Hello all of you technical wizards. I know you have all seen very similar situations, and I have poured over the archives. Now I'm looking for a suggestion. My car is a '93 348, 9,000 miles. About a month ago, my slow down 1-4 light started coming on, with the typical power loss as commonly occurs. I tried resetting the ecu's as described repeatedly in this forum, but the situation would reoccur in short order. Since many of the threads in the old archives, as well as the current board suggest that the exhaust ecu is a very typical problem, I bought one from Sodacom's and replaced the one on the 1-4 bank. I reset the ecu's again and went for a cruise. About fifteen minutes into the drive, I experienced that incredible power loss again, but this time, no slow down lights. Both slow down lights appear to work when I start the car. Both check engine lights work as well. After scanning the archives for the method of retrieving the ecu codes, I found that member Chris (92348ts) had inquired about the same. I PM'd him and he was kind enough to email the procedure and codes out of his workshop manual. I just completed the diagnostic process. Here are the results: Bank 1-4 code 4444 "no error " Bank 5-8 code4122 "catalyzer temperature too high"' So here's my question, is it in fact that my cat's are going bad, or could it be some other sensor etc...? additionally, if the cats are bad, i'm thinking of replacing them with hyper- flow cat's from Sodacom's. And if I'm going that far, I may as well put a Tubi or Capristo on at the same time. ANY AND ALL suggestions, thoughts, concerns and input would be greatly appreciated. Summer is dwindling down, and I have to get this rectified ASAP so that I can have a few nice weekends before the salt and cinders hit the road. THANKS
I jumped into this post in the hopes of helping you. But, since you replaced the ECU, I'm not sure what to suggest. Have you tried running the car with the ECUs disconnected?
tclark: If it isn't too much trouble could I ask you to post the procedure for checking these codes? James
Tom - Depending on the emissions testing where you live, you might think about going to test pipes instead of cats. If you're going to cats, I agree, the Hyperflow from Sodacom seems like the right direction. If you're not too concerned about the cat overheating and causing a big mess, perhaps you should disconnect the sensor, tie it up, and drive around for a little while and see what happens. I'd venture a guess that (having reset the codes), you won't see the temp code reappear. The risk it however, your cats dropping a turd or starting to rattle as the webbing breaks up. That suggestion however is NOT a long term solution. I would not drive around with messed up cats. Hyperflows aren't that expensive (compared to OEM cats) and they're pretty free-flowing. Why not just spend the bucks and be done with it? If it were me (and I'm cheap), I'd replace the cats first and see how things sound. There is no significant labor savings on doing everything at once -- the Tubi or Capistro ought to be a DIY job or <$300 later if you take it somewhere. Just my opinion. -Daniel p.s. Happily the PO of my car put test pipes on, and I've had no issues with temp or Slow Down lights in my 348. Maybe we should just trade cars? Those cargraphic wheels are soooo hot !
Interesting - you said you replaced the 1-4 exhaust ECU and when you pulled the codes most recently you've got no errors on the 1-4 side and hot cat code on the 5-8 side. Would it be worth swapping ECUs from left to right to see if your problem goes with it? FWIW I have a Tubi and Hyperflows - I had to buy cats as the stock ones were punched and I needed to pass California smog. I am pretty happy with the setup although I found out there is a Capristo available for the 348 now which Heiko reluctantly told me sounds better than my Tubi.... Good luck - I have solved the "hot start" 348 problem and the "dirty CPS" 348 problem and the "dodgy mass air connector" 348 problem, and am now on the "passenger power window doesn't work" 348 problem. But it is a beautiful car........ Cheers Kevin
Since you already changed the cat ecu's, then I would say that you have bad catalytic converters. However there is one more thing that can cause the slow down light to come on. That would be a faulty thermocoupler. That is the little wire that comes off of the under side of the cat, and goes to the cat ecu. It is basicly a thermometer for the cat. If that goes bad it can give fause signals to the cat ecu, causing the cat ecu to think that the cat is hot. If the light comes on again, what you will want to do is swap the thermocouplers from one side to the other, and see if you get the light/problem on the other side. Now if after you have done that and you still get the problem on the same side, it would be safe to say that your catalytic converter is shot. Reason being that you have brand new cat ecu's, and after switching the thermocouplers, you still have the problem on the same side. Meaning that you are getting a correct reading from the sensors. Now when you had a loss of power, what happend was that the Motronic ecu will shut down the bank that it was getting the high temperature signal from. It does this to help prevent the cat from over heating, which will damage it and possibly cause a fire.
His first post said he had only replaced the right side exhaust ECU (1-4) so that was why I suggested swapping sides with the ECUs to see if the 5-8 one was bad. Does that make sense? I am pretty new to this stuff but as you would note I am learning quickly.... Cheers Kevin
Yeah Kevin that does make sense. That's what I did when mine was acting up. But mine was easier to figure out, because it came on right away after the car had been sitting all night. I still swapped them just to make sure. On a side note. I saw your car down in Costa Mesa, they were replacing the axle on the left side. I was down there picking up a drivers side radiator, from Michael, for my 348.
I was reading the OEM manual for my 91 last night and it says that if the o2 sensor detects that the temp is too high - it kicks the slow down lights on - if you keep driving and the o2 detects that it is still too hot - it cuts the power to that bank of cylinders - I'm thinking that is what you feel as the massive power loss.
Hey Andy The O2 sensor doesn't having anything to do with the slow down light. The O2 sensor senses if the exhaust is rich or lean, then sends the signal to the Motronic ecu to adjust the fuel mixture. The thermocoupler it's was detects the temperature.
Ernie - I had the part wrong - I read about the thermocouple - on the outlet of the catalyst - if it senses that it is to hot - the injection ignition system disconnects the injection control.
thanks for all the responses so far. Harmony, the procedure is fairly straightforward. Remove the cover behind each seat. With the engine running, press the large button beside the ecu on the driver's side for 2.5 to 5 sec. The check engine 5-8 light on the dash will come on for 2.5 sec, then off for 2.5 sec. It will then flash on and off in .5 second intervals for the first number of the error code, i.e. four quick flashes means the number 4, one flash means the number 1. After a short pause, flashing will resume. As before , four flashes means the number 4 etc... It will do this a total of four times in order for you to read the 4 digits of the error code. The same procedure is followed for the ecu behind the passenger seat for the 1-4 bank. Hope this makes sense. If you just try it, you'll underestand what I'm talking about, if not, PM me and I'll try to make it more clear. Jack Russell Racing: Hello Daniel, I understand your point, but I am extremely concerned about simply disconnecting the exhaust ecu's at this time. If there is any possibility of **** happening, I guarantee it will. Nice to hear from you again. KFHenry: Hey Kevin, okay, so Heiko told you the Capristo is better than the Tubi. Well, more importantly, you said that you are "pretty happy with the setup" referring to the hyperflow cats and Tubi. Don't beat around the bush..... What do you really really feel? Thanks again all, hope to hear more best regards, Tom
Tom I love the way my car sounds now but I don't have anything to compare it to other that the briefest of drives in a 348ts that had what I understand was a Tubi well past its prime and test pipes. I purchased test pipes at the same time I got my Tubi from Heiko, but found I needed cats to pass smog, so got the Hyperflows. Prior to putting on the Hyperflows my exhaust smelled of fuel, so much so that it would stink up my clothing, so I don't really want to fit the test pipes even if they sound better as I'm not interested in putting up with the smell of the exhaust, plus my car with the Hyperflows is very clean on emissions. I have heard Capristos on the 360's and actually like the Level 2 exhaust sound, and I understand generally that the Capristo has a higher pitch than the Tubis based on hearing them, but I don't know what the Capristo sounds like on the 348 so again don't really know. I didn't know that Capristo was developing a system for the 348 at the time I got my Tubi, and had a brief e-mail exchange with Heiko where he said he thought the 348 SOUNDED "better" with the Capristo (not that it IS better as in construction or something) - that is going to be a matter of taste of course. I will say that the Capristos sure look cool, although in a 348 you don't get to see much what with the heat shields and all. Bottom line is that I have other stuff I want to do with my car and I certainly don't need two $3K +/- stainless exhaust systems for my car, but there is just a little tiny demon in me that wants to hear what my car would sound like with the Capristo. So I really really feel that I love the Hyperflows and even if test pipes sound better I am not putting them on for the street, and I would really really like to hear a 348 with the Capristo to compare to my current set up. Really. Cheers Kevin Keep us posted on your current dilemma - it hasn't happened to me yet but I am sure it will.
Cant say if this is relevant entirely or not, but the other day I was driving when the check engine 5-8 lights came on and there was a power loss. This has never happened before with the car. The fuel level was very low on the car, so i tanked her up. After driving for approx 15- 20 minutes all the lights went off and the car is running fine. Could be fuel related.
I tend to agree with Ernie, go ahead and swap around your thermocouplers to determine if the problem switches sides. When I was having the same problems with my 348 it turned out to be a hairline crack on the end of the thermocoupler (inside the cat) that was letting in excess heat, tricking the ECU into thinking the cat was overheating.
I had the same thing happen to me and once I swapped the thermocouplers around the slow down lights moved to the other side of the car. Another thing to check is to make sure that the wire is in good condition running to the thermo. I have seen those crack all to hell from the temps causing the same failure. I just disconnected mine as I have no cats and it was impossible to be overheating the exhaust. Sounds much better without it to!
i was doing some search on ecu-s and needed to clarify this....."shutting down a bank". i don't want to sound stupid but it shut downs the first four cylinders? prob it does sound a little ridiculous but plz explain...thanks
It just runs the fuel injection in that bank at limp home mode, enough to limp but no power beyond that.
The way I understand it is the Ferrari 3.4 is essentially two four cylinder engines sharing a common crankshaft. The left bank is cylinders 5-8 (I think) and the right is 1-4. The crank is unique in that it is a "Flat" type which allows a simple left-right firing order unlike most v8s. With separate fuel pumps, injection rails, ignition modules, intake plenums, and computers, each bank is almost totally independent. If one side shuts down, the engine becomes a four-cylinder engine firing every half revolution just like any four banger. This is not a limp mode as in a modern car but rather a result of loosing half of the cylinders. A number of failures can shut down a bank and in some cases without a fault light. You won't have a lot of power but it runs pretty smooth. Since the two banks don't talk to each other, Ferrari (Bosch?) worried that if you drove for awhile on one bank, unburned fuel could pump into a hot cat and ignite. So, they added the slow-down light. If it gets too hot it will shut down both banks after first warning you to slow down. Dave
