Replaced throttle body....prob persists

[Michael Greenberg]

I had trouble stalling at idle.. it progressed quickly to sometimes bogging down at speed.

When I get up to speed it seems ok, and sometimes it idles fine. So I dont think it is a MAF sensor or o2 sensor or fuel pump or filter (though if someone can help me locate filter id like to change it anyway). It is a fuel prob but it doesnt feel consistent as id expect with clogged injectors

Sometimes I hit the accelerator and nothing happens. When it is trying to stall, I feather the accellerator to get RPM up....sometimes it goes up AFTER I pump accelerator and take my foot off

Getting codes P0174 and P0171. Replaced throttle body and prob is pretty much the same.

Could it be something else, or did i maybe get a bad throttle body?

 

[Jason G Slabaugh]

Have you checked fuel pressure

 

[LoneWolf3574]

I'd take a close look at the old throttle body to see its condition. Personally I wouldn't have changed it at this stage as the codes you gave us don't indicate that is the issue. Codes P0174 and P0171 are lean codes for the right and left banks. Basically these two codes mean that the upstream oxygen sensors are reporting a lean condition (too much oxygen in the exhaust, should be 14.7:1 ideally). For both codes to be generated at simultaneously would mean both upstream O2 sensors went/are going bad at the same time. That is not very likely, not impossible, just very unlikely. Or you are losing fuel pressure which would probably mean your fuel pump is going bad, as Jason G Slabaugh is suggesting.

Other Ideas -
Have you cleaned your MAF sensor? It could have oily residue on it, especially if you use an oiled filter like K&N. If you do clean it, be certain to use MAF cleaner to do so, other cleaners could damage it.
Have you checked for leaking vacuum lines? Your best option when looking for a vacuum leak is to run a smoke test, IF you have access to the machine.
Have you inspected your PCV to see if it is stuck? It should sound like a ball bearing rolling around when you shake it?

Read more at: https://www.obd-codes.com/p0171
Copyright OBD-Codes.com

 

[Michael Greenberg]

thanks lonewolf3574. Apparently, I jumped the gun. Autozone ran the codes along w diagnosis for replacing throttle body. I googled it and it made perfect sense .

So i decided to get diagnostics run at another store, hoping i could get some data on o2 sensors and MAP. Short story they weren't too helpful; mentioned an air temp sensor but wouldn't give me any codes. but before i got home it all cleared up!!!. (I had put some Techron in a few days ago) Idles smooth accelerates without any lag. I let it cool and it started and ran fine. Check engine light went off

FYI onset prob was immediate. I sensed it clearing up driving 5 - 10 miles

I'm gonna keep eating my Lucky Charms. Hopefully I won't have it come back.

Wanted to thank you for your response; all good ideas. If it comes back, I'll test the o2 sensors first (I tested for vacuum and manifold leaks already w carb cleaner) I already put a quick squirt of carb cleaner and blew off w air on MAF...didnt know better, hopefully im ok there and ill check pcv ...easy enough

 

[LoneWolf3574]

Autozone is good for OBDII scans and maybe a printout describing possible solutions and sometimes bench testing alternators (believe it or not, they can screw that up, been there and done that). Beyond that, most the people behind the counter there could barely pass at being a shade tree on a good day and at best, part swappers on a bad day.

If you're able to get live data that logs, see what your O2 voltages are as you are driving. The pre-O2 will vary and the post-O2 should be relatively constant, I don't recall what the actual numbers and range should be off hand. As far as the air temperature sensor failure OBDII code, that is P0113 for Dodge. It is relatively cheap (<$20) and easy to replace being located on the front of the intake resonator between the alternator and A/C compressor. Hopefully you lucked out with the MAF, if not, it is pretty cheap as well (<$25).

 

[Michael Greenberg]

Problem came back

I removed and tested O2 sensors w/ voltmeter and torch(OK), cleaned PCV and MAP sensor (w/ MAF cleaner) replaced air temp sensor (it was air temp sensor, not MAP that I sprayed w carb cleaner ...$13), and lastly checked fuel pressure w/ a loaner from Autozone.

Pressure read 20 psi steady.... I read it should be 49psi, so i think i need to replace fuel pump. I ordered an OBDII scanner that should be in Wednesday, so Thursday I'll be rechecking fuel pressure. If someone could confirm my diagnosis, I am not trusting my instincts on this....partly because i have been wrong before and partly because i see 20 psi steady ; that it should idle (I know it is just a snapshot in time and pump is likely just failing)

Also, ive seen online that it might be easier to pull back bed vs dropping tank on my asphalt driveway. Comments?

BTW i thought old valve body way amazingly clean...a little oily in front and just a little carbon in back. And i ordered an inexpensive obdii scanner for future live diag

Thanks in advance for your help. Much appreciated

 

[Jason G Slabaugh]

If you have 4 guys you can lift the bed off the truck, easier than dropping the tank down. Especially if there's more than half a tank of fuel! 58 psi should be normal on our trucks

 

[Michael Greenberg]

I actually have a block and tackle and a 'shade tree' I figured I'd just lift it. Want to be sure I'm diagnosing it right....its a little above my pay grade

 

[Michael Greenberg]

Just wanting to thank everyone for help. It was the fuel pump (I was afraid of another misdiagnosis)

I used a chain hoist...left 2 back bolts 1/2 way in and just tilted it up. Tight quarters, but it really was not that difficult.