Thread: loping cold start

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My guess is that the mass airflow sensor is dirty or perhaps, defective. The MAF’s “job” it to constantly measure the amount of air entering the intake manifold. This tells the fuel management computer how much gas to inject into the cylinders for proper combustion. Mass airflow sensors use hot-wire-type sensors – which is a short piece of wire kept at a constant (warmer than ambient air) temperature. Current is applied to the wire to maintain its temperature so the current necessary to maintain the temperature is regulated in direct proportion to the “mass” of cool air flowing past it. It’s a little bitty wire and the response rate (to the change of flow) is nearly instantaneous.

Even under the best of conditions, crud builds up and “bakes” on the wire, which effectively insulates it from the cooler air. This “confuses” the fuel management computer as it sees a value for air mass that's out of range and it throws an error code. There’s a “cleaning cycle” that’s akin to a “self-cleaning oven” which heats the wire to a very high temperature. This cycle usually occurs on a programmed basis just after you turn the ignition key off and it is supposed to burn off the wooly buggers.

If the cleaning cycle fails to remove all of the contaminants, the manufacturer (and the dealer) recommends MAF sensor replacement. I'd try cleaning using to use aerosol carb cleaner, or you can also buy MAF Sensor Cleaner. Remove the MAF sensor and be real careful not to touch the wires. I’ve been very successful in spraying the wires and seeing evidence of crud. I run a reusable, washable filter (K&N) and not only does it help a tic on the performance and mileage area, it’s a finer filter and will help keep MAF wires clean longer.

Regards,
Glenn

Originally Posted by glennsexton

My guess is that the mass airflow sensor is dirty or perhaps, defective. The MAF’s “job” it to constantly measure the amount of air entering the intake manifold. This tells the fuel management computer how much gas to inject into the cylinders for proper combustion. Mass airflow sensors use hot-wire-type sensors – which is a short piece of wire kept at a constant (warmer than ambient air) temperature. Current is applied to the wire to maintain its temperature so the current necessary to maintain the temperature is regulated in direct proportion to the “mass” of cool air flowing past it. It’s a little bitty wire and the response rate (to the change of flow) is nearly instantaneous.

Even under the best of conditions, crud builds up and “bakes” on the wire, which effectively insulates it from the cooler air. This “confuses” the fuel management computer as it sees a value for air mass that's out of range and it throws an error code. There’s a “cleaning cycle” that’s akin to a “self-cleaning oven” which heats the wire to a very high temperature. This cycle usually occurs on a programmed basis just after you turn the ignition key off and it is supposed to burn off the wooly buggers.

If the cleaning cycle fails to remove all of the contaminants, the manufacturer (and the dealer) recommends MAF sensor replacement. I'd try cleaning using to use aerosol carb cleaner, or you can also buy MAF Sensor Cleaner. Remove the MAF sensor and be real careful not to touch the wires. I’ve been very successful in spraying the wires and seeing evidence of crud. I run a reusable, washable filter (K&N) and not only does it help a tic on the performance and mileage area, it’s a finer filter and will help keep MAF wires clean longer.

Regards,
Glenn

This engine does not have a MAF sensor. It uses a MAP sensor to measure manifold pressure instead. But yes, if it did have a MAF, I would have looked there 1st.

Guess I will try to check the MAP sensor later today