Alfa 156 Erratic / Bouncing Rev Needle

[ddw78]

Hi,

The last few mornings the rev counter/needle in my 156 has been bouncing around very erratically. It can 'red line' with the littlest touch then return and flicker around 4/5000 revs when it should be reading about 2000 rpm.

It doesn’t actually seem to affect the engine, the vehicle still drives as it should. Also, it only seems to happen whilst the engine is cold.

I've checked the air intake for leaks and also checked the butterfly is clean. Both seem fine.

Had any one else encountered this problem? Is it a common issue?

Thanks in advance for any comments/help.

Cheers,

Darren.

[alfa pint]

Sounds like the lambda sensor and isn't uncommon, nor massively expensive.

Best bet is to get the fault codes read on the ECU (peanuts / free) - that will let you know what it is and how £££ a sort it is.

In the meantime, you can reset the ECU, which should sort it out temporarily.

Soft reset - turn the key so that the ignition lights all come on, but the engine doesn't start. Leave it for at least 45 seconds, certainly a minute. Start the engine WITHOOUT returning the key to the start settings. It might idle a bit high for a few days, but the bouncing should be minimised.

Hard reset - involves disconnecting the battery for a few hours and restarting car with the brown master key. Restores factory settings to the ECU, so you may find the car isn't as responsive as it normally is for your style of driving.

[ddw78]

Thanks for the advice.

I carried out the 'soft reset' earlier and it seems to have cured the bouncing. In fact, in seems to rev more smoothly - or is that just my imagination?

I'll get my garage to plug it in tomorrow to check for fault codes.

Cheers,

Darren.