My 2004 MC40 acts like its too rich like vehicles that have carbs. If I don't give too much gas it doesn't stumble and runs fine.

 

More info please......

How long have you had the car? Has it always done that? If not, did you change something before it started doing that? How many miles on the car? What about plugs and wires?

Have you scanned it for any codes?

 

If you don’t have a code scanner, consider getting one that can log real-time operational data. I have a cheap ELM327 WiFi device and Dash Command on my phone. I can log data and see the fuel trim levels and other parameters for how the car is running. Helps take a little bit of guesswork out, and also serves the very valuable function of letting me read and clear codes.

 

12 yrs. Just started and now as I am paying more attention it appears to occur mainly when cold.
104K.
Haven't looked at plugs or wires.
Haven't check for codes, but will later this month.

 

Didn't know about that scanner but will look into it. Will it work for other vehicles like Porsche?

 

How many miles are on the plugs? When's the last time you changed the air filter? Check the basics first.....

 

Plugs @ 50K.
Air filter @ 69K

 

That's a lot of miles on an air filter. If it looks dirty, swap it out for a new one...see if that helps.

 

Will change out: plugs, wires and air filter whether it needs it or not. 104K on the plug wires do you think that's about the life of the wires?

 

Both need changing. Make sure to use NGK irdium plugs!

 

Researching right now for best prices on the NGK plugs and wires.
Thanks

 

Are NGK BKR7EIX a new number for NGK PZFR6F?

 

These are the correct ones: BKR6EIX you could also use the BKR7EIX

 

Great, air, plugs and wires to be picked up to tomorrow

 

Yes, they’re generic OBDCII devices. They’re cheap as hell (search Amazon) and since they’re so common, you’ll have a choice of apps that can speak to them. Now, being generic, they’ll only give you the information within the ODBC standard. There is also a set of information that can be read and written with a laptop and dedicated cable. For instance, when I was chasing a check engine light, the cable and software not only gave me the fault code, it gave me very long text describing it possible causes and diagnostic procedures, and also the statement that my specific problem was caused by an electrical short to ground. Super valuable, it also a lot more involved to setup, since it’s older Windows software, and there are many somewhat conflicting packages and instructions available. I’d stick with the the ELM327 device for now to get through this problem, then work on installing the software as a side project, so you can have it if or when you need it.

 

I use a Blue Driver all the time. It give information on the trouble codes it generates when plugged into your car, with many suggestions on what the problem may be.
It cost $99.95 on amazon and you have to download the app and I think it may cost $9.99. I always take it with me!

Everyone should carry one! or something Like ICarSoft for BMW & Mini

 

Plug wires are a toss up. The last car I owned with plug wires -- since then all cars have a coil mounted to each plug -- was a '96 Mustang GT and I drove that car 150K+ miles on its original plug wires (and coil) with no signs of any issues but that doesn't mean the plug wires are ok in your car.

Since you are changing plugs and filters consider replacing the plug wires, too. Also, the coil or coils.

For no real reason other than based on my experience with the O2 sensors at 132K miles I felt the coils might be past their change by date, so I replaced the coils at 140K or so miles in my 996 Turbo and the engine ran better afterwards. It was the coils as the plugs still had around 10K miles of service life left and I had the plugs changed several times before (and the plugs changed in my Boxster a number of times too) and not once did either engine ever react favorably to the new plugs.

I did let the Boxster engine air filter go too long and when I did change it the filter was filthy. After the new air filter the engine ran markedly better.

Also, both engines benefited from new O2 sensors. In both cases one sensor (a #1 sensor) was tripping a CEL but otherwise there was no sign of any untoward behavior from the engines. But after replacing the Boxster O2 sensors with easily 150K+ miles on them and Turbo O2 sensors with 132K miles afterwards both engines ran markedly better.

Oh, also it might be worth the effort to check the coolant and intake air temperatures to see if they are reasonable. I had a 2002 VW Golf TDi that had the engine feeling like it was off its feed a bit. Nothing major just kind of flat when it had be anything but that prior. I dug out my Actron OBD2 code reader/data viewer and spotted the coolant temperature gauge reading cold when the engine was not cold and I had the sensor replaced and the engine perked right back up.