Jason's 99 Boxster doc thread

[ike84]

Originally Posted by Radman

Took a buddy out the other night and under acceleration the car started losing power and then getting it back rapidly. A little embarrassing but thankfully the buddy is a car guy and understands **it happens with older cars lol!

I've had O2 sensor codes off and on since I bought it. I have a new MAF and 4 new O2 sensors to go with the CPS, control valve, and fuel filter to replace. Hopefully get that all done next week. If I still get symptoms I'll replace the fuel pump.

Realize to a certain extent that I'm just throwing parts at it, but, it's a 23 year old car and could stand to have some parts thrown at it lol!

I have also added a MB Quart 8" slim subwoofer behind the passenger seat. It really rounds out the sound. For a convertible, it now sounds very good with the top down which is all I could really hope for anyway.

If you're losing power under acceleration, the ECU may be pulling timing or going rich. The former can be caused by knock sensor activation, the latter may be from flipping to open maps if your O2 sensors are bad. Hopefully it sorts out with the planned repairs, let us know!

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[Radman]

Originally Posted by ike84

If you're losing power under acceleration, the ECU may be pulling timing or going rich. The former can be caused by knock sensor activation, the latter may be from flipping to open maps if your O2 sensors are bad. Hopefully it sorts out with the planned repairs, let us know!

Sent from my SM-N976V using Tapatalk

I've replaced the MAF and it seemed to make a difference on the short drive I took it on. I have 2 of the O2 sensors but waiting on the other 2. I've had some error codes in the past that indocated O2 sensors or MAF.

I have a Durametric so may take it with me for a spin and do some recording. It's idled rough in the past as well. Beginning to think this is why the owner before me let it go lol! Just need some patience.

On the knock sensor, I do have a PowerFlex bushing for the motor mount. I don't think that would be enough to activate it and the car certainly doesn't feel like it's vibrating excessively at any point.

On the bright side, I am impressing the hell out of my wife with my mechanical skills lol! I was a nuke mechanic in the Navy, so I have the aptitude but she loves that I'm repairing the car myself vs paying someone else to do it. I can't do much these days due to neck and back issues, but at least working on the car is one of them I can do. It's therapeutic for me, after the f-bombs are done anyway.

[blue62]

Originally Posted by ike84

If you're losing power under acceleration, the ECU may be pulling timing or going rich. The former can be caused by knock sensor activation, the latter may be from flipping to open maps if your O2 sensors are bad. Hopefully it sorts out with the planned repairs, let us know!

Sent from my SM-N976V using Tapatalk

The O2 sensors are narrow band O2 sensors.
They operate in a extreamly narrow band.
To accelerate (other than a very mild acceleration) the engine needs a richer mixture.
That mixture is outside of the O2 sensors ability to read.
So your DME/ECU fueling strategy will always go to open loop fuel mapping under acceleration.
It will do the same thing under closed throttle (deceleration) from higher RPM.
Why???? because the engine is on a lean mixture when decelerating.
That lean mixture is outside the narrow band O2 sensors ability to read
So it is very doubtful that your O2 sensors play any part in your power loss under acceleration.

Your knock sensors are activated by detonation or pre detonation in the cylinders.
Things like Poor fuel .....ignition timing off.... valve timing off... something that affects combustion or combustion timing within the cylinder.
Knock sensors are activated by sound within a frequency range not vibration.
So they (knock sensors) will not be activated by a stiffer engine mount.
Nothing external will activate the knock sensors.