My 1992 512TR has been exhibiting the following occasional symptoms: * Starts and runs fine, but after running 30mins or so on the highway, as I slow down, I sometimes get the slow down cyl 1-6 (or occasionally the light for the other bank) for momentarily - and it loses power as the affected bank cuts out (I guess this is by ECU design which cuts off the fuel) and it coughs and splutters briefly. Typically seems to occur around 2k rpm. * Doesn't seem to happen at higher revs. * More recently, I have had the odd pop in the exhaust as the engine stutters momentarily but no slow down lights come on. This happens on virtually every 2hr drive, typically around 3 or 4 times, and each times only for 1-3 seconds. Otherwise, no sign of any roughness. I am guessing the cat O2 sensors are ok as this is a transient problem. Where should I start looking - cam timing, bad plugs, fuel pump were some thoughts, but before diving into it, just wanted to hear if anyone had ideas? Thanks
I will put together a reply; but in the mean time, you should use the search tool and search the archives. This has been discussed hundreds of times, and you'll find a lot of useful information there. I would use the advanced search, choose "search by thread titles," and type "slow down". Reply to follow.
First -- stop driving the car! Don't continue to drive the car if the "Slow Down" light comes on every time! Your problem is either one or two of the following: there is a significant problem with your car, or there is no significant problem with your car but simply a problem (or problems) with one or more of the components that make up the engine control system. So, you need to take a look at the components and test them out to see whether the system really is doing its job or whether it's throwing the light on erroneously. You see, the Slow Down light comes on because the thermocouple, the thermometer which is connected to the catalytic converter, sends a signal to the thermocouple control module (a.k.a. "cat ecu" a.k.a. "thermocouple ecu"), which then throws on the light. The light is supposed to come on ONLY when the temperature is dangerously high in the catalytic converter. In the case of an actual temperature problem, it would be the case that you should have seen a Check Engine light first, which should have warned of an initial problem with catalytic converter temperature. But even if you didn't see a Check Engine light, we cannot make a conclusion. In the case of no actual temperature problem, a bad thermocouple, thermocouple ECU, or oxygen sensor (this one being unlikely) could be causing the problem and throwing on the light when no actual temperature problem exists. I am sure there could be other culprits, but those are the main ones. Do you prefer doing this work yourself or having your mechanic do it? I'll refer you to this thread where Ernie, one of our esteemed experts and do-it-yourselfers, explains how to diagnose. http://ferrarichat.com/forum/showthread.php?t=236791 However, I will chime in with respect to the area of how to actually determine whether there's a problem with the way your engine is running. If the engine is running rich, over time it will cause excessive heat in your catalytic converter, which will eventually melt internally and cause a host of problems, the worst being throwing your car (and even worse, you, God forbid) up in flames. So, you should have the engine tested. The way to do this is to test the exhaust gases BEFORE the catalytic converters with the oxygen sensors DISCONNECTED. Have a four-gas analysis done and have your mechanic look at the numbers when the engine is tested in the aforementioned way. The engine should run just fine on its own without the oxygen sensors. The oxygen sensors exist to make MINOR corrections to fuel mixture. They cannot, and will not, correct an engine that is running too rich to begin with. And if the oxygen sensors are bad, they can also cause problems. Beware of the mechanic who simply replaces your (expensive) oxygen sensors and declares the problem fixed. So, if the numbers from the 4-gas test are within the usual parameters (any knowledgeable mechanic will know where the HC, CO, O2, and CO2 #s should be), then be grateful. Now you've confirmed you've got a bad part somewhere and not an engine that is running rich due to an unknown and possibly difficult-to-diagnose reason. Oh, and in addition to the three above mentioned components, the bad component could be your catalytic converter itself. A normally running engine that is sending exhaust gases to a catalytic converter that is broken up internally -- already melted -- can heat up the catalytic converter. You can always test out your catalysts by either taking a look at them (they'd have to be out and in your hand), listening to them with a scope, or testing the exhaust gases (with the 4-gas analyzer) at the tail pipes to see if they are doing their job. Once you've gotten to the bottom of this situation and have corrected the problem, I recommend having both stock catalysts replaced because they're crap. Get Hyper-Flows or some other aftermarket catalysts because the Ferrari ones are ceramic inside. The metallic ones stand the test of time to a much more acceptable degree. However, I must stress that even an aftermarket catalytic converter will look like it came back from Hiroshima if your engine is running rich. How do I know? It happened to me. Now I'm an expert on this subject
On another note, you might consider filling out your profile... a relatively new user is more likely to have attention paid to him when he introduces himself and tells the community his name, location, etc.
Thanks for the detailed reply - really appreciated. I did do a quick search earlier (but will dig deeper now). I had been originally tempted to rule out bad ECU/themocouple (given both banks exhibit this behaviour to some extent). I had also thought (maybe incorrectly) that if it was running rich, then the "slow down" lights would stay on for a while or indefinitely rather than flash for 1-3 seconds and then run fine for an hour afterwards as it does in my case. I am about to pull the spark plugs and check those which seems to be another potential cause. Doing the gas test is beyond my ability and tools - so off to workshop I go if I come up blank on other leads. Thanks again PS - yes, good time to fill out the profile!
I would say don't bother with the spark plugs right now. Really. Follow Ernie's procedure that he indicated in the thread I have referenced. In the amount of time you will have consumed to checked the spark plus, you might have easily solved the problem using the time elsewhere. By the way, have you got Ferraris on the brain at 12:30am??
Actually, since you have said you've seen it on both banks, I'm not sure that Ernie's trick will work. So -- the Slow Down light NEVER comes on the dashboard when the engine is cold?
Thanks - yes, to confirm, the lights never come on when cold. I usually warm up on a highway for 25-30mins before hitting the interesting roads, and if the slow down lights flash briefly, it is when I slow down towards a stop sign. When I accelerate away, it would clear. Sometimes it would persist for a few seconds but once I hit 3k rpm, I don't see it again for a (long) while. PS: Yes it is 12.30am, but these gremlins have a habit of keeping you awake!
I've had my 1992 512TR for ten years and it often had this problem, I have test pipes no cats but still have thermocouples hooked up, Euro cars wont run with these disconnected. When it first occured took it to dealer several times to no avail. I was advised to clean all electrical connections and the multi pin plugs to the ECU's. It still does it occasionally, but it does not seem to cause any real problems, so I've learnt to live with it !! stop worrying !
Thanks Bazzis - I have now had this for about a month (4 or 5 long drives). Do you see this issue come up on both banks? I figured that if it was only one bank, then I might be able to trace it to bad ECU, thermocouple etc, but I get it on both banks though the majority is on cyl 1-6. So might be further upstream. Have taken out the cats and checked them out as much as I can, I am going to have the exhaust gas analysis done as suggested by 348SStb, but if I can't nail it and the car (with or without its driver) hasn't gone up in flames from a cat fire, then I guess I'll have to learn to live with it - though it does make me uneasy. Does your problem occur on both banks? Thanks
My car had the same problem a year ago. I replaced the cats with Larini test pipes & the problem seems to go away. Now the exhaust fumes really stink though.
After a search, I figured I'd respond to a slightly older thread, same topic. I took my 'new' to me 512TR on a 90 mile drive this weekend. A fabulous trip, every mile, all fun with the best sounding exhaust of any car I've ever owned. It has a Tubi, still running twin cats. However... TWO times on the trip - once on the way up, once on the way back - the "slowdown 7-12" light came on. Stayed on for 3 seconds or so, went out, just like that. Didn't come on again. Didn't shut the bank down. All I did the first time was back off the accelerator. Second time, just held my speed. I averaged maybe 70-75 the whole time. The next day, went on a 50 mile trip, half expecting the same thing. But no light, no nothing. Background clues if needed - 1. The night before the 90 mile trip, my battery died due to owner error. Replaced with new. Allowed the car to idle the requisite 10 min or so to 'reset'. This according to another thread. 2. After 90 mile trip and before the 'slowdown'less 50 mile trip, I added one quart of oil as per the dipstick. Any theories to the mystery of the 'slowdown' light here?
Hi Alan, Well, my post in this thread (#3) applies. It could be an electrical problem... Or it could be the real thing.
Other things that can cause your lights to come on are the mass flow air sensors being bad or fouled. Fuel pump going bad no fuel pressure. As mentioned above the thermo couplers can cause the issue too but wanted to add on these items as well. Good luck. One test you can do is put your hand next to the exhaust and feel the temp on one side verses another side and see what exhaust gas is hotter.
While I still haven't cured to whole problem, cleaning the connectors to the cat ECU - where the thermocouples go into before the ECU has helped a lot. Definitely worth checking that your cats haven't disintegrated first before taking it out for test runs. I thought 512TRs ECU cut the fuel to the relevant bank when the slow down lights come on - your case where the bank is still running as the lights come on sounds odd. I think the TR with the older ECU doesn't cut the bank.
What a quick response ! I mentionned the same faults with my '92 512TR and no one gave answers with which I could solve the problem... http://www.ferrarichat.com/forum/showthread.php?t=243022 Seems to happen more on the 512TR... I drove it today and again after 10 kms and 20 kms again misfiring and ligts... What can it be... both lights were lit (right bank and left bank...).
We have now tested over 20 hrs on cables, sensors (+O2 sensors) etc.... nothing wrong ! So all electrical things... Not to forget the alarm system but that was not causing errors... Now we will look at the fusebox, fuelpumps ... and hope we can find the malfunction...
Problem seems to be a faulty phase sensor..... (FIG 20; STOCK# 146233; needed: 1; name: Complete phase sensor) We will replace it a.s.a.p and write the results here ! Gr from Mel in NL. Image Unavailable, Please Login
Mine went as mysteriously as they appeared. Went on about a 90 mile drive, didn't get the dreaded lights. I suspect code fault, but am such a lazy person, I haven't even cleaned my electrical contacts. I'm just driving and watching. (Oh, and name is "Adams" like a last name.)
Okay Adams, but maybe the problem comes back one day...... Another suspicous item is (one of) the Angular Speed Sensors.... (Fig# 21, stock# 130975, needed: 2; name: Angular speed sensor) Will let you know... Image Unavailable, Please Login Image Unavailable, Please Login
Angular Speed sensor price................................................ $279.48 each ............ whaauw and you need two..... Phase sensor (Ricambi # 146233) price................................. $719.70 each Image Unavailable, Please Login Image Unavailable, Please Login
Cleaning connectors in the chain from the thermocouples to the ECU seem to have partly solved the same issue on my car. I am curious about how you traced your fault to the phase sensor / angular speed sensor - this is the first time I've seen anyone link the slow down lights issue with these components. A great piece of detective work on your part!
Basically on the 512TR there are only 3 sensors: the 2 Angulars and the Phase sensor. We spend tens of hours checking alarm (cut-out), cabling, other sensors and than returned to these 3 basic ones.... We changed the Angular sensor of bank 7-12 yesterday. We had only one ordered because of the big money they cost ! And happy to tell you: 99% of the problems are now SOLVED ! I drove 125 kms highway this morning and only 4 times a 3 second period red flash ligt and slowdown of the engine... Not anymore every 2 km's or so... Will order also the second Angular sensor and believe we solved this 512TR problem for good. Will tell you more if this sensor is fitted in about 2 weeks from now. Hope this contributes to the knowledge of our cars for all 512TR drivers: it can happen in your car too....
