2007 Pete 379 cat acert c15. Loss of power and engine shakes or shudders under load

You'll never temp gun a twin turbo. Hard to get a good readung. Bad injector harness and you would have a check engine light. Bad ecm and you would have a check engine light. Take it somewhere that has diag tools to run a cut out.

I would start with fuel pressure. Hook a manual gauge to the filter base and drive it under the conditions that makes it run like crap.

Boost leak won't make it shake. Just lack power. I'd say fuel issue for sure.

 

on the a-cert yes you can have a bad wire harness and it wont throw a code--been there done that. but like duamaxx said have it diagnosed with cat et. sounds like a bad injector(yes an injector can go bad and not throw a code) or low fuel pressure or a fuel restriction.

 

Or you could have bad injector o-rings due to excessive heat from a badly seated injector. (Usually #5 on Accert engines) I've seen lots of them. I have a repair, if that is your problem. Look for carbon build-up on the injector barrel, or discolored injector barrel from heat.

 

Injector harness' are an issue on Acerts, they usually log a code, but not always. I'd say that as bad as it sounds, if it were the harness, you'd have a check engine light. The times that it didn't throw a code for me, it was a lacking power complaint, not a miss or running rough. It sounds to me that you have an injector that failed mechanically, but working electrically. You wont be able to diagnose that without a computer though.

If you have a gauge, verify fuel pressure. Pull the return line off the filter housing and put it in a jug submerged in fuel. Run it and stab the throttle a few times to look for bubbles, you'll get some out of the hose at first, but it should clear up. If you get bursts of bubbles when you stab the throttle, I say injector o-rings. If you get a fairly constant flow of bubbles, more as you rev it, you may just be sucking air before the pump. Bad injector O-rings will let compression in the fuel, so you get a rather large burst of air when you stab the throttle.

Acerts had a rocker stud update because they were breaking, you can pop off the valve covers and make sure they're tight and not broken. Run it at an idle with the rocker covers off and make sure all the rockers are moving to see if you have a flat lobe on the cam, which is not common, but check while you're in there. I have seen a few broken rockers before. Also check that all the valve and injector springs are not broken.

 

Cat Technician defines that engine on COLD MODE , ecm turns it on it self untill water temp reach 150° F
In winter or cold mornings just keep acert on idle and move only on operating temp.

 

I know this is a really old post, but did you ever figure out this problem?

 

Yea I’m wanting to know

 

We had same issue throttle body sensor