Leitch

I've not visited the group for a while but I thought I'd check how you were doing. I guess everyone was looking in the right place except the guys with the spanners! That's good news! I'm glad you got it resolved. Terry

Re: measuring the exhaust gas before the CAT. Isn't the 02 sensor before the CAT? Sorry if I sound ignorant but I just have an engine (ie I don't have an Altezza to keep it in!) with a partial exhaust. It has the 02 sensor and a short length of exhaust but I didn't get the CAT when I bought the engine. It might be tricky to get a good seal but can you insert the probe into the 02 sensor hole?

Good to hear you're inspired to keep pushing. A chemist eh! sorry for the chemistry 101 lesson! Colin- I've never heard of the propane trick before and I'll add it to my repertoire! The problem with the air leak as Colin says is that the 02 sensor should compensate for it unless you make the leak so large that it is outside the ECU's ability to deal with it. I'm sure other issues will arise at that point. With regards to the learned trim values in the ECU, I assume that the values are lost (return to default) when the battery is disconnected for a while. The problems I have heard occuring with this are generally to do with OPEN loop mode when cars experience starting problems after major surgery with battery disconnected. Those vehicles had their starting problems gradually disappear after a couple of days of use. I'm not sure that this will have much impact on closed loop mode though because its the 02 sensor thats controlling things. The real issue is why is the ECU not letting the air in by itself when the exhaust is rich? That still points to the 02 sensor. Let us know how you get on.

Hmmm.... Thinking aloud... From memory the catalyst can convert NO emissions fine (>95%) for mixtures that range from fairly rich up to the point that the mixture goes slightly lean then the NO readings go sky high as the mixture leans off and the high temperatures start to cause Nitrogen in the air to react. As your NO is good that is consistent with the mixture being correct or rich. HC tends to follow CO but it's not as sensitive to low oxygen. ie the HC burns better than CO so a slightly rich mix may give you an adequate HC but high CO. Still consistent with a rich mix. I don't know much about the chemistry of the catalyst except that the catalyst by nature does facilitates the reaction but doesn't get used up by the reaction. It seems to me that a catalyst can only fail if it suffers mechanical (heat) damage that reduces it's surface area or it gets clogged with foreign matter (eg leaded fuel). In either case the Catalyst shouldn't just increase CO emissions, I would expect the HC and NO to be out as well (I just read your other thread and you've already been down that path). You can see I'm not convinced on the Catalyst can't you! Only because it's a pain and $'s if it turns out not to be the case. I had a look through some Toyota documentation I have and one suggestion from is that a small exhaust leak prior to the cat can mess the ECU's calculations around. I can't quiet visualise the logic but it might be worth checking as this was specifically targeted at hi CO levels. Something else to try just prior to swapping the cat is to measure the EG emmisions pre and post cat. That should give some indication of how much work the cat is or isn't doing. Always great if you can get another Altezza to compare figures with as well. Also make sure your mechanic is giving you good advice on what he see's. Emissions numbers in the ppm are pretty fine and out by a little in 02 can mean out by a lot in EG emissions. When he checks the 02 sensor make sure that it oscillates between rich and lean pretty rapidly (I think Toyota say ~ 8 times a second). The sensor can be "right" but to slow to respond to changes. Colin has a point about "1" as well. I assumed you meant a balanced (14.7:1) air fuel ratio. Has the vehicle had a few days driving since it's long rest? I ask because the ECU has both short and long term "trim" values that take time to be learnt. I'll ponder as to how you can artificially lean it off for the SVA. I don't see that creating an "air leak" will do it as one person says was done with a RAV4. In closed loop mode the ECU should counter that. Let's see if I can manage to post this just once this time! cheers Terry

Ok, the catlytic converter converts CO to CO2 when it has plenty of oxygen. High CO occurs when the mixture gets rich. So things to check would be anything that creates an excess fuel mix or leads the ECU to believe the mix is lean and needs to be supplemented with extra fuel: Others have already said this but look for things that reduce 02 content: Blocked air filter or Increase fuel: Faulty/Blocked injector. or convince the ECU that the engine is running lean: Faulty 02 sensor Keep in mind that the ECU runs in closed or open loop mode. In closed loop mode the engine trys to keep 14.7 lbs of air flowing for every 1 lb of fuel delivered because the catalytic converter works best with this ratio. The ECU checks to see how close to 14.7:1 the ratio is by measuring the oxygen content in the exhaust with the 02 sensor. Closed loop mode is all about minimising emissions and the ECU can compensate for a lot of little variations in operating conditions to achieve minimum emissions. Closed loop is what should be occuring during your SVA test because your engine is not under load (it's cruising at high rpm). In open loop mode the ECU doesn't care about the 02 content in the emissions and it uses it's internal map of fuel to air ratio's to offer the best drivability/power/acceptable emissions (but not good enough for SVA). There are many instances where the ECU will go to open loop but the two main one are under heavy load when the ECU enters "power enrichment" mode to stop knocking and cold start mode when extra fuel does what a choke did in an older vehicle. I'm not sure about the UK but usually emissions tests are all about testing the engine during a period when the engine would be in closed loop. I doubt that any engine would have good enough emissions in open loop mode. I think that is why some people are telling you to give it a hard run first. ie the engine is warm so it isn't in cold start mode. The 02 sensor also works better at temperatures above idle so heating it up will help. However, I don't believe either of these are really your issue because your engine will be warm during the test and the 02 sensor has an electric heater that cuts in when the engine idles and it gets too cold. I suggest that you verify that the temperature sensor is not faulty/unplugged so that the engine stays permanently with the choke out. Verify the 02 sensor is working. Check air filter. Have injectors/fuel system serviced. Last resort because it's a bigger job is to check/change the catalyst. I'm doubtful that your Cat is the problem because your NO emissions would be sky high if it was dead. If you are looking at a graph of catalyst efficiency vs air/fuel ratio the curve is very steep and a small change in 02 content will give you the change you are looking for. In other words the fault could be pretty minor, just got to find it. Do you have the HC and NO figures? My guess is that your HC will be a little higher than optimal and your NO will fine if your mixture is a little rich. Do you have access to a garage with an EG analyser? I think that will be the way to go before you try out for the SVA again. regards Terry

Did they give you any indication what the problem was? Eg excess NO or HC? That will give you a clue where to start looking.

Breakthrough Engine with Advanced Mechanism System or something like that! Regards Terry

Thanks altezzaz, The oil pressure gauge in the Altezza doesn't give any scale other than High and Low does it? Failing that you would need access to an oil pressure gauge which taps into an oil line most people remove the oil pressure switch (which activates the oil warning light on the dash) which is located next to the oil filter and screw the gauge into there. The two most interesting pressure readings are at idle (the minimum) and at 3000 RPM or above (This should be the maximum pressure and the pressure relief valve should be operating/regulating by then). I've never measured fuel pressure but again you would need the right gauge and a point to tap into the fuel line. This isn't trivial as I have heard speculation that the altezza pressure is around 60PSI which makes it an awesome flame thrower if it all goes wrong! I was hoping someone would have decked out their Altezza with a full set of aftermarket gauges and they could read it straight off. Off course a fuel pressure gauge is pretty useless unless you've extensively modified your engine and you are worried about not being able to maintain it. As for my situation I am buying adjustable fuel and oil pressure regulators. I need to be able to adjust them to the right value. Getting the fuel pressure wrong is not to bad as I can set that by feel and the ECU tends to compensate a little. Oil is a different matter. Not enough pressure and the engine won't last long. Too much and I could blow a lot of seals which will become very expensive. regards Terry

Thanks altezzaz, The oil pressure gauge in the Altezza doesn't give any scale other than High and Low does it? Failing that you would need access to an oil pressure gauge which taps into an oil line most people remove the oil pressure switch (which activates the oil warning light on the dash) which is located next to the oil filter and screw the gauge into there. The two most interesting pressure readings are at idle (the minimum) and at 3000 RPM or above (This should be the maximum pressure and the pressure relief valve should be operating/regulating by then). I've never measured fuel pressure but again you would need the right gauge and a point to tap into the fuel line. This isn't trivial as I have heard speculation that the altezza pressure is around 60PSI which makes it an awesome flame thrower if it all goes wrong! I was hoping someone would have decked out their Altezza with a full set of aftermarket gauges and they could read it straight off. Off course a fuel pressure gauge is pretty useless unless you've extensively modified your engine and you are worried about not being able to maintain it. As for my situation I am buying adjustable fuel and oil pressure regulators. I need to be able to adjust them to the right value. Getting the fuel pressure wrong is not to bad as I can set that by feel and the ECU tends to compensate a little. Oil is a different matter. Not enough pressure and the engine won't last long. Too much and I could blow a lot of seals which will become very expensive. regards Terry

Hi folks, Can someone tell me what the oil and fuel pressure for the 3SGE Blacktop should be? I'm using the engine in a Lotus 7 replica and I don't have the fuel pump/regulator and the Oil pressure relief valve was a victum of the original cars demise! regards Terry