Brand new intake manifold gaskets yesterday

Question

Today I tried to maintain speed over a hill the motor kicked down but it fell on its face I had all codes clear finally but after this incident it's reading 0171 0174 0300 lean on bank 1 and 2 again and misfire it has new coils new mass airflow new o2 sensors new throttle position sensor new plugs I didn't have the misfire code until this happened could the intake have loosened up after driving it of course I had to return the torque wrench I'm at a loss I've tried everything since I bought this truck in april

Answer 1

No, there is even a TSB about replace the intake gasket when there is a P0300 and a lean code condition , The intake manifold gasket is a improved design. There is no difference,if you replace the intake gasket and P0300 set in again.  the reason the most common cause is a hairline crack between the intake valve and the exhaust valve. on one of the cylinders head. If this is a cylinder head problem the code will set when you accelerate. Another very rare cause is the 02 sensor, as being the cause for the misfire condition.

Comments

Thank you I appreciate it I really hope I get lucky and it's just n o2 sensor because if not how would I go about fixing it that's beyond what I've done on my trucks I've never broke a gas motor open

---

When this type of engine comes to the shop I use a cylinder contribution data, with a ignition analyzer to narrow the problem down, this is the only way to determine the problem, this crack is so small that a cylinder leak down test and even a compression test miss the mark, This type of problem is common on this engine, Robots build the engine and if there is flaw in the design, manufacutuer will not change it over, by then it would be to late, one million cylinder heads installed in the vehicle. This problem is inherited in the engine, the fix first just verify that's the problem, The 6.0 is a good engine machine shop tell me  daily this is a common problem.And just to add mystery to the problem its always the number 2 cylinder or the number 6 cylinder, If this ends up being the cylinder head, you would remove the cylinder head, send it out to a machine shop for the fix.

---

Thank you I had a misfire on 2 and 6 with all new electronics I switched around the coils and it went away. I'm going to take it to the shop in the next couple days to get the front end looked at the control arms keep loosing alignment I had to tack weld the alignment pin in one control arm and finally got mad and cranked em so tight on the uppers the gussets are curved in almost to the point of pinching the bushings. I'll have my heads looked at also. I'm starting to think it's time to start building it and considering a straight axle swap I'm sick of spending every cent I have to barely keep it on the road.