hey everyone. little bit of help is needed with the old blueberry j-body (05 cavalier). was driving home and all of a sudden it started to shutter and feel like it was at a loss for gas. Check engine light came on and the dreaded PO171 came on for a lean bank 1. any help would be greatly appreciated
specs on car:
140,000 miles
2.2L Ecotec
-New plugs (month ago NGK's, they were out of ACdelco's)
-AEM intake
Tested so far:
-Ran fuel pressure (61psi at idle then jumps between 50 and 60 while driving)
-checked fuel regulator (FP dropped to 48psi so i think that the regulator is good)
-new fuel filter on its way
-new plugs coming (factory acdelcos)
any ideas? thanks for the help
NgK's are fine for our cars...
Does it currently run? Idle is it rough?
Change fuel filter, change primary o2 sensor.
yes it currently runs. The problem is it doesnt run for long. If you drive it on the highway (while monitoring the fuel pressure) it will start to bog out and start to buck. Fuel pressure drops and starts bouncing between 50-60psi maybe even lower. im gonna run it tonight with the scanner and hopefully get it to fully act up.
Tonight i will swap the fuel filter and possibly the 02 sensor. Are you referring to the 1st O2 sensor, (closest to manifold) right?
Thanks for the help
i would also like to correct my original post in that the FPR dropped to 48psi after i put vacuum on it. But, when i initially removed the FPR line the FP did not rise or fall. Is this a sign that its messed up, i was under the impression FP should rise when the FPR is not connected.
^ Im pretty sure thats the case. Although I couldnt find a post to support it.
Try the fuel filter first since its the cheapest and work from there.
No it is not.
I would be looking for vacuum leaks, do you have any way to check your fuel trims? If so please post.
Yes i will post fuel trims when i get home. And just for confirmation, the fp should NOT rise when the line for fpr is disconnected correct?
Hard to say, some systems do and some do not. I would not follow that path as of yet..
According to GM Service Manual
Fuel pressure
engine off key on 50-60psi
should not decrease by more than 5 psi after 1 minute
idle is about 50 psi
and with no vacuum to the reg its 57-60 psi
no fuel should leak from the regulator with engine off key on or engine on key off when you remove the vacuum line to the FPR
Ok. So i can either post my trims or fill everyone in. So i had the fp gauge hooked up and three scanner showing live data. Everything looked fine 60psi fp, normal idle, within 10% on trims ect ect. So i hop on the highway and start driving, hit about 55mph and the fp starts hopping (between 50-57). Then it all of a sudden starts dropping....45psi....30psi....20psi....then car stalls. Go to re-prime the pump to start it again and nothing. No pressure higher than 10psi. So i get out, kick the gas tank, and cone back in. Boom....instantly rises to 60 psi. Looks like I'm buying a pump and a filter
Ok. So i can either post my trims or fill everyone in. So i had the fp gauge hooked up and the scanner showing live data. Everything looked fine 60psi fp, normal idle, within 10% on trims ect ect. So i hop on the highway and start driving, hit about 55mph and the fp starts hopping (between 50-57). Then it all of a sudden starts dropping....45psi....30psi....20psi....then car stalls. Go to re-prime the pump to start it again and nothing. No pressure higher than 10psi. So i get out, kick the gas tank, and cone back in. Boom....instantly rises to 60 psi. Looks like I'm buying a pump and a filter
I'd check your wiring before buying a new pump. Def replace the filter if its due.
well i checked wiring anyways and everythings fine, tight, and no loose ends. I'd say its time for a pump anyways especially coming close to 150,000 and 8yrs old
. One thing i am worried about though is if i pull the tank to replace the pump and theres gunk of some sort in there. I wonder if theres a way to flush it out
Pour gas in....slosh around...poor gas out....
Its a plastic tank though so prolly going to be clean.
Make sure to replace the fuel filter while your down there.
lol yes i have already presoaked the filter in pb blaster and made sure it came loose. i'll just have to see what the tank looks like. im not worried about rust, im more worried about dirt and water
So the fuel pump and filter went in no problem. But now on the way home the po171 came back. I'm gonna run new live feed and see what my 02 sensors are saying, maybe one is lazy. Is it usually the front sensor that goes bad or can the rear sensor trip the bank 1 lean code.
Did you reset your fuel trims? I think unplugging the battery will do this.
