Excesive fuel consumption on GTV 6

Nikola · March 09, 2010, 10:18:24 AM

Few months ago I finished restauration on my 82' GTV 6 and I started to drive her and I decided to measure fuel consumption because for some reason I was very much suspicious about her fuel consuption.
So I started measuring fuel consumption and I came to conclusion that she spent 19.5 litres on 100 kilometers.I was driving her only in town but I still think that's to much.Why???Because I have also 75 3.0 V6 America also with Bosch L-Jetronic system which has a consumption of 14 litres on 100 kilometers also when driven in town.Now it's winter time in Croatia and I live by seaside and temperatures are from 0 to 20 degrees of celzius which is not to cold and because of that I'm very suspicious about her consumption.
Anybody has some info or idea or previous experience why she is drinking so much fuel???Somebody said that's normal due to old type of Bosh L-Jetronic system but I don't beleive in that story.Thank's in advance.

Nikola · March 10, 2010, 08:50:54 AM

I can't believe that no Ozzy didn't have a problem like mine.Comon guys don't be lazy to write a few tips at least.

dehne · March 10, 2010, 10:05:20 AM

have you checked for fuel leaks when the car is going, being the when the fuel lines are a pressure there maybe a pin hole in the fuel line. thats what the prob with mine is at the moment, also put some injector cleaner in the tank it might be a case of unused fuel being lost when you clean the injection you might find it runs a whole lot nicer to

Al Campbell · March 10, 2010, 01:39:30 PM

Nikola,

Original test for "Hard" driving by the English magazine Autocar consumed about 14 litres/100km. So even allowing for ageing of the car, 19.5 sounds like way too much.

Cooler temperatures should give better consumption anyway.

What sort of condition is it in? You could try the "Greg Gordon" tuning checks:

http://www.hiperformancestore.com/Ljetspider.htm

But... I have a 1983 GTV6 and it seems to use a lot of fuel. So much that I haven't bothered to measure it. I'll try and work it out, but it only gets short trips every day, so it'll take a week or 2.

alfagtv58 · March 10, 2010, 01:53:21 PM

This happened to me on my 3.0l 75. Turned out to be the air flow meter getting stuck open so there was just way too much fuel being pumped in.....new AFM, problem solved.

Nikola · March 10, 2010, 10:52:12 PM

That's the spirit guys.I was so happy when I saw a different types of answers.I will use all of your tips.Thank You very much.Anybody has some other info or clue where I could look at???

Nikola · April 18, 2010, 11:21:52 PM

After almost 6 weeks of testing and checking and in the meantime waiting the gas analyzer to come back from servicing we gained something but still I'm not satisfied.With other words I'm very angry and I'm thinking how to set her on fire.Thirsty bitch.
Driving it 50 kilometers on open road and 50 kilometers in the city I measured 14,2 liters on 100 kilometers.Next 100 kilometers I measured 19 litres consumption which I made in the city with mixed driving which would mean fast and normal.
We checked everything and Greg's web page was also helpful.HC,CO,O2 and rest of the parameters were set to normal thru gas analyzer.
One thing I didn't try.The ECU.I have another one and I think I will try with that one so we will see.ECU which is on my car was allready soldered and trouble shooted because didn't wont to start the engine.That was more than 20 years ago.Maybe there is some kind of problem with ECU???

ANYONE,ANY IDEAS,EXPERIENCES

dehne · April 18, 2010, 11:48:38 PM

hi there see u r still having troubles, i had my 2.5ltr 90 running at 6.2 ltrs the other day on the highway and occassionly gets down to low 5's around town its doing around 10 to 11 it has me stumped at the moment ill ask some other guys i know to see what they say,
on a different note do you see any off callaways gtv 6 twin turbos around over there as i would like to get my hand on a set of turbos from a wreck

Nikola · April 19, 2010, 08:12:13 AM

Callaways You won't find in Croatia neither in the rest of the Europe.Their natural habitat is the USA.
See with those guys You know if there is some kind of good tip or advice.

Sheldon McIntosh · April 19, 2010, 05:07:23 PM

What exactly did you check? AFM?, Cold start injector? TTS? Every joint for leaks (air and petrol)? What colour is the exhaust, and what colour are the plugs? Bit hard to help unless you give us more info.

Last time I measured mine, which was a few years ago now, I'd get around 13-14l/100km in the city, and 9-10 on the highway. So yours does sound a little high. What's the temperature over there?

Quote from: dehne on April 18, 2010, 11:48:38 PM
hi there see u r still having troubles, i had my 2.5ltr 90 running at 6.2 ltrs the other day on the highway and occassionly gets down to low 5's around town its doing around 10 to 11 it has me stumped at the moment ill ask some other guys i know to see what they say,
on a different note do you see any off callaways gtv 6 twin turbos around over there as i would like to get my hand on a set of turbos from a wreck

Wow dehne that must be the best 2.5 V6 in the world if it's that efficient!! Is that the same one with the chip that you've had up to 250km/h? How much do you want for it, that car sounds awesome? I'd be wary of putting turbos on it though, that might lift the fuel consumption a fair bit; probably to the level of a modern japanese 4 cylinder car.

MD · April 19, 2010, 07:49:35 PM

Nikola

I think the diff ratio on your 75 is a 3.59 and one on the GTV is a 4.1 The difference in gearing alone would account for some differences in the consumption between your cars. The shorter one obviously using more fuel. Sticking brakes, low tyre pressures, tight wheel bearings all increase fuel consumption.

Nikola · April 19, 2010, 07:54:12 PM

What was checked on the car???
1.AFM which normaly gives reaction when screwing and unscrewing the spring for adjusting mixture when connected to gas analyzer.I'm not sure did we checked resistance on AFM.
2.Air leaks clogged and settled
3.Injectors cleaned and tested
4.Cold Start Temperature sensor checked and in good condition
5.Coolant Temperature sensor checked and in good condition
6.Aux Air Valve in good condition
7.Cold start injector working fine
8.Ignition in the right place and engine on position.
9.Thermostat working normaly
10.New spark plugs
11.Throttle position switch o.k.
12.Gas pump double relay working fine
Colour of the exhaust is black but car runs great,no smoke whatsoever and quick response to gas pedal.Car is almost in the factory setting concerning the HC,CO,O2 and the rest of the parameters due to gas analyzer.
20 years ago ECU was opened and something was worked on him because car didn't wont to start.They suceded to solder something inside the ECU and car started.But who can say that they missed something or something happened in the meantime.
Tommorow I'm going to my mechanic and first we will check gases with this ECU and then check gases with other ECU.
There was an episode when we set gases to a factory settings and than 3 days later when we checked again everything was nackered like we didn't touch anything.Tomorow we will see are we going to have a rerun.
Experiences???

Simon Aarons · April 19, 2010, 10:00:19 PM

I replaced the 2.5L with a 3L about a year ago. Fuel consumption is quite weird!

For example: Full tank - 60litres (never been able to put 75 in?) Open road and around town driving i will get about 400-450 out of the tank. Pretty horrible.

But the other week i was very low on fuel (so low that the light was stuck on even when i turned right) so i put just $20 in - about 14-15 litres. I managed 135k's before i had to fill up again.

Explain that one! But i can have a heavy right foot - Nikola did you think that your driving style has something to do with consumption?

dehne · April 19, 2010, 11:51:05 PM

Wow dehne that must be the best 2.5 V6 in the world if it's that efficient!! Is that the same one with the chip that you've had up to 250km/h? How much do you want for it, that car sounds awesome? I'd be wary of putting turbos on it though, that might lift the fuel consumption a fair bit; probably to the level of a modern japanese 4 cylinder car.
[/quote]

yes sheldon it is the 1 with the chip in highway driving i can drive from bendigo to syd on a tank (being sensible) on good fuel 98oct and the turbos i was thinking for the race car you have gotta do what you can to get more power than what jim is going to built
rumor has it when hes not using the engine nasa is going to borrow it for the spaceshuttles

Nikola · April 20, 2010, 08:21:22 AM

Quote from: Simon Aarons on April 19, 2010, 10:00:19 PM
I replaced the 2.5L with a 3L about a year ago. Fuel consumption is quite weird!

For example: Full tank - 60litres (never been able to put 75 in?) Open road and around town driving i will get about 400-450 out of the tank. Pretty horrible.

But the other week i was very low on fuel (so low that the light was stuck on even when i turned right) so i put just $20 in - about 14-15 litres. I managed 135k's before i had to fill up again.

Explain that one! But i can have a heavy right foot - Nikola did you think that your driving style has something to do with consumption?

When I drive my 75 3.0 V6 the same way I drive GTV 6 the fuel consumption is less.75 uses 15 litres on lead foot but GTV 6 uses 19 litres on lead foot.