P0174 and P0171

BlackXrunner05 · Jun 14, 2016

My check engine light came on recently, and as my title implies, the codes it's throwing are p0174 and P0171. The only performance symptoms are that my truck is idling low and I get a delayed, sudden surge of acceleration. What parts should I be looking into replacing? Any help would be greatly appreciated!

fishsticks · Jun 15, 2016

P0171 and P0174 are lean mixture codes. Check for vacuum leaks.

asianized · Jun 15, 2016

Mines threw those codes too cause of my dtlt had cracks in em where they connect to the y pipe

Gadget · Jun 15, 2016

What air intake do you have?

BlackXrunner05 · Jun 16, 2016

I'm running a TRD intake and have the Thorley Long tubes, with the URD sim.

asianized · Jun 16, 2016

BlackXrunner05 said:
I'm running a TRD intake and have the Thorley Long tubes, with the URD sim.

Same set up as me, I'm assuming u have the Trd 1st gen intake, I'd check for exhaust leaks also

NHXRUNNER · Jun 16, 2016

asianized said:
I'm assuming u have the Trd 1st gen intake

Pretty sure this is where Gadget was going with his question. The 2nd Gen is known for causing a lean condition.

30Birdy · Jun 16, 2016

I threw those codes a few weeks ago. Turned out to be a vacuum leak on the intake. Any un measured air that sneaks in after the MAF will set those codes.

BlackXrunner05 · Jun 17, 2016

I have the first gen TRD intake...I'm planning on replacing the spark plugs , the ignition coil packs, and cleaning my air filter and MAF sensor... If that doesn't do it, I'll replace my PCV and start looking for leaks

sixstringdave · Jun 18, 2016

Mine did that a couple years ago. It was the bolts that connect the long tube to the Y-pipe. Tightened it up and reset the ECU. Like it was mentioned, check for leaks (vacuum and exhaust). Mine was really tough to see. It was barely loose. Keep your eyes peeled! Good luck bro!

whippersnapper02 · Jun 18, 2016

No need to replace the coil packs unless you know they are bad.

sixstringdave · Jun 18, 2016

whippersnapper02 said:
No need to replace the coil packs unless you know they are bad.

I agree. If the coils were bad i dont think the thing would even start.

Torspd · Jun 19, 2016

It won't be the coil packs. Look at the silicone couplings of the intake. If you have the original ones, they are likely cracked from age.

Look at the vacuum hose attached to the intake tube, which routes to the passenger valve cover. It could have splits. Then look at the vacuum hose right after the throttle body, as well as the one from the pcv valve to the upper plenum.

Ridefoxone · Jun 22, 2016

Are you running a Walbaro fuel pump?

BlackXrunner05 · Jun 23, 2016

I found the leak! Turns out it was my TRD intake. The coupler connecting my intake tube to my throttle body was torn... I took it off and it shredded... It felt melted and super soft? Is that normal?

Slywhitty · Jun 23, 2016

BlackXrunner05 said:
I found the leak! Turns out it was my TRD intake. The coupler connecting my intake tube to my throttle body was torn... I took it off and it shredded... It felt melted and super soft? Is that normal?

Mine did that too when I had that intake. I've heard of others doing the same

BlackXrunner05 · Jun 23, 2016

I ordered some new couplings hopefully they'll work.... I have my stock intake but I can't find the filter or any of the screws lol

Torspd · Jun 24, 2016

Afe sells the replacement couplings. Did you buy those or others?

Glad you found the issue, and it is common with the age of those. The new ones are a better grade I believe.

BlackXrunner05 · Jun 24, 2016

I had to get to work this morning so I went to the hardware store and bought the plumbing couplers lol! Now the fluctuation in my RPM is gone, but it's idling at 1500 RPM when it's starts? After driving for a while it lowers to about 900ish... Is that normal. It seems high. I cleared the codes this morning and they didn't come back, but I don't think I've driven far enough yet

Torspd · Jun 25, 2016

Try disconnecting the battery.

Welcome!

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