Rough Idle

[The real Apache]

I've been having issues with this on the Alpina and can't seem to get to the bottom of it, I've swapped out the MAF, checked the inlet and exhaust manifolds for leaks, checked the lambda etc. On diagnostics an Indie found that the return from the MAF was at 2 or 4 volts (can't remember which) when it should have been under 1 volt, they managed to bring it in by partially blanking the MAF, this also improves the idle.
This is beginning to bug me, any ideas?

[The real Apache]

fesuvious said:

Is the MAF a genuine part?

Have you cleaned the plug with contact cleaner?
Have you sprayed contact cleaner through the old MAF and then refitted?

both are Bosche, both have been cleaned, both have the same characteristics

[Ernst Blofeld]

issue in the wiring harness

[spikeyhead]

Ernst Blofeld said:

issue in the wiring harness

Or possibly on the connector where it meets the ECU, or even inside the ECU.

It could also be a dodgy earth.

[The real Apache]

The ECU has been out and interrogated....the only irregularity appears to be the higher than normal return voltage from the MAF

[spikeyhead]

The real Apache said:

The ECU has been out and interrogated....the only irregularity appears to be the higher than normal return voltage from the MAF

Has this voltage been measured directly or is it what a computer is saying the ECU is measuring?

[The real Apache]

spikeyhead said:

The real Apache said:

The ECU has been out and interrogated....the only irregularity appears to be the higher than normal return voltage from the MAF

Has this voltage been measured directly or is it what a computer is saying the ECU is measuring?

I think so, it obviously showed up on the output readout but I think he was able to meter it as well. I'm sceptical that the MAF can actually do this so feel that something else is up the duff

[spikeyhead]

The real Apache said:

spikeyhead said:

The real Apache said:

The ECU has been out and interrogated....the only irregularity appears to be the higher than normal return voltage from the MAF

Has this voltage been measured directly or is it what a computer is saying the ECU is measuring?

I think so, it obviously showed up on the output readout but I think he was able to meter it as well. I'm sceptical that the MAF can actually do this so feel that something else is up the duff

I suspect that if two MAF sensors are overvolting identically, then the ECU is failing to properly load the ouptu of the MAF sensor so it's showing a higher reading. It would be worth putting one of the MAF sensors in another car to check.

[The real Apache]

I've disconnected the MAf and the idle becomes really rough