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No Throttle Response

Ok..here it is. The connections on both look good, no oil dirt etc. I'm getting 5ish to each sensor..I can crank truck with both plugged in, and read on the BARO gauge "14"...the boost gauge registers also as it should when in a load, and it riggt on with my analog boost gauge I installed. Idles fine, runs fine except when barely on the throttle while driving, it will command 19k to 21k rail pressure, and actual will be 16kish and throw the code when I hammer down.....but, I can unplug just the baro gauge, then, boost gauge doesn't work and it doesn't "command" so much rail pressure, AND, when it does command 21kish at WOT the actual rail pressure will keep up! Beats anything I've ever seen. And, my EGTS are at least 180 degrees lower....go figure..???? Lol
 
ok all is fine with the map and baro sensors. what your are doing by disconnecting the baro is essentially forcing "limp" mode on the engine. the ECM will derate fuel and power to give you the ability to drive safely to get out of arms way. we need to look closer at the code it throws when all is connected.
 
Ok, sounds good. So far, when all is plugged in, the only code is "P0093 Large fuel leak detected".....I'm hoping it ain't injector bleed off, but I'm afraid it might be. It just won't keep the actual pressure up to desired. It will jump up to 21 and immediately start falling off, going up and down from 18.5 to 19.5 then steady out to 17.8ish till it pops the code and goes to limp mode, and it'll only turn 2k rpms till I clear the code. Could be a weak cp3 tho.
 
I was just reading up on this, and could very well be any of what you mentioned. best thing is to check all of the easy stuff first. fuel filters, air leaks, lift pump operation and pressure and whatnot. then it will be testing injectors and more on to the expensive stuff.
 
make sure there are no visible fuel leaks anywhere on the engine. I'm not that familiar with the duramax engines, more so on the IDI engines where everything is exposed. if I had to guess, your injectors are all under the valve covers where you can't physically get to the high pressure lines to see any leaks.

check to see if your engine oil smells of diesel. that would be a dead giveaway that injectors are leaking down and not holding. that will also wash down the cylinders, injector pissing streams of fuel instead of spraying fine mist causing catastrophic damage over time (worst case)
 
Well, honestly I have done all that in last 8 weeks or so. Lift pump, all new fuel lines, bypassed fuel lines and ran out of a jug, multiple filters, bypassed original filter housing, also got a new one of those, you name it....man it has wore me out. I can unplug the FPS and make it command 21k on an idle and it will do it...I have been avoiding the injector bottle test, but I reckon on Sunday thays what I'm gonna do.
 
Just be careful, I'm used to the older IDI's only around 2k to 3k psi on injectors, your's runs over 20k psi. nothing nice to play around with when testing injectors. especially when a leak is involved!
 
Ok, I appreciate you telling me that. Definitely makes sense. I imagine anything that pressurized would cut a finger 'or hand" slap off..nothing to play around with, I agree with that. Again, thanks so much for the kindness, and willingness to help. Much respect 🙏.
 
Our old IDI engines runs about 1800 to 1900 PSI fuel pressure.
The direct injection runs in the 20,000 or more PSI range,
Nothing to mess with at all.
Even the very slightest pin prick can cause a whole world of pain, misery and flesh rott.
 
MrMarty51 said:
Our old IDI engines runs about 1800 to 1900 PSI fuel pressure.
The direct injection runs in the 20,000 or more PSI range,
Nothing to mess with at all.
Even the very slightest pin prick can cause a whole world of pain, misery and flesh rott.
Click to expand...
Ok, I appreciate the heads up. Will DEFINITELY be on high alert ⚠️ and will follow protocol on "unloading" the pressure before injector testing. Thanks again yall.
 
I will post here everyday on anymore codes, problems or fixes, along with the result of the bottle test. I've read thru so many posts on this subject on many forums, but never seen a follow up on what was going on. I do know that Kennedy diesel has a program for these 01 models, where he tweaks the ECU to not throw the P0093 code and I've considered doing that also.
 
So true. I have been told the same thing with hydraulic systems too.

how many miles are on your truck? on our IDI's we recommend replacing the injectors at 100k. if your's is up there in mileage, if might be good insurance to replace them.

while I was reading up on this issue and the code your getting, I did come across a site talking about some sort of factory programming flaw from GM. after you find and fix your issue. that might be something to look further into as well.
 
dbrannon79 said:
So true. I have been told the same thing with hydraulic systems too.

how many miles are on your truck? on our IDI's we recommend replacing the injectors at 100k. if your's is up there in mileage, if might be good insurance to replace them.

while I was reading up on this issue and the code your getting, I did come across a site talking about some sort of factory programming flaw from GM. after you find and fix your issue. that might be something to look further into as well.
Click to expand...
Truck has 220k, and when I bought it 3 months ago, I was told injectors were just done 5k miles ago....but....I don't know what kind of injectors, or the quality of them. I've heard horror stories about reman injectors of certain brands.
 
since they were done not too long ago, you might get lucky and find a pressure line fitting simply loose at one of the injectors or at the rail. IDK if they are under the valve covers or if they are out on the head like ours. if under the covers, look for a "clean" spot around the line nut where diesel has washed away oil in that area.
 
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