Hi guys, I'm pretty new as i just got my first F355 1996 Spider Manual last week but i already read a lot here. First thing first, i'm from Quebec, Canada (French county) so my english can sound's bad sometime... sorry for that! Let start, i picked her up 300km away and drive her maybe 5 or 6 time after that. I never abuse and never passed 5500rpm. ( The car has only 16,000miles and has been stored most of the time so I went to the dealer for Oil change and decide to run the first 500-1000km slowly as "break in" period. Now the two last time i took the car after maybe 4-5 kilometers Slow Down Light goes on directly solid. (Both time was on Highway) Car goes in limp mode, i stop then after waiting SDL goes of and i can drive slowly. After trying to get my OBDII codes for maybe 2hours (Thanks all of you for all the great information here about OBDII plug malfunction) i got the following code. (No Check Engine Light) P0102 (MAF Circuit) P1124 (Long Term Fuel Trim Additive Air) P1126 (Long Term Fuel Trim Additive Air Bank 2) P1448 (Catalyst Temperature Right) P1449 (Catalyst Temperature Left) P1454 (Catalyst Protection Active Left) Now, from what I know. I dont have the green Thermo ECU but i'm not thinking of a bad ECU as two of them make codes and SDL system seems to work has it is supposed to. (I mean goes ON on highway when it "can" be HOT and after cold down, turn OFF.) I'll start trying to find a infrared thermo reader tomorrow to check if the catalyst temperature is higher than what is supposed to be. Any clue on that?
Yes, properly diagnose system before you start throwing parts at it. Checking the true CAT temperature is the first step. Don't be driving the car in limp mode. Johnk will hopefully come in to discuss this....
OK, so I checked and temperature at idle is around 500 to 600 +- what is suppose to be the right temperature for good catalyst. I also tried to switch the Bypass Thermo ECU (this one is actually green) with the Right Cat Thermo ECU and still got P1445 and P1449. If the problem is the thermo ECU, i'm not supposed to see a 1448 (cat bypass) after that? Thanks for your comment!
Let's focus on these codes: P1448 (Catalyst BYPASS flap circuit) P1449 (Catalyst Bypass Temperature) P1454 (Catalyst Protection Active Left) If you solve 1448, then 1449 will likely go away. They are related. But, 1448 says the operation of the bypass valve is faulty, not necessarily the TCU is faulty. You swapped the center TCU for the right bank TCU and you are still getting error on the left bank TCU. That did not say much 1448 has nothing to do directly with the TCU. It says your Bypass valve is not working. It is either not open at the right time, or not closed at the right time. Work on one code at a time and don't try to solve everything at once. For 1448, check to see if the bypass is actually working. You most likely can hear the difference in the exhaust when the valve opens up at 4000 RPM in second gear. If there is a very audible sound difference and you are getting 1448 code, then the TCU is probably faulty or the thermal probe is faulty. If there is no audible sound change then you have to see if it is getting the signal from the ECU, signal at the vacuum switch, vacuum at the soup can, and vacuum at the bypass valve. Solve that, then move on to the left bank code.
My bad, i'm sorry. In my post I wrote P1448 (Catalyst Temperature Right) instead of P1445. I don't have P1448 code...with that say my by pass valve seem to do not work as I don't ear it anymore. Few day's before the by pass valve stocked open even if i was on idle and now seem to be stock closed at all time. I tried to move diaphragm rod manually and move well.
As what I said in my first post all code instead of 1448 was there. I make a mistake as i wrote 1448 instead of 1445 on writing. So it was not 1448 but 1445. To be clear I never get 1448, never.... even if i think that my by pass valve dont open. Now after switching the Bypass Thermo ECU with one of the CAT Thermo ECU and after reseting all codes I took the car to drive around and under 2 kilo-meters I got the Solid SDL and theses 3 codes remain registered. P0102 (MAF Circuit) P1445 (Catalyst Temperature Right) P1449 (Catalyst Temperature Left) Thanks for your help!
Difficult to diagnose remotely but given you are getting cat temp codes on both sides at the same time leads me to believe the codes are real (along with the MAF code) If the cats are truly over heating, you could have big problems. Was the temps you posted in F or C?
@Dave Temperature was in F. idling between 450-550 F even when SDL comes up. Also I never see the SDL blinking. I think that if the cat was overheated i'll see SDL blinking then SOLID right?
Ok, I feel better that it was F. Do you smell fuel at idle? It is possible the old TCU's are shot but it's a strange coincidence that both are bad (or all 3) You would thing a blinking SDL should come first but I'm also troubled that you don't have an issue when cold (correct?)
I don't have any experience with the MAF code - 5.2's only have one MAF sensor. Perhaps the guys with experience on the code can provide some insight. Maybe that is causing a rich condition?
Usually that is the case but also when you slow down the light usually would go off within a few seconds to flashing then off. In my experience the cats cool down quite fast once the fuel feed is reduced. You can also fix them with a soldering gun quite often. It is posted here somewhere Get a temp gun and when the sdl start flashing pull over and check temp asap. It should be well over 1500 F
Smell good at idle. Exact I don't have issue when car is cold and even if car get warm and stay at idle. The only time that the SDL comes up in when driving and goes directly SOLID then goes in limp mode if i dont slow down.
Already done, temperature was about 500-550 F even with the SDL Solid and as I say SDL never goes flashing they alway went to SOLID directly.
Send me an email with your address and I will loan you a TCU (green potted) to try. Dave.lelonek@**********.com
There is a good thread in here about sdl by BoB read it and understand it. i would say your sdl circuit is not functioning correctly. Those of us who understand it would not take long to figure out. If possible try to understand the thread. Depending on year of car you have 2 or 3 catalitic thermocouples. First need too know how many. Get a shop manual and read that section as well, this will explain to you how it works. Or just take it to someone who understands hiw it works. It is not that complicated but also not that easy to explain over the net. Not sure if someone has explained it but the system that has 3 has one for each bank of cylinders and one xfor the bypass. If the cats get too hot it is supposed to flash and then roughly 65 degrees F later come on solid and shut the bank down. About 1720 and 1785 F
Honestly, I think a read mostly every tread about SDL but if you find the one that you are talking about please copy link here for me. I understand pretty well how the system work but i dont understand my SDL situation! *Edit : If you read my other post i have a 96 with 5.2 what's meant 3 Thermo ECU and i already try to switch one of the "black" CAT Thermo ECU for my "green" by pass thermo ecu.
