Starting problem

[Grantus]

I have an E34 520I with the M50 non vanos engine. When I start it it runs ok then starts to surge the revs a little with an irregular pop (backfire?) on the inlet side, definitely not the exhaust, all this at idle.

Is this likely to be a vacuum pipe leak somewhere under the inlet manifold? I checked the brake booster pipe and it seems ok. There doesnt seem to be a fault code system on this car ( I tried the stomp test) no warnings on the dashboard either apart from service light.

Fuel pump and filter checked out ok, I'm about to check some sensor voltages.

Any help will be much appreciated.

[632 Regal]

old school rule of thumb. backfire through intake carburation, through exhaust electrical. Check the intake side real closely for leaks.

[whiskychaser]

There doesnt seem to be a fault code system on this car ( I tried the stomp test) no warnings on the dashboard either apart from service light.

.

If you are in the States stomp test should work. If in Europe it wont.

[Grantus]

I am in NZ. I have looked and felt for a broken pipe and cant find one, no hissing sound can be heard.

I am checking the MAF sensor. I need a picture of what the wires inside the throat should look like. Bentley's pic is not very clear. Does anybody have a clear pic of how those wires should look?

[Ken35i]

Surging RPM indicates faulty Idle Control Valve (ICV), yes?

[Grantus]

Thanks.
Is the spitting back part of the symptoms for that?