Hiya,

I posted a while ago about my occasional  overboost problem on a 2010 focus 1.6tdci 109. Ive been getting an occasional overboost code at fairly high revs and little load. I don’t get it for instance pulling up a long hill on the motorway….

I thought I’d try some turbo cleaner through a full tank of fuel….I’ve been down to Kent this week circa 500miles all 70ish mph getting everything I expect nice and hot and other than driving in a way to not rev high in low load situations its behaved lovely.

Until….I got off the A1 last night almost home after 3 hours steady 70, approx a mile off the A1 i was approaching a roundabout and thought I’d drop a few gears and give it a boot full…

almost instantly got the light and beeping etc and it almost cut out. Never happened before the overboost always just tends to in effect turn off the turbo. The code I got was ref EGR stuck P042F

SO is it reasonable to suggestfirstly the two errors are not connected i.e. an EGR fault can’t cause overboost and vice versa

AND that its quite possible the bottle of Wynns if it does work at all has likely had a similar cleaning effect on my EGR as is intended for the turbo? And quite possible I’ve given it a boot full for the first time in 3 hours and it took a big deep breath which may have dislodged a whole load of gunk and stuck the EGR up a bit?

It wobbled a little this morning but with a mile or so of mid range and working the engine it seems ok currently.EGR is comingnoff for a clean today anyway but was trying to determine in my own mind if my overboost pre existing issue was or wasn’t linked.

Thanks

 

Were there no clues in the Freeze Frame data.

I suppose that if the EGR was sticking then the MAP would not be what the PCM was expecting and there is no direct feedback for EGR flow in these engines.

It would be a good idea to monitor Live Data and try to induce the fault. The max MAP should be around 240Kpa but only briefly. 

 

Whatever it is the egr fault seems to not want to come back currently. But my overboost is still there, around the 3.5k rpm mark low ish load like hard acceleration in 1st/2nd

Will have an investigate on the actuator/linkage etc….

5 hours ago, bantam_dave21 said:

But my overboost is still there, around the 3.5k rpm mark low ish load like hard accele

That is when there should be maximum boost, which is why I was wondering how high the boost was getting when it threw a fault code.

I'm still of the opinion that if you Live Monitor the MAP, MAF, Turbo and EGR there may be some clues. 

try a 50 50 water methanol decoke = mist in fairly large quantities the other side of the air filter on a warm running engine - blip the throttle to get the swirl flaps / wastegate / variable geometry / EGR to move

did on a merc tractor 3 litres in 20mins - 15 mins in to the process all the crap came out and its never run better since

don't get that ***** on the wiper blades

On 2/26/2022 at 5:50 PM, Tizer said:

That is when there should be maximum boost, which is why I was wondering how high the boost was getting when it threw a fault code.

I'm still of the opinion that if you Live Monitor the MAP, MAF, Turbo and EGR there may be some clues. 

Thanks Tizer

I'll have a run out at the weekend with ForScan and see what it throws up. I've brought my laptop but not my forscan lead.

I had my cheap code reader plugged in at the weekend when it was behaving itself and was very slow in responding and was around 260kpa and hadn't gone into fault. But as I say there was a huge latency.

Will try ForScan and report back. In the meantime I'll go away and try and work out/understand the relationship between MAP, MAF etc (when I gave up working on motors as my main job MAF were only just getting fitted to diesels - so all a bit foreign to me currently.

18 hours ago, Botus said:

try a 50 50 water methanol decoke = mist in fairly large quantities the other side of the air filter on a warm running engine - blip the throttle to get the swirl flaps / wastegate / variable geometry / EGR to move

did on a merc tractor 3 litres in 20mins - 15 mins in to the process all the crap came out and its never run better since

don't get that ***** on the wiper blades

Is this the DIY version of the these carbon clean mobile people that are doing the rounds?

3 hours ago, bantam_dave21 said:

I had my cheap code reader plugged in at the weekend when it was behaving itself and was very slow in responding and was around 260kpa and hadn't gone into fault. But as I say there was a huge latency.

I don't know what the trigger point is for a fault code but 260 is a little bit higher than I thought. It may be that the trigger point needs to be exceeded for a number of seconds and/or more than once per driving cycle, a lot of fault codes are like that.

If it wasn't for EGR and temperature effects on pressure then the MAF should graph out the same as the MAP, there is no Throttle to confuse things. 

If it is a pure mechanical problem then sticking Turbo Vanes are the most likely reason or a fault with the Actuator. Maybe the last owner change the Turbo or mucked about with the Actuator.

55 minutes ago, Tizer said:

If it wasn't for EGR and temperature effects on pressure then the MAF should graph out the same as the MAP, there is no Throttle to confuse things. 

This is what I'm trying to understand - can a EGR issue cause a higher than expect pressure? i.e. from too much exhaust gas entering the manifold? I'm clearly having EGR issues so am likely to swap that anyway the cost if I'm seeing the right ones is not too terrible vs the time and mess of cleaning it out - assuming of course its not a unit fault rather than gummed up. Cheaper than replacing the turbo. I'm fine with the issue and I just drive it so as to not make the fault occur. But in the coming weeks it will become the mrs's car and if it happened to her she'd not cope and pure stress from that point forward....

3 hours ago, bantam_dave21 said:

4 hours ago, Tizer said:

 

This is what I'm trying to understand - can a EGR issue cause a higher than expect pressure?

I don't know the answer to that. 

1 hour ago, Tizer said:

I don't know the answer to that. 

maybe I might by the end of this lol

On 2/28/2022 at 8:26 AM, bantam_dave21 said:

Is this the DIY version of the these carbon clean mobile people that are doing the rounds?

not sure I expect they use posher stuff but its 120 quid - a 5 ltr bottle of methanol is 5 to 10 quid - great degreaser for other stuff too

On 2/28/2022 at 1:17 PM, bantam_dave21 said:

This is what I'm trying to understand - can a EGR issue cause a higher than expect pressure? i.e. from too much exhaust gas entering the manifold? I'm clearly having EGR issues so am likely to swap that anyway the cost if I'm seeing the right ones is not too terrible vs the time and mess of cleaning it out - assuming of course its not a unit fault rather than gummed up. Cheaper than replacing the turbo. I'm fine with the issue and I just drive it so as to not make the fault occur. But in the coming weeks it will become the mrs's car and if it happened to her she'd not cope and pure stress from that point forward....

if its all gummed up, blocked up and misbehaving anything is possible - the EGR valve can burn itself out trying - as can turbo actuator on VGT ones