Problem Of Engine Warning Light Coming On

As far as I know I’m the only Belgian Speedster driving an exhaust with no cats at all. (extra power) But even after resetting the engine computer, after ca 35km the EML-light comes on . As you know some VX with 100 cell (even some 200 cell) sportcat’s have the same problem. It’s mostly very ennoying. But also dangerous, because the engine management system also use the same warning light for other more serious problems who need your immediate attention. And because the EML-light is already on, you wan’t notice ! Because after asking around, nobody seemed to have found a solution (except for putting the original cat back under ), I studied the principles of Cat’s and Lambdaprobes, and designed my own electronic circuit which emulates the signal of the second Lamda-probe. I hooked it up to the engine computer via the original probe-plug and I drove with it up to now for about 500 km. And I can officially confirm. It works! I mounted the component with some velcro in the trunk, to shield it from the dirt and heat. For the moment I’m testing in which range I can let the output-signal vary without the EML-light coming on (just for fun). Attached are photo’s of the mounting and the circuit.

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And a picture of the mounting

Why not just get an exhaust which doesn't set off the EML?

Has anybody had problems with with british approved 200 cell cats?

Why not just get an exhaust which doesn't set off the EML?

Cost ?

Why not just get an exhaust which doesn't set off the EML?

Cost ?

Fair point but I don't understand the desire to potentially screw a £1000 ECU by bypassing one of its measurement functions designed in part to save the engine

Has anybody had problems with with british approved 200 cell cats?

Have you?

Has anybody had problems with with british approved 200 cell cats?

I can only speak for Milltek, but the answer is no, none.

Has anybody had problems with with british approved 200 cell cats?

Have you?

First sign of madness.

Why not just get an exhaust which doesn't set off the EML?

Pipo was discussing this in Lux. I think it's availability of parts in Belgium.

Ok, let me answer the questions first. In Belgium an exhaust wich delivers the same gain as a straight pipe exhaust can't be find. Second, this mod didn't cost me anything . It took me only some work. And gave me the satisfaction of doing it myself. A new exhaust doesn't come cheap. Of course I still have an original exhaust in reserve for the annual technical checkup I'm obliged to do here in Belgium every year from the moment my car becomes 4 years of age. The exhaust I modded was a broken one who was already written off. And Thorney, I don't screw up the ECU at all . The 2nd Lambda probe is only there to check the good function of the cat. It has nothing to do with the rest of the engine management. And because I removed the cat, there is no need anymore to check if it works properly. But I don't have the possibility to reprogram the ECU so it doesn't keep looking invain for the signal of the 2nd probe. So I simply reproduce that signal and the ECU is happy. That's all. And I get rid of the EML coming on all the time to tell me the cat isn't working. Just because I know the ECU use that same EML to warn me for other possible disfunctions I wanted it to be free for as the ECU needs it. I mentionned my solution here in this forum because I remembered to have read some time ago about someone who had mounted a sportcat and had the problem of the EML coming on every now and then. He bought an electronic device in the USA (about 50 £) which should have cured his problem, but it didn't work. So if someone is interested, I can display here the schematic of my circuit so they can copy it (or I mail it to them). Good function is guaranteed. It didn't cost me anything because I used some old electronic parts I had on stock. But if you should buy everything it would only set you back some 15 €. For the rest all I can tell you is that I simply like tinkering, and I'm crazy about car-technology. So give me a break, will you

The 2nd Lambda probe is only there to check the good function of the cat. It has nothing to do with the rest of the engine management. .

Interesting , would vauxhall use it just to flag up a light to tell you the cat is stuffed?

I mentionned my solution here in this forum because I remembered to have read some time ago about someone who had mounted a sportcat and had the problem of the EML coming on every now and then.  He bought an electronic device in the USA (about 50 £) which should have cured his problem, but it didn't work.

that was me...
bought this device from the US,
http://www.milelimin....com/index.html
but did not do shite....and, one year later, I found out the soldering was disconnected...
now the kat is back on, no more MIL.... and no worry or fuss to re-install it for the annual test.... that is a relief IMO.

the MIL (or EML) light is just a general warning, so you take the car to the main dealer, they connect their diagnostic tool and see what the problem is about...
EXCELLENT job you did though, if you post the diagram it will be much appreciated, I know at least one or two italian owners that have a sport kat WITH the EML on...

Edited by Ricky2772, 01 September 2004 - 07:04 AM.

I think it is a great invention! Do you have a wiring diagram?

Interesting ,  would vauxhall use it  just to flag up a light to tell you the cat is stuffed?

I've seen this before on Hondas but a lot less complicated. When they were decatted the single sensor wire had to be cut and earthed and this kept the check engine light off. All it did was check the temperature of the cat - too hot (as damaged or empty cats get) and the light came on. It sounds like the VX one is more complicated and looks for a specific range instead while having nothing to do with the actual fuel trim?

Pipo, I would also like a copy of the circuit diagram please. Nice work

Scott.

Edited by nonterraquous, 01 September 2004 - 02:40 PM.

Does not removing both cats mean you are spewing out untreated exhaust fumes ? is so its hardly eco friendly

As far as I know I’m the only Belgian Speedster driving an exhaust with no cats at all.

I know at least 3 other belgians without cat:
- Filip who has made his exhaust system at Qvick in Oostende.
- "Unknown" who has made his exhaust at Motortec at Overijse.
- Sam who has prepared his Speedster (with a Motortec exhaust) at PowerPlus in Brussels.

It would be o.k to de cat and re cat yearly for MOT if it wasnot such a bitch of a job. How many little horses does this give you?

Attached you find the electronic schematic off my circuit. The circuit aroud T1 provides a stabelised 5 VDC wich is fed to T2. Via P1 you then can adjust the level of the output signal between 0,1 and 0.9 Volts DC. To mount it I did cut off the original wire of the second Lambda probe about 50 cm for the plug. You leave the probe in place, just isolate the wire-ends. From the wires coming from the plug you connect the 2 white ones to the input of the circuit. Just have to measure which one of the white wires is the plus (+), and which one the ground (-). For the heater of the probe it didn’t make any difference, but for the circuit it does. By my car the white wire at the outside of the plug was the plus, the one in the middle the ground. To the output of the circuit you connect the black wire to the plus (+) side, and the grey wire to the ground (-). Then with RUNNING engine you adjust P1 while measuring the output signal with a DIGITAL voltmeter. Theoreticly the output voltage may vary between 0.4 and 0.7 volts (The engine computer accepts a rather broad setting). I drove several hundreds of km with my circuit adjusted on 0.7, 0.6 and 0.5 Volts, and all settings worked fine. Finally I left it on 0.5 volt. The circuit only consumes around 20 millivolts, and is made short-circuit proof. And even with a input voltage varying between 5 and 20 Volts DC (and then something is seriously wrong with your car electrics ), the output voltage stays almost stable. So don’t worry, your engine computer is save. To Whiteboy: Yes, Opel (or Vauxhall) just uses the second lambda-probe to check your maincat. For instance if it’s stuffed, or if you used leaded fuel and distroyed it. The first probe (before the cat) activates the emergency management program, the second probe doesn’t, it only activates the EML light. To Pter141: You’re right, it’s not very ECO friendly. But then I use my Speedster for max 2000 km a year. So the ECO effect isn’t noticable. And coming from the recycling sector, I can assure you that making or recycling cat’s is far more polluting then driving a few thousand km without. To Whiteboy: Because I practiced already a lot (took off and mounted the exhaust already 5 times ), it only takes me 2 hours to change the exhaust. So to do that once a year I find it reasonable. Because the final reprogramming isn’t done yet , I can’t tell you the horses it will deliver. But at the moment with the modified airfilter and exhaust, I have (tested on rollbank) 155 HP. The sound is much improved without being intrusive, and the engine revs noticably more freely and pulls harder away on high revs.