clipod

Hi ,
I have a boxster 01 with 90K. I am not the first owner of the car. My car had a AOS failure and it has been repaired by my mechanic. After I got the car back I had a techron run, cleaned my MAF. It was working fine and last summer one of my CAT's were gone. Had it replaced with a used cat. My performance became a little bit better. But its not even close to the same car when I brought it. Problems which I have are,
1) Performance goes bad after 15 to 20 min of drive.
2) Throttle response is not good. After I step on the gas it takes considerable amount of time to reach a partiular RPM. I generally drive between 2500 and 4000. Previously when my mechanic told me to rev higher than that, my clutch got screwed up because when I shift gears in higher RPM it gives jerky motion and it became worse. I spoke with my mechanic and he said dual mass fly wheel is bad.
If I accelerate quick the motor cuts out and it takes a couple seconds for it to actually accelerate. If I slowly press on the pedal it drives fine.
3) Whenever i stop at a signal close to a minute, as soon as I move the initial 5 seconds will be good at the throttle response and then it goes back with lazy accelearation.
4) When I start the AC its a night mare, I feel that my car is towing a big trailer.
5) Getting a constant ticking noise and it increase as I rev more.
6) My car smells bad at times.
7) I got this from durametric "Heating and Air Conditioning: 31 Fresh Air Blower Fault" ( I got this when I did a quick scan when my engine is not started). Should I turn on the engine before I do this scan?

What I am thinking of as problems are:
1) Bad MAF because of delayed response in accelaration.
2) Replacement of o2 sensors as it has been a while and also because I had to replace one of the CAT's.
3) Cleaning of radiator because of AC acts like an overload.
4) Vacume leak because I kind of listen to hissing sound and also my whole engine kinda bulges out when I push the gas pedal.
5) Made a recent oil change with my regular mechanic and I dont remember what he used but feels like a lifter noise.Whats the recommended oil ?( I live in Texas.)
7) Bad smell is because of failing cat?
8) Should I change spark plugs?
9) Also can this be a problem with my fuel pump and fuel filter?

I recently brough a durametric reader and took a video of values of o2 sensor. I drove the car for 20 min and then took those values when idling. This is the youtube video

Please let me know if I need to do anything else with the durametric to get more information.

update:
Just cleaned my MAF sensor. The first few minutes of my drive until the temparate gauge crossed 180F was fine. After that its the same. Lucky enough here its not hot and its night and the temperature is 68F so its better or else my drive would have been worse

Macster

There's a lot going on.

First the engine should sound ok with Mobil 1 0w-40. But you can run any approved 5w-40 oil, and there is even a 5w-50 (not a typo for 15w-50!) oil approved.

When you remove the oil filter housing make sure you have a clean drain pan to dump the oil into along with the filter. What you see or do not see determines what you do next.

If you see metal bits or any real amount of anything that's it. Stop.

If you see nothing then you can proceed.

I assume the CEL is off -- does the CEL light up when you first turn on the ignition key? -- and there are no error codes?

If the CEL is off and if the bulb works then things are maybe not too bad. Maybe.

But I'm at a loss to read so of so many issues, at least symptoms, with no CEL. You sure the bulb works?

The plugs were changed. I assume the right plugs were used? Even though there are no misfires if the coils are ratty looking best to replace them.

Let's see...The engine runs ok then after a while it doesn't...That could be a MAF. One shady tree "trick" is to disconnect the MAF and clear the error codes -- resets the trims among other things -- then see if the engine runs better without the MAF.

I do not know the history of the car so I have to ask: When was the fuel filter changed? Is the air filter ok? Look for signs of rodents. The car might have been homesteaded by mice while it was in the shop. (I had a Mustang in for some work and the dealer service department parked it out back in some high grass. A week later I got the car back but with snails all over the engine compartment.)

Another source of the deteriorating engine performance is a failing fuel pump, or declining fuel pressure. My money is on the fuel pump. I can't imagine -- doesn't mean one doesn't exist -- a failure mode than can have the fuel pressure dropping after 10 or 15 minutes.

The bad smell -- sorry to jump around -- is probably due to the engine not running right. (But mice litter or even mice (dead of course) on the engine can make the car stink. They like to get in the A/C air vents and the air coming from these can have a foul odor.)

Anyhow, the converters can get off on the wrong foot, chemically speaking, and produce a rather noxious odor. Even if the engine is running ok once in great while I have smelled a foul exhaust odor. Oh, if it persists and you find no other explanation for it you might change brands of gasoline.

For the #1 O2 sensors you want to see the voltage -- this is at idle now with the sensors hot -- swing from under 0.1 volt to over 0.7 volts or higher. At idle the swing might take a second or so. At higher RPMs the swing happens in less than a second. If you get a real time trace of the voltage signal you can see this. If you just get some sensor readings every so often the scan tool can't read the data fast enough to give you a complete picture, but over time -- 10s of seconds time -- you should the min and max readings to have confidence the sensors are working ok.

The #2 sensors once hot along with converters you want to see the voltage stay around 0.6 volts are a bit higher.

What to look at? Well, everything. At idle look at the short term fuel trims. If both sides look goofy -- what is goofy? -- well, it varies. Often one has a good bank and a bad bank so one can compare the two readings and note which one is the goofy reading. The few times I've looked at goofy short term fuel trims the readings were swinging rail to rail, that is from around +10% to -10% as if the DME couldn't make up its mind. However, the readings might do this as a result of clearing the CEL which resets the long term fuel trims and the DME then will strive to relearn the fueling.

Look at the idle speed. Is it going up and down? That is often an air leak. And what do you mean about the engine bulging out?

Look at the timing advance. It should not be too much -- IIRC 5 debs or so -- but it should be rather consistent.

Look at the coolant and intake air temps. A bad coolant temp sensor can cause the DME to fuel the engine for a colder or warmer temperature than really exists. Does the intake air temperature look reasonable? It can be a bit over ambient if the engine/engine compartment is warm. But given the engine's behavior I think you are looking for big errors not a few degrees difference.

Last be sure to look at MAF reading.

I hope I'm wrong but given the symptoms and their diversity I'm thinking mice have been gnawing on the car.

gfl

I cannot fathom that a car that runs like that has no codes. Pull codes. First check for readiness.

I also cannot fathom how so much could be wrong. I think yu need to do some basic diagnosis - fuel delivery, codes, pull 02 sensors to test function (but, again, codes, codes).

Grant

gfl

....but one would think that THAT would in itself eventually cause a code condition!

good luck, start simple.

Grant