hi my buddy has a 97 jimmy 4x4 4.3 l sfi v6 and he has a major bogging issue
like from zero to go you can lightly press the gas and it will take off fine and drive fine (wont go past like 100km/hr on highway) as long as you lightly touch the gas petal

but as soon as you go to like press the petal to the floor it bogs out and starts to lose speed ?

any help or area i should tell him to start looking?

thanks for your time !

could this be a spark plug issue?

 

Check fuel filter for restriction.
Check fuel pressure and leakdown.
Key on, engine off, fuel pump running: Fuel pressure must be 60psi to 66 psi and must remain above 55psi for 3 to 5 minutes after the fuel pump shuts off.

 

i have same problem as you i read this if it helps
http://bb.bc4x4.com/showthread.php?t=148482

whats that

 

I believe this is what CH was trying to link to:
2nd Gen Fuel System Diagnosis

That will explain all of your questions regarding fuel pressure testing and fuel pressure leak down.

 

UPDATE
We went out and bout a code reader and we got the following codes
p0131 o2 curcit low voltage bank 1 sensor 1 -- we got this code x2 idk why

p0140 o2 curcit no activity detected (bank 1 sensor 2)


so his O2 sensor gone ? is that what this is telling me gould this be the cuase of the prplem stated in 1st post?

 

Getting the codes doesn't necessarily mean that the O2 sensor is bad. They are simply a diagnostic starting point.

Here are the sheets for the P0131 code:
P0131 - HO2S Circuit Low Voltage Bank 1 Sensor 1

The code below is for the B1S1 sensor as well, but it will run down through the diagnosis of your B1S2 sensor (the sensor directly ahead of the catalytic converter).

I would swap the B1S1 & B2S1 sensors side to side and see if the code changes over to a P0151. These are the two upstream sensors located closest to the exhaust manifolds.

I would also swap the B1S2 & B1S3 sensors front to back and see if that code changes to a P0146. B1S2 is directly ahead of the cat and B1S3 is directly behind the cat.

If the codes change to those indicated, then it is pretty sure that the sensor is the cause.

If you do find that the sensors are faulty, do yourself a favor and purchase AC Delco sensors. In my experience with aftermarket sensors, the AC Delcos are definitely worth their higher cost.

 

what is b1s1,b2s1,and b1s3? where can i find these sensors and also what do you mean swap them like take them all out and switch them around ?

could an o2 senser really cause his jimmy to bog out like that ?

also my parts store only carries oem o2 sensor and its 90 bucks

 

What brand is it? Like I said, it pays to get the AC Delco sensors.

And yes, the B1S1 sensor definitely could cause the engine to run poorly if it is reading incorrectly. An exhaust leak ahead of an O2 sensor can cause it to report false readings to the PCM. Hence the push to diagnose the issue.

This diagram has been posted quite a bit in the past and should help you find all of the O2 sensors:

 

ok im reading and understanding the code rite up one thing im not clear is on step 10 it says vcm what and where is that

its napas brand the sensor can i by a ac delco one online or mabey i can ask them to order it

 

VCM (PCM) is the box on the passenger side fender.

You have to have a Tech2 to do some of the VCM scanning functions. But most of the other tests can be run with a general scan tool, a good multimeter, and some time.

As far as places to get AC Delco sensors, see if there isn't an AC Delco dealer close by you (via ACDelco.com). RockAuto.com carries them. You can also find them on eBay (AFS105 fits all 4 positions).