2000gt

Hi guys! I got a 01 996T 6speed that I am having some problems with and would like the help of fellow P-car owners

cars has been sitting for a year. as of late I started working on it.
have changed the following parts:

-fuel filter
-fuel pump
-spark plugs
-air filter
-new gas
-coolant flush

car did not want to start at first but after changing the plugs it, it started fine.
I dont get any codes. It does run ok on idle put once you apply gas it starts to choke and backfire,even though it will rev to redline no problem. I ran it with and without the MAF on but nothing changed. I took the exhaust off to check for clogged cats but everything was fine. It would still choke and backfire. I also have more than half tank of gas but still read below empty on the fuel gauge.

my next step was to check injectors and check for vacuum leaks or check for fuel pressure...
So has anyone experienced these symtoms before?
What else should i test?

thanks for input towards this problem in advance.

Kevin

It should run better with the MAF unplugged.. Bad MAF Unless >>

You have a intake leak or

Fuel pump failure/hose split

993GT

take a video or datalog and post

Macster

Was the engine running fine when the car was put away a year ago?

If the engine is backfiring through the exhaust that's a sign the engine is running too rich. That can be from a bad MAF, a malfunctioning coolant temperature sensor (it reports the coolant temperature is colder than it is), or a fuel pressure problem (too much fuel pressure).

If the engine is spitting back through the intake that's a sign the engine is running too lean. Again that can be due to a bad MAF, a malfunctioning coolant temperature sensor (it reports the coolant temperature is hotter than it is), insufficient fuel pressure or supply, or an intake leak.

Unfortunately I can't tell you which one of the above is to blame -- and it may be something else.

With an OBD2 code reader/data viewer you can observe the intake air temperature -- a function of the MAF -- and the coolant temperature and confirm these are reasonable and remain reasonable as the engine runs.

That the engine is fine at idle and yet when RPMs are raised acts up suggests -- but not in a conclusive way -- the problem is with the MAF for as RPMs are raised it obviously must recognize the engine requires more air and correctly signal the DME this.

Last but not least anytime I come upon a car that has been left to sit unused for any length of time and is now manifesting odd behavior I always think about mice. They can get into a car in nearly no time and gnaw on many things.

I've seen a 996 Turbo Cab in for engine problems, CEL, and the engine acting up, and the cause was rodent (rats in this case) damage. Extensive damage to not only the interior but to the engine wiring harness and yet not very obvious without checking the car over some. The tech suspected what he was up against when he found nest trash on top of the plastic under body panels.

In another case -- a Cayman -- mice chewed through various plastic tubes including the one that carries vapor from the fuel tank to the engine.

You removed the exhaust to check for blocked converters. You need to check the intake system, at least the filter and air box and as much of the intake as you can get to with a reasonable amount of effort for the possibilty of rodent damage.

Then look over the top of the engine for any rodent sign.

"02996ttx50

i vote for imminent failure of the fuel pump/line. it's possible you got a FP with a spit line. that seems to their source of failure.

2000gt

I have a friend who has the same car, I will take the maf of his car and try it on me see if it changes anything.

will report back.

thanks guy!

2000gt

Hi everyone.

I was able to scan the car and get the following codes.

P0056
P0030
P0050
P0161

All are for 02 sensors. The car currently only has 2 02 sensors. Would that mean I now need 02 sensors?

I have switched the MAF around and it didn't change anything,borrowed a friend's MAF.

Car had a buff of black smoke when revved hard and you can easily smell raw fuel-running rich.

Macster

What do you mean by "the car currently only has 2 O2 sensors"? AFIAK it should have 4.

Anyhow, the codes...


P0030 - HO2S Heater control circuit bank 1 sensor 1

P0050 - HO2S Heater control circuit bank 2 sensor 1

P0056 - HO2S Heater control circuit bank 2 sensor 2

P0161 - HO2S circuit low voltage bank 2 sensor 2

That's a lot of O2 sensor errors. I've had O2 sensor errors pop up in both my Turbo and my Boxster but just one error shows up. For a number of different sensor errors to appear suggests a common failure that affects rather separate and isolated -- they are opposite sides of the engine -- sensors.

Did you check for rodent damage?

I have a section of the Turbo factory DME 7.8 manual which gives a couple of pages of diagnostic tests for P0161. The other error codes are not listed in this manual.

PM me and supply me an email address that can accept a PDF and I'll make a PDF of the P0161 section and send it to you.

993GT

should be 4 O2 sensors, 2 pre cat and 2 post cat.
Firstly, find where all 4 sensors are and then I would check the wiring.
Noticed you are in Ontario, how long have you had your car? There was a 6TT for sale at a independent dealer about 1.5 years ago that I inspected, would 'fit the bill' with this situation.... Post cat 02's wrapped up in shop towels in the engine bay, beside the hacked airbox and deleted S.A. pump

Drinaldis

Really guys? "chokes on load" in the title? This is an entirely different thread than I originally thought.

2000gt

I bought the car last year. But never really worked on it until this year.. I had another 996T that only had 2 sensors on. The others for the after cat had Oxygen Spacer Sensor extensions. Never had a problem with that car.

Going to test the 02 sensors before going out and buying 2. Also the car has no rodent damage anywhere