaned all the connections on the engine wiring harness, cleaned the stepper motor etc and now it's nice and smooth!
It used to be a bit "lumpy" and suffered from shunting but then my mechanic retarded the ignition a bit, cleaned all the connections on the engine wiring harness, cleaned the stepper motor etc and now it's nice and smooth!
My car has had 3 engines so far (purely for mpg comparison purposes of course, not just a thirst for power 
)
As a 400, it did 27 mpg
As a 500 is did 21 mpg
As a 4.6 turbo it does 23-23.5 mpg
Doesn't seem to matter much how I drive it with the exception of track days - they are around 12 mpg less on all engines.
)As a 400, it did 27 mpg
As a 500 is did 21 mpg
As a 4.6 turbo it does 23-23.5 mpg
Doesn't seem to matter much how I drive it with the exception of track days - they are around 12 mpg less on all engines.
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