jadh

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!


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

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!


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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

jlmartin94

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 ....

Vandit

Are you running the heater in the operating temperature vids?

jadh

Hi jlmartin!

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!


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Hi Forumers, I need your help!

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!

jadh

No heater and no air-conditioning on during the videos

JasonAndreas

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?

jadh

I don't have the KTS tool and this car doesn't have the Check engine light. And I didn't had the opportunity to go to my specialist up to now
I don't know about cylinder head temp, but lubrication oil temp indicator was roughly horizontal during the test.

jevvy964

have you tried unplugging the ISV to take that out the equation?

that "chuff" noise sounds like the ISV to me?

boxsey911

In answer to your question, no mine is not as lazy as that. Sorry I can't be of more help than that at the moment.

jadh

Hello Jevvy, What are the words for ISV (Intake S? Valve)? and please what is the unplugging procedure?

Thanks

jadh

Thanks for this information!

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

crg53

ISV= Idle Stabilisation Valve, located on top of the intake.

LPMM

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.

jadh

@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?

jevvy964

Previous replies should have helped you with the ISV location. Once at hot idle just pull the electrical plug at the top of this pic:



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.