Bosch VE CSD

[meerkatmag]

Hi, I'm trying to figure out why my 2.5 tdi idle drops when the engine is at very high temp. This only happens when the oil gets up to high 90Cs. If I stop at lights after a long run heavy loaded the oil temp will be high but fine, never seen it get to 100c. The coolant is also fine, sometimes it gets high ish on the dial but nothing crazy. However on stopping the idle drops and the oil pressure therefore drops to alarming levels, sometimes as low as 8psi. Normally it's around 15psi at idle. A tiny bit of throttle will bring the idle up and oil pressure back to normal so I don't think it's oil or oil pump related.

My current idea is it's the bosch VE pump altering timing as it gets hotter, and after a long run the pump gets heat soaked and retards timing causing the low idle.

Does that sound plausible? any other ideas? Or ideas on how to fix it?

[meerkatmag]

in case anyone wants more info on this problem. I noticed that when the tank is empty, the revs drop more at idle (when hot). And then with a full tank it stays pretty much the same. So I turned my attention to fuel pressure, I have an electronic lift pump which is quite old now. So I swapped it out for a Facet Posi Flow 10psi pump. A quick drive and all seems good but I'll need to wait until the fuel is low to fully check it's helped. Maybe with low fuel pressure the pump is having to work hard to pump the fuel from the tank, and getting hot under load.

[97transit2.5D]

hiya...im sick of mechanical lift pumps....can you advise what electric lifty pump to install for a smiley mk5 ,1997 year non turbo???

and where do you mount it and how to get 12 Volts to it and from what place on the wiring harness??

thks

[meerkatmag]

hiya...im sick of mechanical lift pumps....can you advise what electric lifty pump to install for a smiley mk5 ,1997 year non turbo???

and where do you mount it and how to get 12 Volts to it and from what place on the wiring harness??

thks

I have a facet posiflo 7-10psi pump. It's fitted just after the tank. I have it wired, via a relay from the alternator wire. This is only live when engine is running so it doesn't pump endlessly when ignition on. Ive also installed a prime circuit which comes on before start but it's super complex and probably not worth the bother.