Post L29 Build gremlin - need ideas

[Philip Parker]

Well I got my truck all put back together and it hauled an 11,000 pound trailer 1400 miles with 1,000 pounds in the back from Colorado to Michigan. It was 101 degrees through South Dakota and the ole girl did what I asked it to do. Trailer was probably a bit heavy but the brakes and controller on the rig performed as expected and safely.

When I arrived in Michigan I started getting some weird things happening while accelerating (unloaded after our big trip). The truck has aftermarket brodix heads and a custom tune. Here's the jist:

It started pulling timing at low throttle input. At first it was a little and now it will pull from 25 degrees down to 8. Truck creeps along when it does this. I have new NTK O2 sensors which are reading a very lean condition when this happens. I have replaced the MAF sensor, replaced the plugs and wires and cap and tried to reset cam retard 0 however the Summit distro seems to be off. The closest I can get to 0 degrees is -5 with the space I have to adjust the distro. When I adjust a tooth retarded and turn the distro to get the last -5 out I can only rotate it enough to get +11. I have tried to perform a Crank Relearn on my Snapon 2500 but it will not finish the test procedure for some reason. Might have to go to the dealer to have them do a crank relearn.

I have unplugged the knock sensors and the ECU still pulls timing like this.

My current guess is because it is getting progressively worse is that I have a slowly failing fuel pump (will be testing FP this week after it stops raining) or that the tune is simply too lean. All of my lower and upper intake gaskets are the beefy felpro versions and are new, however that engine bay got very hot during the big tow here, so I may need to reseal them. Truck never overheated.

Anything else I'm missing?

Thanks

Philip

 

[618 Syndicate]

Cats clogged?

 

[Philip Parker]

Cats clogged?

That is a distinct possibility and I know for a fact one cat has some significant holes (will leak condensation). Will that cause a lean read by upstream O2s?

 

[618 Syndicate]

I don't know for sure, but I know it will cause some of the symptoms you describe.

 

[Supercharged111]

I'd be all over fuel pressure for a lean condition.

 

[Jermaine Smith]

Just curious what kind of trailer weighs 11000 pounds?

 

[Schurkey]

tried to reset cam retard 0 however the Summit distro seems to be off.

I've heard that about aftermarket distributors. Can you modify or replace the distributor clamp to allow full rotational travel?

My current guess is because it is getting progressively worse is that I have a slowly failing fuel pump (will be testing FP this week after it stops raining) or that the tune is simply too lean.

Let us know what you find.

 

[yevgenievich]

if distributor is similar to 4.3, then the piece that rotor sits on is just pressed on. Had to fix one where it spun throwing timing off. Notched in correct place and reinstalled with hopefully better method for keeping it put. But essentially, rotor position can be adjusted as needed by removing and reinstalling that piece. In my case the threads were also stripped, so tap and different screws were used to hold the rotor

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[Schurkey]

the piece that rotor sits on is just pressed on. Had to fix one where it spun throwing timing off. Notched in correct place and reinstalled with hopefully better method for keeping it put. But essentially, rotor position can be adjusted as needed by removing and reinstalling that piece.

THAT's something I've not heard of before. That'd change rotor position, but also the triggering of the cam sensor--which is what's important for cam/crank sensor synchronization.

Thank you.

 

[Philip Parker]

Just curious what kind of trailer weighs 11000 pounds?

22 foot enclosed trailer with tons of tools and most of our household in it.