Technical HGT Percentage throttle body 183A1000 Step A

[FrankS]

Hey,

can anyone tell me the factory percentage of the throttle body when idle?

Sometimes my engine is stalling when pressing the clutch from normal revs.

In MES the idle percentage is 0% when I'm off the pedal. Shouldn't it be 2-3% ?

When I press the pedal the data makes sense without any jumps.

In the photo i've marked the moment the engine is stalling.

It only happens when the engine is warm, but the lambda data is fine. Checked with MES and an additional lambda gauge in the cockpit.

New parts:
Vacuum hoses
Lambda sensor
Variator spring
Idle valve (with battery off/ on and let it idle from cold to warm)
Cleaned the mass air flow sensor
Coolant temp sensor
Spark plugs
Timing belt (timing is set correct)
Cleaned and tested the PCV Valve
Tested with 2 fuel cut off switches and 2 fuel pumps

Cheers Frank

 

[GrandePunto PL]

If this car has separate air way for idle (idle air control valve), throttle can be fully closed.
Otherwise it cannot (like in Grande model, no IAC, so flap has an intentional gap).

Timing is good, so what? You must verify real crank and camshaft positions.
To see if the crankshaft wheel (timing belt cog/pulley) has broken "key".
Other thing is valves. Valve clearance/lash. Both mechanical or hydraulic lifters should be inspected.

VVT? Solenoid valve (remove and check, clean).

Nice graph. But useless. Show other data, throttle position (not gas pedal).
Note that FES/MES reads parameters in order. Just how they are listed.
You can get rubbish data (for example throttle moved before you stepped on the gas pedal)!

Real diagnostics is done with oscilloscope. OBD2 data is only an initial direction (what to check next - real hardware Check, not software tricks).
https://www.youtube.com/c/AutomotiveTestSolutions/videos

 

[jonik]

Mine goes from 0 to 95%. I had the same problem for years before I modified the pcv valve to allow more air flow, no problems since

 

[FrankS]

Mine goes from 0 to 95%. I had the same problem for years before I modified the pcv valve to allow more air flow, no problems since

Thanks,

may I ask you how you modified it?

 

[jonik]

I took about 2mm out of the valve head so it will still work normally but there's more air going through. Couldn't get washer back into the groove so I just welded new one with a slighty bigger hole. You should check that there's is no residue inside the intake manifolds hole, mine was almost completely blocked

Here's a video where I explain the problem (with English subtitles):

 

[FrankS]

Thanks for your response and all the HGT stuff on Youtube.

I installed a new idle valve from China: 46473851
Battery off/ on for 30min and let the engine idle from cold to warm.
When i pushed the gas pedal the engine revs automatically 10 times between 2000 and 1500 rpm before setting to 900 rpm. On the next stop 9 times, on the next stop 8 times and so on. After 20min the idle valve was working as it should be. But as soon as the coolant was warm the engine stalled again on every second stop.

I installed a new PCV valve from a Subaru: 11810AA060
The intake manifolds hole was free.
Battery off/ on for 30min and let the engine idle from cold to warm.
When i pushed the gas pedal the engine revs automatically 10 times between 2000 and 1500 rpm before setting to 900 rpm. On the next stop 9 times, on the next stop 8 times and so on. After 20min the idle valve was working as it should be.

And bingo!

I drove 800km this weekend with a lot traffic jam stop and go and the engine didn't stall even once.

Clean and quiet idle and no more rpm falling to 500 and maybe stall or not game.

Cheers Frank

 

[jonik]

So exactly same problem I had for at least 3 years before I found out the reason, I replaced every sensor etc in the process. The design is just plain stupid because it allows x amount of airflow bypass the butterfly/idle control valve and when there is a tiny amount of residue blocking it the engine will stall

 

[PuntoHowTo]

I see you have resolved your problem but just going back to your graph at the top of the thread. assuming this is an electronic throttle pedal as most mk2 and mk2b cars are, the "Gas Pedal Position" is the position of the gas pedal and if your not pushing it then it will read zero, it will have no bearing on the "throttle position" which is usually done off the sensor on the throttle body.

Though in this instance you have an idle air control valve so the throttle position sensor may also read zero at idle. @GrandePunto PL did raise this point in his post above, it helps to know what you are actually looking at an how that relates to what you expect to see.

 

[FrankS]

Hello,

the 183a1000 M1 Step A engine has a throttle cable, so @GrandePunto PL was right that the throttle can be fully closed at idle.

Cheers Frank

 

[Mike1alike]

It's a good thing you made the engine run better now.
But... considering the detail of problem only manifesting on worm engine, I recommend you to have a look at the oil pressure, do a reading and make sure that is right.

 

[FrankS]

Hello,

can you tell me the story behind your advice please?
What experience did you made on this engine with this failure and oil pressure?
I'm curious.

Cheers Frank

 

[Mike1alike]

You can read about it here.

 

[FrankS]

Hello,

despite the fact that my engine doesn't stall anymore i did a intake system smoke test.
My intake manifold is leaking at the VIS shaft.
Has anybody had the same issue and found a solution?
Has anybody done a manifold swap from plastic to aluminum?
Does the throttle body and the fuel rail fit?

Cheers Frank

 

[Mike1alike]

What do you mean by 'VIS shaft'? What are you calling like that?
Post a zoomed out photo of that area.

 

[GrandePunto PL]

Maybe there is something "Variable", like flaps inside the intake manifold etc.
HGT has also a VVT (but it's not a part of the intake)...