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Help code 44 on chevy 350

hello agein i have a 1987 chevy c10 with a code 44. 350 fuel injection. could 44 is a lean condituon. but i’m trying to figure out what is wrong. i replaced all bad vacumm lines form what i can see. it runs and drives good, but for some reason dose want to idle well seem to me that it is to low, also has a lope to it. but very small

will timing it help the idle if the timing is off?

Is this Throttle Body Injected? What is the mileage on the truck? You need to check everything that could be letting air into the engine, examples are intake manifold gasket, vacuum lines, brake power booster, accessory vacuum devices, and emissions devices i.e gulp valve if this has one. Use a vacuum gauge to monitor the vacuum at idle. Also look at ways air can be getting into the exhaust ahead of the O2 sensor. So look at exhaust manifold gaskets, exhaust manifolds for cracks, header to manifold gaskets, headers, and cat integrity. Also check out the AIR system because it can be pumping air into the exhaust system even though the ECU is commanding closed loop.

Hope this helps you narrow down the problem. Get back to us with further questions.

I agree with using a vacuum gauge to verify if there is an air leak. There are a number of places where it could be sucking air that are not visible to the eye; cruise control servo, brake booster, intake manifold gasket, vacuum pods/controls in the dashboard, etc.

For TBI applications, there are two common sources; TBI base gasket and throttle shaft wear. The gasket is only a few bucks and the throttle shaft can be bushed if necessary. Try the old trick of spraying carb cleaner around the base gasket and then the throttle shaft ends. If the engine revs up or smooths out, you found your leak.