1999-2009 [Subscribe to Daily Digest] |
Couple of thoughts, here, as I do believe from owning SAABs for 20 yrs that SAAB engineers did not purposely overlook reliability when designing the DI :
Fuel. There is growing use of non petroleum products in US gasoline, as we subside the use of ethanol from corn in gas, with percentages of 10% and above in the mix. Does ethanol burn higher than petrol ? What is used in Europe, and does SAAB experience less DI failure there ? Also do we experience more knock from US fuel, due to differences in octane additives as well as fuel composition. As you know, pinging causes the timing to be retarded, and later timing typically = higher heat in combustion chamber.
Measured temperature in the space where the DI sits. Do not know if such a thermometer exists, but it would be interesting to remove the DI and put a thermometer in there and take a read on a hot day after a some stop and go driving with the AC running. Think of these conditions, hot day, AC running causes higher heat from condenser exhaust as well as additional engine load. Then when engine is shut down, as heat percolates upwards from the top of cylinders to the area where DI sits, the DI spark plug cleaning cycle kicks in for 30 seconds, as the capacitors, coils, and likely ICs or diodes of the DI produce their own heat in the cycle, which probably consumes more energy than any other time to clean the plugs. All these electrical components have nominal and sometimes maximun temperature ranges listed by their manufacturers. So if temp reading exceeds any of these specs, faulty design. In any event, high temps do shorten electrical component life spans dramatically.
I do not know if this is factual or not, but with my old 1986 9000 I seem to recall the radiator cooling fan running a lot more frequently than with the 9-5 in the summer months. I recall reading a posting, maybe from Townsend suggesting replacing the radiator fan thermostat switch with one that kicks on at a lower temperature, this might be something I'll do, as it would seem to help keep temps down at the engine, and cool it down better at shut down.
posted by 198.81.26...
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