P0156, Rough Idle, Jerking at 60mph

When I thought she was finally ready to hit the road again, my truck starts acting up!

Yesterday on my way home on route 80, I stepped on the gas a little and noticed some sort of jerking or jumping that occurred between 60 and 70mph. I pulled over, checked all the fluids, everything was good.

Went back to sit in the car and it was idling funny and actually died once on my way back home at a stop light.

This morning I pulled a pending code P0156 which is a post cat sensor... usually these only measure emissions and shouldn't have anything to do with fuel or air, correct?

No misfire codes or anything else besides that, I put new plugs in the day I got her from the PO. Any ideas?

 

Ran a compression test, 175psi on the 7th cylinder.

205-210psi on all the others. This is one of the worst spring vacations I've ever had...

This was done with a dry test. I plan on doing a leak down test tomorrow. I could look at it on the bright side and say I only got the truck for $2400.

 

Bummer bud. You think your rings are shot?

 

I'm hoping they aren't. But the leakdown will tell me for sure. If it's the rings, the plan is just to get a lower mileage engine. I put no more than 1000 miles on it, but I've already fallen in love with it. It won't be leaving anytime soon unless the frame decides to rot out overnight...

 

Important update:

Although I may end up looking completely stupid I'm hoping my stupidity will help clear any problems for someone else out there...

I've been fixing some stuff on the truck and waiting for the right opportunity to buy another engine thinking this one was trash. Today I installed a new fuel pump as the car no longer wanted to even turn on, nor did I hear the pump priming with the key on the ON position. After installing the new pump, I went and cranked the car, still no start...

I thought to myself, hell I guess there's not enough compression to kick her on anymore. I went inside the car and decided to check the codes on the OBD2 one more time. I pulled up the usual oxygen sensor code I already had and a new p0335 code (crankshaft position sensor). Took a lunch break, came back out and went for the sensor.

Apparently the PO must've thought it was okay to leave some wire dangling next to the belts causing it to slowly but surely cut right through the crankshaft sensor and what I believe is the oil pressure sending sensor.

I redid the connections, turned the key, and she fired right up! But this time, no weird idle, no hesitation. I then decided to be a risk taker and taker her on the parkway... 50mph, 60mph, up to 85mph, and no more misfiring. Tested it some more (with no other traffic besides me) and still nothing. Stopped at a light, waited it for it to shake and sputter, still nothing. Back on the parkway, pushed it up to the 80s again and it seems the problem is solved.

I am extremely happy that I did not jump on an engine right away. I understand my compression numbers are still a little off, but she seems to be functioning properly as she should.

I'm wondering whether it was the wiring fix or the actual fuel pump replacement. Or maybe a mix of two.
Regardless, she is back on the road. NOW, time to get rid of that take off vibration!

Sorry for the long post but I hope this helps someone...

 

Good deal! All’s well that end’s well! Congrats on figuring that out, that’s gotta be a great feeling!

I hope you get to enjoy that Tundra for many years to come!