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Re: [T3] 72 square, rough idle


On 6 Mar 2002, at 19:05, Dyscord wrote:

> Valves all adjusted to .006 (most of them were VERY tight)
> Compression tested, all cylinders 110 to 120 psi
> All spark plugs gapped to .024
> Dwell set to 46 deg.
> Found out #3 and #4 injector connections were reversed, corrected.
> Throttle switch adjusted
> Dist does not have any noticable side play
> Removed and cleaned FI contacts in dist (man they were nasty, but did work) Idle
> set to approx 850 Somewhere previously someone has installed a set of resistors
> inline with the head temp sensor, to enrich the mixture Im guessing.

Good, you've found and fixed some important things. Keep in mind that this 
still MAY not be a FI problem, although things are pointing in that direction.

> Also found out the throttle shaft in the air distribution box is leaky (shot
> some chemtool on the shaft) I guess this is the reason that I feel no vacuum on
> the port that goes to the vacuum retard on the dist.?

Small vacuum leaks, especially here, are NOT a problem with the D-jetronic 
FI, and they do not explain the lack of vacuum on the retard. Are you sure 
you are looking at the retard? The advance port will never show any vacuum 
in your driveway, and the retard is down lower somewhere (this is a 72 
feature only and I can't quite picture it now.)

> Drake (getting close to putting the FI system in a box and installing carbs, but
> having a blast diagnosing the problem) Lawson San Jose, Ca

Perhaps there's someone on this list who has one of the Bosch testers near 
you. I'd try to get your car to one of those and check the resistance of the 
electrical circuit thru each injector. It is common for the contacts on the 
injectors themselves to be loose and this can intermittently keep any injector 
from firing. To test this you need to gently wiggle the injector wire while you 
check the resistance; if it jumps around you have found a bad connection.

This test is rather quick and easy with one of the official testers. It can be 
done with just an Ohmmeter and a manual, but it may take an extra pair of 
hands.

Once you work your way thru this you'll find that the FI is strong, 
economical, and reliable. Switching over to carbs only seems easy, but is 
usually expensive and takes a lot more followup work than the people who 
sell them to you will want to admit. It will also make your car unable to pass 
future DMV inspections in CA.

-
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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