Motronic 4.1 in 91 Spider

[Ralph Fetsch <rfetsch@xxxxxxxxx>]

I need help from all you motronic experts on the digest. Saturday I
drove form Houston, Texas up to College Station to the Texas World
Speedway for the vintage races, which is about 110 miles from my house.
After about 90 miles my 91 Spider with an automatic transmission
developed an intermitting miss. This has done this before, about a year
ago on the same drive. When I got to the track I asked one of the
driver/mechanics I know about it and he thought it might be that the
vent for the fuel tank was plugged and to stop the next time it did it
and loosen the gas cap and listen for air coming into the tank through
the cap.

On the way home it started after about 25 miles, I didn't stop until the
missing got really bad. I pulled over and released the cap, nothing. The
car continued the intermitting miss for about another 30 miles and then
started miss really bad, I wasn't sure I would make it home. No the
funny part as soon as I got within 10 miles of downtown Houston the car
started running great.

I checked the car the next day and the only thing I could find is the
the VCT is not working, when you put 12 volts to the coil the solenoid
pin goes in but does not change the idle speed. According to the manual
it should either stop or idle really rough. The car has approximatey
148,000 miles on it, the compression is good both dry and wet, the
valves were adjusted within the last 10,000 miles, new coil, plugs and
plug wires, cap and rotor. My questions are:

1. Will the VCT not working give an intermitting miss?

2. Will driving from near sea level to 650 above sea level effect the
running and if so.

3. What part of the motronic system corrects for changes in altitude.

When this happen last year I thought maybe the coil was breaking down
under the heat since I had about 120,000+ miles on it. I want to drive
this car to Kansas City in June and want to correct this problem be
then, your help will be greatly appreciated.

Thanks

Ralph Fetsch

Houston, Texas
1991 Spider Veloce w/auto 147,00+ miles
1964 Giulia 1600 Spider

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