Ferrari uses a reduced tip design on the probes as well. In my research into this I was told by a number in the industry that it is of negligible significance. The probes do need to be in the exhaust flow though and thus the length requirement. On 355s because of the shape of the CAT and the location of the bung, the probe is longer than on 360s and 550s.
Latest update on the 355 cat ecu - there's a video link inside. Cat ECU Project - Update 13th September 2015 And here's the video link by itself for those who only like to look at pictures ;-) https://www.youtube.com/watch?v=Ub6dUIPGT74 Car sounds a lot rougher than it really is - the mobile phone mic is pretty awful and the audio seems to be heavily compressed.
3Richard that is just perfect!! No tapping of signal lines to know real time what voltages the ecu is seeing and troubleshoot from there. I hope you can figure out a way to make this available.
Nothing new to report at the moment but I'm still working on it. Just had to spend time doing something else for the last week or so. Will get back to it soon though.
Not really a project update, but here is my latest activity. I've actually been diagnosing a fault with my car which I've nailed down to the left hand thermocouple. Cat ECU Project - Update 5th October 2015 I'm still considering how to make these available to others. I don't know what the uptake would be, but one thing I'm interested in is whether having an OEM mounting solution is important to anyone. I found during testing that getting my unit away from the low down right hand side position was quite important to its reliable operation so the mounting solution doesn't have to be the same and without a good source of OEM boxes the 3d printed ones are quite expensive - they actually cost more than the electronics do in small quantities! If I do make them available I think it will be in some sort of kit form. I'm still some way off being able to do it yet though.
Great work as usual Richard. I to had an intermittent TC that was creating occasional SDLs. Installing new ones corrected all of that. I had the output line tapped so could see the voltage and by wiggling the TC lead and connector, etc. I could never really pinpoint what the issue was with the TC but it would occasionally spike to over 4 volts . I believe they get an internal short that may be temp affected. I have advocated that anyone trouble shooting their SDL tap the outputs so that they know what they are dealing with when diagnosing. YOur solution negates that ais much more elegant. I think if you were actually selling these for profit that OEM size boxes and mounting would be ideal. You could offer suggestions for better mounting locations and leave that decision up to the user. Many like to keep their cars as OEM as possible and true plug and play option in the same location would fill the bill. YOu might run into harness and TC lead length whne/if you move the ECU locations as well. Just a thought that can be worked around of course.
Remember the old days of heathkit? An sdecu diy kit might be doable. If SRI can do it with the complexities of the gold connecter kit you could do it with this. You might want to ping dave and cribbj who did the maranello skunkworks projects. They could tell you about the complexities of doing this having done it many times before. Perhaps they could even be enticed to help with the project.
Doing some research on this old thread on SDECUs. Assuming that there was a situation in which the SDECUs are doing their job properly, and there was a thermal event at the cat causing a spike in temperature, would there be a corresponding spike in engine water temp or oil temp?
I would say generally no, there would not be a corresponding increase in coolant or oil temperature. The correct cause of this alarm event is generally a misfire causing fuel to be dumped out of a cylinder in to the exhaust system without having being burnt in combustion. This gives rise to overheating of the Cat, causing the alarm.
Got it, makes perfect sense. Since the SDECU deteriorates over time and starts giving false positive warnings, many owners have learned to ignore the slow down warning popping up periodically, but in fact it could actually be a true early warning of a real problem, then should the SDECUs be replaced on a regular schedule on a preventative basis, much in the same way as timing belts? And if so, what would be a sensible replacement schedule?
I don't think many people would consider replacing these as a preventative measure. They do generally last a long time. Certainly my car was 10 years+ old before I encountered any issues. When they start to create alarms it's quite easy to determine a) whether or not it is a false alarm and b) which component is at fault. Assuming you have a fault you can simply replace the offending item and rock on, maybe for years before you have another failure. I would recommend that you get an IR thermometer and put it in the glove box. These are less than €20 these days. You can then quickly check the temperature of your Cats and determine if you really do have a problem or not. In truth, if you have a real problem, your warning will normally be accompanied by a poor running engine so you'll normally have a pretty good idea that something actually is wrong.
What sort of temperature range would be best for this kind of thing, Greg? I see one on eBay for U$42 which goes to 1050C, but I'm guessing this isn't hot enough for some exhaust components. Above this temperature, they tend to get a bit expensive. Thanks.
I think normal running temperature inside the cats (where your thermocouples are situated) is abut 650c, at which time the external cat temperature is about 400c I think. Something that goes to 1000c is loads. Useful bit of kit to have for all sorts of reasons. Checking tyre temperatures after hard running or track use can indicate if your pressures are bad or you've too little camber set. Measuring Exhaust outlet temperatures will also immediately reveal which cylinder isn't firing correctly if you have a problem.
Thanks for the suggestion - that's a good idea. Always a sucker for another gadget. The rough running as a indicator of a real incipient problem can be hard to tell, given that the SDECU cuts power to the engine. Having something to confirm/reject the high temp would provide peace of mind to limp the car home or make the call for a tow truck.
