thermocouples

On your model there is no "intelligent" connection between the overtemp warning light ecus and the engine management system -- so, they only turn the lights "on". (On later F models, they did add an intelligent connection to disable the injection system because no one would ever stop! )

Try a search on "thermocouple mv" and/or "thermocouple type" -- I didn't look at all of them, but this is an example with some good data/info:

http://ferrarichat.com/forum/showthread.php?t=58614

If you are running active cats, it's best to try to have a working overtemp detection system IMO. If you don't have active cats, you don't need this system. If you need a new one, I'd start with the usual (non-dealer) F suppliers (Rutlands, RicambiAmerica, eurospares, AllFerrariParts, GT CarPart, etc.). Unless the price is just really, really stupid, it's hard to justify the time/effort required to design your own IMO.

 

Depends somewhat on the design of the muffler that you are using. If you know that the muffler you are using is symmetrical inside, or if the two paths are completely independent, an unbalanced flow at the tailpipes would be a clear sign that you still have an obstruction inside. The "stock" muffler is not symmetrical inside, so the flow at the tailpipes is not equal even when all is OK (so you really can't use this "tailpipe" test to determine if you got it all out or not). If you want to go beyond the "when I shake it, I can't hear anything rattling inside" or looking inside with a flexible boroscope, they do make pressure gauges to measure the exhaust pressure, but these usually are designed to screw into the O2 sensor fitting; however, your model doesn't have O2 sensors, so if there isn't an "inspection" fitting on the cat inlets, you might have to add some sort of fitting to use this type of tool.

 

Steve do you know what the normal exhaust header, cats and muffler temps are ?is it normal to get 900-1000 temps ?

 

A really good resource to have is a schematic for the engine. It is worth tracking one down 'cause you can follow the the wires from the thermocouple...type K....to the ecu and to the dash lamps. I was measuring 276 deg. C in some cats on a 355 after a short warm-up to fans turn-on. And the red wire is negative and yellow is positive. FWIW


Jeff Pintler
89 348tb,86tr

 

Headers and mufflers are usually only in the 300-400 degree range. Cats are much higher, in the 900-1000 range when they are working properly, they wiil be much higher if they have unburned hydrocarbons (raw fuel) going into them. I have seen some glowing bright orange at night.