Dennis wrote:
> My son drives a 1999 Escort ZX2 with the L4 2.0 liter engine. He was
> complaining that the car doesn't
> have as much power that it used to and that it idles rough. I connected my
> scan tool to check things out ( I'm new at this and far from an expert) and
> noticed that the mass air flow sensor was 2.7 volts at idle. The specs are
> .6-.9 volts.
> The calculated engine load was 59.2 % at idle. The long term fuel trim
> showed 2.3 %. There were no trouble codes set. Is this enough evidence to
> replace the MAF sensor? I hear they aren't cheap so I need a second opinion.
> Thanks so much for any help.
>
> Dennis
>
>
On a Ford MAF check the baro reading. Off more than 8hz from 159hz or
so (depending on where you live) clean or replace the MAF. A bad MAF
will usually show minus trims at idle and plus trims under load.