Hi all. First post and guess what?...I'm asking for help. A few weeks ago I swapped in a 99 1/2 engine. It ran great! I drove it today (I rarely drive it) and my boost wouldn't pass 14psi and I see zero black smoke. The only thing I can figure is maybe the fuel filter. I tried my edge evolution CTS and Bully Dog. Could it be as simple as the filter?
Lost boost idk why?
- Thread starter 3Deez
- Start date
Egts were up around 11-1200. Mods are just the evolution CTS or bullydog. Also put a bts valve body in the trans. Usually just use the CTS but I tried the bd today to rule that out...it's leftover from unlocking the pcm on my 2014 Ram.
ghohouston
Active member
And check the map sensor hose
I did tighten everything up. I had a cracked exhaust manifold and bought a dorman. When I switched motors,I broke the dorman at factory torque specs. I got another and put a thin film of high temp silicone on the gasket because salt had corroded underneath the other one. Do you think a tiny skim of ultra copper could have failed? I don't see any soot around it. Shouldn't I see smoke from low boost?
Blown262
New member
When I got my truck, it would peak at 17psi and would struggle to break 15 when hot or with the AC on. No boost leaks. My issue seemed to be my fuel pressure from the factory pump. I would sit at 58-60 idle and drop all the way to about 20-25 WOT. When the fuel in the tank started to get hot, I wouldn't see anything over 15 psi and there was a severe drop in performance. It's still a minor issue to this day when the fuel gets hot, but I have twin 45GPH pumps that are capable of peaking at 80psi. My fuel pressure doesn't go below 45 psi WOT anymore. Hopefully this helps a bit
Hey! That thing is a little brittle and a tad loose. So if the sensor isn't seeing the boost,the truck won't fuel as much either,right?
I probably should upgrade my fuel system. I will replace the filter soon. It's not very old though.
Oh I left that part out too! I put the good bellowed up pipes on it. Thanks
ghohouston
Active member
Yeah, if the map sensor is loose, it'll cut your power down. Replace it and report back.
Will do. Thanks
Blown262
New member
Well I'm no expert on these trucks. There's people here with vastly superior knowledge. Personally, I would by a threaded adapter and gauge and check your post filter fuel pressure in the bowl before spending another 30 bucks on a filter. And if your MAP is loose, I'd replace that before going any further.
Thanks. I just can't believe that slightly loose hose could do so much,but I'll find out.
Blown262
New member
Well the MAP sensor in any vehicle plays a very key role in fuel delivery. There's no mass air sensor that I'm aware of on a 7.3, so the PCM needs to be able to see, based on pre written parameters, how much air the motor is getting to adjust the fuel table accordingly. I would imagine it's more important on a diesel as there is no throttle plate to control air flow. If the MAP sees that you have a manifold pressure of 22psi, but you really have 30psi, the PCM will deliver enough fuel for 22psi of MAP and you'll go very lean as all that extra air will try to force it's way into the motor. Does you turbo and/or boost gauge flutter at the threshold?
ghohouston
Active member
If the map sensor hose isn't tight on both ends, or has a crack/tear anywhere in between, it can definitely cause power issues. They get old and brittle. Sometimes they're fine for a long time, and then you remove it to replace injectors, or a turbo, and that old brittle rubber cracks, you don't notice it, and you're suddenly wondering what happened. Or sometimes they do it on their own.
I had a local guy on here once with a 6.0 who did an egr delete, and couldn't figure out why he couldn't build over like 10 psi boost. I went to check it out, and in 5 minutes found his problem, his original map sensor hose "looked old" so he replaced it with a new hose, that was too big, and didn't make a seal on the intake manifold nipple, or map sensor. We tossed the old hose back on, and all was better.
I had a local guy on here once with a 6.0 who did an egr delete, and couldn't figure out why he couldn't build over like 10 psi boost. I went to check it out, and in 5 minutes found his problem, his original map sensor hose "looked old" so he replaced it with a new hose, that was too big, and didn't make a seal on the intake manifold nipple, or map sensor. We tossed the old hose back on, and all was better.
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Arisley
Moderator
It sounds different and it reads zero psi until I lean on the throttle more than usual.
Ok,Thanks.
