Stanky's Car Fixing Thread - Looming MOTs and a day out 06/06

[hairnet]

all german cars are r........etc etc

 

[Stanky]

Engine. 5 codes:

P2042 - throttle control valve

P200a - throttle potentiometer

P2001 - throttle potentiometer

P2035 - ECU

P203b - rear lambda sensor

Instrument - 3 codes

B110d - aac push button canbus intermittent

B1119 - ahe trailer recognition intermittent

B1121 - head unit control intermittent

ESP- 2 codes

C1174 steering angle sensor not initialised

C1024 - can communication with engine faulty

Sam - 6 codes...

[Stanky]

Fucking hell...

Right let's clear some and see what comes back

[SiC]

20 minutes ago, Stanky said:

P2042 - throttle control valve

P200a - throttle potentiometer

P2001 - throttle potentiometer

 

My money is on this!

59 minutes ago, SiC said:

I don't know about Merc but on Renault, critical throttle body faults (iirc pedal faults too) make the engine rev between 2k and 3k.

Most of those other modules codes because the ECU has gone into major limp mode and stopped talking to the rest of the car. 

[SiC]

27 minutes ago, Stanky said:

RUDE 🤣🤣🤣

If I'd known, with those symptoms I'd have suggested disconnecting and reconnecting the throttle body connector to see if that fixed it enough to get home! I was on the train at the time and was staring out the window for a change rather than on AS 😂

[Stanky]

Ok been out for a drive, 20 - 60mph and it's fine, no faults at all. Got up to temp fine, ran perfectly. 

WTF

[SiC]

 

[Stanky]

Cant get rid of these. 

Instantly come back. All other codes are cleared and have stayed off. Doesn't trigger anything on my test drive, all seems fine

[Stanky]

9 minutes ago, SiC said:

 

Thanks, that's exactly what happened earlier. Will go and Google fixes. I assume new throttle body? Odd how it fixed itself though?

[SiC]

19 minutes ago, Stanky said:

Odd how it fixed itself though?

Possibly dodgy/dirty connector. Which would explain how it fixed itself.

Also they are resistive tracks which have a wiper on them. They can wear out at particular points - especially idle where they spend a lot of their life sitting around (and hunting on that bit).

[Stanky]

I'll clean the connector, but possibly new throttle body time do we think?

Incidentally, I don't seem to have much luck with throttle bodies generally. I had a Mk3 golf which would only idle when hot due to the engine temp sensor not telling the TB it was cold. I had a skoda felicia which had an overtightened throttle cable and would idle at silly high RPM and wouldn't pass emissions at the MOT, then I had the issues with the ICVs on the daihatsu! so on that basis maybe I'll just replace it anyway!

[Rust Collector]

For the steering angle sensor, have you reset it by turning the steering wheel lock to lock after restarting the car? I alway forget to do that on the E class when I do anything on it and then shit myself when I get the ESP fault afterwards.

[Stanky]

20 minutes ago, Rust Collector said:

For the steering angle sensor, have you reset it by turning the steering wheel lock to lock after restarting the car? I alway forget to do that on the E class when I do anything on it and then shit myself when I get the ESP fault afterwards.

Thanks, yes that's a 'normal' code and easily reset! 

[SiC]

1 hour ago, Stanky said:

I'll clean the connector, but possibly new throttle body time do we think?

Possibly! Inspect the connector first to see if that is an obvious fault to root cause it. If this car must be up most reliable without question, then I'd throw another known good on it personally 

Of course could be the ECU connector side or even the wiring. But throwing a TB at it should mark the TB off the list. 

How many miles has the car done? Might be worth looking at the TB for a date code to see if it's been done before too. 

[Stanky]

9 hours ago, SiC said:

Possibly! Inspect the connector first to see if that is an obvious fault to root cause it. If this car must be up most reliable without question, then I'd throw another known good on it personally 

Of course could be the ECU connector side or even the wiring. But throwing a TB at it should mark the TB off the list. 

How many miles has the car done? Might be worth looking at the TB for a date code to see if it's been done before too. 

Car has done 130k and is 22 years old. I'll check the connectors to it tonight when I get home from work and use some contact cleaner for good measure. 

I can grab the part number from the TB too, if its what I think it is, then secondhand warrantied ones are ~£30 on ebay so that might not be too harrowing a job tbh. 

hey ho, This is why I have multiple cars!

[Dave_Q]

A classic SHAID array of vehicles (Shitting Heaps Always In Disrepair)

[SiC]

How difficult is it to get the side panel off the TB? Even if not repairable, might be good to have a look to see to wear. If it's obvious then you know you've got the smoking gun. 

[Stanky]

9 minutes ago, Dave_Q said:

A classic SHAID array of vehicles (Shitting Heaps Always In Disrepair)

SHAID 5 with unreliability striped across multiple vehicles. Will tolerate the loss of one complete vehicle at any time

[Stanky]

37 minutes ago, SiC said:

How difficult is it to get the side panel off the TB? Even if not repairable, might be good to have a look to see to wear. If it's obvious then you know you've got the smoking gun. 

It might be gummed up so I'll probably have a crack at removing the TB, giving the connector, barrel & butterfly a thorough clean and seeing if I can get the side panel off, then refit it and do the calibration procedure and see how it behaves. I can get the part number too just in case.

[richardmorris]

Hope you can fix it. As an aside, what code reader tool are you useing?

[Stanky]

2 hours ago, richardmorris said:

Hope you can fix it. As an aside, what code reader tool are you useing?

A knock off Delphi ds150e, they're great things!

[richardmorris]

12 minutes ago, Stanky said:

A knock off Delphi ds150e, they're great things!

Any link? Having spent an hour in the dealer last weekend while they had four goes to get rid of a change oil message I’m tempted to DIY.

[Stanky]

1 hour ago, richardmorris said:

Any link? Having spent an hour in the dealer last weekend while they had four goes to get rid of a change oil message I’m tempted to DIY.

Sure, there are many options but this is as good as any:

https://www.aliexpress.com/item/1005005753248053.html?spm=a2g0o.productlist.main.1.73821547xMkoTZ&algo_pvid=d7c23aa9-5363-4f52-a919-7babf36fe479&algo_exp_id=d7c23aa9-5363-4f52-a919-7babf36fe479-0&pdp_npi=3%40dis!GBP!43.39!34.71!!!388.42!!%40212244c416904051227015781d0785!12000034230063758!sea!UK!2568944510&curPageLogUid=lcyQdaJd8rzL

You'll need a laptop to run it on, and I'd suggest it has its own dedicated machine because its not entirely legit. Its basically cracked Delphi software which would cost ~£2k + £500/year to have a genuine version of. It is, however, extremely good. Installing it is a bit fiddly but once you're running its fine. The above is a listing for the software + the thing you plug into the OBD port on the car. You just need a low-end laptop. The laptop I'm using for example proudly states its 'windows vista ready' to give you some idea of the calibre of the machine! It'll run on Windows 7, 8 and 10 for certain, probably windows 11, and probably older windows too. You might even get it running on Linux with a Windows emulator if you hate yourself enough to want to go through that!

I'm happy to bring my setup to a meetup at some point and show you what its like, set off all your airbags - you know, the usual stuff.

[Stanky]

Having played musical cars earlier I was able to get the mercedes into the garage and out of the drizzle to have a proper look at the throttle body as suspect #1

Nice and easy to access, I took the elbow off the air intake pipe and undid the 4x allen bolts that hold the elbow to the throttle body to the inlet manifold. Immediately an issue was found

I'm pretty sure there is 25% of the o-ring missing? Lets furkle about and see what we can find. Lift the throttle body off the inlet manifold having disconnected 1x vacuum line, 2x coolant lines and the fly-by-wire throttle cable

Oh, there it is... The missing 25% of an o-ring was sitting in the little basket under the throttle body butterfly. Ummm I don't think its supposed to be like that is it? Ok, lets look at the TB itself

Topside is clean enough

underneath is a bit grotty but I've seen worse. Gave it a blast with brake cleaner and agitated with a toothbrush and ta-dah

Nice and clean. Next I gently prised the clips off the housing that keeps the butterfly gears safe and clean

 

Gears move nicely, tracks looks fine to me? I cleaned them up a bit with some clean rag then carefully refitted the cover

I gave the accelerator wire connector a clean with some electrical contact cleaner while I was at it, then put it all back together, minus the o-ring. I let the car do the throttle body adaptation thing by opening the bonnet, putting the key in and switching to position 2 and leaving it for 3 minutes while it whirrs away to itself then quietens down. Removed key and took it for a drive.

It runs perfectly now, just like it did the other night once I'd got it back from the breakdown.

All i can think is that somehow the o-ring slipped out of place and got partially eaten by the throttle body butterfly, sending it into a total shitfit because presumably with the o-ring trapped in the butterfly of the throttle body it couldn't close properly and so the stepper motor info was out of whack with the accelerator pedal info and the ECU flipped its lid? Then between the incident and getting it back here, having left the ignition on for a bit, its done enough adaptation cycles to slice through the o-ring jamming the throttle butterfly open, the 25% bit has dropped through and the butterfly can close again, returning signals to normality and allowing it to drive normally again?

does that sound mental? can anyone else see anything amiss? Those tracks look OK to me, no burnt bits or anything grotty?

The car drives fine minus the o-ring but I'll phone mercedes tomorrow for a price on a MB A 029 997 71 48 - looks like it might be anywhere up to £6 for it. Outrage.

Oh, I also replaced the bulb for illuminating the ashtray with a new LED T5/286 bulb which works so I can sleep soundly tonight.

[Dave_Q]

If you've got a set of calipers to accurately measure it I rate simply bearings for odd bits of O-ring although TBF with postage and that Merc might end up being cheaper. 

https://simplybearings.co.uk/shop/

[Talbot]

https://www.bearingboys.co.uk/Orings-1050-c

Similar type of vendor.  Good service from them in the past.

[SiC]

Without knowing the exact internal logic of the TB control loop, I think your hypothesis is likely correct.

From memory and looking at you picture with just the two electrical contacts to the motor, I don't think they use a stepper motor. It's a DC motor that they vary the PWM to, to vary the force and thus drive it to a particular position. 0% PWM should turn the motor off and put it in the closed position from the big spring acting on it. Iirc it's not completely closed on anything reasonably modern as that puts wear on the contact surface. So they run the motor in reverse to fully shut (or shut more) when needed. 

I can certainly speculate and imagine the ECU throttle control demanding the TB control loop to be closed. TB control loop tries this but the o-ring is stopping it. Worse, the rubber isn't a hard obstruction and springs back the butterfly valve to a different position again. This is different from carbon build up as that is sticky and stops the movement rather than acting back on it. That just needs to keep applying force until it gives way and then overshoots, causing the unstable idle. A hard obstruction or a springing one, the control loop must go wtf is going on, keeps trying for a bit and eventually goes fuck this I'm giving up as all signals out of tolerance. ECU has lost the control loop thread and thus sees the TB as out of action. Something like that I bet.

I mean if you're designing this control system, it'd be unlikely that you'd worry it dealing with permanent obstructions. As if there is one, there is bigger problems with the TB and engine. 

Those tracks look perfectly fine to my eye. It's worn but not worn through the resistive substrate. Likewise the pins are golden and clean. 

[SiC]

Too late now, but I wonder if there was any witness marks in the dirt around the lip if it was fighting an o-ring. The rubber likely could have cleaned up a section as it rubbed. 

[Stanky]

10 minutes ago, SiC said:

Too late now, but I wonder if there was any witness marks in the dirt around the lip if it was fighting an o-ring. The rubber likely could have cleaned up a section as it rubbed. 

Ah, I didn't think of that, oh well! I'll take it for a longer run at the weekend and see how I get on. Fingers crossed it's that bizarre occurrence and now sorted with the o-ring removed. 

[Stanky]

Ordered the o-ring from Mercedes, £4.32 and should be ready for pickup on Saturday. I can't grumble too much about that.