Help! I think I'm running rich - 986 Forum - The Community for Porsche Boxster & Cayman Owners

farewellregret · 09-17-2007, 01:29 PM

As in fuel, I’m not that arrogant. I wanted to know if anyone here knows of any air/fuel gages available for the boxster. Also any ideas of safe ways too lean it out a little?

Thanks – Sock

racer_d · 09-17-2007, 01:53 PM

I would be suprised the car wouldn't throw a "check engine light" if that was the case. These cars are very sensative to emissions related issues and running too rich is certainly one of them.

Pat · 09-17-2007, 01:55 PM

What makes you think it's running rich?

farewellregret · 09-17-2007, 02:07 PM

Quote:

Originally Posted by racer_d

I would be suprised the car wouldn't throw a "check engine light" if that was the case. These cars are very sensative to emissions related issues and running too rich is certainly one of them.

I should have mentioned I have a moded car and it doesn't twrow codes because it's set up that way....However I waste a lot of gas so I wanted to lean it out for daily driving.

Pat · 09-17-2007, 07:47 PM

Knowing specific mods would help in diagnosis.
Also, you still haven't told us why you think it's running rich other then poor gas milage.

farewellregret · 09-17-2007, 10:45 PM

Ok so the reason I think it's running rich is because of the poor gas millage the way it sounds and carbon deposits on my tail pipe. Also I was told it would be running a little rich by the guys who did my engine swap. They said it would give me a better top end, as it would lean out at higher speeds. As for the mods well I have a 3.6 engine, ecu (don't know what kind), headers, de snorkel, just took out my K&N and I have no cats.

farewellregret · 09-17-2007, 10:47 PM

It smells like it's running rich.

racer_d · 09-18-2007, 04:51 AM

Sounds like the shop did a partially half -assed job to me. These motors dont "run rich" in a 996, they shouldn't run rich in your boxster. Unless they have tried to re-map the timing or reprogram the A/F ratio, they should be able to control and set properly all settings electronically. Having a K&N (or not), No Cats and headers doesn't make a car run rich.

Secondly, if they claim its set up to run "rich" due to high rpm/high speed use and you find that this doesn't gel with your actual driving styles, why have it set up that way?

Wonko The Sane · 09-18-2007, 05:03 AM

To add to the above post, there shouldn't be any "set up to run rich so it turns lean at high RPM" or whatnot with a fuel injected vehicle. That used to be the way with Carburetors, but not so with EFI.

For anyone who has not tuned EFI, there is a very specific map that states "At X RPM and X throttle (or air flow or Manifold Air Pressure, depending on setup), put in X fuel." This means that if you wish to have it run lean @ 3000 RPM under light load it can be set that way while keeping you rich @ 5000 RPM under heavy load. There's no knob or anything that sets X amount of fuel to use across the entire range, each point on the map is individually set.

What I'm really going for here is that either it wasn't done right if it was a stock ECU swap, or the time was never really spent to tune the programmable ECU better.

Wonko The Sane · 09-18-2007, 05:07 AM

I guess it would help if I actually answered the question, sorry!

If you have a stock ECU/injectors and you're running rich, it most likely means that the ECU isn't hearing something from the emmissions/oxygen sensors and is putting in more fuel to compensate.

My guess is that you have a standalone or piggy-back fuel system, though, which means you would have to get readings from the oxygen sensors (or EGT), and tweak the fuel map to give you less fuel in the required areas. That will require a laptop and the software to interface into the fuel system, as well as some dyno time (for best results).

Cheers!