1990 G60 Fuel Problems... Costing me a fortune in gas ):

[cope 0]

Hi there,

 

Appear to be back here once again haha.... but hey you guys are great when it comes to helping us stupid non mechnical guys out (:

 

Ok, my main issue is that my MFA1 reading for the litres/100KM (Im in Canada so it in Kilometers)

will not go below 12 Litres/100 KM on the highway. Before i was able to get like 8ish give or take. In the City it would be around 9 or 10ish, but now it ranges between 25-16 Litres/100 KM and its costing me alot more since ive noticed this.

 

I really do not know the differece between the MFA1 and MFA2 reading, but the MFA2 reading is lower. IE MFA1 16, and MFA2 would be 10.

 

It just seams that my fuel mileage is crap. For example I put 10$ of Supreme 91 octane gas aprox 10ish Litres, and Im lucky if I can drive 30 Kilometers in the City, so if that was averaged out, for 40$ (Full tank almost) I could do about 120 Kilometers in the City, and about 3 hundred Kilometers on the highway.....

 

I Do not have a gas leak, but my fuel casing was cracked and it was replaced about 1 month ago. I would not think this would have anything to do with it.

 

Any ideas on what would make my readings so high?

 

Some people have mentioned Timing belt may need to be changed? seems a bit odd to me.... or a fuel injection cleaning?

 

Spark Plugs and Rotor and Distributor cap changed about 3 months ago

 

Any ideas would helps.

 

Thx!

[Jim 2]

Well because its the only one I can answer, the difference between MFA1 and MFA2 is that MFA1 is basically information for the 'current drive' - so start the car in a morning and drive to work, and MFA1 is showing you all the current information in real time. If you leave the car parked up for more than 2 hours, MFA1 resets itself and is back to starting from fresh whenever you drive again.

 

MFA2 is basically cumulative or average.. so doesn't get blanked when you stop the car. Tells you your average MPG over the past few thousands miles, average oil temp, etc etc.

[h100vw 0]

Bad lambda probe or blue temp sender in the top hose are the most likely causes of poor 'gas mileage'. Or the wiring. Have a look on http://www.snstuning.com for troubleshooting guide for stuff like this.

You can swap teh blue and black plugs over and see if there is any difference in the way it runs? A new temp sender would only be about $20 US max, I have no idea on the Canadian exchange rate sorry.

Gavin

[cope 0]

Thx guys... ah so thats what the difference is between the 2... kewl kewl. Greatly appreciated.

 

The blue temp sensor huh,... .guess that would suggest why sometimes my temp gauge doesnt work... or starts working like after 10 mins the car is warmed up and voila bolts up to the correct termp.... usually 98-102 dg. Does that blue sensor cause that too?

 

Ok that makes sense.....

 

Lamda probe meaning the CO2 sensor in the exhaust before the manifold? I put in a universal one because the mileage was way way out of wack and that was about 7 month ago. Guess its a possibility..... but the car rights good from what im used to... lots of power still, not chugging or anything, boost is good, just the mileage is shitty.

 

Hmmm.... ill try the blue sensor and get back to you all.

 

Thx

[h100vw 0]

The blue sensor feeds the ECU with engine temp. If it dies the ECU will assume the worst and overfuel in case. Hence the poor mileage.

 

Gavin

[cope 0]

Would the temp gage tell you if its not working? Because my gage reads the temp fine, but the odd occassion it doesnt and stays at 0 then 2-5 mins later it jumps up to 90ish

 

When the mileage is crap (all the time now) the gage in the cluster is fine unless it does like i said above... (IE sitting at 90ish give or take)

 

Ive bought a new sensor, cost 20$ Canadian tax included so that is not too bad (:

 

Here is one more question..... when the car is cold, it doesnt start properly.... engine turns 2-3 times (or the starter) and then seems like its going to start then dies. But as soon as I turn the key off, and try to start it again.. voila starts perfectly first shot.... Then when it hot, I could turn it on and off and it starts perfect..... only does this when its cold.... any ideas?

[Henny 0]

there are 2 sensors in the same place...

Blue one ONLY feeds the ECU to let it know the operating temp of the engine.

Black one ONLY feeds the gauge on your dash to show your water temps.

[cope 0]

Thanks for the Info Henny,

 

I am replacing the blue sensor as soon as the car cools down... last thing i want to have happen is coolant splash me in the face

[cope 0]

ok tried a brand new sensor from the dealer.... same readings.... hovering around 20 litres/100 km

 

Sooo guess that didnt work.

 

Any other ideas that it could be?

[stevemac 0]

cope,

 

1. Is your car using oil ?

 

2. When was the charger last reconditioned ?

 

3. Did your "using too much fuel" happen just after anything else was done to the car ?

 

4. Check & clean up the earthing point on the bracket that the CO2 sensor wiring plugs into - bad earth here is common & may stop your sensor working properly.

 

5. Check your rear brake calipers - seized handbrake mechanism on the back of the caliper will cause your rear brakes to bind.

[cope 0]

Thx Steve Mac, ill check these out.

 

Consumption based on MFA is a little better, Highway was 10 Litres/100km to the city, and back home it hovered around 12ish.

 

City was 12-14 today so thats alot better than the 20 ive been getting.

 

Any ideas on why it would fluxuate so much?

[stevemac 0]

Any ideas on why it would fluxuate so much?

Sounds likely to be a dodgy earth somewhere - start with the CO2 sensor earth as described above.

The other engine & gearbox earth straps can also affect the ECU - check & clean those also. :wink:

 

Just a thought - check the rear calipers first. Go for a drive & if the rear calipers get very hot (too hot to touch) - they're binding.

[cope 0]

Well my car was stolen today!! Guess I can no longer have any more problems huh !!!!

 

Im sooo angry right now. Damn Alarm etc doesnt do anything for those stealer