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+--- Thread: 3406E warms up looses boost ? (/showthread.php?tid=9849)
3406E warms up looses boost ? - Heavyhauler - 12-10-2024
My 3406E series cat runs like a dream. when the truck warms up on warm days it seems to loose boost and struggle and become lazy per se. On a chilly winter day she will pull like a freight train because the fuel is in fact cooler. live dated says all the injectors are good, brand new fuel lines start to finish , return lines included ( from cat) new fuel filter housing , filter as well. New primer and Heui pump. Checked the Turbo center bering seems fine, new turbo charge cooler , all hoses and clamps. Really blown my brains out. Ive done 90,000 miles since all repairs. runs every day just about 5 days a week steady. Hasn't gotten better or worse. no check engine lights .... ever. indicator light works, data communication is complete with live data scanner with no indication of current or historical codes.
Could the ECM have an issue in reading temp of fuel/truck/engine/ and not throw a code because it can't self identify? Im still chasing this mystery. (30,000 hours on ECM)
I feel like if I put an after market fuel cooler it would help but still wouldn't be a proper repair.
RE: 3406E warms up looses boost ? - tree98 - 12-10-2024
(12-10-2024 )Heavyhauler Wrote: I feel like if I put an after market fuel cooler it would help but still wouldn't be a proper repair.
I doubt the fuel temp has anything to do with it. I would suspect a wonky intake air temp sensor, if it has one?? I'm not familiar with 3406E's.
RE: 3406E warms up looses boost ? - Heavyhauler - 12-10-2024
yes I do have a air intake sensor. when we changed the temp sensor and wiring, we changed the intake pressure sensor for hopes of good luck. with no probable cause that either of those where an issue. no check engine lights or anything. it certainly is a mystery. I'm talking to Milton cat and trying to go to dinner with one of the older techs. bring him up to speed per se and show him the truck. Then send in the truck for him to have a shot at it. he is specifically good with cat and cat programing/live data. when I do figure it out I'll be sure to post. but I'm open to any an all ideas
RE: 3406E warms up looses boost ? - Rawze - 12-10-2024
not a cat guy but an enigne that was over-boosting all the time would have similar symptoms.
what is the boost and the EGT's doing during colder weather .. and in hotter?.
RE: 3406E warms up looses boost ? - Heavyhauler - 12-10-2024
the EGTs are always at 650. if its an extreme hot day and a long hard pull I could see 700 but rarely. the EGTs never seen to change, they did drop after I hollowed out the mufflers. prior to that the EGT temps where at 900. that was also about 50,000 miles ago.
RE: 3406E warms up looses boost ? - Rawze - 12-10-2024
(12-10-2024 )Heavyhauler Wrote: the EGTs are always at 650. if its an extreme hot day and a long hard pull I could see 700 but rarely. the EGTs never seen to change, they did drop after I hollowed out the mufflers. prior to that the EGT temps where at 900. that was also about 50,000 miles ago.
those egt numbers sound waay too low for a diesel engine that is running properly. In a hard pull, the EGT's should be 1000+F - 1150F post turbo. Does not matter how free-flowing you make the exhaust.
Your posts are still somewhat pointing towards possible over-boosting?.. especially if you removed exhaust components and the EGT's dropped that much. I.E.> Removing the muffler and it dropping EGT by measurable amounts = the turbo is spooling even harder now due to less exhaust restrictions.
-- over-boosting will cause that exhaust to run cold like that, the cylinders run waay too lean, and its very harmful to the engine.
boost levels?.
RE: 3406E warms up looses boost ? - Heavyhauler - 12-11-2024
That simply makes sense, low EGT means not enough fuel. I had the mufflers off for other work and (thought) hollowing them out might have helped the truck breathe better. The boost is usually around 20/28 pounds. When the truck throws its fit randomly she will struggle to build boost loaded or empty. Which I assume in full circle ... no fuel no spool. I always noticed that the fuel tanks would be so hot you couldn't touch them. once that happens she will be stuck in her funk. Then if I park it for a few hours and things cool off it'll run good for a bit till everything warms up. Buy new stacks to lift the EGTs to start ?
RE: 3406E warms up looses boost ? - Heavyhauler - 12-11-2024
I truly do appreciate all the knowledge and help.
RE: 3406E warms up looses boost ? - Bengy88 - 12-11-2024
Your truck wouldn’t happen to have one of the resistors that plug into the fuel temp sensor and boost pressure sensor to fool the ecm into over fueling your truck would it? If so throw them in the trash asap, I can’t throw the name of the company that makes them out here but I’ve seen a lot of performance issues out of trucks with them on cats. Also has the truck ever been tuned? A lot of guys will throw a tune in these engines that you can get for free from other forums and 80% of them are complete trash. Rawze is 100% correct. Low egt’s are just as bad as high egt’s. if you want you can pm me your contact information and I’ll help walk you through some things.