‘74 1.8L L-Jetronic Cold Start Low Idle, Mystery solved! Options

[Van B]

Ok fellas, here’s the run down Aux Air Regulator (AAR) and Cold Start Valve (CSV)/injector both work fine. Many of you have also been keeping up with my high idle issue that we figured out.

But yet, when the car is cold, i.e. room temp, I don’t get the high idle I should on start-up. Instead she cranks a bit and then lumbers to life. Idle lopes around 700-800rpm and then smooths out as it warms.

In all other aspects of operation, the engine seems to be pretty happy.

Thoughts? Experience? (IMG:style_emoticons/default/confused24.gif)

-Van

See post #419 on page 14 for a synopsis of the outcome.

[Van B]

That's right wonki. Bypassing the AFM will throw off the whole fueling equation. It opens more variables than it eliminates. Popping the line to the AAR to check for air draw is feasible once the car is running. But I'm opting for pinching the short line in order to keep everything else accounted for. If pinching that line during cold start makes the condition worse, then to me it makes a strong case that the AAR is not meeting air flow requirements. Conversely, you could say that the engine is being over fueled, but given the objective of higher RPM than normal for engine warm up, such a statement doesn't make sense.

So, I start the car and then pinch the line:
1. RPM increases
2. RPM decreases
3. RPM remains the same

If #1 happens, then it's a lean condition I'm suffering from during warm up. If #2 happens, then it's a rich condition. If #3 happens, then the AAR is already closed.

What am I missing?