1999 Gen VI EFI to Q Jet 4L80E

[amrush2112]

Ok here’s a question. On the 93 6.5 diesel trucks that had an automatic with a 4l80e and mechanical injection (no engine computer) did it have a stand alone computer for the transmission or was it mechanically controlled? Mine is dead so not sure if it does or not. Swapping a 350 in it as well.

 

[Spareparts]

From what i have read it would have had a stand alone trans controller.

 

[Scooterwrench]

From what i have read it would have had a stand alone trans controller.

Because it's a diesel would the shift points be much lower?

 

[Spareparts]

Yeah, I have also read they have lower shift points and are programmed for a engine with 3,500rpm max.

 

[L31MaxExpress]

This is just not true.

98-2001 black box and 0411 DO revert to full line pressure on the stock OS's if you don't change the settings like is described in my previous posts' linked thread on the HP tuners forum. It is not because the data isn't there for it to function, but because the OS is set up to do that when the MAF is failed. There are options in the OS to turn that off. A 2002 0411 OS will not default to full line pressure if the MAF is failed properly. There ARE custom SD OS's, but those are usually only to allow the 2 and 3 bar MAP sensors so that you can run boost. It is standard to fail the MAF sensor in the OS to revert the system to SD so that you can dial in the VE tables. Most people just let it go to full line pressure while doing this, since it doesn't really hurt anything. It just makes the shifting much harsher at low throttle conditions. I'm running an '02 OS, so I don't have this issue at all.

If you fail the MAF in the tune and then just hook up a line pressure gauge to the trans, you can tune the normal and abuse mode tables to set them properly based on what the PCM thinks the engine is doing.

WRONG! The 0411/P59 fails to higher line pressure for a good reason, my van shifts so violently hard it barks the tires with nearly no throttle and rattles inside everything when the MAF is failed. It shifted so hard when I was tuning the marine intake that it popped the conversion center console loose from its mounting clasps and shifted it 8" back.

The PCM code is not setup to correctly calculate torque production in speed density and I would highly recomeend adding about 20% to the line pressure tables to keep from smoking the clutch packs if you disable max pressure fail DTCs.

 

[BeXtreme]

WRONG! The 0411/P59 fails to higher line pressure for a good reason, my van shifts so violently hard it barks the tires with nearly no throttle and rattles inside everything when the MAF is failed. It shifted so hard when I was tuning the marine intake that it popped the conversion center console loose from its mounting clasps and shifted it 8" back.

The PCM code is not setup to correctly calculate torque production in speed density and I would highly recomeend adding about 20% to the line pressure tables to keep from smoking the clutch packs if you disable max pressure fail DTCs.

What part exactly is wrong? Are you saying that you are running an 02 OS and it is failing to max line pressure? Or that you shouldn't disable the max pressure fail DTC's and tune the tables with a line pressure gauge connected? I have read multiple posts on other forums of people saying the 2002 OS does not have the max pressure fail DTC's.. I don't know whether that is true or not. I do know that A LOT of people run 0411 OS's as a stand alone trans controller using just Tach and TPS inputs and then tuning the shift points and pressures per the tables and a line pressure gauge.

 

[L31MaxExpress]

What part exactly is wrong? Are you saying that you are running an 02 OS and it is failing to max line pressure? Or that you shouldn't disable the max pressure fail DTC's and tune the tables with a line pressure gauge connected? I have read multiple posts on other forums of people saying the 2002 OS does not have the max pressure fail DTC's.. I don't know whether that is true or not. I do know that A LOT of people run 0411 OS's as a stand alone trans controller using just Tach and TPS inputs and then tuning the shift points and pressures per the tables and a line pressure gauge.

What I am saying is that 2002 does in fact have max pressure fail and that disabling it is not a good idea without increasing the line pressure table. Speed density mode or any form of operation without a functioning MAF is asking for problems. Even when I ran my van on a carb, I still had the MAF. You will never get a consistent line pressure reading without the MAF. If you are going to delete the MAF, delete the EPC and put the vacuum one in its place.

 

[92Raiderburban]

You'll be spending about 4x as much just to convert the engine to carb... but whatever.

Actually...NO. LMAO I converted my '99 L29 to carb (manually shift the 4l80 with a vac modulator installed) and it cost me less than $160. Unlike the L31, the L29 heads accept ANY old carbed intake dating back to 1967. Yea i have a '69 396 aluminum intake thats LIGHTER than the factory L29 intake, and an 800 cfm Quadrajet. She lost no p0wer from the conversion. still doin 0-60 in 6 seconds flat.

 

[92Raiderburban]

You are talking about doing the thing that is going to require enough knowledge and skill to hack apart the stock system and slap several different parts together into a cohesive whole. you want to switch to carb is exactly the reason you are likely to have major issues.

a carbed intake and HEI doesnt require any "hacking". just a lil rewiring

It's a lot more complicated than it appears at first glance depending on how much you are willing to compromise. Do you want all of the things in the truck to function as they did before? Cruise control? AC? Keeping the OD? Want all of the stock gauges to continue to function? The simplest and easiest solution if you are wanting big HP and ease of use with what you already have is to just pull out the entire harness and swap to the carb/HEI and buy a standalone trans controller. You might not be able to retain a working speedometer and cruise control if you do that without getting creative. The stock PCM controls a lot of things though, so just be warned that there might be other things that stop working as well.

crusie control and A/c have 0 to do with the EFI part of it. O.D can be obtained via toggle switch by tapping into the brown wire under the hood at the ECM, its next to the 4l80 Solenoid A and B wires (yellow/black stripe and light green) and applying (-) GND to it. All my gauges work as they did prior to the swap. the tach wire was tapped into the (-) side of the HEI coil like any 70s and 80s GM factory vehicle. These trucks gauges are the same as anything back in the day, NOT LS1 pcm controlled where it has to absolutely stay stock to work right. althought the gas gauge is different on 98 and 99 those can be converter back to a one wire setup like 97 and older.

 

[92Raiderburban]

Tell me how long you expect a 4L80 to live running full line pressure all day every day? And what would ECT and MAP require in terms of adjustment to provide anything useful?

And I misspoke on the ECT with regards to TCC function, that's a function of TFT which stays in this scenario.

itll last about 8 months, my '92 i had lost reverse first and then 3 rd gear after running it full line pressure. but why even tinker with a computer tho when the company TransGo makes a vacuum modulator kit to dictate line pressure via intake manifol vacuum likes it daddy the TH400? no u dont have to drill thru the case i drill thru the pan and it worked great for YEARS. smooth shifting anf i id id tow with it. $90 on ebay and that problem is no more