Help with RoverGauge results - poor idle

[Adrianw]

My griffith has started to develop a very rough/poor idle , when cold or hot the idle will drop when stationary to around 200-400 rpm .

I run up the Rovergauge , but i can't see any obvious issues , except that both Lambada sensors are reporting a fault code.

Is the first step to try replacing these with new items ?

I can PM the log file if this helps or screenshot

Adrian

[bomb]

do you have plug extenders on at the moment ?

[Adrianw]

Hi i have usually metal ones. I have checked all are correctly seated includling no 8. The lambda's show fault code on both banks after a couple minute throw errors. The long trims are a zero after 3 minutes hot idling. Will put a screen shot up shortly . Cheers

[chris52]

This could be the relay that powers the lambdas this is also the fuel pump relay. Info below I got from a previous post with a similar issue

Fuel pump relay
Pin 30 Purple/White (supply)
Pin 87 White/Orange 2 wires. to lambda sensors.
Pin 87 White/Purple to purge valve. Black to fuel pump via immobiliser and inertia switch.
Pin 86 White/green supply to the relay coil.
Pin 85 Blue/Purple coil earth connects to ECU

[Adrianw]

Good thought on the relays , i will check

here are some screenshots , the long term lambda trim does seem to move even after 3-4 minutes of idles , which i think is okay. The short term trim is adding lots of fuel ?

[Adrianw]

more

[Adrianw]

better quality

[blitzracing]

The bottom line is "adding fuel" means you have no voltage from the Lambda probes as this represents a very lean condition. You will get this if either the 12 volt supply is missing from the probes, or you have a bad misfire, as un burnt fuel looks like a lean mixture to a lambda probe. If you have 12 volts on the lambda red wire (heater voltage) then have a closer look on at your ignition system, as this may not be an ECU or sensor issue at all.

[Adrianw]

Hi Mark , many thanks for the advice on checking the power supply to the heater side of the lambda . Will update my findings over the next couple of days.

Cheers

[Adrianw]

Just an update , poor idle now solved by Dan (+1 TaylorTVR)

Took Dan a few days to solve , but it turned out to be a failing MAF and leaking hose at the back of plenum.

MAF worked fine when driven under load , but just couldn't manage the keep idle from hunting.

I do recall a thread somewhere about checking the voltage at start-up and a slow reaction time indicating a poorly MAF

Middle range now feels nice and strong , just need some nice weather to enjoy it before the chassis off restoration

Cheers