Per my radio issues thread I finally got the double-din Sony installed when I discovered a previous owner had monkeyed with the Porsche wiring harness. The constant 12v was no longer receiving power and they had run a new constant 12v, which was tied into the 12v switched, and a new "ground" which may have been the cause of my alternator whine.

Everything is now working, the new speakers sound great(though still lacking bass), and I did not experience alternator whine when I took it out for a drive yesterday.

Oh, and I replaced their jury-rigged parking break switch as well.

[QUOTE=Radman;638164]Yep, that was the plan. The CEL only happened once, but the engine had been rough at idle since purchase.

In other news, my attempt at replacing the instrument cluster LED backlight bulbs with LED's has been a failure lol! I ordered a 5 pack

Hey Radman

Can you tell me what leds you ordered please?

Cheers

[QUOTE=jarjar;648239] They were B8.4D-NWHP from superbrightleds. They didn't fit though so I wouldn't repeat my mistake.

Are you still happy with the Powerflex? Is it this one?


http://986forum.com/forums/uploads02...1660618327.jpg

http://986forum.com/forums/uploads02...1660618266.jpg

Yep, that's the one and I'm still very happy with it. I can't really compare it to stock though as my original mount was completely shot.

Having some warm start issues. From reading it seems the CPS is usually the culprit so I now have one in hand. Am also getting a P0446. I ordered control valve. If that doesn't work I'll order the evap cannister.

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!

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.

Still have only replaced the MAF and the issue has returned. Seems to go away when the car is warm and does not manifest when the clutch is pushed in when it's cold and I rev the engine up.

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.

Maybe a vacuum leak?

If your referring to a vacuum leak as a possible cause of power loss under acceleration???
Probably not the cause of power loss under acceleration.
common vacuum leaks have there greatest effect at closed or near closed throttle.
Less and less effect the farther the throttle is opened.

The reason for that is:

As you open the throttle greater and greater amounts of (metered) air enter the engine.
While the vacuum leak.... be it a lose hose, cracked hose, or what ever remains the same size and can only allow so much (un-metered) air into the engine.
So the ratio of metered air to unmetered air changes as you open the throttle.
So the vacuum leak has less and less effect the further you open the throttle.

You could still have a vacuum leak but it is doubtful that it would cause power loss under acceleration. unless it is a huge leak.

If it is a vacuum leak associated with something like your evap system they can act a little differently.

If you going to try to fix your power loss under acceleration issue you need to fix "ALL" OBDII codes issues first.

Fair enough. Thanks for the feedback by the way. It truly is appreciated.

Replaced the crank position sensor, upstream O2 sensors, and the purge valve under the left side intake manifold.

P0446 code went away but I get O2 sensor codes without a CEL. Hopefully it's not an issue with the wire harness but once I get new anchors installed for my lift I'll start rotating the O2 sensors and see if any codes follow particular sensors or not.

On the bright side, the car drove much better. Very happy to be able to take her out for a spin again.

If you do a little research on how the Durametric or rather "Porsche" portrays or interprets fuel trims you can use the Durametric to tell which O2 sensor or sensors are causing the codes.
Not hard to do you just have to understand Porsche's fuel trim methodology and the relationship between O2 sensors and fuel trims.

If you have access to an OBDII scanner that shows fuel trims as a percentage rather then the Porsche Durametric method it is a little easier to interpret the fuel trims.
fuel trim data can be very useful in diagnostics of engine performance (running) issues.

Although switching sensors around to see if the signal or code follows a sensor is a common practice it is not a good one. It can cause other issues.
Everything on these cars and any modern day car is electronic so they can be tested with a scanner or Oscilloscope or something as simple as a Digital Multi Meter.

I take it that if your not getting a check engine light but your seeing codes....So your looking at pending codes???? What are the codes specifically.????

How many miles on the O2sensors????
They tend age or the signal from them tends to begin to slow down as they age.
Usually starts around 100000 miles

Yeah, I had to google how to find fuel trims on the durametric lol!

The 2 precat O2 sensors are brand new, but not Bosch. Basically bought them for troubleshooting purposes. No idea if the others have ever been replaced but the car only has 75k miles so I doubt it.

Yes, the codes are pending.

They are:

P0131
O2 sensor ahead of Cat conv. Cylinder (1-3)

P0137
O2 sensor ahead of Cat conv. Cylinder (1-3) short circuit

P0151
O2 sensor ahead of Cat conv. Cylinder (4-6)

P0157
O2 sensor behind of Cat conv. Cylinder (4-6)

I don't need emissions so in a perfect world I could just get rid of the O2 sensors and the cats.

You mean in an "imperfect world". Why do you want to purposely pollute our air?

So first things first;)
Generic O2sensors are well known for their non compatibility with Porsche systems.
Secondly:
All four codes are pointing to the same thing: This is how it is described in the Bentley Book.
"Short to ground/below lower limit/lean mixture threshold."
So basically three possibilities.....but sense you have used generic brand sensors I would suspect an electrical issue with the sensors......the short to ground.

So first replace the 02sensors with Bosch.....
They developed the first automotive O2sensors so they know what they are doing.
Then go from there as a good starting foundation....

If you eliminate your cats and post O2sensors you will likely always have a check engine light on unless you find a work around..So if you have an OBDII issue you will not know it because the check engine light is already lit.

If you want to learn about "fuel trims" or O2sensor signals and how to read them and how they are related to each other. Go to youtube and look up "ScannerDanner" he is probably one of the best on youtube for teaching automotive sensor diagnostics. And automotive diagnostics in general.
That will allow you use the Durametric to much greater potential.

Thanks again for the feedback.

I'll throw the old ones(Which are Bosch) back on and see what happens. If the codes stay I'll order one new one to move around and see if the codes go away. Don't want to spend the $ for all 4 in the hopes it makes the car run better. But, if this is a dumb idea, please let me know lol!

Screw it, just ordered 2 new Bosch units. Will report back.