Lazy starting from cold/warm 940 Turbo 2.3

[mikkey850]

Hello everyone.

My Volvo 940 Turbo 2.3 has an issue regarding starting up and idling.

You need to hold the throttle down a little for it to start or else it just splutters and dies. once started you need to slowly release your foot off the throttle or again it will splutter and cut out. After running for around 10 to 15 seconds it will idle fine and drive as normal.

I have noticed when it does this it smells fuelly but I haven't noticed any smoke from the exhaust.

Sometimes whilst its trying to idle the lambda light will come on briefly until the revs are raised.

Any ideas as to what it could be? Doesn't smell fuelly after it has been running for a while and had the plugs changed at its last service 600 miles ago.

Thanks in advance!

Michael.

[TonyS9]

My first thought was idle air valve, not allowing enough air, but another cause of the rich mixture could be leaky injectors or faulty fuel pressure regulator.

the o2 sensor is not used during start up so something is causing a rich mixture, sounds like the o2 sensor is working properly and indicating a fault elsewhere. If the light comes on if the rpm is very low that would be normal. What are the rpms when it comes on?

Normally the engine gives the idle air a little extra air at startup with a short rev, if the idle air valve is not responding it could give this symptom.

No other problems like hesitation on acceleration?

[czech240]

for sure check the above..common problem...

[mikkey850]

Hello everyone and thanks for the replies.

In answer to your question. The lambda light came on for a split second as the car shuddered to just below 500rpm before recovering, once the car has "sorted itself out" it idles fine and returns to idle nice and smooth!

I don't recall the engine revving up when started like most cars I have owned (as in a quick blip up to 1200/1500rpm or so then settle to idle instantly)
It just kind of shudders up from whatever the RPM the starter motor takes it to and then it gradually builds up to idle.

I have noticed there is a fair amount of play on the throttle cables and linkages. (so much that I have reason to believe that is why the cruise control doesn't work!) and I see this is all linked to a butterfly valve on the intake manifold. could this be the reason why?

Thanks,

Michael.

[bongodave]

If it's spluttering and slow to get going, I'd say you're using the wrong kind of coffee in the header!

After you've woken it up, change the fuel pressure regulator for a scrappy jobbu, or go posh and spend 20 squids on a bilet adjustable fuel regulator with built-in pressure gauge on Ebay.

They come in lots of nice, shiney colours and look smart/perform well. It'll prob cure your fault with added benefit of a bit more poke low-down.

Take out your stepper motor/idle air control valve first and give it a good clean with wd40. Don't use carb cleaner, like many, as it'll bugger up windings in electro-magnet. After you done that, clean out throttle body (with carb cleaner) and adjust linkages.

Don't forget the coffee!

[TonyS9]

Not sure how cruise control affects it but the air valve allows air to bypass the butterfly valve and control the rpm for loads from ac, steering etc. Sound very like it is not responding or stuck. Easy to get 2nd hand, usually reliable but I do hear of some failures.

[James_N]

Originally Posted by mikkey850

In answer to your question. The lambda light came on for a split second as the car shuddered to just below 500rpm before recovering, once the car has "sorted itself out" it idles fine and returns to idle nice and smooth!

I don't recall the engine revving up when started like most cars I have owned (as in a quick blip up to 1200/1500rpm or so then settle to idle instantly)
It just kind of shudders up from whatever the RPM the starter motor takes it to and then it gradually builds up to idle.

Mine does this, and quite often stalls when trying to hot start.

I've always just assumed its the idle control valve but I just got used to this over the years.

[TonyS9]

Unexplained idle problems are often caused by dirt/carbon buildup in the throttle body.