Diesel Revs When It Starts

[richaber]

Ok, the problems with the poor performance continue, but now everytime it fires up it revs to about 2000 rpm before settling to an idle. Any ideas?

[Guest gooner52]

ive had this a bit

 

got told i need new glow plugs

 

but will look more into this first

 

does not do it all the time,just now and then :)

[Guest MATT jr]

does your engine temperature needle work ok?

 

MJR

[Guest neil_wiles]

The common cause for the reving of the engine in a diesel at start up is often air in the diesel and more often that related to the lift pump or injector pipes leaking.

[Guest gooner52]

The common cause for the reving of the engine in a diesel at start up is often air in the diesel and more often that related to the lift pump or injector pipes leaking.

 

 

might it then be my airbox as its a bit naffed,all cracked :lol: :D

 

 

plus the other day my glow plug light sayed on for about 10seconds ,been ok since

[richaber]

Hi, the temp needle works ok I'm sure. I'll check later. Air in the fuel lines??? Where to start looking?? :lol:

[ade]

I had the same problem for about a month then had no *ommph*. Thought Maf sensor was dead, got new one, but still no go and revving at start.

 

Got VAG-COM to work it said there was a mechanical fault with the fuel cut-off valve.

 

Took all the inards out , and the *ommph* returnd for about a day, then same thing, with VAG-COM still saying mechanical fault.

 

Put all the bits back and now 3months later (fingers crossed) everything is working tickaty boo.....even had a gps speed of 115mph....not bad for a 98 tdi 110 gal.

 

Oh just a thought Frauds wanted nearly

[Guest gooner52]

not got any probs with power its fine there

 

done it again tonight only the once

 

:D

[richaber]

I had the same problem for about a month then had no *ommph*. Thought Maf sensor was dead, got new one, but still no go and revving at start.

 

Got VAG-COM to work it said there was a mechanical fault with the fuel cut-off valve.

 

Took all the inards out , and the *ommph* returnd for about a day, then same thing, with VAG-COM still saying mechanical fault.

 

Put all the bits back and now 3months later (fingers crossed) everything is working tickaty boo.....even had a gps speed of 115mph....not bad for a 98 tdi 110 gal.

 

Oh just a thought Frauds wanted nearly

[Brookydave]

Sorry to be a real bearer of bad news, but its often due to the turbo bearings spilling oil into the inlet manifold / intercooler on rundown. What you are doing is burning oil not fuel. Is the revving accompanied by blue smoke?? One of mine got so bad I had to start it in gear to try and dump revs!!!!

[Guest gooner52]

my turbo is fine ,no blue smoke on start up

 

just evry 1 in ten starts revs up 4 about 2 seconds then is ok

 

and with the glow plug light staying on 4 about 8 seconds,seems its something else on mine :D

[richaber]

Sorry to be a real bearer of bad news, but its often due to the turbo bearings spilling oil into the inlet manifold / intercooler on rundown. What you are doing is burning oil not fuel. Is the revving accompanied by blue smoke?? One of mine got so bad I had to start it in gear to try and dump revs!!!!

hmmm, it does start with a cloud of smoke as if it's overfuelling but it could be oil... :D

[richaber]

Sorry to be a real bearer of bad news, but its often due to the turbo bearings spilling oil into the inlet manifold / intercooler on rundown. What you are doing is burning oil not fuel. Is the revving accompanied by blue smoke?? One of mine got so bad I had to start it in gear to try and dump revs!!!!

hmmm, it does start with a cloud of smoke as if it's overfuelling but it could be oil... :wub:

 

It's fixed it's fixed it's fixed.

Excuse the bad form of replying to ones own post. So overnight we

experienced this loss of power. Bloke down the road reckoned he's

plugged in and diagnosed MAF. Changed the MAF, no better. Tested both

MAFs on the car, 4.3 V output at flat out which is correct according

to Pierburgs bumff. Put the old MAf back on. Replaced all the vacuum

tubing associated with the waste gate actuator, no better. Tried

different combinations of valve bypassed, disconnected etc, no better.

Took off the inlet to the turbo and could spin the fan by hand, so

happy it was not siezed. As a last resort was going to remove the stop

solenoid to see if it was restricing the fuel. Couldn't shift the damn

thing, access a bit poor. Gave up and came home for lunch and f**k me

the bloody car went like a rocket... So either we sorted something

while wrestling with the wiring round the injector pump as we tried to

get the stop solenoid out or the vacuum pipe thing worked and it takes

a few runs to get back into the swing of things. Either way, it's

working but am a bit concerned that I don't know what the problem was.

Thanks all of you that responded to my pleas for help.

 

I don't know if this will stop the revving on start up but it hasn't done it yet. There was an oily film in the intake pipework but it was from thecrankcase breather (ie was there upstream of the turbo). So maybe there was a dodgy connection in the injector pump area, or water temp sensor, that is close by.

[Guest gooner52]

glad u got it sorted m8

 

:wub: