Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Vamps]

The Beastie is cat exempt, doesn't have any, expensive waste of time!!! 8-)

How is that then? I thought all cars had to have them from the very early 90's  :-/

[Kevin Wood]

The Beastie is cat exempt, doesn't have any, expensive waste of time!!! 8-)

How is that then? I thought all cars had to have them from the very early 90's  :-/

They do. You need a bent MOT tester - or swap them back on for the test.

Kevin

[3.2 manual]

i think 92 was the last you could de cat. i did a 90 gsi 3000 24v and a 92 gsi 3000 24v and a 92 senny 12v, when done with a nice free flowing exhaust system, they needed to be chipped to fuel properly at wide open throttle, as lambdas werent used at wide open and they fell back to preset maps( which caused them to run slightly weaker) if i remember rightly. if the mig fails, ill cut the pipes weld on flanges bolt em in and give the four, i still have from two them cars another outing! with the option, then of decat between mots...niccce, should give a good bit of time to learn how to fool the computer, im thinking it may be possible to use resistors in conjunction with the sensors either in series or parralell depending on which way voltage needs moving. to modify the sensor voltage returns, so the computer can still use the sensors to make adjustments but thinks all is good, what do you reckon kev? may also be possible to cure 420, 430 like this without moving anything, by moving sensor returns back into spec?

[3.2 manual]

just been out to freeze frame car to find out when 420, 430 last, and under what conditions occoured and after resetting 2 days ago the light is(said to be) off, no codes in module, what are the chances it loves doing this fault!

[Kevin Wood]

You're correct to point out that at full load the engine will go open-loop. However, the fuelling will still be based on the intake airflow from the MAF so I would have thought that it would handle a small increase in "breathing" without going lean.

The tool you really need to tune it is a Wideband Lambda sensor that can tell you what's going on over the full range of mixture. http://wbo2.com/

I mapped my Westfield using one of those in 30 miles on the road (from no map at all - well, a guessed one!).

As for fooling the signals to prevent 0420 and 0430 I have seen reference to this done on other cars. Depends exactly what the ECU is looking for from the post-cat sensors. The digging I've done suggests that the cat can become "saturated" with oxygen or with fuel. In either case, as the engine mixture switches between lean and rich there's a delay between the front and rear lambda sensor detecting it due to the "memory" in the cat. The longer the delay the more efficiently the cat is working.

Suggests just an RC network to delay the switching of the rear sensors might work. :-/

Kevin

[3.2 manual]

my thought was along the lines of, if the rear sensors say just for an example, while following the front sensors went high everso slightly, a very low value resistor in the signal wire, may stop it going out of spec. id heard of fiddles and the such to fix errors like this, if its more a timing side of the signal problem, its more hassle than the worth of it to fix.

[Kevin Wood]

Here's another idea. The delay is effected by adding a spacer which "slows down" the response of the sensor.

http://forums.evolutionm.net/evo-how-requests-questions-tips/114931-how-install-spark-plug-anti-foulers-remove-ses-cel-light.html

.. And here's an example of the "low pass filter" route:

http://cobrasvt.homestead.com/files/milelims/mil%5B1%5D.htm

None tried on an Omega AFAIK, but potentially less hassle than relocating the lambda sensors (known to work).

Kevin

[Kevin Wood]

There's an interesting description of a cat monitoring algorithm (not necessarily the same as an Omega) here: http://www.stangnet.com/mustang-forums/7767223-post25.html

Kevin