Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hi guys I need some help so I got this 2005 Dodge Durango with the 4.7l in it it was running fine the other day and then last weekend star running rough like it was misfiring so I plug my obd2 and I got the codes P0300,P0172,P0175 so a friend of mine told me that the P0300 could be something so simple as a tune up so he did change sparks plugs ,coil packs ,IAC Valve ,EGR Valve also the TPS SENSOR, MAP Sensor ,PCV valve and after all he did the P0300 it's gone but I still have the P0172 and P0175 and the truck still running really rough even stalls at idle he check the short and long fuel trims and they're at minus 30% and minus 25% he said It could be a vacuum leak but he doesn't own a smoke machine there's another way to check that out without the smoke machine and you guys think that could be something else the truck only have 118000 miles
That was indeed a tune up ). That is not a vacuum leak. P0172 and P0175 are system too rich bank 1 and bank 2. Both banks are unlikely for injectors to leak but still a possibility. You should check fuel pressure first and if it is holding after you turn off the car. I guess it is returnless design with pressure regulator in the tank?
We need to know if you can look at live data and give us the o2 sensor voltages. If you can see the data then you can try to create a vacuum leak by pulling to vacuum hose off the brake booster and see if the o2 sensors react (voltage should go towards zero)
"Silver bullets are for killing Werewolves, not fixing Cars." -Rob Longoria-
Everyone else is right on track here. Looking at the upstream O2 sensor signals while creating a lean condition will be a big help in deciding which direction to go.
Hi guys sorry I didn't get an update on my truck before I was out town so I check the fuel pressure on the rail and with key on engine off I'm reading about 53psi and with the engine running the needle on the gauge It goes jumping between 50 and almost 70 psi and after I turn the truck off the pressure stay at 53 for almost 30 minutes I unplug the vacuum hose the one it goes to the brake booster and I realize that the truck still running rough but it doesn't stall also I realize that with the old and the new egr valve on the live data I got a commanded egr about 7.1% the o2 sensors readings with key on engine off are 1.275 and with the tuck running I got between 0.400 and 0.900 both banks
Agujfigu wrote: with the engine running the needle on the gauge It goes jumping between 50 and almost 70 psi
And all that while idling?
Fuel pressure spec is 58 psi +-2, however it doesn't specify at which conditions. For sure it must not jump all over the place.
I have the same problem with my 2002 4.7. P0172 and sometimes it shows missfire codes for cylinders one and eight but the misfire codes come and go. It's always missfiring but doesn't always set a code for it. Fuel trims are -30 to -33. I can not find any vaccuum leaks. Upstream and downstream O2's have been replaced. I have been chasing this problem for about 2 1/2 months now and can not figure this out. Can someone please help me before I completely loose my mind?
Looking at the upstream O2 sensor signals while creating a lean condition will be a big help in deciding which direction to go.