Low power rough running e tech 460

[07cl733]

I have a 2000 ch with an e tech 460 that recently blew a head gasket. Compression overcame the fire ring and cut through the fiber gasket. I replaced the gaskets under both heads and swapped heads front to rear. I measured the sleeve height from the deck and they all checked out. I decided to swap heads around in case it happened again, I would know if it were the heads or the sleeves. When it was all back together I started it and it runs rough, not quite a miss, but it shakes the truck a little. I would think it normal if it were a Cummins. Also it is very low on power and only builds 26 lbs boost at max. I suspect it is under fueling because pyrometer  temps are much lower than usual, 850 on a hard pull, it smokes less than usual and the water temp runs cool as well. I changed fuel lines while it was apart. which caused me to suspect an air leak or blockage. I changed them again and checked my fuel pressure. I've cleaned the cam sensor and the rpm sensor thinking it may be a timing issue. I've been through the valve adjustment 3 times and it checks out each time. There are no codes coming up. I've also recently had oil samples tested and everything is in acceptable levels. I sent another today and am awaiting the results. Has anyone damaged an injector while cleaning it? Is this what it would act like? Thanks for reading my long post and any help will be greatly appreciated.

[Mack Technician]

It isn’t uncommon for people to pull the heads and set them on a steel table while the injectors are still in. The injector tip protrudes just enough to be destroyed on the bench when set down. Did you pull them first?

460 (and 427) you will want to go max sleeve protrusion(if in such case the engine was apart). Heads bounce. The 460 bounce lots. 

Good idea on head swap over. 

Did you pressurize your charge air system for leakage Check? Usually pyro climbs if leaking........but I’d still check. 

Did you check fuel pressure at idle or under load?

Edited April 27, 2018 by Mack Technician

[07cl733]

I did not pull the injectors first. I was careful not to set the heads on the injectors. I also used a brass wire brush to clean them as prescribed by the manual.

I didn't go any deeper than the heads, I'll keep the max protrusion in mind if I do.

I checked the charge air system.

Fuel pressure only at idle. It runs rough even at idle and high idle.

Good thoughts, thanks.

[OldRedMack]

Could be an eup, my engine ran smooth before I went up a size in injectors.  As soon as I fired it up after injector swap it was a ruff idle, turned out number 6 eup was weak.  

[07cl733]

I changed the injectors and it seemed to help the power a little. Thanks Oldredmack. I'll have to look there next. Did you get a code on the eup? How did you determine it was number 6?

[OldRedMack]

No codes came up at all, had to start the truck and leave it running, then loosen the injector lines individually.  There should be a definite change in the way it is running when you open the lines that are at full strength, and probably no change when you get to the one that is bad.  And I would also suggest that when/if you find 1 that is bad to just replace it.  Do not try and swap it out with 1 that is working correctly to make sure that it is bad.  I attempted that and snapped the screw that holds the wires on and had to replace 2 eups, at $500.00 a piece. 

[Jamkar]

Hi OldRedMack, was yours a 460 & were you happy with injector upgrade?

[OldRedMack]

370,  I only went up 1 size to the 427/460 injectors.  But that is a hard question to answer, because at the same time I upgraded the turbo and exhaust manifold.  Overall I am very happy with what I have done.

[07cl733]

On 5/3/2018 at 6:45 PM, OldRedMack said:

No codes came up at all, had to start the truck and leave it running, then loosen the injector lines individually.  There should be a definite change in the way it is running when you open the lines that are at full strength, and probably no change when you get to the one that is bad.  And I would also suggest that when/if you find 1 that is bad to just replace it.  Do not try and swap it out with 1 that is working correctly to make sure that it is bad.  I attempted that and snapped the screw that holds the wires on and had to replace 2 eups, at $500.00 a piece. 

Okay, thanks. That gives me another direction to go. It has been hard to track down the problem since the motor isn't running real bad. It still fires in all cylinders, maybe,  just not as good in one of them. I'll take that advice on not swapping good for bad.