What is happening over 4000rpm?

[wawa]

What is happening in our engine over 4000rpm? I'm asking because I have an intermittent problem that I cannot find. When I push a little the engine, I often but not all the time have the engine cuting. I lift the gaz and its ok, run fine. It feels like ignition cutoff. I have change twice the MAF and twice the AOS, but still the same. I have no CEL code, and engine idle smooth and run smooth under 4000rpm. But over, it sometime cutoff, sometime not.

I know the variocam are activated at about 4000rpm, could it be related? How does it work? Could it be something else? Any idea or suggestion?

Model is a 2000 S

Thanks
Chris

[thstone]

Your car has the original Variocam which works via a solenoid which changes the tension on the timing chain to alter the valve timing to give more power at high RPM. As such, it is either on or off based on a pre-set RPM controlled by the DME.

Your problem could be Variocam related but high RPM drivability can also be fuel related (fuel filter, fuel pump, or injectors not flowing enough fuel at high RPM).

[wawa]

Fuel filter is change, air filter too and also spark plugs. I put injecter cleaner in last time I fuel up.
Would bad injectors or fuel pump cause a sudden cut of power? It really feel like I'm hitting a fuel cut at high RPM like some car have.

Thanks
Chris

[Bmod986]

Check the coil packs because if they are cracked then your not receiving the proper sparks at the right time. So this could cause this cutoff sensation. I know that for me, my power stopped at 5,000 until I changed one of my badly cracked coil packs and now she runs good. I suggest giving that a shot.

[stephen wilson]

Just a thought, does your car have PSM? Does it do this in all gears?

[wawa]

Yes it have PSM but it does not feel like it. You think it could have something to do with it? It's random but I have experience it in 2-3-4 for sure.

Thanks
Chris

[stephen wilson]

Well, it doesn't seem likely in 3rd and 4th gear. I had a problem with my PSM kicking in when I increased the air pressure in my non-stock (wider & taller ) front tires .

[Jager]

Have you checked the fuel pressure? Fuel pump might be going out.

[wawa]

That is where I'm heading now. Fuel pump is my next target cause last night the boxster was missing in all gear and at idle. Had a hard time getting back home. Stall a couple time. Start and die seconds later. Sound more and more like fuel pump.

Now, the fuel tank is full and I'm scared to go for a ride to brun fuel. Will have to fine à big container.

Later all
Chris

[Homeboy981]

KennyBoxster had the same problem due to MAF being a "newer" model than what our ECM expected. There is an upgrade to the software, or you can run an older MAF unit.

It took KB 3 MAFs and hours to figure out. There is a report out on it…Kenny transcribed it from German! Now that's devotion to fixing a problem!

Another problem was 2nd gear shifting, slight pause or engine cutout right after shifting. All due to the wrong MAF, or too new for the car to read correctly ALL the time.

We drove around for hours, and it was only intermittent at best. We even unplugged the MAF (do NOT personally recommend that) and it RAN BETTER!

Good luck!

[Jager]

Originally Posted by wawa

That is where I'm heading now. Fuel pump is my next target cause last night the boxster was missing in all gear and at idle. Had a hard time getting back home. Stall a couple time. Start and die seconds later. Sound more and more like fuel pump.

Now, the fuel tank is full and I'm scared to go for a ride to brun fuel. Will have to fine à big container.

Later all
Chris

Bad fuel pump will not necessarily throw a CEL. You now have the same symptoms that I had a few years ago... Bad fuel pump.

[Kenny Boxster]

Unplug the maf, undo the battery and drive the car around for 10 miles. If it improves, you may have the wrong version of the MAF. The TSB for 2000 year Boxsters can seem ambiguous and conflicting regarding MAFS. PM me if unplugging the MAF improves your situation so I can try and help you find the right version.

[wawa]

Homeboy981 & Kenny boxster, your puting more doubt in my head now. The fuel pump is already order so I will change it anyway. But could you double check if I got the right MAF from pelican parts?

On the box it's says:
986-606-125-01-M14. 2000 from chassis 986YS62041 through 2004, or chassis 980YU625100 through 2004. Boxster S

My serial number is: xxxxx2988YU660299
2000 boxster S

Thanks
Chris

[Jager]

Did you measure the fuel pressure?

[smagerstein]

Hi, I had the same problem last week and apparently it was fixed when they replaced the 'Magnetventil'. (car still with them having some other work done at the same time)

It threw a flashing CEL.

This is what they call it in german, dont know what its called in english. Price was 240€ for the part at the dealer.

Picture of problem part below.

[wawa]

That is the impulse sender. How could it be part of my problem?

I have not check fuel pressure. I dont have what it needed for it.

Later
Chris