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2000 Volvo V40 Starts but Dies Unless High RPM (Stalls Out if Idle Slows)

I’m struggling with an intermittent (of course) issue where, esp. if cold, I can’t start my car unless I give it lots of gas. If I take my foot off the gas at all, it will stall, which means I drive this automatic two-footed (one foot on brake, one on gas) , giving it lots of gas at all times, including when stopped. After about 10 minutes it is fine, and is then good for the rest of the day. My trusted Volvo-spscific repair shop has tried replacing booster pressure sensor, fuel pressure regulator (both indicated by engine codes) and new plugs. The end result is I’ve got $500 into the car that does seem to run better when it starts, but the original issue is unsolved. I was thinking something is sticking with a cold start, or idle speed is incorect, but can’t figure it out. Seems like it should be an easy fix. Any ideas?

First I would make sure that there are no cracks in the air inlet tubing from the mass airflow sensor to the throttle body. While I was inspecting that, I would clean the throttle body and (if your car uses one) the idle air control valve.

If the problem is still there, I would check all the temperature sensors. There are at least two, one that measures inlet air temperature and one that measures water temperature for the fuel injection system (your dash gauge and electric fan will use separate sensors). The symptoms you describe sound like a problem with the fuel injection system’s water temperature sensor, but this other stuff should be checked and cleaned on a 13 year old car anyway.

Correction: When I said “all the temperature sensors” I meant all the temperature sensors that talk to the fuel injection system.