Volvo with valvesaver- a real mess!

[John W]

Guys

Quite a long thread setting the scene, so please bear with me!

Recently bought a Volvo V70 (2005) 2.4 petrol with OMVL sequential LPG and valvesaver. It ran fine for a couple of weeks, but one day starting from hot it started to misfire and threw up limp mode and warning lights. Switched it off and restarted and it ran normally. This has continued to happen but is gradually getting worse.
Now I wondered if it was an LPG problem as it hot starts on gas, but when misfiring, switching it to petrol made no difference-ran just as bad.

Anyway, I was asking for advice on the Volvo forums. Apparently the V70 is renowned for problems with the throttle body if it becomes dirty and gummed up, so I figured I had nothing to lose by taking it off and cleaning it up. I removed it to discover that the rear side of the butterfly and the inlet tract behind it were full of slimy, almost silicone type particles-absolutely filthy, black and clear plasticky residue.

I don't yet know if this was my problem as it started raining so I had no time to refit, BUT the valvesaver tube enters the inlet manifold just behind the main butterfly- would it have caused this mess, and if so, is it in the wrong place?

Many thanks for your advice.

[Brian_H]

You generally want the valve saver entering where the air afterwards doesn't need to go upwards to enter the engine - Without knowing what the manifold looks like from here its hard to say, but the advice I was given was to avoid putting it before any low points (some manifolds loop down and back up after the throttle, leaving like a u bend at the bottom, which could fill with lube).

Generally you'd want the lube going in as close as you can get it to the valve inlets as you can get it, its possible to get spiders to feed to multiple cylinders in this state as well to make that easier.

Any idea what rate the lube is being used at, if its a manual system there should be a visible sight glass, this should allow you to see how long it takes for a droplet to form and then be sucked in, if its electronic may be easier to go off how often you have to top it up and how much with, should work out around 1ml to a litre of fuel used if its correctly adjusted.

Hard to say if its the cause, sounds to me like something else is in there as well, Is there any signs of oil in the intake before the butterfly? Which type of lube system is it, and what lube are you using in it?

Also worth noting that some faults can cause gas to leak even when the system is switched back to petrol (leaky injectors or a vapouriser thats leaking via its vacuum port), at least until the pressure in the vapouriser has dissipated. This should be relatively easy to determine if suspected to be the cause by monitoring the pressure with the lpg diagnostics if you have access to them - if its dropping gradually when switched to petrol you know theres a leak, but the first question there really is do you have any access to the petrol obd diagnosics, and what faults are being logged (is it always the same cylinder showing misfires, same pair or all of them or something else?).

[classicswede]

I very much doubt it is being caused by the valve saver.

The throttle body gumming up is common for causing issues and having a bit of gunk in the manifold is nothing unusual. I would give it all a good clean and clean/replace the PCV.

I would check teh vapouriser is not leaking gas into the manifold and also clean the injectors as a starting point.

Is it every hot start that there is a problem? If you switch to petrol before starting does that help?

[John W]

Thanks guys. Unfortunately I don't have LPG diagnostics so at the moment i'm trying as much as I can without.
I cleaned the throttle body and replaced it. No improvement, in fact it seems worse now. Started to become rough whilst driving
and so I pulled over. Revved it a couple of times and the idle speed went mad, up to 2K back to nothing, up to 2K again etc. Just managed to get it home.
The only codes the car is throwing up (I have a basic OBD device) are:

P0507 Idle control RPM higher than expected
P2177 System too lean off idle bank 1

Yes, it is only when the car is hot. Initially it was only on hot starting but yesterday it randomly started whilst driving and wouldnt clear this time-had to limp home.

Does any of this sound like problems with the LPG system, or is it more likely car related do you think?

If it was an LPG problem and I start on petrol and run on petrol, would it disappear?

Many thanks for all your advice!

[Brian_H]

I'd start trying it on petrol and see what happens. It might take a few minutes to burn off excess pressure if it's leaking gas into the manifold, but it would be the first basic trourbleshooting step to take.

[Gilbertd]

Sounds to me that you've shifted some of the crud out of the throttle body and moved it into the idle control valve.

[John W]

I'd start trying it on petrol and see what happens. It might take a few minutes to burn off excess pressure if it's leaking gas into the manifold, but it would be the first basic trourbleshooting step to take.

I tried this yesterday- its exactly the same on petrol and has now got so bad that it's in permanent limp mode. Waiting for my mechanic to have time to look at it. He thinks MAF, oxygen sensor or throttle body.
Thanks for all the advice-at least I think I can now rule out an LPG problem anyway.

[Brian_H]

If it is the idle control valve it might not be too difficult to get at it, just depends whereabouts on the manifold it actually is. Generally most of them don't have any sensors on them to tell what position its in, so if its got stuck it won't usually log any fault codes for it either. Given that it seems to have got worse on cleaning the throttle body it does sound possible. Its also possible that the throttle body is the fault, as if a fly by wire one fails the ecu doesn't have proper control of it (can only assume its fly by wire rather than a manual cable given the year).

If your obd device can see live data you could check the functioning of the oxygen sensor, but if its just a basic code reader it probabbly won't give you enough info to go on (torque used with a phone and bluetooth dongle will do on most stuff, don't know on Volvo though).

[classicswede]

No idle control valve as it is fly by wire.