Found a company that has a performance box that plugs between the ECU and the wiring harness, Its made by AG Diesel solutions, just curious if anyone has tried it before. I tried calling the company to get info but keep getting women in the tech department who sound like they are reading a text message back for answers, and who cant answer any questions. According to online it works on all 3126B and 3126E and C7's. Not looking for a big improvement in power but was thinking about adding an intake and trying to get 5-10% power increase might be nice with some ECO hubs.
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3126 CAT ECU MODS
- Thread starter brainsboy
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I see a tsunami coming
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Run away. These kinds of things are a bad idea.
Not positive about 3126, but c7 you can load a map up to 370hp.
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It's a piggyback - it sits between the engine sensors and the ECM. It tells the ECM that the fuel pressure is lower than it actually is, so the ECM will command a higher fuel pressure thinking it's too low. This creates additional wear and tear on the fuel system that is now running a higher base pressure than CAT intended. I suppose in the HEUI world this is modifying HEUI actuation pressure since the ECM has no control over fuel delivery pressure since that is mechanically regulated.
At any rate it lies to the ECM to get it to add more fuel.
I'm not a fan of lying to the ECM, and looking at older posts it looks like you have a 2001 LMTV so you would have the 275 HP flash. I can flash your ECM to the MTV's 330 HP spec. Ship me your ECM and I'll turn it around in one to two business days with the upgraded performance and any other options you want like changing the PPM for the ECO hubs and enabling cruise control, etc. That's a 20% increase and it's an actual CAT sanctioned flash file. All you have to do is add the missing atmospheric pressure sensor - remove plug, and wiring harness cap. Screw sensor into valve cover and plug it in. No wiring or introducing poorly tested electronics from China with unknown side effects.
As @aw113sgte said - RUN, don't walk, the hell away from that product..... IMHO. I tune vehicles of many kinds on a daily basis and piggyback solutions are NEVER something I recommend...... 1996 called and wants it's bad idea back.
At any rate it lies to the ECM to get it to add more fuel.
I'm not a fan of lying to the ECM, and looking at older posts it looks like you have a 2001 LMTV so you would have the 275 HP flash. I can flash your ECM to the MTV's 330 HP spec. Ship me your ECM and I'll turn it around in one to two business days with the upgraded performance and any other options you want like changing the PPM for the ECO hubs and enabling cruise control, etc. That's a 20% increase and it's an actual CAT sanctioned flash file. All you have to do is add the missing atmospheric pressure sensor - remove plug, and wiring harness cap. Screw sensor into valve cover and plug it in. No wiring or introducing poorly tested electronics from China with unknown side effects.
As @aw113sgte said - RUN, don't walk, the hell away from that product..... IMHO. I tune vehicles of many kinds on a daily basis and piggyback solutions are NEVER something I recommend...... 1996 called and wants it's bad idea back.
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TM shows it as a 194-6723
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I see there's a boost sensor and atmospheric sensor differing by one number value. Cat parts says the -23 is a 339kPa And the -22 is a 116kPa
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Yeah the TM is not super clear on which one is which. Ultimately it's best to order it from CAT with the serial number of a 330 HP engine, etc.
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Here's what the TM shows - both of the sensors are referred to as " SENSOR,MANIFOLD ABS" 
Definitely would be good to figure out the exact part number for you 3126b guys. I just tell customers to go to CAT and give them a 330 HP serial number off an engine sticker from a govplanet auction since those are easy to find on your phone and they typically take a picture of the engine serial for crate motors, etc. The sticker will say 330 HP.
Definitely would be good to figure out the exact part number for you 3126b guys. I just tell customers to go to CAT and give them a 330 HP serial number off an engine sticker from a govplanet auction since those are easy to find on your phone and they typically take a picture of the engine serial for crate motors, etc. The sticker will say 330 HP.
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I realized I might just have one already sitting on the barn lolHere's what the TM shows - both of the sensors are referred to as " SENSOR,MANIFOLD ABS"
Definitely would be good to figure out the exact part number for you 3126b guys. I just tell customers to go to CAT and give them a 330 HP serial number off an engine sticker from a govplanet auction since those are easy to find on your phone and they typically take a picture of the engine serial for crate motors, etc. The sticker will say 330 HP.
View attachment 927923
View attachment 927924
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This is what CAT says as being an "exact fit" for a 330hp 7JZ 3126. Seems to me the description is indicative of the function since 116kPa is 16.8psi. That's the perfect instrument span for atmospheric sensing whereas the -23 part number with 339kPa is 49.2psi which is a span for boost pressure sensing..
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The pressure spec doesn't tell the entire story since it doesn't say if that's gauge pressure or absolute pressure - referenced to sea level or referenced to outer space...... but seems like it's certainly gauge pressure given the max reading. CAT changes part numbers like most people change underwear so the current part number likely IS different than the original or the TM listings. NSN is what matters - the underlying part number can change. I'll pull up the listing for the original and see what the part number history looks like.....
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Top secret don't look!
I just checked on that crate engine which you verified as 330hp. Pretty clearly shows boost is -23 and atmospheric is -22...that happens to match the TM parts diagram in TM9-2320-312-24-2 for the 3126 engine. That TM describes it as a 3126E engine but IDK if this crate is a B or E engine.
the boost sensor on this crate is busted off but the atmospheric is pristine. Golden! Just saved $247
Crate:
Existing B engine..
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I have been meaning ask about this. I thought I'd read somewhere here there was an added sensor for the 330hp tune—
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I'm going to try the 194-6722 since it's what was on this crate engine I have, which is a 330hp version 3126. That's as close as I can technically get without the NSN detail that Rick can do.
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Keep us posted, please. Rick did our tune, we need to add the sensor, too—
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Sure thing
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The ECM will throw a silent code for that sensor with the 330 map. Not sure how necessary it actually is - probably just some kind of minor altitude fuel trim for emissions. I've never had anyone say they noticed a difference with or without it.
As you go up in power, more fuel is required and that starts impacting emissions. They probably have to derate the engine and start pulling out fuel as the altitude rises and you don't have the oxygen to combine with the fuel anymore so it won't piss off the EPA. Not having the sensor has the computer assuming you are at sea level. My assumption is that since the fault code is completely silent and thus a failure of this sensor would never alert the driver or the maintenance department that the results of not having it are probably entirely benign or possibly may even result in better performance due to the additional enrichment.
Another interesting thing I noted on my C7 - I got a new wiring harness from CAT for my engine (ordered by serial number) and they deleted the low pressure fuel lift pump sensor connector. So I just didn't plug it in because that wiring is apparently deprecated. ECM didn't give a shit. Not even a silent code. I guess that was there to populate a data stream that the computer doesn't actually monitor and I guess they decided it's just irrelevant. Another.....
As you go up in power, more fuel is required and that starts impacting emissions. They probably have to derate the engine and start pulling out fuel as the altitude rises and you don't have the oxygen to combine with the fuel anymore so it won't piss off the EPA. Not having the sensor has the computer assuming you are at sea level. My assumption is that since the fault code is completely silent and thus a failure of this sensor would never alert the driver or the maintenance department that the results of not having it are probably entirely benign or possibly may even result in better performance due to the additional enrichment.
Another interesting thing I noted on my C7 - I got a new wiring harness from CAT for my engine (ordered by serial number) and they deleted the low pressure fuel lift pump sensor connector. So I just didn't plug it in because that wiring is apparently deprecated. ECM didn't give a shit. Not even a silent code. I guess that was there to populate a data stream that the computer doesn't actually monitor and I guess they decided it's just irrelevant. Another.....
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Do you tho
Do you think the difference with or wo the sensor, at 7300ft, will be observable in a straight line acceleration test? I can't really do a flat road test bc there are no flat roads here but I have one 1/2mile spot where I could do a timed accel to say 50mph, but it's 6500ft.The ECM will throw a silent code for that sensor with the 330 map. Not sure how necessary it actually is - probably just some kind of minor altitude fuel trim for emissions. I've never had anyone say they noticed a difference with or without it.
As you go up in power, more fuel is required and that starts impacting emissions. They probably have to derate the engine and start pulling out fuel as the altitude rises and you don't have the oxygen to combine with the fuel anymore so it won't piss off the EPA. Not having the sensor has the computer assuming you are at sea level. My assumption is that since the fault code is completely silent and thus a failure of this sensor would never alert the driver or the maintenance department that the results of not having it are probably entirely benign or possibly may even result in better performance due to the additional enrichment.
Another interesting thing I noted on my C7 - I got a new wiring harness from CAT for my engine (ordered by serial number) and they deleted the low pressure fuel lift pump sensor connector. So I just didn't plug it in because that wiring is apparently deprecated. ECM didn't give a shit. Not even a silent code. I guess that was there to populate a data stream that the computer doesn't actually monitor and I guess they decided it's just irrelevant. Another.....
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This was answered on post 32 here.
2003 M1078A1 3126B 330 horsepower flash
Bummer, I hope that cable shows up quickly for ya.
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