Hello I have a 91 TR that idles great once warm and drives great. When it's cold, sometimes the cold "Fast idle" kicks in and it runs smooth, but most of the time it revs then drops down, sputters a little, never stalls. Begin driving and it sputters a little, sometimes a backfire for the first 30 secs of the drive, then it's near perfect. Once warm no problems. I was hoping for some advice on fine tuning this system. The cold start injectors, axillary air valves and all related sensors. Because the car runs great otherwise, I am assuming that these are all the components that will need to be cleaned, repaired or replaced. Any advice on whether to clean or replace the cold start injectors, and if so, where is the best place to buy. Thanks. Brent.
The components chosen for the TR were adapted to it from other applications and were not a great match to the engines needs. The cold enrichment in the US car especially was not a good match. The car was homologated with a very lean mixture set hot without the O2 sensor attached and is what is published as a tuning spec. Ferrari told us from before the cars were even here to ignore that and set it to about 1.25% in an effort to make the car tolerable when cold. When hot in most driving conditions the O2 sensors correct the mixture so adjusting it a little richer to make it more livable when cold doesn't hurt anything. The best thing you can do is to insure it is in a good state of tune in every way and run it just a shade rich. If you do that it is OK cold. As far as bad components, cold start injectors just help it start. If it is starting ok but not running well you can probably forget those. Most of the cars we run into need injector nozzles. A bad pattern hurts cold running more than hot running. Make sure you dont have any vacuum leaks. That is another area that causes more trouble cold than hot. The connector hose between the throttle and plenum chamber is responsible for many of those.
