| Author | Message | ||
| Julio Valladares (Jbanzai)
Junior Member Username: Jbanzai Post Number: 107 Registered: 2-2002 |
Well I did receive the Stebro Resonator to replace the CAT, and I had installed it. At the time I installed the test pipe I removed the Thermocouple, and suddenly found the cause of my Slow Down light. The Thermocouple cable had a tear in the shield cover. The tear was hidden beacuase was exactly in the point where it gets into the trunk by a little hole. The tear was big enough that at time each part of the shiels did not make proper contact, therefore breaking the circuit and turning on the Slow Down light. Wiht the vibrations will make conntact at times, and then the light will turn off. Does enybody know if I will alter the thermocouple properties if I cut the cable and fix it and putting it back together by soldering the interior cable and then joining the shield again? Also, although, the test pipe does not have a place to insert the thermocouple, it will be relativly easy to make a small hole and solder a screw with the same metric than the Themocouple. Will that be better than taking it out? Thanks. | ||
| Julio Valladares (Jbanzai)
Junior Member Username: Jbanzai Post Number: 70 Registered: 2-2002 |
Thanks DGS, that is great info. I might look into it, I was reeading in the net about some programable thermocouple controllers. They can be configured to rise an alarm or ground a connection at any setting desired, and they where not as expensive, they where 150 Euros. I am going to try to get more info about these devices. They might be a good way to test, and then it will be easier to make a substitute controller for that board. Julio. | ||
| DGS (Dgs)
Member Username: Dgs Post Number: 338 Registered: 5-2003 |
*sigh* I knew I was going to have to dig out the wiring diagram again.  Pin 4 of the CCU and pin 6 of the lambda computer are wired together. That connection also connects through a diode to pin 19 of the Marelli ignition computer and to the idle position of the throttle microswitch. From the wiring diagram, when the car is at idle, the idle microswitch grounds pin 19 of the Marelli and pin 6 of the lambda computer, causing them to respond accordingly. My best guess is that the CCU grounds its pin 4, causing the lambda computer to think the car is idle, but - because of the diode - doesn't send that ground to the Marelli. I'm guessing that pin 4 is ground until the cat reaches 300C, at which point pin 6 of the lambda computer works normally -- closed loop, except at idle. (Or at WOT which the lambda computer gets separately on pin 12, or cold coolant temp, via pin 7.) If that's the case, then the car should operate almost normally with the cat control module removed entirely -- it will stay in open loop until the coolant reaches 57C, the oil reaches 25C, and whenever the idle is fully open or closed. The only difference is that it may operate in closed loop with the cat still cold. That might be a problem if the O2 sensor isn't getting hot enough from its internal heater, and isn't giving accurate readings yet. Of course, without the CCU, you don't get a warning ("slow down") when the cat gets too hot. A simple thermocouple driver, a couple of voltage comparators, and a 555 osc (to flash the light at warning) should be able to replicate the functions of the CCU. That might be an interesting project. Of course, I've already got projects stacking up, collecting dust.  The same coolant temperature switch also grounds that solenoid, directly above check valve #3 in your diagram, so a short to ground there might have been giving your lambda computer a bogus "cold" indication. That's what I don't like about Bosch systems from the '80s -- too many inter-dependent parts, with no self checks at all. You pretty much have to test everything, one by one.  Oh, and Bill, I've got an 8088 sitting up in my attic, too. But I haven't tried booting it since 1989. I've even got an old Atari 800 and an original Radio Shack Coco stuffed away in storage, somewhere. Maybe my heirs can open a museum.  | ||
| Julio Valladares (Jbanzai)
Junior Member Username: Jbanzai Post Number: 65 Registered: 2-2002 |
My work is in Information Technologies and I see that everyday. Still I bet that the ECU units in the car are more complicated than that board, and they are only a fraction of the price (it is a pitty that I am so affraid of trying to take it appart). The real difference I think is that the ECUs are BOSCH manufacture and common or similar to other K-Jetronic injections, while that CCU box was probably custom made for Ferrari. As you say, if we had the electronic design of it it would easy nowdays to replicate it, if not improve it, quite posible even to replace the Thermocouple + CCU together for a way cheaper solution in the 10s of Dollars instead of the 1000s. Reverse engineeing will be expensive, in materials and time, first of all because as you said, needs to be done over a functioning design, which I am not sure I have. However Tillman mention that there was a gentelman who already did that reverse engenieering on the CCU, and the only remaining thing was to know when the CCU had to really set the closed-loop. So it should be at 300C, right? Even if the CCU is not who sets the closed loop what it sure it does is setting up (or down) one of the signals for that to happen when the thermocouple reaches 300C, right? That might be what this gentelman needed to know. Thanks again. | ||
| Bill White (Nc_newbie)
Junior Member Username: Nc_newbie Post Number: 168 Registered: 2-2003 |
DGS, I've got one of the very first 64K IBM PC with the 8088 if you want it! Bill | ||
| DGS (Dgs)
Member Username: Dgs Post Number: 336 Registered: 5-2003 |
From the tech notes, the CCU (cat control unit) enables closed loop at 300C (not 300F). From the tech specs, the "slow down" light should flash (warning) at 900C (+/- 20), and light steady (error) at 940C (+/- 20). It's not clear from the wiring diagram exactly what the circuit is doing to enable the closed loop at 300C -- some direct testing on a functioning circuit would be required. For the "slow down" light, grounding the lead at the CCU would make the lamp illuminate. With some tests to work out the exact functioning of the lambda loop interactions, it wouldn't be very hard or expensive to whomp up a circuit to do the same thing, using today's technologies. The high price comes with getting an original, made for the Ferrari, circuit -- designed 15-20 years ago. When these cars came out, the hot "personal computer" was an IBM 8088, with a 10MB hard disk (on the high end units), and with a 5.25" floppy that really was floppy. Try to find one of those today that still works, and the price of an "original" Ferrari CCU might not seem that far out. | ||
| Julio Valladares (Jbanzai)
Junior Member Username: Jbanzai Post Number: 59 Registered: 2-2002 |
Thank Bill, Is just that what the CAT Control Unit does? It just set the closed-loop when the CAT reaches 300 F, and ground the Slow DOwn light when the temp reaches 650 F? It should be failry simple to build an electronic circuit to do the same thing, even to make it adjustable, or simpler, timed. Please tell me that that 2200 US$ box does something else. ;) Thanks. | ||
| Bill White (Nc_newbie)
Junior Member Username: Nc_newbie Post Number: 167 Registered: 2-2003 |
Gentry Lane in Canada did have one on ebay a while back for $199 USD. You may also try GT car parts. I don't think it would be a issue running open loop because it would just be a little richer. To put it into close loop you ground the orange/pink wire. You could build some electronic to do it add a switch or just leave it open or closed. It might feel a little lean when cold if you leave it in closed loop. | ||
| Julio Valladares (Jbanzai)
Junior Member Username: Jbanzai Post Number: 56 Registered: 2-2002 |
Thanks Bill, I haven't posted anythink lately regarding this because I am not sure what is going on. It could be a bad contact, it could be bad ground , a bad thermocouple, or a bad CAT Control Unit. Now, sometimes the light flashes like if there were a bad contact or ground. However I have tested the conntacts and they are good. I have unplugged both ends of the cables and tested them against ground, and they are good. So this is quite unlikely. So today, I have tested again the Thermocouple, and now I am getting wrong readings, I am getting +70 milivolts at ambient temperature. So in some way that will make sense, and the light should be on, as the ECU will think the cat is well over 1000F, except that when in the car if I accelerate and the cat gets hotter the light turns off, whick makes no sense as the thermo couple readings reaches occasionaly 1 volt. I am the point that all I want is to get a Test Pipe or resonator and remove the CAT and the danm, Slow Down light. But, if the close-loop/open-loop is controlled by the CAT Control Unit, wich only sensor is the thermocouple, how will I get it to work properly once I remove tha CAT? The test pipes have a place for the oxygen sensor, but it does not for the thermocouple. Do you guys know where can I get a cheaper thermocouple than the one sold by Ferray UK so I can test it. I do not want to spend 250 Euros on something that I might not need. Thanks. | ||
| Bill White (Nc_newbie)
Junior Member Username: Nc_newbie Post Number: 166 Registered: 2-2003 |
Julio, I think your problem could have been bad contacts on the 4 wire connector? Tillman, I just checked in and saw your note about my designing a new ecu. I just ordered a raytek temperature sensor this weekend so I could calibrate my design. I am going to put in the CIS control but needed the raytek to set it to go into closed loop at 300 deg. Bill | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 50 Registered: 2-2002 |
I do not know what to think now. Today I started the car and give a short ride. The Slow Down light was on when I started the car, after about 2 miles the light started flashing on off like when there is a bad contact. And then, it went off. I stoped the car, and look if everything was ok, and did not see anything wrong. Then I started the car again and returned home. To my surprise seems like the Slow Down light works again like it was suppoused to. It turns on when I start the car at the same time than the security belt light, then I start the engine and the light goes off, as it did before I had the problem with the air valves. So I was suspiciuos that the whole thing did brake, the thermocoupler and the Control unit. So to test it I removed the thermocoupler and applied a lighter to it, and voila, after a while the Slow Down light was on, I removed the lighter and suddenly went off. Off course I am not sure if it does it at the right temperatures, but it seems to. So I do not how, suddenly it seems to work again. Is it posible that when the car had the air valves problem some unburnt gas got into the cat, and that today after a short run that gas was burnt at the cat and everything returned to normal? Thanks. | ||
| Tillman Strahan (Tillman)
Member Username: Tillman Post Number: 957 Registered: 11-2001 |
Just to be clear, I only recently (2 months ago) discovered the problem. However, the car has run fine. Once I get through emission testing in October, I may simply put a test pipe/resonator on it. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 47 Registered: 2-2002 |
Oh well, what worries me is what DSG said bellow: "If your thermocouple control module is bad, then you might also running the CIS in "open loop", as the module enables closed loop operation above 300C." I guess I will try to drive it and see if I have any problem, short rides, then longer ones. I hope this gentelman you mention finds a way to replicate the circuit. Please let me know if I can help in any way.  Thanks. | ||
| Tillman Strahan (Tillman)
Member Username: Tillman Post Number: 955 Registered: 11-2001 |
That's why I have a fire extinguisher Seriously, it has apparently been broken since before I owned the car. I've had it a year next month and put almost 10,000 miles on it. I'd like the thermocouple/light to work, but I can run without it for now. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 46 Registered: 2-2002 |
Do you drive your car? As I just got this problem about two weeks ago and I am still affraid of something else being the problem and running with the CAT too hot and being a fire hazard. Thanks. | ||
| Tillman Strahan (Tillman)
Member Username: Tillman Post Number: 953 Registered: 11-2001 |
Ok, I misspoke. It is the resin block that he's reverse engineered and has created a replacement circuit board. The last I heard there was some debate about when to pull the fuel injection into the closed loop mode | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 45 Registered: 2-2002 |
Thanks Tillman, but it is not the ECU, although is related. It is part #61402500. In fact I almost wish it would be the ECU instead. The ECU is cheaper, 'only' 600 Euros (about 540 US$) according to www.ferrari.co.uk parts service. This is a small control circuit covered with a plastic resine that sits beside the ECU. However it might be good to have that contact, he might know what is inside that thing and a 'better', meaning cheaper, replacement, could you send me an email with it? Thanks in advance. | ||
| Tillman Strahan (Tillman)
Member Username: Tillman Post Number: 949 Registered: 11-2001 |
There is a gentleman on here working on a replacement ECU for the 3.2. I have his info at the house and can get it to you if you want it. I am in the same situation (bad ECU) and am awaiting the final configuration. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 44 Registered: 2-2002 |
Ok so I umplugged the CAT Contol unit and the light was off when the key is in the ignition position. Then I tested the 4 pins in the CAT Control unit and none was grounded. Then I tested the 4 pins in the cable side and 3 were grounded, the black (off course), the brown(redish) and the blue. The yellow/fucsia (looks yellow to me but it coul well be an orange or light browndecolorized) was the only one not connected to ground. But as when the unit is discconnecte the light stays off I guess that what is broken is the CAT Control unit. DSG, if I did read correctly your post the Slow Down light should be off when the ignition is on before the next turn to start the engine, and in my case, that is only true when the CAT Control unit is not pluged in. Danm, that little white electronic brick is ridiculously expensive. Is there any way to diagnose it before I drop +2000 Euros for that thing. Of course if that is my alternative, and because I am in Europe, I rather replace the CAT with a testpipe and diconnect that light. Thanks. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 43 Registered: 2-2002 |
Thanks DGS, Yes, the light comes on with ignition before even starting the engine. I will look for the ground problem this weekend then. If is that, it was an unlucky moment to show up, at the same time than another problem, who diverted my atttention to other possible causes. I will let you know if I found it. Thanks again. | ||
| DGS (Dgs)
Member Username: Dgs Post Number: 333 Registered: 5-2003 |
The cat thermocouple control module (on the ECU board under the right side of the rear storage bay) grounds the "slow down" lamp to light it -- the bulb gets voltage from the instrument cluster. If the (Rosso-Marrone) wire from the lamp to pin 2 of the control module is shorted to ground, your lamp will be on, regardless of what the cat ECU is doing. If the "slow down" lamp comes on with the ignition, without even starting the engine, this may be the problem. In this case, unplugging the wire from the thermocouple control module will not make it go out. If that isn't the problem, you might have a bad thermocouple control module on the ECU board. The lamp is supposed to come on steady only when the cat is above 940 degC. It's supposed to flash above 900C until 940. If your thermocouple control module is bad, then you might also running the CIS in "open loop", as the module enables closed loop operation above 300C. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 41 Registered: 2-2002 |
OK, so the slow light is not on because of the Thermocoupler. I tested it as described and it seems to be fine; no canble problems, no shorcuts and the probe is good and reacts to heat changes as it should. Then I started the car with the Thermocoupler detached from the CPU, but the Slow Light was still on. All my problems started the valve #3 in this diagram broke, by age, my car has 68000 miles.  The Slow Light did not come up then though. I arrrived home stoped the car looked for the noise and found that the valve #1 was melted and the noise came from exhaust air coming through the tube where that valve was atached before. It was then when Slow Down light came up for the first time, right away when strating the car, as always it is on with the contact, then just after starting it goes off, except this time it did not, and it is still the same. Steve Magnuson explained me why the valve melted: http://www.ferrarichat.com/discus/messages/112/309352.html?1062545377 . When removing the parts I found that a lot of crap that was done to the exhaust system by previous owners, but I have not touch anyting of that... yet. So 2 days ago when I got the parts I replaced those two #3 valves and the #1 valve, and put everything together. Now the car sounds fine and other than the light I can't see anything wrong. Only that the Slow Down light does not go out. I do not know where to look next, and I am afarid to drive the car because of the fire hazard in case that the light is on because something is really wrong with the cat. Any a ideas on what could be causing that Slow Down light to stay on? Thanks in advance. Julio. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 40 Registered: 2-2002 |
Thanks Bill, so the ff the cable is broken the volt read will be 0, right? Therefore the Slow Light should be off, unless the box checks for the integrity of the circuit. I will remove the thermocouple tonight and test it, although for your descripton on how it works, I think that I either have a bad thermocouple, or I have a bad gnd in the cable. Thanks again. | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 533 Registered: 5-2001 |
Julio, Thermocouples are not resistance sensors. They physically generate a DC voltage. I'm not sure of the color of the insulation on your 328 thermocouples, but on my 78 308, the OM says they are yellow and red (paired wires for each thermocouple). Assuming they comply with the ANSI color code for thermocouples, the red and yellow insulators are consistent for type-K (chromel-alumel) thermocouples. The sensing end is screwed into the body of the cat and senses the local gas temperature. The other end is terminated at the sensor box, probably in the passengers foot well. I can't help you with testing the box itself because I have no information on the internal circuitry. The thermocouple itself, is very simple (just 2-wires joined on the sensor end) and easy to test. To test the sensor itself (just the thermocouple), one could disconnect the box end of the thermocouple and attach a voltmeter, + side to the yellow and - side to the red. Set the scale to the DC milivolt range as you will be reading very small voltages. Withdraw the sensor end from the cat. Apply heat, from a lighter or torch, to the tubular projection. Assuming the box end is at 70 F, you should read a dc voltage of: 0.00 volts when the sensor end is at 70 F 2.4 milivolts when the sensor end is at 212 F 9.0 milivolts when the sensor end is at 500 F 20.6 milivolts when the sensor end is at 1000 F a (-) voltage when sensor end is below 70 F These values will change slighly if the box end is at a temperature other than 70 F. A thermocouple generates a DC voltage based upon it's ends being at different tempertures. In the case of the box end, we are assuming both the red and yellow ends are at the same temperature. | ||
| Julio Valladares (Jbanzai)
New member Username: Jbanzai Post Number: 39 Registered: 2-2002 |
My Slow Down light is on upon start of the car, the light did never come up before , even after a hard drive. It jus dis some days ago when I started the car, and it never goes off. I am suspicious of the Thermocouple probe or the cable connections, as the car recently had the exhaust tighten up and I am suspicious of something related to the thermocouple getting lose or broken. I was wondering how could I test the Thermocouple to be sure if that is the problem or if I have a real problem with the CAT. I guess it is just a resistor senible to the heat and I should be able to read it with a tester, but how do I know which are the right readings? Thanks. |