Engine cold and warm reaction
#1
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Thread Starter
![Question](https://rennlist.com/forums/images/icons/icon5.gif)
hello,
I have noticed that engine reaction to acceleration is different depending if engine is cold or warm. Indeed, my engine is more lazy when hot.
Please watch the following videos before posting.
Here is video of engine reactions when cold : ie just after engine start.
--> I like this quick reaction of the engine when I kick the accelerator! ![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
Here are the videos when engine is at service temperature.
From the engine bay
and
From the driver seat
--> you can see the revs falling down when I am close to idle and when I quick the accelerator. I do not like ![Mad](https://rennlist.com/forums/images/smilies/mad.gif)
My engine is a 1992 full stock and has 103 000km
QUESTIONS:
Do your 964 engine has the same LAZY mode when hot? I mean less reactiv when hot comparing with cold.
For Rennlisters with a stock 964 engine, could you post the videos of your engine reactions, specialy if hot engine reactions are more reactiv when comparing with mine?
Thanks for your help!
--------------------------------------------------------------------------------------------------------------------------------------------
Abstract of the Answers
Points to check :
- KTS diagnostic. How to do : go to your Porsche specialist and ask for a KTS diagnostic
- Lazy O2 sensor. How to do : KTS diagnostic
- is the vacuum system ok? How to do : just start the engine to make sure a vacuum is there then the resonance valve should move the next time the ignition is switched on. The resonance valve is a small black actuator operated by a solenoid / vacuum. It is located on the lower inlet crossover but is not visible. You can hear it 'clack' and see the spindle move when stood looking at the engine. ------> OK
- Check Idle Stabilisation Valve. How to do : Once at hot idle just pull the electrical plug Idle should stay roughly correct then try opening the throttle like in the other videos. Any different?
- Check both the ISV and AFM to make sure they are clean. How to do : https://rennlist.com/forums/964-1989...low-meter.html and https://rennlist.com/forums/964-foru...-answered.html
- Have a vidéo of a unlazy stock engine. How to do : A (nice) Rennlister to make the vids
I have noticed that engine reaction to acceleration is different depending if engine is cold or warm. Indeed, my engine is more lazy when hot.
Please watch the following videos before posting.
Here is video of engine reactions when cold : ie just after engine start.
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
Here are the videos when engine is at service temperature.
From the engine bay
From the driver seat
![Mad](https://rennlist.com/forums/images/smilies/mad.gif)
My engine is a 1992 full stock and has 103 000km
QUESTIONS:
Do your 964 engine has the same LAZY mode when hot? I mean less reactiv when hot comparing with cold.
For Rennlisters with a stock 964 engine, could you post the videos of your engine reactions, specialy if hot engine reactions are more reactiv when comparing with mine?
Thanks for your help!
--------------------------------------------------------------------------------------------------------------------------------------------
Abstract of the Answers
Points to check :
- KTS diagnostic. How to do : go to your Porsche specialist and ask for a KTS diagnostic
- Lazy O2 sensor. How to do : KTS diagnostic
- is the vacuum system ok? How to do : just start the engine to make sure a vacuum is there then the resonance valve should move the next time the ignition is switched on. The resonance valve is a small black actuator operated by a solenoid / vacuum. It is located on the lower inlet crossover but is not visible. You can hear it 'clack' and see the spindle move when stood looking at the engine. ------> OK
- Check Idle Stabilisation Valve. How to do : Once at hot idle just pull the electrical plug Idle should stay roughly correct then try opening the throttle like in the other videos. Any different?
- Check both the ISV and AFM to make sure they are clean. How to do : https://rennlist.com/forums/964-1989...low-meter.html and https://rennlist.com/forums/964-foru...-answered.html
- Have a vidéo of a unlazy stock engine. How to do : A (nice) Rennlister to make the vids
Last edited by jadh; 12-01-2013 at 03:38 PM.
#2
Advanced
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
hi jadh
hope 964 rennlisters will be more objective than french forumers ...
It seem that everybody think there is trouble with your engine but nobody want to put video of their own motor reactions ....
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
hope 964 rennlisters will be more objective than french forumers ...
It seem that everybody think there is trouble with your engine but nobody want to put video of their own motor reactions ....
![Wink](https://rennlist.com/forums/images/smilies/wink.gif)
#4
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Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Hi jlmartin! ![burnout](https://rennlist.com/forums/graemlins/burnout.gif)
I am not surprised to meet you in Rennlist Forum. It's always a pleasure to read you!
Yes you are true, I want to enlarge the scope of forumers for a better sharing about engine reactions.
Let's see if we get more (open minded & constructive) feedback here.
I am sure we will!
-----------------------------------------------------------------------------
Hi Forumers, I need your help!![Frown](https://rennlist.com/forums/images/smilies/frown.gif)
Do your 964 stock engine got the same lazy reactions as mine when engine is warm?
The French feedbacks are fifty/fifty about it! And moreover, I need a video of a 964 stock engine with "best in class" reactivity.
So, If you think that your engine is "Best In Class", please put a video of its engine reaction at sevice temperature.
Thanks a lot for your help!
![burnout](https://rennlist.com/forums/graemlins/burnout.gif)
I am not surprised to meet you in Rennlist Forum. It's always a pleasure to read you!
Yes you are true, I want to enlarge the scope of forumers for a better sharing about engine reactions.
Let's see if we get more (open minded & constructive) feedback here.
I am sure we will!
-----------------------------------------------------------------------------
Hi Forumers, I need your help!
![Frown](https://rennlist.com/forums/images/smilies/frown.gif)
Do your 964 stock engine got the same lazy reactions as mine when engine is warm?
The French feedbacks are fifty/fifty about it! And moreover, I need a video of a 964 stock engine with "best in class" reactivity.
So, If you think that your engine is "Best In Class", please put a video of its engine reaction at sevice temperature.
Thanks a lot for your help!
![thumbup](https://rennlist.com/forums/graemlins/thumbup.gif)
#6
Technical Guru
Rennlist Member
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
What is the cylinder head temperature in the warm videos? You could have a lazy O2 sensor. Do you have access to a Bosch hammer or Doug's scantool?
#7
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Thread Starter
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I don't know about cylinder head temp, but lubrication oil temp indicator was roughly horizontal during the test.
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#9
Nordschleife Master
#10
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Thread Starter
#11
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Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
It is very helpful to read that your car is less lazy!
For sure you can help very simply, if you agree and if your car has a stock engine a 20sec video (engine & driver seat) could help me in setting the target to achieve.
Thanks for your help
![thumbup](https://rennlist.com/forums/graemlins/thumbup.gif)
#13
Drifting
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Check both the ISV and AFM to make sure they are clean.
https://rennlist.com/forums/964-1989...low-meter.html
https://rennlist.com/forums/964-foru...-answered.html
Other quick checks: vacuum leak, FPR
PS: Here is a Visual Guide to the 964 Engine.
https://rennlist.com/forums/964-1989...low-meter.html
https://rennlist.com/forums/964-foru...-answered.html
Other quick checks: vacuum leak, FPR
PS: Here is a Visual Guide to the 964 Engine.
#14
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Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
@Crg53 & LPMM : Thanks!
I will have a look to linked threads.
But the problem I have is the following: I don't know what is the "normal" stock engine reaction sound?? So, if I perform some test, I will not be able to tell if I am closer to the target.
Anyone to help me with vids on that point?
I will have a look to linked threads.
But the problem I have is the following: I don't know what is the "normal" stock engine reaction sound?? So, if I perform some test, I will not be able to tell if I am closer to the target.
Anyone to help me with vids on that point?
#15
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
![](https://rennlist.com/forums/attachments/964-forum/105436d1142567037-cleaning-isv-how-update-the-question-has-been-answered-initial.jpg)
Idle should stay roughly correct then try opening the throttle like in the other videos. Any different?
I will try to get a 964 cold/hot video for you over the weekend.