s60 with gas issues

[NI_Volvo_Nut]

Its been cutting out when cold and switching over to gas and is very hard to restart, as if its flooded. I'd suspected the petrol injectors may be leaking, but I removed them today and they where dry. Now since removing them, its running slightly rough on gas, is a bit smokey, more so on gas, not as bad on petrol, and is very slow to return to idle on gas, runs faultless on petrol. I'm thinking maybe the gas regulator is allowing water into the gas system? Doesnt explain the idle issue though? Anyone any thoughts or advice??

[Pete_c20]

Just a quickie that may help to shed more light on the problem....could you elaborate on 'and is very slow to return to idle on gas'. As that sounds a bit odd.

[V8 Disco]

I have no experance on LPG on Volvos, but I had very odd issues with my V8 Discovery when the gas tempreature sender failed ... odd its worse after the petrol injectors have been removed

[NI_Volvo_Nut]

Originally Posted by Pete_c20

Just a quickie that may help to shed more light on the problem....could you elaborate on 'and is very slow to return to idle on gas'. As that sounds a bit odd.

Not returning to idle, hovers around 2k and slowly drops to idle, up to 10 seconds

[Pete_c20]

You might have a sticking idle control valve. Easy to check and clean. The valve bypasses a bit of air round the throttle plate on idle. The wider forum has some posts on it on checking and cleaning the valve.
Ages since I messed with mine. A thought - I've seen some users take the idle valve off and put a gasket in that completely covers the internal hole and put the valve back to keep it in place, thus disabling the valve. You could then simulate its operation by putting in a shim on the throttle stop so the throttle plate never quite closes at idle and see if the problem disappears. Just a thought and your setup could be different and I could be talking pants! If you have an ODB2 reader you'll also see a leaking idle valve in raised fuel trims.

[NI_Volvo_Nut]

Would the idle valve not cause issues regardless of petrol or gas??

[Pete_c20]

Originally Posted by NI_Volvo_Nut

Would the idle valve not cause issues regardless of petrol or gas??

I know what you're saying but some faults show more on one system than the other.

Originally Posted by NI_Volvo_Nut

I'd suspected the petrol injectors may be leaking, but I removed them today and they where dry. Now since removing them, its running slightly rough on gas, is a bit smokey, more so on gas, not as bad on petrol, and is very slow to return to idle on gas, runs faultless on petrol. I'm thinking maybe the gas regulator is allowing water into the gas system? Doesnt explain the idle issue though? Anyone any thoughts or advice??

Now I read your OP again, I feel it might indicate something else. Look at the bit I've highlighted. The petrol injector Orings aren't easy to re-seat sometimes. If the seals on them are slightly misplaced then you may have introduced a slight air leak. You can easily test for this by spraying a bit of carb cleaner around where each injector seats, with the engine idling, a slight change in revs will tell you have a leak at that point. If the seals need a little lube to help them in try some engine oil but nothing that's silicone based.
If it isn't that can you think of anything else you may have changed at the time?

[NI_Volvo_Nut]

Yep, tried wd40 round the injectors as I thought no 1 cylinder seal wasn't great, but they all seem ok. Checked numerous times and can find no leaks.

[Lpgc]

Would need a bit more info on what LPG system your S60 has fitted, do you know what the system is? Or is this a factory system?

You mentioned water leaking into the gas via a leak in the reducer, possible but very unlikely. If there is such a leak it would be far more likely that gas would leak into the water and presurise the cooling system but you haven't mentioned related issues. Water in the gas wouldn't cause a higher idle, neither would gas in the water, the latter often misinterpreted as a head gasket issue.

A more common type of reducer leak, one which cold potentially cause the kind of symptoms you're seeing, is if the reducer has a leak which allows gas to exit it's vacuum connection - Effectively such a leak would cause the engine to run rich at idle and low loads. When the engine is idling high on gas, does the exhaust smell rich?

It is true that if there is a problem with your ICV (idle control valve) these sorts of problems can occur on one fuel more than the other. Also, depending on what type of gas system is fitted, the TPS (throttle position sensor) could cause the same.

Simon
www.Lpgc.co.uk

[NI_Volvo_Nut]

Originally Posted by Lpgc

Would need a bit more info on what LPG system your S60 has fitted, do you know what the system is? Or is this a factory system?

You mentioned water leaking into the gas via a leak in the reducer, possible but very unlikely. If there is such a leak it would be far more likely that gas would leak into the water and presurise the cooling system but you haven't mentioned related issues. Water in the gas wouldn't cause a higher idle, neither would gas in the water, the latter often misinterpreted as a head gasket issue.

A more common type of reducer leak, one which cold potentially cause the kind of symptoms you're seeing, is if the reducer has a leak which allows gas to exit it's vacuum connection - Effectively such a leak would cause the engine to run rich at idle and low loads. When the engine is idling high on gas, does the exhaust smell rich?

It is true that if there is a problem with your ICV (idle control valve) these sorts of problems can occur on one fuel more than the other. Also, depending on what type of gas system is fitted, the TPS (throttle position sensor) could cause the same.

Simon
www.Lpgc.co.uk

Its the factory fitted necam system. I'll try the spare regulator / reducer I have and I'll also clean the throttle body and report back.