Hi all I’m still trying to fix faults on my Skoda scout 2010 model with BMM engine.

 

car drives great but within a few miles glow plug light comes on. Read codes I get glow plug open circuit 1,2,3 and 4.

ive replaced all the glow plugs have no starting issues. It didn’t always put this fault into the fault code memory it’s a bit intermittent.

ciukd any one tell me how to check the glow plug relay/ controller. Also how to check and if nesasary replace the glow plug wiring loom.

 

the other 2 faults that get stored in the memory are maf implausible signal.

egr excessive air flow.

 

if I clear it will drive ok for 10 mins then logs the same codes again glow plug and elm light come on.

 

i would like to try to diagnose and repair in the right order.

 

should I repair the glow plug loom relay issue first.

 

then I would like to test the wiring and plug off the loom to the maf sensor.

to make sure it’s good .

Does anyone know how I do this thanks.

lastly if I repair fix the maf sensor or wiring issue might this sort the egr excessive airflow fault . It has had a new genuine Skoda egr valve. Does the Egr operate from information given to the ecu from the maf sensor anything else I should be checking ?

map sensor ?

Thats it I really wanted to get it running Properly as it’s a great car👍😂

no really it is .

 

any help guidance greatly appreciated.

i forgot to say the symptoms when fault happens is between 2000-3000rpm when accelerating up the gears you feel a momentary hesitation for a 2nd or two as the revs rise as the Rev needle goes from 2-3k you might feel it 3 time as it pulls through the Rev range.

 

 Thanks in advance.

ps I have Vcds but I’m still Learning how to use it fully. But if I can does some tests with it happy to try with a bit of guidance 

 

thanks

 

simon

Check that engine bay fuse number 27 (50 amps) for the glowplug module is intact, and not loose in its contacts.

 

There are separate output pins/wires from the module for each glowplug, so it seems improbable that all of the wires have broken.

Two thin control wires to the engine ECU could be worth continuity checking end to end. Pin 10 on module to 30 on ECU, pin 9 to ECU pin 63.

 

After that, if no contact corrosion at the module connector, substitute another glowplug module in and see if those faults vanish.

 

The modules are solid state, with no relay contacts to wear out, so a secondhand/scrappie one ought to be worth a try rather than spending on new.

 

 

Nice one that gives me something to work through.

ill sort this first then see what happens.

regarding the egr excessive air flow and maf implausible signal intermittent .

 Thanks for the reply I’m having a full day on it tomorrow. Can anyone tell how to check the maf using vcds

 

thanks again 👍

On 21/09/2021 at 17:02, Vstorm said:

Nice one that gives me something to work through.

ill sort this first then see what happens.

regarding the egr excessive air flow and maf implausible signal intermittent .

 Thanks for the reply I’m having a full day on it tomorrow. Can anyone tell how to check the maf using vcds

 

thanks again 👍

 

Anyone watching this post I thought I would share the final fix .

i checked all the glow plug wring pinged it out to relay holder,fuse box power supply and all way back to Ecu all good fitted new . Relay still same.

moved on fitted new maf sensor readings 550 mg/str but static dosnt move when engine revved.

scratched head some more thought new one might be faulty. So got another reading still same 550 !

so now thinking wiring to maf .

stumbled across some info saying that fuse 29 drivers side fuse box below a post powers the maf.

checked fuse 28. No fuse fitted wtf 😂🤷‍♂️

Fitted 10amp fuse cleared egr excess flow, glow plug open circuit,and maf implausible signal faulty codes just done extensive road test no faults present all good . Now I have a 2 nd fault not logging codes slight stutter on boost I have graphed it and can see boost drop off I have s high pitch squeal when this happens I think I have a leaking gasket on the pressure side but car now is otherwise spot on.

hope this helps someone else .

 

 Thanks for the help from the people that replied 😂👍

Interesting. That fuse also powers a thing called "N79 Heating resistor for crankcase ventilation" on some cars (wiring diagram says "* only on vehicles with optional equipment").

Those heaters have been known to fail short circuit and blow their fuse.

 

I wonder if someone in the past has removed this fuse to stop it blowing without realising it also powers the MAF?

 

Keep an eye on it and find and unplug that heater if the fuse blows again.  It has yellow/red and brown wires going to it, not sure of location though, or what optional equipment leads to it being fitted.

Will do it seems that the maf has is interconnected wither the glow plug relay and as there was no power to the maf it was seeing it as open circuits for glow plugs I guess it must take an air temp reading to now when to turn glow plugs on and off maybe?

also I think the egr excess flow was caused by incorrect signal from maf tone I then ecu to egr opening and closing based on the information the maf wasn’t giving accurately.

so the MAFs signals seem to effect quite a few systems if it’s sending wrong /corrupt readings to the ecu.

this in turn requests or give wrong info to other components .

wish I’d have spotted the missing fuse first 😂 

might not have needed the relay.

since fitting the maf all the egr readings and maf reading are spot on 👍

Just now, Vstorm said:

I guess it must take an air temp reading to now when to turn glow plugs on and off maybe?

Good thinking. That may well be right.

 

1 minute ago, Vstorm said:

also I think the egr excess flow was caused by incorrect signal from maf

Yep.