Technical Doom and Loom Ducato egr woes

[Abarthment]

Hiya everyone. Last week I found out for the 1st time in 3½ years that my 2012 3.0 Ducato has a EML light ( it's been brilliant until then).
Anyway plugs it in and P0638 is my code so I started to Google The main consensus is to order a genuine throttle body and that will come with a short loom that I guess makes an updated throttle body comparable with an older vehicle. So I ordered a genuine throttle body and loom from Costal Motorhomes. It arrived super quick and I've fitted both earlier. I cleared the codes and started the van and the EML light came straight on again . I continued for a while to clear the P0638 code with no joy. Could it be that I don't need the short loom I wonder and does anybody know if it would be safe to try the throttle body with out the short loom ?
I hope someone can help as it seems a common fault on the elderly vans like mine.

Cheers for listening

J

 

[jackwhoo]

Speak to coastal motor homes.... they should be able to tell you if have ordered the correct parts and if you need both parts.

 

[Abarthment]

Speak to coastal motor homes.... they should be able to tell you if have ordered the correct parts and if you need both parts.

Thanks , I wasn't sure if they offered technical support so I'll give them a buzz . Thanks

 

[Abarthment]

Thanks , I wasn't sure if they offered technical support so I'll give them a buzz . Thanks

So I phoned Costal Motorhomes earlier and I've been told I need the extra loom. I've fitted a new genuine throttle body and loom and still have a EML light .

Would trying with out the loom do any harm would anyone know or do I risk doing damage ?

Cheers

 

[Anthony489]

Hi

The Throttle Body (TB) is part of the EGR system, and comes into play under light load conditions. By restricting air flow it reduces the pressure in the inlet manifold and encourages the flow of recirculated exhaust gas. It also shuts on engine switch-off to prevent judder.

It would help if you could tell us the manufacturer of the old and new TBs and describe the electrical connector on each and the number of pins. The factory fit changed over the years so its hard to tell if an adaptor cable is needed. What state is the old TB in, i.e. does the flap move with finger pressure, is there a build-up of oil/carbon etc ?

The adaptor cables which I have seen have simply consisted of 3 wires (Power, Ground and PWM control), with a connector one end to mate with the "old" loom (typically 4 pins) and one the other end to suit the "new" TB (typically 6 pins).

If there is a wiring fault to the TB, this could cause the ECU to log a P0638 code.

The early vans had no electrical feedback of TB flap position to the ECU (Even if a feedback potentiometer was incorporated in the TB). So when they throw a P0638 code I think its possible that its because an incorrect TB flap position is being indirectly deduced by the ECU monitoring other engine parameters. This does leave open the possibility that something else is responsible for the fault code, e.g. the manifold pressure sensor. There is nothing I have found published on this, so its just educated guesswork !

If you have multiECUscan, you can activate the TB and watch the position of the flap (you need to have the air hose removed). Alternatively, watch the flap when you switch off the engine - it should shut to starve air and prevent judder, then open again after a pause.

 

[Abarthment]

Evening mate , I'm not sure of the make of the faulty unit that I removed but the new one is an iveco unit as is the new piece of loom . I'll do my best to explain pins. Starting with the van . The original loom has a four pin plug with four wires going into it. The new short loom has a four pin plug with 3 wires at each end. The new genuine iveco throttle body has a four pin socket with four pins in it.

As I mentioned above, if I use the new loom I still have the eml and p0638 code. I'm tempted to try the new unit without the new loom and see what that does but I don't want to risk blowing fuses or melting something .

 

[Anthony489]

Hi again

From what I can glean, Fiat changed from Wahler TBs to Pierburg in about 2009, so your van may not count as "earlier"

It is tempting to just try it without the adaptor cable, and I'm pretty sure that you wouldn't cause any damage, but it's your van, not mine !

I think this is one of those situations where you need the help of a co-operative Fiat dealer, and go armed with your VIN, engine code (e.g. IVECO F1CE3481E 177 PS) and the TB part numbers. This 3 litre engine was also used in IVECO vehicles, plus the Citroen Relay and Peugeot Boxer.They should be able to tell you for certain if the adaptor is needed, as they would be in the same situation if doing the TB replacement for you.

The Fiat/IVECO TB part number is the one to use on the Fiat system, but note that the TB may actually be made by someone like Pierburg or Marelli.