cam sensor no replaced, didnt fix it. crank sensor will be done after work tonight. it is running horrible even on start up, col, warm.... it is running bad the whole time. the scanner didnt give me anything that pointed at anything, even the parts store told me that the scan tools stink and that was after i tired to buy one so i could have one at home. i am running out of ideas. almost wonder if it is a computer issue. oh i disconected the maf and nothing changed
need help on a 2005 impala with 3.4
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are you loosing any coolant?...3.4 had the lower intake problem which was supposed be fixed in 2003 but they still had problems. If it's leaking into the cylinders the plugs may be fouling.
Regalman,
How did you check the fuel pump, you hooked up a pressure gauge to the schrader valve and pressure was ok? Or did you just disconnect the fuel line at the filter turn the key on to cycle the pump a few times? If you have to mash the accelerator to get it to sputter to start (which is putting the ECM in flood mode) it's fuel delivery. Your pump, relay could be intermittently going bad. On the fuel side you could also look at injectors, make sure they're firing and firing correctly. A bad pulse width / non-fire would cause the same issue. Also look at the regulator, perhaps the diaphragm is bad or you got a crack in the line.
A temp sensor is possilble but you'd be smelling raw fuel constantly and it would run o.k. at first then would crap out.
Have you checked your coil packs for cracks / breaks? Had one on my 3.1L go bad and it run like crap. Would run great when cold, then would misfire when warm hot because the crack opened up, also causing the voltage to short to ground.
Depending on the code reader it should tell you which cylinder has the misfire as Joeyg said - if so pull that plug / wire and check it. If it's plug(s) and wires check out & a multi-cylinder misfire it is probably the crank position sensor.
Good luck man.
How did you check the fuel pump, you hooked up a pressure gauge to the schrader valve and pressure was ok? Or did you just disconnect the fuel line at the filter turn the key on to cycle the pump a few times? If you have to mash the accelerator to get it to sputter to start (which is putting the ECM in flood mode) it's fuel delivery. Your pump, relay could be intermittently going bad. On the fuel side you could also look at injectors, make sure they're firing and firing correctly. A bad pulse width / non-fire would cause the same issue. Also look at the regulator, perhaps the diaphragm is bad or you got a crack in the line.
A temp sensor is possilble but you'd be smelling raw fuel constantly and it would run o.k. at first then would crap out.
Have you checked your coil packs for cracks / breaks? Had one on my 3.1L go bad and it run like crap. Would run great when cold, then would misfire when warm hot because the crack opened up, also causing the voltage to short to ground.
Depending on the code reader it should tell you which cylinder has the misfire as Joeyg said - if so pull that plug / wire and check it. If it's plug(s) and wires check out & a multi-cylinder misfire it is probably the crank position sensor.
Good luck man.
U can check the crank sensor by checking the RPM signal on the data stream. Without a scanner U can check it with a volt/ohm meter. A crank generates its own voltage. It gives off a digital AC signal. Hook the meter to the yellow and purple wires that plug into the ign module and turn the engine over see what kind of signal u r gettin..
i checked the fuel psi with a gauge, 55 pounds. thats the first thing i did. coil packs were all checked and my fingers can vouch for that as well, holy crap them things hurt! intake and head gaskets were replaced by the dealer at 50k which was 30k ago, they did a full overhaul under warnatee due to piston slap, claimed that it wasnt a issue, i told them to call me when the car was done lol. might try tps before i take it to the shop, i have already bought 150 bucks worth of crap trying to figure this out 🙁 so whats 1 more sensor? right now i can get it to barely start and barely stay running when its cold, also the same when it is hot. im stumped if the crank sensor isnt the issue
no its original but i have checked it like 6 times now, that was my original thoughts. the pump is 300 bucks so i would rather not replace it unless i have a reason to
after 200 bucks worth or replacing random things i finally figured it out, the 10 month old fuel pressure regulaotor was bad, i replaced it christmas eve last year. i puled the vacuum line off and it was shooting gas all over, i pulled it off 2 other times and it was ok too... i still have enough money to get me 5.3 for my lsx swap started! woohoo
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