Greetings all! Let me contribute my tale of woe about engine surges.As a preface, this is the latest afted spending about 4000$ in 6 months on repairs. BEHAVIOR: well, at about 1200 rpm the engine getas stuck in some sort of feedback loop oscillating vroom-vroom -vroom between 1200 and app. 2000 rpm. it is then nearly impossible for my wife to drive, bucking wildly in city traffic. DIAGNOSTICS; everything seems to point to the control unit. first we replaced the temp sensor [thanks joel!] no luck! if another new sensor is clipped into the wires and the new one warmed up it still oscillates. checked oxygen sensors, for air leaks, replaced and cleaned grounding connectors , checked wiring harness, idle stabilizer... [is there anything else?] WITH THE WIRE TO THE TEMP SENSOR DISCONNECTED it does not oscillate. If the idle is turned down below 12000 it doesnt oscillate at idle but still does at the magic 1200rpm.oh,-new O2 sensor also. CONJECTURE;: there is a bad circuit in the EXPENSIVE control unit. A local vw garage also rechecked everything and suggested the following which is reasonable given we're not sure , local dealers dont stock '85's control units ans there's no return for electronics. They will call as soon as an'85 comes in which runs OK, if swapping the units fixes the oscillations they will immediately order one for my car. [of course the local junkyards dont have any] TEMPORARY FIX: You'll love this! they rigged the following up so my wife can drive the car. Disconnected the connector to the temp sensor and ran a wire from there to the rear window defroster switch, defroster on= circuit grounded, defroster off= circuit broken, one way to start the flip the switch when the oscillations begin. How's that for an antitheft device!
SOOOOO, does anyone have an extra control unit for an '85 GL they are not using???? Bill
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