Van engine issue

[Rich2484]

Ok. Here goes.

 

Got a Renault b120 with a funny issue.

 

When on tick over it runs perfect, put your foot to the floor and it will hold on the redline for 5-10 seconds, then the revs drop to around 3000 and it will run really lumpy like it's missing. It will then not rev up to red or even off the green turbo band, but back to idle for a few secs and foot down again it will rev up to redline the drop after the time.

 

So first thought, fuel issue, as it sounded like it was missing, removed and checked injectors and I can say I'm 95% happy they are fine.

 

So what's next, fuel I'm steering away from, as it isn't lumpy on tick over and the throttle is very responsive. Can blip it all day long and nothing, it purrs like a kitten. Just trying to get to the top of the revs, it's just drops down.

 

Fuel is getting to the injectors, cleaned it right out. Tank pickup right up to injectors.

 

When the van was brought a few years ago it used to fly, and could really feel the turbo. Over time the power has dropped, it is no where near what it used to be.

 

Air filter is fine. Throttle is fine.

 

But surely if it was fuel pump or injectors it would run rough throughout the range rather than the top end and funny drop.

 

But it's absolutely fine below the turbo band.

 

So is the turbo at fault.

 

Head gasket is fine. No drop in oil or water and no mixing of the two either way.

 

Could it be the pickup for the oil pump. Throwing enough oil up to turbo at first and then dropping out.

 

The exhaust is acting like a miss and puffing.

 

Will answer any more questions best I can.

[treequip]

Have a look at the hoses on the vac side if the system, they can de laminate and restrict air flow which would give the symptoms you describe

[Little Steven]

Gasket on exhaust side leaking, allowing turbo to boost, but no power.

Are you getting lots of smoke?

[mixedangased]

is that the same as the renult traffic ?,if so thats normal its the rev limiter in the ecu.

[Rich2484]

Good point, will check them out. There isn't that many one there and they are easy to get to. One from the intake manifold and the is really easy to get out. There is another.

 

They don't look worn on the outside, but will get a look.

 

It's funny as a few months ago a pipe from the inter cooler came loose and it really run with no power at all.

 

Will check these out. Thanks.

[treequip]

is that the same as the renult traffic ?,if so thats normal its the rev limiter in the ecu.

 

The b120 is old school, I don't think it has an ECU

[Rich2484]

Gasket on exhaust side leaking, allowing turbo to boost, but no power.

Are you getting lots of smoke?

 

No leaks on either exhaust or intake, but there is white smoke. Always has been really until it warms up. But a bit more now.

 

is that the same as the renult traffic ?,if so thats normal its the rev limiter in the ecu.

 

Same as the Renault master or messenger. But it's not the rev limiter, it will rev up to that and hold there but drop right back down. Has only started doing it.

 

And if going up hill with a load like the cm220 it struggles. Revs just drop out. Annoying when pulling up a hill start as it just hasn't got the grunt. And runs very rough.

 

6.5t van by the way.

[gensetsteve]

I would do a search on the net first known common faults and failures. Recently I have found with vans alot of it is design faults. Trying to diagnose with out the help of a laptop can be really hit and miss. It could be as simple as a small vac hose off or blocked exhaust. Is your engine designed to be redlined out of gear ? some have software to cut back the pump if say the turbo starts to run away. The lack of performance may be service related an oil change with filters can work wonders. Check the turbo can be turned by your finger ( not when running ) start with simple things and work forward.

[Rich2484]

I would do a search on the net first known common faults and failures. Recently I have found with vans alot of it is design faults. Trying to diagnose with out the help of a laptop can be really hit and miss. It could be as simple as a small vac hose off or blocked exhaust. Is your engine designed to be redlined out of gear ? some have software to cut back the pump if say the turbo starts to run away. The lack of performance may be service related an oil change with filters can work wonders. Check the turbo can be turned by your finger ( not when running ) start with simple things and work forward.

 

This van tipper is old school as tree quip said. Now laptop confections, the only electrics are standard stuff.

 

It does it in or out of gear, moving or not.

[div_h]

Air flow meter . Any fault codes stored? U don't usually get 1 for the air flow meter but air temp u might. What engine is?