I have been having issues with my 2003 dodge ram 1500 5.7. 178k miles.
I recently changed the throttle body but the sensor keeps coming on while driving it. It idles back and forth between 500rpms and 1500 rpms. It shakes when you re decelerating between 45 and 55 mph.
The truck throws up 3 codes. P2173 p2106 and p0172
Based on those 3 codes, I’d say you should be looking for a significant vacuum leak.
We been looking but can’t find exactly where it’s coming from
Running rough/misfiring? Any valve train noise? A broken valve spring can throw the MAP value off and cause those fault codes.
On a 20 year old vehicle every vacuum hose and connector is suspect, you’ll have to inspect them all carefully.
Try unplugging the MAP sensor to see if that stabilizes the idle.
Tester
When using a scanner, there are no codes. I obtained these codes via the truck itself by turning the key to the on position and back off 3 times. The idle stabilizes once the vehicle is completely warmed up And unstabalizes hen the thunderbolt symbol appears on the dash. Once that occurs, I have 30 seconds or less to pull over and restart the truck or risk, losing all power and steering. I don’t see it being a valve spring as the vehicle performs perfectly until the thunderbolt symbol appears I did replace the entire throttle body as well as O2 sensors, as stated before have yet to check plugs and coils for the misfire, but at the moment, more concerned about the ETC light putting us in danger as we drive
I checked the MAP when I replaced the throttle body, it is functioning. No problem there.
Several possibilities, your shop will have to test & eliminate each of them, one by one.
Major vacuum leak. Ask shop to test if propane gas wand (some use brake cleaner) directed at a certain spot causes the engine rpm to increase rapidly. If so, there’s a vacuum leak there.
Throttle position sensor faulty.
Faulty throttle actuator.
Problematic MAF sensor. Seems unlikely since you replaced the throttle body, but still possible.
MAP sensor, the sensor itself could be working ok, the problem is wiring to the computer. Or the computer itself. Test by reading the MAP sensor output using a scan tool. When engine is off it should read atmospheric, about 15 psi.
O2 sensor. The airflow measurement may all be good, and the problem is an inaccurate O2 sensor. The O2 sensor has to match the intake airflow sensors, otherwise it confuses the computer. If engine runs ok immediately after starting, the O2 sensors are ignored then, so this could be the cause.
PCV system problem. Do the basic tests.
EGR system problem. Ditto.
Engine coolant temp sensor problem.
Could it possibly be the ACCP?
If you mean the accel pedal position sensor, yes, that’s another possibility. Seems unlikely but easy enough for your shop to test the pedal and throttle valve positions are matching up using their scan tool.
Alright thank you I will find a way to test the things you listed and will update when I do
Once you get it working ok, suggest to record the baseline data for all of those sensors at warm idle. Then if this sort of problem reappears , you’ll have something to compare against to narrow down what’s causing it.
No. Fault P2106 (Electronic throttle limp mode) is a reaction to another fault, likely P2173.
The intake manifold vacuum is erratic or unstable. Connect a vacuum gauge and read the manifold vacuum.