Idle high when rainy. Drops to 1000 when car comes to a stop

[griston64]

Here you go

[SalvadorP]

Originally Posted by griston64

Here you go

What does it mean "to the stop but no further"?
Am I supposed to turn it all to the A side, then turn gently until the click is heard (which I did hear) and then keep turning until the end?

I don't understand what "stop" means, or "no further". If it's the end, you couldn't really turn it no further, right?
Also I don't understand what it means to hold the "throttle disc".
Does that mean I have to disconnect the inlet hose and hold the disc/butterfly closed and turn the sensor all the way after the click, while guaranteeing the disc remains closed?

Did you get the chance to see my comment with the codes i read from the car? Any opinion?

[baggy798]

I just turn it gently one way and then back the other way until it clicks, then tighten the bolts and open the throttle and listen for the click again. Sometimes tightening the bolts can alter the position just slightly and stop it clicking - might need a couple of goes at it.

I don't think this is your cause of high idle though, unless it is not clicking now?

[SalvadorP]

Originally Posted by baggy798

I just turn it gently one way and then back the other way until it clicks, then tighten the bolts and open the throttle and listen for the click again. Sometimes tightening the bolts can alter the position just slightly and stop it clicking - might need a couple of goes at it.

I don't think this is your cause of high idle though, unless it is not clicking now?

Griston's argument was that the idle was high anyways.
But i was explaining specifically that my idle stays at 1500 when it's rainy/wet. And it stays that high until the car stops moving. I think it eventually normalizes after a while. but I still have the pesky vibration and inconsistent idle that i haven't solved yet.

[baggy798]

Ok. My idle is 850-900 and rock steady but the idle valve is bypassed so not really comparable. Never seen the 1500 (sometimes stays at 2000) rpm idle issue ever definitely solved, otherwise I wouldn't have bypassed it!

Do you mean a slight fluctuating idle when you say vibration? How crusty are your intake manifold and throttle body gaskets? I think you've changed all the vac hoses already? Do clean the idle valve and/or test a second hand one.

[Rversteeg]

The only function of the TPS is to tell the ECU when the throttle is closed. Together with the current vehicle speed the ECU decides when to stop injecting (during coasting) or when to re-adjust the idle speed. For obvious reasons the ECU should not re-adjust the idle engine speed if a higher speed is caused by pressing the throttle pedal (TPS open) and/or if caused by the vehicle speed driving the engine (vehicle speed > 0).
A correctly set TPS will open just when the throttle cable starts to open the throttle plate. If this is set too critical, the ECU will not adjust the idle speed and maintain the initial idle speed setting of when the (cold) engine was started.

Note it will also not re-adjust when the vehicle has been constantly moving since its first startup. Re-adjusting takes one or two seconds of standstill with a warmed up engine.
The idle speed may be higher than normal, but it should not be vibrating or being irregular (or is the AC switching on/off?). Is this only in wet / damp conditions? That would be pointing more towards bad HT leads / distributor cap.

[SalvadorP]

Originally Posted by baggy798

Ok. My idle is 850-900 and rock steady but the idle valve is bypassed so not really comparable. Never seen the 1500 (sometimes stays at 2000) rpm idle issue ever definitely solved, otherwise I wouldn't have bypassed it!

Do you mean a slight fluctuating idle when you say vibration? How crusty are your intake manifold and throttle body gaskets? I think you've changed all the vac hoses already? Do clean the idle valve and/or test a second hand one.

The car has like a fluctuation between 1000 and 900 at idle and the car shakes when the needle drops. Also shakes at 1500rpms. Fine at other speeds. It's like a misfire. I have video of it if you wanna see.

How did you bypass the IAC? I have cleaned it, but it is one of the suspected culprits. Other being MAF.
Intake hoses are in great shape. Turbo inlet too. Vacuum too. i haven't switched some of the hoses that go inside the car. I suspect that one goes to the instrument cluster, the other is AC related!? And the cruise control!? It's the ones that are plastic. But they look fine.
Also vacuum tests didn't show leaks. Intake gasket looks great. It only has 50k km or so. I'm at a loss with this crap.

EDIT: Here is the link to the video of the "misfire"/fluctuation and vibration/shake: [YOUTUBE]https://youtu.be/bTt45bXXayA?si=OwaxsYwq6VZ2rviQ[/YOUTUBE]

[SalvadorP]

Originally Posted by Rversteeg

The only function of the TPS is to tell the ECU when the throttle is closed. Together with the current vehicle speed the ECU decides when to stop injecting (during coasting) or when to re-adjust the idle speed. For obvious reasons the ECU should not re-adjust the idle engine speed if a higher speed is caused by pressing the throttle pedal (TPS open) and/or if caused by the vehicle speed driving the engine (vehicle speed > 0).
A correctly set TPS will open just when the throttle cable starts to open the throttle plate. If this is set too critical, the ECU will not adjust the idle speed and maintain the initial idle speed setting of when the (cold) engine was started.

Note it will also not re-adjust when the vehicle has been constantly moving since its first startup. Re-adjusting takes one or two seconds of standstill with a warmed up engine.
The idle speed may be higher than normal, but it should not be vibrating or being irregular (or is the AC switching on/off?). Is this only in wet / damp conditions? That would be pointing more towards bad HT leads / distributor cap.

So, the vibration and fluctuation of idle speed might not be related to the high idle when wet. In fact this high idle thing is only when it's rainy. The "rythmic misfire"/idle fluctuation happens all the time. Also the car shakes at 1500-1700 specifically too.
It has nothing to do with the AC. Also Ht leads are new, plugs well gapped, etc. IAC cleaned but not tested. MAF tested and it gave abnormal readings. At the time I asked you your opinion about the values, because you were helping me figure it out, but you must have missed my reply.

This wet thing does sound a lot like rotor/cap cause I've had similar issues on an Opel Corsa years ago. But the cap and the rotor do look in great condition and I cleaned them and it made no difference.

Here is video of the needle at idle, like it is normally, when the air is dry/normal. Do you think it's is a misfire?

[YOUTUBE]https://www.youtube.com/watch?v=bTt45bXXayA[/YOUTUBE]

If you see the video, you can see and hear the car shake when the needle drops.

[Rversteeg]

It seems very rythmic, as you say. It could be the IAC fluctuating, but also a variable load on the engine. Have you tried running it with the alternator belt removed?

[SalvadorP]

Originally Posted by Rversteeg

It seems very rythmic, as you say. It could be the IAC fluctuating, but also a variable load on the engine. Have you tried running it with the alternator belt removed?

IAC fluctuating, means faulty IAC? Should I test or try to replace?
No, I have not. It never occured to me to do that. Your reasoning is that a faulty alternator could make the load on the engine be uneven and therefore make the idle drop when it's under increased load?

Do you think this could be at all MAF related?
When I tested MAF these were the values: "I've tested voltage between #2 and #3. 1.42 with ignition on. At idle, 2.4, under acceleration 3.09."