sudden increase in fuel consumption- help needed!!

Wed Feb 23, 2011 11:02 am

Hi folks,
I have a '93 3.18i touring, I use it daily for commuting to work, approx 50miles a day round trip with 80% on motorway usually at 65-70mph. After accidentally making a bow wave through a pond on the A8 the car has not been running well, I'm down on power and my fuel consumption has probably dropped from around 33-35mpg to low 20's. I found some slight corrosion on the rotor and dissy terminals, all spark plugs look good and all was give a light brush with fine sand paper to clean up. I haven't checked the resistance in the HT leads but plan to this week but on visual inspection they looked fine. Is there any other areas that are well know for this sudden loss of performance????
Help would be much appreciated as my boss is threatening that I should take the offer of a company car and having car trouble only bolsters his arguement.
Kind regards

Murdo

Wed Feb 23, 2011 2:21 pm

Checked the air filter?

Wed Feb 23, 2011 2:33 pm

Also check the ECU is getting the correct engine temp from the famous blue temp sensor.

Wed Feb 23, 2011 3:07 pm

cheers for getting back to me fellas,

Mr Benn, yes I have checked the air filter, it seemed fine and was replaced last year. I shook out what little stoor there was. I was planning on driving it without the filter in for a short run but so far it has been raining when I've had time to try that.

Mr Lee 30, how would I test the ECU signal? Would this be a garage and diagnostics test? Where is the famous blue temp sensor?

thanks again

Thu Feb 24, 2011 5:41 pm

bump bump bump... I checked the resistance in the HT leads last night, all between 5.6 and 6.3K ohms, the coil to dissy cap lead was around 2K ohms. I'm pretty sure the she is running rich; I can smell petrol out of the exhuast, probably very rich as I only got 23mpg on my last full tank!! Nightmare with these petrol prices. Any suggestions please. Is Brian Moore out there???

Cheers Murdo

Fri Feb 25, 2011 4:55 pm

Use the multimeter set to measure ohms. Find the blue temp sensor located toward front of engine near the inlet manifold and where the coolant hose leaves the engine remove the Plug and measure the resistance across the terminals. Should be around 3k when cold and about 250 when hot.

Try this first. Then next is to check the same signal at the ECU, I need to find which pin it is on your car.