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> Low idle cold, high idle warm
aexe
post May 15 2019, 04:41 PM
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My second post today, thanks all. My 1974 1.8 (L-Jet FI, Pertronix ignition) is having idle issues. When I start it, it fires up almost instantly and then the idle drops to very low, under 500rpm typically. I usually have to keep my foot on the gas a bit to keep it from dying while it warms up, and then it idles great around 1000-1200 when warm. Once I begin driving, often for 30-60 minutes (my daily driver!), I will hit a light after the freeway and the idle comes down only to 1400-1800. I have replaced so far the AFM (previous flap was bent and rebuilt was an improvement for sure), the Head Temp Sensor (new), and the Aux Air Regulator (used, also confirmed 12v at connector). Valves adjusted two months ago. Admission: I have a large hole in the muffler. Would love advice on this issue! Thanks.
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Dr. 914
post May 16 2019, 08:25 AM
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sounds like an air leak. You could smoke the intake and see if anything is leaking anywhere, like the hoses , a split in the intake boot, the oil cap seals, the aux air valve not closing.

We have had problems with the pertronix causing funny problems. First make sure that your point plate moves with the retard vacuum and also that your rotor twists and springs back to make sure both vacuum retard and mechanical advance works. If you have an early 74 then you have vacuum advance also


QUOTE (aexe @ May 15 2019, 04:41 PM) *
My second post today, thanks all. My 1974 1.8 (L-Jet FI, Pertronix ignition) is having idle issues. When I start it, it fires up almost instantly and then the idle drops to very low, under 500rpm typically. I usually have to keep my foot on the gas a bit to keep it from dying while it warms up, and then it idles great around 1000-1200 when warm. Once I begin driving, often for 30-60 minutes (my daily driver!), I will hit a light after the freeway and the idle comes down only to 1400-1800. I have replaced so far the AFM (previous flap was bent and rebuilt was an improvement for sure), the Head Temp Sensor (new), and the Aux Air Regulator (used, also confirmed 12v at connector). Valves adjusted two months ago. Admission: I have a large hole in the muffler. Would love advice on this issue! Thanks.

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