Intermittent loss of acceleration?????

Hi All, I hope someone can help. Its the first time i have had a problem with the engine, the rest of the bodywork has been falling off around it regularly! Its a 300tdi that will start and run ok, then when i stop and go to pull away it sometimes will not rev. If i blip the throttle for a few seconds it will eventually pick up with a big plume of black smoke and then clears and goes ok. If i turn the ignition off when it does this and restart it, its ok!
I have searched but havn't found anything the same, apart from a potentiometer thread but can't find one and don't think its on a deisel.
Any ideas would be greatfully received.
Regards Gary.

is it a manual or auto?

so it's edc pump then ?

I'd start by checking all the air intake pipes, to turbo, from turbo to intercooler and back from intercooler to pump. Take them off, look for sludge inside, there will be some, but shouldn't be dripping, clean them all and check the inside of the tubes for de-laminations, bits of tube that are falling down and blocking the airflow.

I'd maybe also check the fuel pump, but the black smoke suggests plenty fuel available ..

Hi Thanks for replies, its a manual by the way with the vacuum pump. I wouldn't think its the pump as the black smoke suggests plenty of fuel, but will clean out all the pipes for the air flow and turbo, thanks for that. Will also clean up electrical connections to the air meter and throttle control valve. Hopefully its just crap or blockage!!

Hi All, Just tried the old girl after cleaning all the electrical connections and turbo pipes, but still buggering about on occasions when you slow down and the revs drop to idle, it occasionally won't pick up. I have looked at the throttle control sensor on the top of the fuel injection pump, considering turning it against the throttle direction to confuse it in thinking the throttle is open more! Idea thought of as when i drive it and keep the revs up around 1500-2000rpm (breaking with left foot after coasting to stop) it dosn't have a problem!
Has anybody done this or think this would be a problem????

Fuel pipes under the lid in the boot floor? Rusty?
Had similar but more severe problems on my -98 300 auto when i bought it..hence the good price..
Turned out to be a microscopic rust hole on the fuel pipe causing the lift pump to suck air into it..keeping the revs up helped as the the lift pump delivered more fuel then the engine needed but on idle, at red lights etc. the engine would cough and stall..
according to the guy i bought it from it started of with symptoms similar to yours, sorting after ignition off/on, and then got worse.
I sorted it with a good go with a silicone gun and eventually changed the sender unit..
//M

busagsx1300 said:

Hi Thanks for replies, its a manual by the way with the vacuum pump. I wouldn't think its the pump as the black smoke suggests plenty of fuel, but will clean out all the pipes for the air flow and turbo, thanks for that. Will also clean up electrical connections to the air meter and throttle control valve. Hopefully its just crap or blockage!!

Click to expand...

If it's an original manual gearbox it will be non-EDC so no airflow meter and no fly-by-wire throttle, so no throttle control valve.

It's a manual pump no ECU and the electronic control on top of the pump is only for the EGR valve.

it could be duff injectors.

Thanks for more suggestions, will go through the fuel lines and lift pump this weekend and see about checking the injectors if thats possible? Dont really want to throw to much money at it as looking at a series 2 lwb this weekend. Would prefer to throw the money at that to get it on the road if its going to be a good one to start with, Catch 22 as could have needed the disco today to save getting soaking wet on my motorbike in the torrential rain!
Many thanks for the replies, hopefully be able to sort the old girl out.

Still not fixed but found the problem!
Fitted new lift pump as i had one and checked fuel pipes, all ok.
Started jumping out and lifting the bonnet when it played up and found the top hose from the intercooler was collapsing!
I expect i have a breather or blockage somewhere? There is oil in the intercooler but not excessive, so the seals have probably worn on the turbo i guess?
But does anybody know why the hose would collapse?
I will replace it as it has now got weak, but would have thought it was something else causing it?
Help greatfully received.

busagsx1300 said:

Still not fixed but found the problem!
Fitted new lift pump as i had one and checked fuel pipes, all ok.
Started jumping out and lifting the bonnet when it played up and found the top hose from the intercooler was collapsing!
I expect i have a breather or blockage somewhere? There is oil in the intercooler but not excessive, so the seals have probably worn on the turbo i guess?
But does anybody know why the hose would collapse?
I will replace it as it has now got weak, but would have thought it was something else causing it?
Help greatfully received.

Click to expand...

The top hose is collapsing because there is a blockage somewhere between it and the turbo, most probably in the rubber elbow at the base of the turbo.

What happens is this hose delaminates internally, but when the engine is running, the inlet manifold is sucking like mad and collapses the top hose.

My advice? Replace both hoses.

Many thanks The Big Lad, will be replacing both, getting on Flea Bay now to order up!

busagsx1300 said:

Still not fixed but found the problem!
Fitted new lift pump as i had one and checked fuel pipes, all ok.
Started jumping out and lifting the bonnet when it played up and found the top hose from the intercooler was collapsing!
I expect i have a breather or blockage somewhere? There is oil in the intercooler but not excessive, so the seals have probably worn on the turbo i guess?
But does anybody know why the hose would collapse?
I will replace it as it has now got weak, but would have thought it was something else causing it?
Help greatfully received.

Click to expand...

See post #4 ...

Hi Paul, i did check the hoses and they dont look delaminated inside, but did feel a little soft.
The top hose was a replacement with a de-EGR kit i purchased not too long ago, so it hasn't lasted long!
But hope this is the only problem, will find out when i receive the hose kit i ordered and get it fitted.
Thanks for the help.

Hooray, All sorted with the replacement turbo pipes, She rattles and runs like before!
Thanks for all the help, will get on with my 2" lift now!