Full Acceleration Pause

[EasyDDI]

Hi Gents,

 

I have a a very nice 1998 3.4 Carrera and I encounter the following issue:

When I floor completely the gas pedal, the car's acceleration pauses at 4'300 RPM, and again around 5'300 RPM and sometimes get trouble to reach 6'000 rpm.

When I press the pedal to 90/95% the car accelerate like a rocket, goes all the way to 7'000 rpm without pause.

So far we replaced the gas pump, which was necessary but does not resolve the issue. We tried the new MAF, no change either.

Anyone had something similar?

 

My mechanic thinks it could be an air leak somewhere but we could not identify the root cause.

 

Any idea would be welcome.

 

Thanks,
Easy

[judgejon]

Am I correct in thinking your car does not have e-gas accelerator pedal?

How about your throttle linkage?  Injectors clean?  Maybe run a bottle of Red Line through the fuel system?

this doesn't sound like an internal engine issue to me.  Something going on with the bolt on stuff.  Good luck.

And welcome to the forum.

[EasyDDI]

Thanks for the answer. The engine runs very well, so yes, it does not look like an engine problem. Throttle linkage might be a venue (I do not think the car is an e-gas). Maybe the throttle itself. I will investigate further and let you guys know.

[Loren]

It is likely that your (cable driven) throttle is going past the 100% open and the butterfly is partially closing again.

You can check this with a second person - just have one person slowly push the accelerator pedal (no need to start the car) while the other observes the throttle butterfly. I suspect the butterfly is going past "wide open".

If that is the case then you will need a Porsche PST2 or PIWIS tester to re-calibrate wide open throttle. 

[EasyDDI]

Hi Loren,

 

Thanks for the very kind advice as usual. It is really helpful. Intuitively, it looks like the most likely possibility. 
I will take it back to the garage and have the guys perform the test.

 

Again, thanks a bunch. I will keep you posted on the outcome.

 

[GEORGE S]

I would change the fuel filter. A partially clogged one will not supply enough gas for full throttle.

Sent from my N9518 using Tapatalk

[EasyDDI]

Thanks George,

 

The fuel filter was changed at the same time as the fuel pump. So this part is covered. We had the same line of thought.

 

So far I have done the throttle reset (60 second key in position 2, 10 second wait, start the car) and I find it runs better under hard acceleration than before. Next stage will be to test the throttle completely and re-calibrate it properly using a Porsche diagnostic tool.

 

As will post further information once this is done.