Hey guys, I have a 99 ws9 trans am with the 5.7 liter engine and a 6 speed trans, recently I've noticed from take off if I punch the throttle my engine will start to bog out at higher rpm's in 1st,2nd or 3rd gear.I took it to gm and they changed the fuel pump and told me it could be the o2 sensors or the throttle body, so they cleaned the throttle body and I've changed both front o2 sensors that they said could be at fault and the car still seems to fall on its face at the higher rpm's, any ideas, thanks

 

Any codes?

 

2 codes came up, they were P0137 and P0157, here is what they said:check lack of pwr/ses-road test on parkway/ lack of pwr on hard accel,fuel trims high & 02 sensors drop to near 0mv. Also noticed maf sensor only reached 50gps.Clean maf sensor, also noticed pcv not secure (possibly causing vacuum leak on accel) road test maf reached 80+gps now, fuel pressure ok now

 

could it be still the throttle body or maybe mass air flow sensor?

 

Only time mine has bogged out at a high rpm was because of faulty spark plugs. Check them. If it's "spurting" then it's your fuel pump. Ask me how I know all of this

 

can't see it being spark plugs, just installed new Bosch Iridium plugs along with MSD 8.5mm Super Conductor Wires

 

Did it only start doing this after you changed the plugs and wires?

 

started just after I bought it I thought it was bad gas cause I filled it up with just regular unleaded, but then found out it was weak fuel pump, haven't tried putting in old plugs then taking it for a drive, you all know what a pain it is to change plugs

 

I give it a 95% chance that this is a dirty/fouled MAF, 100% caused by a K&N (or other oiled) air filter.


Do you use one of these filters?

 

Bosch Iridium plugs along with MSD 8.5mm Super Conductor Wires/ started just after = and you didn't start fault trace by verify if something could be wrong with the new parts?

 

yes I do use a k&n filter, never thought of that, will have to pull it out and air hose the sensor out

 

The only way to correct the problem long term is to burn the K&N filter and go back to paper. The snake oil that K&N sells doesn't really work in the first place and the MAF's that are installed on the LS1 just don't get along well with the oil that they shed.

You will need to get a special MAF cleaner from the parts store to clean the thing. (Air won't work.) The MAF has a heating circuit on it, which burns off contaminates, but the oil from the filter is just too much. The stuff will be crusty and caked on. (You can see it with a good magnifying glass as black crud.)

Electrical contact cleaner will also work, but the MAF cleaner is supposed to be safer for the plastic pieces of the sensor.

 

Thanks for the input would not have thought k&n oil would do that.Will have to look at the MAP sensor when I get home friday night, if that's the case will be getting rid of the filter for sure, and getting some of the cleaner for sure

 

I had to deal with this the hard way. (After shelling out money to help find the problem.) GM issued a bulletin on it many moons ago and K&N has responded with an extensive propaganda program: http://www.knfilters.com/MAF/massair.htm

I think the posts and experience on this site have shown definitively that the problem is real and K&N's tests don't hold for the conditions on our cars.

 

thanks again for your input, I went home bought some mass air flow cleaner, cleaned the sensor and know car runs fine

 

Glad to hear.