RPM drops low when engaging clutch

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Ortovox77
480 Newbie
Posts: 48
Joined: Fri Sep 14, 2018 10:50 pm

RPM drops low when engaging clutch

Post by Ortovox77 » Tue Sep 07, 2021 12:26 pm

Hi,
I'm currently putting together my 2.0L 1995 GT to get it out on the road, all is mostly working but I have an problem that is annoying.
The car starts and run ok and the idle is ok around 750rpm and stable. The problem I have is that when driving each time I engage the clutch to shift gear the rpm drops so low so that it nearly dies, it has died a few times also.
Just standing still and reving and releasing throttle fast has same result.
After the rpm drop it will go up to between 500-750 before it will be stable at 750 again.

Checked oil, air temp sensors (changed air sensor, runs maybe little better but no change to my problem)
Cleaned Throttle body and throttle body sensor
Cleaned Idle valve, was very little dirt (tried a used one also I have laying around with same result)

Removing the idle valve connector would raise idle to 1100rpm, it not as stable as before but if I rev and release throttle it does not drop low.

Searched here but could not fins anyone with same problem.
Hope to get some help before I start removing and changing everything.

Regards Jonas
------------------------------------------------
Volvo 480 Turbo 1994
Volvo 480 ES/GT 1995
Volvo 480 Turbo 1988
Volvo 480 Turbo 1990 (will be scrapped)
BMW Z4 coupe (ESS supercharged)
Saab 9-5 2006
Rotax DD2 Gokart
------------------------------------------------

Spainal
Started learning about 480
Posts: 66
Joined: Mon Mar 16, 2015 7:38 pm
Location: Russia, Siberia, Krasnoyarsk
Contact:

Re: RPM drops low when engaging clutch

Post by Spainal » Tue Sep 07, 2021 1:36 pm

Hey!
I would look at the beginning at the throttle valve, what readings it gives if you abruptly close it.
When you stand still and do the same (just keep the revs as if you were driving and suddenly throw the gas, the revs also fall to a minimum?) Are the revs normal?
Volvo 480 Turbo!
I was born and live in Siberia! :hopping:

Ortovox77
480 Newbie
Posts: 48
Joined: Fri Sep 14, 2018 10:50 pm

Re: RPM drops low when engaging clutch

Post by Ortovox77 » Tue Sep 07, 2021 11:05 pm

Hi thanks for the answer.

Revs also drop to a minimum when standing still and reving like Im driving and releasing the gas quickly.

The throttle valve is that one under the throttle body? How do I measure it?
I have cleaned it but I have 3 used spare ones that I can test with also.

Regards Jonas
------------------------------------------------
Volvo 480 Turbo 1994
Volvo 480 ES/GT 1995
Volvo 480 Turbo 1988
Volvo 480 Turbo 1990 (will be scrapped)
BMW Z4 coupe (ESS supercharged)
Saab 9-5 2006
Rotax DD2 Gokart
------------------------------------------------

Spainal
Started learning about 480
Posts: 66
Joined: Mon Mar 16, 2015 7:38 pm
Location: Russia, Siberia, Krasnoyarsk
Contact:

Re: RPM drops low when engaging clutch

Post by Spainal » Wed Sep 08, 2021 3:11 am

Ortovox77 wrote:
Tue Sep 07, 2021 11:05 pm
Hi thanks for the answer.

Revs also drop to a minimum when standing still and reving like Im driving and releasing the gas quickly.

The throttle valve is that one under the throttle body? How do I measure it?
I have cleaned it but I have 3 used spare ones that I can test with also.

Regards Jonas
You need to look at the evidence of the damper sensor, if the readings are good, you need to look at the idle speed sensor.
The throttle valve and the idle speed sensor are responsible for idling.
When you release the gas pedal, the idle speed sensor opens the throttle to supply a certain amount of air to the intake. here it is necessary to figure out what's the matter.
Volvo 480 Turbo!
I was born and live in Siberia! :hopping:

Ortovox77
480 Newbie
Posts: 48
Joined: Fri Sep 14, 2018 10:50 pm

Re: RPM drops low when engaging clutch

Post by Ortovox77 » Fri Sep 17, 2021 10:01 pm

I changed to another throttle valve sensor and that made it little better but still not as good as I want.
Then I did some washing of the engine bay and after that the engine got a really high idle around 2000rpm and it would only go down after driving so the engine got warm so I will go over ignition parts and check them I guess
------------------------------------------------
Volvo 480 Turbo 1994
Volvo 480 ES/GT 1995
Volvo 480 Turbo 1988
Volvo 480 Turbo 1990 (will be scrapped)
BMW Z4 coupe (ESS supercharged)
Saab 9-5 2006
Rotax DD2 Gokart
------------------------------------------------

triumphtoledo
Started learning about 480
Posts: 76
Joined: Wed Oct 26, 2005 2:30 pm

Re: RPM drops low when engaging clutch

Post by triumphtoledo » Fri Oct 22, 2021 12:11 pm

Is the speedo working OK? The 2.0-litre uses road speed data in the injection algorithms.

Also, what do the diagnostic flash codes say?

R

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