HPD195

2000 Express van 155000 miles 5.7 engine. It studders and has no power when I first start and take off. after about 100 feet it seems fine but maybe some loss of power under load/towing. It has a loss of about 2 mpg. check engine light on but no real errors maybe a lean bank indicator. changed the cap and rotor. has about 20,000 miles on fuel pump. changed fuel filter and air filter.

It recently would not start at all and had the igniton sensor replaced but still have the studder and loss of power.

All the local Mechanics check the error codes and just say well lets wait till it quits..

I did clean the MAF sensor with spray and it seemed 90 percent better but now after 2 weeks its getting worse or hesitating more.

should I just replace the MAF sensor? I hate to start guessing with parts.

It feels sluggish and loss of power and smells abit fumey at start up.

canucklehead

post the error codes. Make sure the mechanics are using a shop size code reader not a little handheld. The codes will usually point to the issue.
Sounds like rich fuel delivery or mixture, which could be a bad o2 sensor....

wyn_fox

Mine is the same year and was doing the same thing. I changed the coil with the cap and rotor and it runs perfect now. I changed coil because i saw a little white arc spot on it too. How long has it been since you changed plugs and wires?? The coil is above cap and towards the front a little bit. It did feel like a gas problem at first ,but heard pump and smelled gas. By the way i had no fault reading either or engine light on.

wyn_fox

By the way remember this if you change the coil, it's on by studs and they have to be chiseled of and nuts and bolts to reinstall. Another fun thing for chevys to mess with our heads lol.

edac

Plugged cat?

Foxi D'elegance

Thottle Positioning Sensor or Oxygen sensor would be my first guesses. Get it scanned for free at an autoparts store and see what generic codes come up. You can tell if its a plugged catalytic converter problem if when you idle to a stop sign foot off the throttle and the window down you can hear it rattle. Just in case may want to check the contacts in your ignition switch. It sounds silly but I had a '99 Honda Accord and my friend had an '02 Chevy Malibu that did that and both of them wound up being the ignition switch contacts. Had this problem on a 93 Buick Park Ave and it was the grounding to the ignition module. (grounding wire loose or pinched) Could be many things but good luck man, hope you find it.

jimmyblue

"lean bank indicator" would only happen after the PCM
has false-trimmed you past 25% and this would suck
for idle (and wherever else, fuel trim cell wise) you
are laying down that excess (bogus) enrichment. The
first place to look is the front O2 sensor for that bank,
the other things that are mentioned (MAF, TPS, etc.)
are going to act equally on both banks. Plugged cat
is something I see brought up often, but rare in real
life (and would affect the big end more than idle or
cruise).

I'd start with a PCM reset and then see if things are
initially good again, but go south with a little drive
time. If open loop / long term fuel trims zeroed is OK
but closed loop fully learned is bad, then learning is
the problem and the O2 sensor is behind it.

My '02 is on the edge of this, sensor codes come and
go, fixing to swap them both out pretty quick now
(have parts, need time on a dry driveway).

HPD195

This is where Im at now.... I have replaced the Air Filter, MAF Sensor, Cleaned Intake, replaced Plugs, wires, Cap Rotor, Fuel filter, all 4 O2 sensors and kicked the cat while I was in the garage. The van simply has no power studders under a load. If i start it, put it in gear and foot on brake, try to accelerate it(like ole school burn out) it looses power spudders, its like it slipsas if I would push the clutch in but without the rpms and its NOT a standard. If I try to kick it in passing gear and pass a car or pull the boat up the ram (load) it just seems to not be able to produce power. The fuel pump is 4ish years old and 30,000 miles maybe.... Thank goodness for a set of craftsman tools and a garage, I think Im about to give up....$$$$

SnlpeR

i had a studder under load
i replaced the coil, spark plugs, wires, fpr, cleaned the cap and rotor
i found excessive play in my distributor rotor. it would turn more than it should and rise.
i fixed it by added a shim but it still would studder.

i replaced the whole distributor and it runs fine.