Fault code 45

[bubblehead]

Long story short, after a service and new set of ht leads fired her up and all seemed well, however when i revved it up from the engine bay i could see the vacuum unit moving about on the dizzy,secured it back in place and took it for a test drive.....It felt like it was missing and didn't seem to clear until 3500rpm or so. Disconnected each lead in turn and all were firing and effected the idle when removed. Felt like ignition so i've replaced my new ht leads with the old as well as an old coil,rotor arm, cap and amp which i kept as spares. No fault codes were present the first time i checked but after another run i got a lambda out of range code, sure enough the plugs on the offside are sooty and the nearside are grey, checked the voltages and the nearside is switching fine but the offside is stuck reading 1v. Question is am i seeing the cause or effect of my problem, got myself a bit confused here, is it reading 1v constantly because it is rich or is the 1v causing the ecu to make it rich....and would the rich mixture cause the miss i could feel?
Cheers Bubbles

[taylormj4]

bubblehead said:

Long story short, after a service and new set of ht leads fired her up and all seemed well, however when i revved it up from the engine bay i could see the vacuum unit moving about on the dizzy,secured it back in place and took it for a test drive.....It felt like it was missing and didn't seem to clear until 3500rpm or so. Disconnected each lead in turn and all were firing and effected the idle when removed. Felt like ignition so i've replaced my new ht leads with the old as well as an old coil,rotor arm, cap and amp which i kept as spares. No fault codes were present the first time i checked but after another run i got a lambda out of range code, sure enough the plugs on the offside are sooty and the nearside are grey, checked the voltages and the nearside is switching fine but the offside is stuck reading 1v. Question is am i seeing the cause or effect of my problem, got myself a bit confused here, is it reading 1v constantly because it is rich or is the 1v causing the ecu to make it rich....and would the rich mixture cause the miss i could feel?
Cheers Bubbles

This is interesting. I'd guess at a leaking injector but not my area of expertise. Come on guys, someone must be able to answer this....Blitzracing ?

[blitzracing]

The 1 volts is over rich, so all the symptoms tie up, so you have a fault on that one bank. The lamda probe is working as it should and the ECU has picked the fault condition up because of the stuck voltage. Its worth bearing in mind that a misfire can black the plugs as the one cylinder thats misfiring looks like a lean mixture to a Lambda probe (unused oxygen is high) so the ECU puts in more fuel, but id still expect some switching of the probe in this case.

This is well worth a read:

http://www.g33.co.uk/images/PDFS/14cux%20faulot%20...

You could just have crossed to plug leads over?

Edited by blitzracing on Tuesday 14th June 11:57

[bubblehead]

Cheers Blitz i'm working away from the car for the next two weeks but the link you posted was a good read. I'm kicking myself that i only removed one plug each side now but i was pushed for time however i did strobe it after i found the vacuum unit almost off the dizzy, the timing marks stayed super steady and then occasionally would disappear momentarily which i presume was the slight miss i could feel whilst driving.

[bubblehead]

Quick update now i'm home, removed all the plugs and all on the drivers side were sooty and all on the passengers side were grey. Checked the injectors by removing them from the plenum and then pressurising the fuel rail and no leaking injector(s). Checked the resistance of both banks from the ecu and they were the same and agreed with the figures in the bible. Went out for a spin to see if i could generate a fault code......this time i got a tune resistor out of tolerance. Checked it and its bang on the figure in the bible, thought i'd recheck and see what the lambda was doing and this time it's stuck on 0.2 volts but hasn't given an error code After more fiddling about and applying some contact cleaner to the ecu plug all now appears to be fine with the probe switching away merrily and no more fault codes but i'm not sure thats the real underlying problem. Can lambda probes stick either high or low or is this an issue with the ecu or was it really just dirty connections at the ecu plug ? Any thoughts?

Cheers Bubbles.

[blitzracing]

The Lambda probes are resistive devices, taking the voltage from the heater supply wire, so they could stick low if the voltage was missing, or the probe had gone open circuit, and high if the probe goes short circuit, but that would show 12 volts on the output not 1 or 2. Its true that bad connections can cause issues as the lambda voltages are low, so more likely to be effected by high resistance joints.

[bubblehead]

Well she went through the MOT yesterday with no snags, the emissions were pretty much the same as last year so i'm hoping that it was just dirty contacts. Time will tell.....