hdi 90 misfire lumpy idle

[adam03031980]

hi all started car this morning and was its usual slow self however after stopping at my destination 10 miles away it was very lumpy but got better as i revved it anyway after i drove home with the problem still there i disconnected the battery and left it for while, upon reconnecting the problem went away any ideas what it could be

[rwb]

All that springs to mind from what I've read on here is MAF sensor.

Ideally, get your fault codes read...

[Welly]

The MAF sensor on the 90bhp doesn't really do much other than to check the egr function I believe.

Maybe just a glitch, could be system voltage low perhaps causing a duff injector (they need 80 volts to run) you could maybe check the injector wiring/harness/connectors for chafing or tightness (with the ignition off!!). It doesn't hurt at this time of year to go around all the engine earths and battery earth and give them a squirt of WD40 etc.

[piglet]

Adam, have you got Siemens or Bosch injection?

[adam03031980]

Hi i have a siemens system seems to be running ok but when the cold weather cam at like -6 thats when the trouble started i only replaced the glow plugs in january

[piglet]

Join the 'Siemens smooth running fault' club.
What's it like at 1500 rpm? ie 30mph. Mine is fine at tickover so might be unrelated.
How can we measure injector voltage given that it will be pulsing?

[adam03031980]

tell me about it i wish i had my 110 as that was a bosch system and never played up i think having a tank pump help a lot i also find the starter slows down in the winter

[adam03031980]

i did a leak off and that was fine im pretty sure its electrical but where i dont know ive read it could be in the injection ecu but tbh i could spend so much but dont want to i keep meaning to take the earths off and clean them up

[Doggy]

I know yours is a Siemens and so will have a different ecu, but on mine disconecting an injector brought up an immediate EML / Antipollution Fault.

PP2000 can display the injector supply voltages, (at least on a Bosch ecu), these are generated internally and don't have access for external testing AFAIK.

Planet's your best bet - be happy to take a look for you if you want.

[Blubayou]

Hi there,

Mine is Siemens too, as Piglet says, it's not the best.

Mine shudders at 1500rpm when cold, has always had odd flat spots and always has air in the feed pipe at the filter. Giving it a good aggressive pump on the hand bulb with the engine running always seems to make it run better for a while.

On the plus side, after 30'000 miles it's shuddered, misfired, surged but never actually stopped!

[Blubayou]

Sorry, just remembered why I posted,

I seem to remember the MAF output is only used for acceleration not steady state conditions. I may be wrong tho....

[rwb]

...always has air in the feed pipe at the filter

Siemens 90 here with bubbles in the clear tubes to the filter too. Been like that for years

The MAF sensor on the 90bhp doesn't really do much other than to check the egr function I believe.

Isn't it used as part of the fuelling calculation?
I believe with the MAF, if you pull the connector you can expect to notice a big difference. If you don't then it's a likely cause of the problem. (By the way, the coupe club spotted some well priced MAF sensors.)

(EGR might be something to disable on the off-chance. Just pull and bung the vac supply -- assuming that the valve isn't stuck open. Mine's a bitch to drive when the EGR is open: lumpy and hesitant.)

Any fault codes?

[piglet]

Deja vu
I gave up hunting for a ghost fault and just drive round it, but it's a pig sometimes.
Best result was a good hard blat to the alps & back in feb. This would imply that it's at least partly related to sooting up,
I bought a can of EGR cleaner but havent got round to it.
My hunch is there's an underlying EMU issue, I don't hear any Bosch owners complaining.

[adam03031980]

I tried the egr cleaner but to no avail and made A really loud and worrying diesel knock the injectors are VERY rattlly compared to the old bosh system as well i had, which i feel could be the air in the pipes as it eventually goes away. Strangely she fired straight up probably because it has got warmer i dont know wether the battery is too weak as my mates 90bhp 306 hdi has a massive battery compared to mine

[lozz]

The Diesel knock with use of Egr cleaner is normal,

it wont do any harm to a Derv engine as long as you stick to 3-4 secounds blasts of the egr cleaner going in,