Long Term Fuel Trims and Misfire Help

I installed a new engine recently and am trying to get a few things ironed out.

My LTFT’s are pretty far apart at idle and I’m seeing some pending misfire codes for cylinders 1,3, and 5.

Could the timing be off a tooth cause this? If so, is there a way to confirm it without having to tear it all back apart?

I’ve checked the vacuum hoses several times, and I’m not seeing any vacuum leaks.

It has:
All new Denso O2 sensors
New Denso coils
New spark plugs
New short block
Refurbished heads
New timing chain set
URD exhaust cam gears
DTLT headers
(Rear O2’s have anitfoulers)
New OEM fuel pump
New Denso fuel pressure regulator
All injectors were tested/cleaned
New OEM MAF
New throttle body with tps
New EVAP valve
Etc..

 

I think you need to verify exhaust cam timing, the inverted fuel trims suggest a timing issue.

 

Is pulling the valve covers and intake the only way to do this?

 

Without an oscilloscope and in-cylinder pressure waveform analysis yea pretty much.

You could run a compression test and see if you have a difference in average compression between bank 1 and bank 2, that may give you conclusive evidence of the timing being off.

 

Thanks for the info. I’ll get some compression test #’s and report back.

 

Results are in:

Bank 1 cylinders (passenger side)- all had 120 psi on the compression test

Bank 2 cylinders (driver side)- all had ~165 psi

Will the front cover have to come off to get everything timed up correctly? Or is it possible to just make adjustments to bank 1 with the valve covers off?

 

If just the bank 1 exhaust cam is off (which I suspect it is because the intake cams are monitored and would set a timing code if they were off) you should be able to re-time it by just pulling the valve cover.

 

Looks like I’m off a tooth on the exhaust cam.

What’s the best way to get it back in the right position without messing with the main chain?

Is there a way to remove a link from the chain, move the cam, and then reconnect the chain link together?

 

You should have to mess with the intake cam to fix the exhaust cam timing, how did you install the URD cam gears?

 

I installed the URD cam gears following the factory service manual. I don’t remember seeing any instructions that mentioned installing them in a different manner.

 

I'm pretty sure you don't need to disturb the intake cam to time the exhaust cam.

 

I think I’m being thrown off by this pic/step. It makes it seem like the #1 exhaust lobe is in line with the cam alignment pin, and it’s not.

If the lobe is straight up, the alignment pin is at roughly 10 o’clock.

 

Retested compression and still showing 120 psi.

I’m not sure what I’m doing wrong here. I feel like I have all the timing marks line up correctly.

The main thing I notice is that when they’re all aligned with the timing marks, the #1 exhaust lobe is no longer pointing straight up.

 

I'm not sure, I haven't had to mess with the timing on one of these yet. Maybe someone that has will chime in.

@Bishop84 thoughts?

 

I don’t understand how everything looks aligned on the engine stand, and now the marks look completely off.

I feel like I’ve rotated around 50 times by hand hoping they line up again, but they don’t.

 

The colored chain links are only for initial installation of the chain, they won't line back up once the engine has been rotated.

 

lol. That’s good to know. Thanks so much!

I went back made sure #1 was at TDC. I lined up the yellow link on the intake cam dot and then lined up the dot on the exhaust cam with the other yellow link on both sides.

That should be all there is to it, right?

 

Just started it up and it’s missing and shaking. Looks like I need to tear the front cover off and start all over again.

 

bank 1 cam seems off but my 5 year old is bouncing off the ceiling, ill try to remember to look closer later.

 

Bank 1 is out.





Same for Bank 2 but harder to tell.