Erratic throttle on acceleration

[Iceman]

Ok folks a new problem has reared its ugly mug with the D40...
When accelerating up through 2 - 3krpm the throttle starts to surge. Its like im pumping the gas pedel. If i give it a bootfull it will sometimes go into limp mode. Started with a computer reset which helped for about 80k but then came back.
On my list of suspects:

Fuel filter blockage
Suction control valve
Boost controller
Aliens

Anyone else had a similar issue and how did you sort it?

 

[Old.Tony]

I'm thinking aliens too, but just in case it's not, try loosening the fuel cap and see if it changes anything. If it does, it's most likely the SCV - give it a clean.

If you can hold the engine smoothly up a hill at 3500rpm it won't be a filter blockage. If you can accelerate mildly (2500rpm tops) to 80km/h and then have it go limp by planting your foot to the floor it's your SCV.

Boost controller will probably be causing black smoke to appear more than usual and power to be down.

So yeah, aliens. Probably flying the Solar Constellation Vehicle.

 

[Iceman]

Thanks Tony that pretty much sums it up so SCV clean time this weekend. Woohoo...
BTW no black smoke, no smoke at all in fact but it does have a DPF so guess at least that works!
It will hold revs up a hill but the surging gets worse and makes me feel sea sick if i dont back off. Will have a search of forum and see if i can find what to do with SCV, other than throw it away :/

 

[Old.Tony]

Clean it, reinstall it. I've heard one person use turps to do it (success), you could use petrol too, but be sure that you give it a bath in diesel before you reinstall it.

 

[Iceman]

Removed the SCV today for a clean. What a prick of a thing to get at! Once it was out i squirted it full of electrical non residue cleaner while working the plunger in and out a few times. I didnt wet it with deisel before re install so hope that wont cause an issue. I couldnt see any crud in it but you never know. Also reset the ECU and cleaned up all the earth points as well as the connections to the ECU. Only driven a few km since but so far seems alot smoother and alot less knocking at around 2,500rpm. Guess we will see how it goes.

 

[Iceman]

Well! What a difference!!! Drives like a new one. Surging is gone, engine is way smoother and quiet. Turbo lag is nill. I think the real culprit was the earth from the ECU. Did 300 km today with the new shocks in and the ride is excellent now. It doesn't try and fling itself off the road at every bump. Mental note... Stock shocks are ****!