Boxster losing power

[barthol]

Hi Forum,

After the winter stand stil I realized that my 2,5 boxster 1998 had a hard time raving beyond 4000 rpm at load.
It has no hesitation, misfire or anything else and it starts idle and actually drives quite smoothly.

I notised hat I have two codes which keeps coming back P1123/25 Oxygen sensing limit adaption range 1 ( cyl 1-3) and ( 4-6)

Consequently we did put it on a Dyno , see photo below
were sad results, only 122HP at 5000RPM

The guy stoped the dyne run here explaining that it had sever fuel starvation.
( he had a probe in the exhaust, and I guess that he meassured it to be lean)
I guess that that matches the codes.

Is there any obvious places to look except for the fuel filter.



BR
KIm

[steved0x]

Look at the Mass Air Flow Filter (MAF) - when this part starts to fail, it often exhibits the symptoms you describe. A quick test is to disconnect the sensor and let the car run using a default map - if it runs better, you know you have a failing MAF sensor.

Porsche Boxster Mass Air Flow Sensor (MAF) Replacement and Troubleshooting - 986 / 987 (1997-08) - Pelican Parts Technical Article

[Gelbster]

Agree - replace fuel filter and do the MAF-disconnect test.
But maybe time for a big service?

If you didn't put Stabil in the fuel, it may have gelled ?
Fuel pressure regulator ?
If the O2 sensors are getting 'old & lazy' ,changing them and the plugs may help.
Air filter?

[barthol]

Hi

Thanks for the advises.

Fuel pressure checked today by my mechanic , and it was OK.
The Airflow through the MAF was according to the Mechanic measured to be too low .

I guess that this will reduce the amount of injected fuel accordingly?

New one is ordered and it will be installed tomorrow.

BR
KIm

[Paul]

Make sure rodents have not built a nest in your air filter.

[barthol]

air filter is brand new:-)

br kim

[Gelbster]

Bart,
Slow down.
The only piece of diagnostic data (not performance data) you've got is :
"The Airflow through the MAF was according to the Mechanic measured to be too low "
Please don't feed us info piecemeal and partial. If the Mechanic has done a complete test ,give it to us - the RKAT,FRA ,fault codes - all of it. Otherwise this is just random speculation which will waste time(ours) and money (yours).
Airflow - we need the actual value in gramms.
Meanwhile remove the airfilter and retest briefly .Big change ? Check/clean the TB .You are looking for obstructions.
Please tell us you don't have a K&N (or similar) filter fitted.
Without a Durametric connected and freeze frame data to post this will be difficult to diagnose logically and methodically.

[barthol]

Hi Gelbster,

Airflow was 90 ltr/sec and the Engine incl filter is all stock.

Anyway the MAF was exchanged and all the power is now back 213 HP /270 NM
Not bad for a 19 year old car which has done 156.000 km :-)

BR
KIM