Fault code P0638

[tidewatcher]

Management light came on after a very minor misfire that lasted seconds. Got the code read and it is the butterfly regulator, it only happpened after rain and when going over a bumpy part of the road. I fiddled about to see if anything was loose and sprayed with WD40 then started the engine few times. Next morning the light was out for a good few miles, stopped and went for a walk. When I restarted the light was on again but the motor running fine.

So in the camper van in France at the moment, tempted to drive it until either it remains the same and the engine runs fine or it gets worse and there is a definite fault to fix.

Having a bit of a dither as to how serious the problem may develop or just carry on with care. Is this a common problem?

Any experience in this problem would be appreciated.

 

[gus-lopez]

That sounds like the "rusty throttle body" caused by rain(any) water running down & entering the throttle body. Plenty of threads on here about it. If you can dr it out/keep dry should be ok until you get home .Also needs the rain cover to prevent it happening fitted

 

[jerryz]

Its the Throttle valve actuator mine my 2009 fiat did it for 6 months I just reset it ,but eventually it will die and strand you so change it soon the Part is £234 from Coastal Motorhomes,, I did it myself ,its only held in by 4 bolts but they rust into the block i had to drill 2 of them out and re tap the threads ,, job time if no busted bolts 1 hour , with busted bolts 4 hours , but my van now runs sweetly ,
, A fiat dealer will charge you £1200, and independent about £700 plus Vat

 

[tidewatcher]

Its the Throttle valve actuator mine my 2009 fiat did it for 6 months I just reset it ,but eventually it will die and strand you so change it soon the Part is £234 from Coastal Motorhomes,, I did it myself ,its only held in by 4 bolts but they rust into the block i had to drill 2 of them out and re tap the threads ,, job time if no busted bolts 1 hour , with busted bolts 4 hours , but my van now runs sweetly ,
, A fiat dealer will charge you £1200, and independent about £700 plus Vat

Thanks. Just came on for the first time so fingers crossed as in France for four weeks more. Restricting mileage which is no real problem along the dordogne and Gironde area as plenty to see. Does take the edge of the enjoyment though.

 

[tidewatcher]

OK so hobsons choice really. Drive it and keep mileage down to a sensible level ( Pyrenees binned for this trip) and if it does get worse bite the bullet and find a local repairer. Have breakdown cover if it does gasp it’s last to get us to a repairer. Luckily in the wine region….

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[gus-lopez]

Or spray all around it with wd40 regularly, then spray the 4 bolts daily with penetrating oil to ensure they will come out when you want

 

[Landy Andy]

Just keep doing what ever you want, and deal with it, when or if t happens.

 

[tidewatcher]

did some wire wiggling the a good dose of WD40 around the area and light didn’t come on this morning. First start of engine after turning off with light on. Didn’t do the five or so restarts. I think it’s little electronic brain is messing with me.

 

[tidewatcher]

And the latest is… got the van home from France though it was not a relaxing journey. Light came on again and some misfiring. Have now removed the throttle body, the butterfly is free and no signs of sticking. There does not seem to be any water ingress into the actuator area, however there is a big build up of soot in the body itself and also the inlet manifold below it. So, how to test the actuator, why is there such a build up of sooty deposits?

 

[Jimbohorlicks]

Some info here if it helps

https://www.aulro.com/afvb/the-verandah/276914-what-causes-inlet-manifold-deposits-how-do-you-avoid-them.html

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[Landy Andy]

And the latest is… got the van home from France though it was not a relaxing journey. Light came on again and some misfiring. Have now removed the throttle body, the butterfly is free and no signs of sticking. There does not seem to be any water ingress into the actuator area, however there is a big build up of soot in the body itself and also the inlet manifold below it. So, how to test the actuator, why is there such a build up of sooty deposits?

The reason you have all that soot in there is to save the world apparently. You have a connection between the very dirty exhaust to the “clean air” intake of the engine. The great design/idea of an EGR valve.

The soot also will have covered your MAP sensor which you can now get to as you’ve got the TB off.

Whilst the TB is off put a tight sealed pipe up the EGR cooler exit, and see if you can blow through it. This will let you know if it is stuck open, then by fiddling with the EGR valve, test if it opens. You may well find it stuck open. Hence your problems.