forum.audiv8.com Foren English Audi V8 Forum Audi 4.2 V8 big fuel consumption, other questions.

Well, seems like my V8 has some kind of a drinking problems ..

its 1991 Audi V8 4.2 automatic
on highway 90km/h its like 13/14l per 100km/h on steady road and steady speed..
what have i done and checked:

New spark plugs (NGK)
Plug wires
rotors
rotor caps
measured injectors 16-16.2 resistance (ok as autodata says)
measured TPS and recalibrated as needed
changed lambda sensor with bosch original.
measured fuel pressure,air temp sensor, coolant temp sensor (one behind engine), ISV..

Gives me no fault codes..

Any answers would be appreciated cause its drinking like a scott and i have no time to get from gas station to gas station ..

And BTW Greetings from Estonia : )
Thanks
Silver

First of all: Fill out your profile (car details, location,...) and provide your correct name. That's common in here and a requirement when requesting help.

Second: Do you have the possibility to make a measurement block analysis? Double-check the G62. And: Does your engine get up to 90°C temperature? Or does it remain cold? Try to find out your ignition point (degrees before 1st cylinder upper death center) and if it's too late - could be an indication which sensor is broken.

Regards

Bastian

Sorry, My name is my user name

thnx for advice, i'l check them out and let you know

tried to figure out how to see what degree is btds but hopeless..

engine gets up to 90c , no problem with that and ECT sensor is within specified resistance..

i do get 2342 error all the time from blink codes..

i have already changed lambda sensor (OEM)..

Maybe your Lamdba grounding is the problem. Plug off the Lambda and drive without it for some days. Does anything change?

It's not uncommon that the grounding of the exhaust gets worse over time and then your Lambda values are erronous. The only solution is to install an extra grounding wire and/or buy a 4-pin Lambda sensor.

It could fit the error.

Bastian

well, groundig is good, tried that already.

i just checked some things...

when i switch on ignition, lambda probe heater relay does not click and i get votage 11.05 and higher but relay does not click...

it gets voltage by checking terminals... and relay click if i put voltage on it by hand on battery...

so we have electrical issues, what to check, anyone have ideas ?
ECU fried ?

Wiring problem?

Bastian

No wiring problem, already checked ALL the wiring, took 4+ hours on the job but its done ..

fuel filter is new?

bad coolant sensor on back of right cylinder head will cause bad gas mileage. Use uses this sensor to enrich fuel during cold start up. If the ecu thinks the car is still cold due to faulty sensor, is will continue to enrich fuel even while warm. This is what cause poor mileage. I always change this sensor when I do the o2 sensor. Allan