knockout87

H!

I have an 996 - 99mod manual 3,4L.

When i start up it seems like it misfires. It`s kind of a knocking sound. Sometimes it stops on idle.
When i push the throttle for a ouple of seconds, it smokes a lot and then the knocking goes away.
After that, I let it Idle - but it slowly rises from 800rpm to around 2000rpm, then it drops to 800rpm again and do the same thing over and over again,

Does anybody have a clue?

This is the fault codes i found:

P1601 - CAN timeout - instrument cluster
P0600 - CAN timeout Tiptronic
P0102 Hot film MAF sensor (erased and didn`t come back)


60 - Central locking limit pos
13 - Left door secured, but not locket
14 - Left door secured, but not locket
16 - Signal from airbag
1 - Doors secures and terminal 15 on
43 - passenger - side release stuck
44 - Driver-side release stuck
61 - Central locking limit position Unlock not reached

Slakker

Grasping at straws here but have you gotten any water in it? Particularly on the driver side floorboards.

spruden

What color is the smoke? White, blue, etc...

knockout87

Hi!
I don`t think the car has suffered from any water. What`s under the carpet driver side?

The color of the smoke is white. It`s not as much as shown on Youtube when the air/oil (AOS) is damaged.

DBJoe996

Unplug the MAF sensor and see what happens. While the engine is idling remove the oil filler cap and observe change in idle, then let us know. When did you last service the car? Plugs and coils? How many miles on the car? Have you cleared/checked your drain tubes? I don't understand the CAN timeout for Tiptronic when you have a manual transmission.

Slakker

The immobilizer is located under the driver's seat. If it got wet all sorts of strange things can happen. This doesn't apply to the smoke or MAF errors, just the locks etc...

FYI, the 99 MT still has a CAN Bus on it. The DME takes the input from RPM, Throttle position, and outside air temp, and transmits it onto the bus. The entirety of the bus consists of two pins that have no corresponding wires on the DME connector.

Well, unless you manually add wires to tap into the CAN of course. I have a really cool USB Can Bus adapter from Amazon that I connected up and sure enough, it worked. But that's not really relevant here.

Macster

Quite a collection of codes...

Slakker stole my thunder but he's spot on asking about water in the cabin.

Check under the seats. The security module is located on the cabin floor under the passegener seat.

Check along the bottoms of the doors for any dampness. Water can get in/collect in one or both doors and if not promptly addressed can cause electrical gremlins with the doors/windows. If left to go too long gremlins at other places can begin to appear.

While the engine sounds like it is misfiring with no misfire codes it is not misfiring. It certainly reads like it is not running well.

Before I go on I have to mention the possibility of mice being at the car. These critters can chew wiring and hoses and such and the car can manifest a real mix of seemingly unrelated error codes.

Check on top of the engine very carefully for any mice sign. Look on top of the underbody plastic panels for mice litter.

Kind of a long shot but be sure the battery's good and the alternator is putting out the juice. An engine with a low battery or one that is not being topped up by the alternator can manifest all sorts of weird behavior.

Beyond the above all I can offer is the only times my Boxster engine idle speed has varied and it has never varied that much is when the 1st AOS was on its way out. While the RPM varied it didn't vary much. Maybe at the most just a couple of hundred RPMs if that much.

The other time was when the passenger side VarioCam solenoid/actuator was acting up and both eventually were replaced.

In this case the RPM went pretty low to the point the engine felt like it was going to stall. At this low engine speed the engine can sound pretty bad, can make knocking noises, the low oil pressure light might flutter or come on, and in general just sound/run like it is at death's door. Then the RPM's go up to 1K or higher and the engine sounds a bit better.

In this case the CEL was not on but there was a pending code related to the solenoid.

I turned off the engine and restarted it and it ran fine and continued to run fine for the 30 mile drive home.

Unless you are a pretty good home mechanic my advice is to flat bed the car to a qualified shop and have a pro give it a look/see.

Slakker

Emphasis on qualified. So sick of the "I took it to the shop with a bad battery and now they have pulled the engine and say it will take $5k to fix it" stories. Ask for Rennlist recommendations or find out if you have an IMS Solution certified installer near you and ask Flat Six Innovations for a reference on them.

Good luck!!!!! I hope it turns out to be something simple.

ditto

You got the codes, does that mean you have a Durametric? If so continue reading.

Seems like there is either a general comms breakdown between the DME and a bunch of engine sensors, or a sensor fault that is giving the DME fits. With the Durametric you can generate plots for sensor performance. When you do that, you can see what is flatlined. If there are a bunch of sensors that are flatlined its a comms problem. If not, its a sensor.

A wet DME, or a loose connector would cause a comms problem. It would also give you those non engine related codes. The non-engine related codes could be a separate problem. Seems like getting the engine running well is more important.

When was the last time the drain lines were blown out?

Macster

Emphasis indeed on "qualified". And experienced. And reputable. And so on.

Too often someone with a sick car jumps from the frying pan into the fire with his choice of where to take the car.