Problem: engine surging/hesitation, from idle to highway speeds. It will start and run fine, just hesitates/surges when gas is applied.

Before I pulled the codes, I tried seafoam in the gas tank, cleaned MAF sensor, cleaned throttle body, checked air filter, changed fuel filter, pulled/cleaned plugs, nothing helped.

Then today I finally used a scanner and pulled codes (my CEL doesn't work) and I got 157 and 158 MAF sensor fault, high and low voltage. I am reading about 6v on the C and D terminals of the MAF, I know that is much higher than normal, but what does that tell me? Why both high and low voltage readings? Just a bad sensor, or wherever that voltage comes from, ECM?

I also pulled 189 HEGO H02S sensor fault, unable to switch/lean during part throttle. What does that mean, just a bad O2 sensor?

Last I pulled a 542, fuel pump secondary circuit fault. Does that mean the fuel pump is bad or going bad?

More importantly, what should I troubleshoot first, would any of these codes cause my problem?

Thanks in advance!!

Andrew

 

Try cleaning the MAF sensor if you haven't already.

http://www.therangerstation.com/tech.../CleanMAF.html

 

Welcome to FTE.

You've been busy trouble shooting this puppy. Good idea to have scanned the computer for trouble codes & posting the code Numbers, as they can offer up good trouble shooting clues & from the codes posted, you seem to have more than one problem. Make sure that you've posted All code Numbers found. Seeing as how you say the CEL is out, had it been on for a long time????

Generally we're supposed to work & put right the lowest number code/s first & work our way up to the higher number code/s.

The 157/158 codes confirm your MAF voltage is out of spec, high & low.
The 189 code = Rich limit partial throttle, lean bank #2.
The 542 code = Fuel pump circuit open PCM to motor ground.

Taken all codes together, you might begin by checking the vehicles grounds, from body, to engine, to battery. Check for corrosion or loose fit at the battery posts to cable clamps & at the other end of Both the B+ & B- cable connections to the engine, body & under hood power distribution box & alternator. Connections need to be clean, bright & tight.

To isolate suspect connections, perform voltage drop tests across the connections by following directions in the link at the end of the Battery Tutorial thread atop this forums thread index page.

Once your certain all B+ & B- electrical connections from the battery to alternator & battery to body & engine grounds are sound, load test the electrical system by turning on all lights & the cabin blower motor to High speed & measure voltage across the battery Posts, then across the battery cable clamps, then at the power distribution box B+ connection to a good clean engine & body ground, to make sure the computer & its sensors are getting a good electrical feed & post up how things go.

You may have other component problems, but first make sure the electrical system, (battery, alternator, battery cables & their connections to body, engine & under hood power distribution box) are good.

 

Thanks Pawpaw. I will defintely do all the tests you describe. I just got the truck about a month ago and the CEL has been out since I got it. It ran great until just a few days ago when the surging/hesitation started. I'll post back here after I do all the electrical tests. Thanks!!

Andrew