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[theolodian]

I still think they're right about the fuel filter/fuel pressure.  If not cats, that's where I'd look next.  Plus only costs a tenner for the filter.

[Rock]

Ok, we have more news this morning.

Fuel filter is going to be replaced, but the fault seems to be electrical.

1) If the dbw throttle is unplugged, and the car started, then the car will sit and idle quite happily for as long as you like and sounds fine. No missing etc.
2) Plug the throttle back in while its running and it dies immediately.
3) If the fault codes are cleared it seems to run like a bag of bones until they are stored again. Then next time of running, and thereafter, it seems to run ok again.
4) Manual opening of the throttle does not increase revs, but garage man believes that might be because other parts of the system are not expecting it to be opened??

The garage are wanting to replace the throttle body assy. as they say they have tested the connector / wiring. This is a non returnable part so if they go ahead and order it and it makes no improvement then its still going to cost me nearly £300.

Can anyone help me and tell me if you run the car with the throttle unplugged, and plug it back in, does it still run? Also, if you manually open throttle with it unplugged, does it increase rpm??

I would REALLY appreciate your help on this one.

[TheBoy]

Ok, we have more news this morning.

Fuel filter is going to be replaced, but the fault seems to be electrical.

1) If the dbw throttle is unplugged, and the car started, then the car will sit and idle quite happily for as long as you like and sounds fine. No missing etc.
2) Plug the throttle back in while its running and it dies immediately.
3) If the fault codes are cleared it seems to run like a bag of bones until they are stored again. Then next time of running, and thereafter, it seems to run ok again.
4) Manual opening of the throttle does not increase revs, but garage man believes that might be because other parts of the system are not expecting it to be opened??

The garage are wanting to replace the throttle body assy. as they say they have tested the connector / wiring. This is a non returnable part so if they go ahead and order it and it makes no improvement then its still going to cost me nearly £300.

Can anyone help me and tell me if you run the car with the throttle unplugged, and plug it back in, does it still run? Also, if you manually open throttle with it unplugged, does it increase rpm??

I would REALLY appreciate your help on this one.

Soz, can't test mine as its not DBW like yours

Are the electrical bits (servo and pot) available as seperate part?  Can they do a live data test on throttle position and movement?

[Rock]

They have borrowed a proper tech2 and have tried to control throttle through this but are unable to?

Apparently its only available as an assembly.

[theolodian]

You can really get into an expensive wild goose chase here.  What is critical is if the alignment process is successful.  There should be error codes if not.  However, if the alignment is not successful there is more than just the TB that may be the cause.

If at all possible try to borrow used parts to prove what is wrong.  I had a similar problem once on a DBW car.  Borrowed a TB, it helped me find the problem but the TB was fine.

[Rock]

What do you mean by alignment process?

I realise the whole wild goose chase can get expensive, but i don't know anywhere i can borrow a TB from and its a factory order item with Vx apparently.

I was hoping someone on here with a 2.6 or 3.2 might be able to unplug their dbw throttle and see if the behaviour i described was normal.

Should Tech2 be able to control the throttle?

[theolodian]

Every time the ECU loses power, and maybe if you unplug the TB, the ECU has to go through an alignment process where it learns the motion range of the TB.  This usually happens automatically if you turn the ignition on without starting the car and leave it for 3-5mins.  You must not touch the accelerator pedal during this process.  If you listen carefully you can hear the TB clicking back and forth.  When it is done you can start the car.  If this isn't done correctly then you may need to clear error codes before it will do it properly.

What is critical is the error codes in the ECU.  Also, I'm surprised it runs with the TB unplugged.  Never tried it though, and don't suggest people try it.  Could cause problems that might require use of a Tech2 to resolve.  A Tech2 should be able to go through a diagnostics process where it moves the TB through the full range, but I have never used a Tech2 so can't say for sure.  However, something like the alignment could keep that diagnostics from working.

[TheBoy]

Should Tech2 be able to control the throttle?

I believe so...   ...not having dbw, i cannot 100% confirm

[Taxi_Driver]

Ok....from how i see it.....garage is diagnosing throttle body fault.....now this is the same part you took apart for cleaning.....so is there any chance that you have somehow not put it back on correctly??

Does the garage know you've had it apart for cleaning?

A new throttle body may cure it.....but taking the old one off and reassembling again may do the job as well.

I would have thought too that a tech2 should be able to control throttle......i read that a tech2 can do a compression test on the cylinders.....so if it can do that....controlling the throttle should be a doddle for it. (in my can i justify buying a tech2 or shud i buy another cheapo 'techy2 type' lead)

[Rock]

Ok....from how i see it.....garage is diagnosing throttle body fault.....now this is the same part you took apart for cleaning.....so is there any chance that you have somehow not put it back on correctly??

Does the garage know you've had it apart for cleaning?

A new throttle body may cure it.....but taking the old one off and reassembling again may do the job as well.

I would have thought too that a tech2 should be able to control throttle......i read that a tech2 can do a compression test on the cylinders.....so if it can do that....controlling the throttle should be a doddle for it. (in my can i justify buying a tech2 or shud i buy another cheapo 'techy2 type' lead)

I guess it is possible i didn't do something right when i took it off and put it back. Yes i told the garage EVERYTHING and they have had it off and replaced it but no improvement.

I have now told them to go ahead and get a new throttle body so we'll find out in the morning if thats what was causing the problem...

[TheBoy]

i read that a tech2 can do a compression test on the cylinders

 

Now that would be impressive. But I suspect it can't  :-?

[Taxi_Driver]

i read that a tech2 can do a compression test on the cylinders

 

Now that would be impressive. But I suspect it can't  :-?

Apparantly it can.....ive read up a bit on tech2....to see i can justify buying one  :-/
You can put in a mode where it increases the idle revs (hence why i said in earlier post i should be easy for it to control the idle revs) to about 1000rpm iirc then it shuts offs one injection valve at a time....and revs should drop by 100rpm on each cylinder it does it on, if compression is ok (think this might have been for a v6 tho  :-/ )....i remember from what i read that revs might drop by another 50rpm if cooling fan cuts in......this reading came from a prog that i dont have  

[TheBoy]

i read that a tech2 can do a compression test on the cylinders

 

Now that would be impressive. But I suspect it can't  :-?

Apparantly it can.....ive read up a bit on tech2....to see i can justify buying one  :-/
You can put in a mode where it increases the idle revs (hence why i said in earlier post i should be easy for it to control the idle revs) to about 1000rpm iirc then it shuts offs one injection valve at a time....and revs should drop by 100rpm on each cylinder it does it on, if compression is ok (think this might have been for a v6 tho  :-/ )....i remember from what i read that revs might drop by another 50rpm if cooling fan cuts in......this reading came from a prog that i dont have  

Ah, right, so can't tell you compression, but hints that compression is OK?

If you are thinking of getting one, you need more than Tech2.  To authorise it to do certain stuff, you need a valid subscription to TIS complete with valid Vx registered dongle.  For your Veccy-C, you also will need a CANdi lead...

[Rock]

If you are thinking of getting one, you need more than Tech2.  To authorise it to do certain stuff, you need a valid subscription to TIS complete with valid Vx registered dongle.  For your Veccy-C, you also will need a CANdi lead...

How much would all of that lot set someone back?

[TheBoy]

If you are thinking of getting one, you need more than Tech2.  To authorise it to do certain stuff, you need a valid subscription to TIS complete with valid Vx registered dongle.  For your Veccy-C, you also will need a CANdi lead...

How much would all of that lot set someone back?

You really do not want to know....