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33 for spares ... with few miles left to serve hopefully

785 Views 4 Replies 3 Participants Last post by  88liam
I bought a metallic green 1991 33 1.7 I.E. few months back as a spareparts car

Didn't pay much attention to the car when I bought it as it was going to be dismantled and the price was "almost free", but the guy who I bought it from said the car would pass MOT if I fixed the leaking exhaust pipe.

I drove the car almost 200km to my garage and during that time it worked like a charm.

Haven't had much time to inspect the car untill now. I spent 2 days fixing the 3 doors and trunk lid that wouldn't open plus the drivers door window that wouldn't stay up... and I have dismanteled most of the back interior by now.

Been driving the car in and out of my garage, so I thought I'd give it some time to charge the battery by letting it idle for a while on the yard. After a minute I noticed an odd "pulsing" sound from the air filter side of the engine... Like a hamster in the engine being squished to bits while it is screaming for it's life *eeep* *eeep* *eeeep* ... then after ~4minutes of idling the engine started to die out, lowing rews really low, but still managing to stay on. Reminded me of them videos in youtube where they seized engines by removing the oil and letting them run (thou the 33 has oil in the engine).

Any pointers on what the problem might be? it's not going to pass MOT if it can't idle for 5 minutes!
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An idea for the irregular idle:
As the coolant reaches about 40*C the thermal contact will close at the front of the RH intake port.
As soon as the thermal contact closes the bimetallic throttle bypass valve (mounted to the RH intake
port too, under the intake manifold) will close in order to lower the idle RPM, and the ECU will start using
the lamda sensor's signal for the mixture formation. Considering the leak in the exhaust the lambda sensor
may sends inaccurate signal to the ECU, especially when the sensor is old. Try to disconnect the signal
wire of the sensor to see it makes any difference (on some model variations the lambda sensor is omitted.)

If the idle RPM is still low/irregular at operating temperature (with lambda sensor disconnected) there might
be a leak in the intake system, which could explain the screaming hamster. (as the throttle bypass valve
closes the depression between the the valve outlet and the intake will raise significantly that alters the suction
noise too)
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