J2F42C

Have you had a mechanic test the fuel pressure?

The codes are thrown at all speeds (idle to 70MPH+) correct?

craist

Yes it does at all speeds.

Fuel pressure has been tested and is ok

craist

More things tested.

Spark plugs - grounded each and checked for spark - OK
Crankshaft position sensor - OK
Camshaft position sensor - OK
O2 sensors - OK
Throttle position sensor - OK
Swapped spark plugs around - No change

I think what is happening is that it is running lean causing the misfire.

Any other advice?

Texas_Ace

Running lean is possible, I considered that, or running too rich. It is VERY odd for it to start misfiring on those 2 cylinders at the same time though.

craist

I know it is running lean. Toyota did a four gas analysis test on it and like I mentioned in original post. It should be 14.7-1 and mine is 28.38-1.

Texas_Ace

It is not that lean for sure, it will not run that lean. My truck will misfire and have one heck of a bad day if it gets much above 16.5:1.

You should also get a code if it is running that lean and you said you don't have a CEL.

J2F42C

What was the fuel pressure reading? It may be a regulator problem.

Jomoka

Yeah, a reading that lean is more of an indication of a leak in the exhaust system. The engine just won't run if it was actually that lean.

craist

fuel pressure is 60 psi

Timing is fine, crankshaft key way is fine, timing advance is fine.

I took it to a different mechanic, one I trust. His snap - on professional stand up diagnostic machine can only read one bank (IE it is only getting data from one side of engine) and without that information he doesn't know where to go and can't fix it.

I have run out of things to test.

anyone with any other ideas?

craist

ok if that is so, can that be causing my problems?

Texas_Ace

It could be a problem or it could have been a sensor/testing error. Or a leak at the bung where they put the wideband sensor, lots of possibilitys. For it to read that lean you would hear the leak for sure.

60psi fuel pressure is too high I am pressure sure. Usually it is around 43psi.

j2the-e

Check the valve clearance! No its not done as regular maintenance at the dealer. Pull the valve cover on the easier side and specifically check the exhaust valves under the flat side of the cam with a feeler gauge. The spec is under the hood. They tighten over time and will get to the point that they wont close all the way when hot. Check it and fix it before you burn a valve so you can avoid a complete tear-down and valve job.

J2F42C

Fuel pressure is too high as TA said earlier. When you pull the vacuum line off the regulator, can you smell gas?

But also do a smoke test and/or spray test on the exhaust. I do know of someone who had a tiny hairline crack in their exhaust manifold that caused a misfire once in a Lexus ES300.

craist

Well as it turns out, Toyota didn't check the crank pulley bolt like I had asked and paid them to do. Long story short, pulley bolt had come loose causing all kinds of problems.

It has since been fixed. Thanks for all the help

J2F42C

I am glad you got it figured out. I guess the bolt was loose from when the TB was changed last time. You were lucky that the loose bolt did not lead to bigger problems.