• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Conversion from DS4 to DB2

A

Acesneights1

New Member
Messages
10,018
Reaction score
36
Location
Northeast CT
Ok, probably got Bobbiemartin's attention for sure. I still have diagnostics to do on my new burb but if the IP for some reason is dead I am seriously considering canning it for a DB2. Here's my thought process. I have a reman db2 sitting on a truck I am going to most likely dismantle, however it is not a 4911. It's the 6.2 one (don't remember the number) will that pump put out enough fuel if I turn it up ? Not looking for performance. If that DB2 turned up can match a stock DS4 tune I would be happy. Also what lines do I use ? AFAIK I would need lines from a 93 6.5TD or a 88+ 6.2 . Any issues with the 6.5TD intake clearing a DB2 ? I don't think there is but here's how I'm doing the math.
To fix with DS4:
DS4=7-800$ for GOOD rebuild(not pensacola crap)
PMD relocate kit 3-400$
Heath Tune so I can loose the vac system=4-500$
So that is min 1400$ and still stuck with the same PIA DS4 System
If I convert USING WHAT I HAVE..:
DB2=free
Lines=???
Compushift standalone controller for trans=11-1200$
I know Bobbie will chime in on a cheaper way to use GM TCM for the 4L80e but I think I would go with the Compushift for ease of install and more veristillty programming the trans.
So I would have a trouble free great running truck for less than replacing the DS4.
The only sacrifice I can see is no cruise control which the Burb currently does not have anyway although if I fix the DS4 or don't need to, I will install cruise.
My experience is the DS4 is a royal PIA. Even with the PMD relocate, D tech etc...They still fail. Even Heath's fails. Mine did after 2 yrs. I have 2 dead d techs on my bench less than 2 yrs old so I am getting a bad taste for the DS4 but I probably wouldn't convert iof I had to buy a DB2 but being that I have a nice reman one, it's seems worth it. My only concern it will a 6.2 DB2 put out enough fuel ?
 
BTW even If I don't do this I thought it would be interesting. I know some have swapped DB2-4911s but what about the DB2-XXXX from a 6.2 ?
 
Acesneights1 said:
Ok, probably got Bobbiemartin's attention for sure. I still have diagnostics to do on my new burb but if the IP for some reason is dead I am seriously considering canning it for a DB2. Here's my thought process. I have a reman db2 sitting on a truck I am going to most likely dismantle, however it is not a 4911. It's the 6.2 one (don't remember the number) will that pump put out enough fuel if I turn it up ? Not looking for performance. If that DB2 turned up can match a stock DS4 tune I would be happy. Also what lines do I use ? AFAIK I would need lines from a 93 6.5TD or a 88+ 6.2 . Any issues with the 6.5TD intake clearing a DB2 ? I don't think there is but here's how I'm doing the math.
To fix with DS4:
DS4=7-800$ for GOOD rebuild(not pensacola crap)
PMD relocate kit 3-400$
Heath Tune so I can loose the vac system=4-500$
So that is min 1400$ and still stuck with the same PIA DS4 System
If I convert USING WHAT I HAVE..:
DB2=free
Lines=???
Compushift standalone controller for trans=11-1200$
I know Bobbie will chime in on a cheaper way to use GM TCM for the 4L80e but I think I would go with the Compushift for ease of install and more veristillty programming the trans.
So I would have a trouble free great running truck for less than replacing the DS4.
The only sacrifice I can see is no cruise control which the Burb currently does not have anyway although if I fix the DS4 or don't need to, I will install cruise.
My experience is the DS4 is a royal PIA. Even with the PMD relocate, D tech etc...They still fail. Even Heath's fails. Mine did after 2 yrs. I have 2 dead d techs on my bench less than 2 yrs old so I am getting a bad taste for the DS4 but I probably wouldn't convert iof I had to buy a DB2 but being that I have a nice reman one, it's seems worth it. My only concern it will a 6.2 DB2 put out enough fuel ?
Click to expand...
If you think an $800 dollar IP is better than a $ 300 one,think again.They just allow more for warranty.:rolleyes5:
The DB2 ain't foolproof either.

I think you're just unlucky when it comes to the DS4;),wanna try one of mine;)
 
Acesneights1 said:
Ok, probably got Bobbiemartin's attention for sure. If that DB2 turned up can match a stock DS4 tune I would be happy. Also what lines do I use ? Any issues with the 6.5TD intake clearing a DB2 ?
Click to expand...

Pump - I know others have used a 6.2 DB2 (.029" plungers) with success. It will not match the larger .031 plungers, but if you turn it up it should be OK. It will not harm anything and you can always change it out later if its not powerful enough for you.

Lines - Use the lines that are currently on the 6.2 DB2, unless its a real old one with the odd injectors. If you need some, they are not hard to find or terribly expensive used. You might want to check the classifieds if you need a set.

Intake - No problem at all with clearance. You can do away with the boost & temp sensors and the vacuum pump as well if you go Turbomaster.

You will need a gas pedal from a gasser, they are in almost every junkyard in the USA, so easy to find. You need a throttle cable. You might get one from a dealer, availability has been spotty though. LMC list them as well. Again, might want to check the classified section, never know what you may find there.

Cruise is not a big problem. GM cruise control boxes are in almost every junkyard. You can't get the factory 6.5 DB2 cruise cable anymore and I do not know of any aftermarket source. But, its not real hard to modify a cable from the junkyard to work, so other than a small amount of fab work, its no big deal. You can use the same stalk you have now to operate it.

On the transmission, do you have a 4X4? If so, you need to check something on the Compushift. Will it allow you to electronically change the input ratio of the rear transmission speed sensor? The DS4 trucks use a speed sensor in the transfer case. When you put it in low range, the PCM can compensate for the speed difference of the sensor - its spinning at whatever the low range ratio is, I think about double, but not sure exactly. This is the big problem with 4X4's. The factory TCM cannot compensate for this, so you are no better off there. Possibly the Compushift can, but if not you have to install a rear speed sensor in the transmission. Now the case is cast for one and so that is not the problem. The problem is the reluctor wheel that triggers the sensor is not there in most 4L80E's. For whatever reason, some auto 4X4's have a rear speed sensor, but most do not. And a few that do not may have a reluctor wheel, but most have neither. At least that is what I have found. Now, installing a reluctor wheel is no problem in a 4X4 trans, but it requires a complete trans disassembly to do so.

I don't know if there would be enough interest, but what do you think of having a sub section on the 6.5 area for DB2 swaps? It seems like there would be enough interest.

Kenny, PM me and I can help you on the swap.
 
I think you can just keep using your PCM to shift the 4L80E if you maintain the sensors like CPS. Maybe Kojo would do a DB2 swap tune that disables the OS codes, pulse width codes and unused APP channel codes and you just plug the TPS into one of the APP inputs. The GM manual defines which of the 3 APP inputs is also for TPS input. The lines that go to the DS4 would just be left unused and the PCM would be none the wiser.
 
buddy said:
I think you can just keep using your PCM to shift the 4L80E if you maintain the sensors like CPS. Maybe Kojo would do a DB2 swap tune that disables the OS codes, pulse width codes and unused APP channel codes and you just plug the TPS into one of the APP inputs. The GM manual defines which of the 3 APP inputs is also for TPS input. The lines that go to the DS4 would just be left unused and the PCM would be none the wiser.
Click to expand...

You can use the existing PCM by cobbling up throttle pedal with an arm to actuate the APP, but I have never seen one shift correctly. You can get it to work OK, but not perfect. Synching up the pedal with the pump and the APP throughout the range is just not possible. I spent weeks trying, using various length arms, adjustable rods, heim joints and just never got satisfactory results.

However, using the PCM with the single input from the DB2 TPS, now that is something I have long thought would be the way to go. If you use just one input in place of the APPs 3 inputs, the PCM wants to go in limp home mode. But if the PCM could be modified to accept one input, then you would be home free. That would make swapping to a DB2 easy for most any engine/trans configuration.

Back when I did my conversion, I corresponded with several people that I thought might have a commercial interest in producing something like this, but they had no interest at all. While the PCM mod would work, I have another idea that make converting to a DB2 even easier. I would propose a small box that would take the single input from the DB2 TPS and convert it to the triple APP signal. I even spoke to a guy that designs stuff like this. He was sure he could make one, but he wanted several thousand dollars up front and I just didn't have that kind of money to invest in something that speculative. With such a device, you would only need to do the mechanical work, run a couple of wires inside the cab and plug it into the box, which would in turn replace the APP. The modded PCM would be about the same. If you can entice Kojo to do one, I'm sure there is a market.

While we are on theoretical solutions, there is one other idea that may work, if the PCM mod never comes to fruition. This is only speculative, but I have reason to believe it would work. I know the PCM can compensate for the transmission signal while in low range. My guess is (and that is all that it is) there is somewhere on the PC board where you could solder a wire and have the correct trans signal. You could then take this wire and use it to feed a standalone TCM. That would make converting an automatic 4X4 the same as a 2WD. Still more work than a modified PCM, but since at this time there are no modded PCMs that will work, it may be something to look into. It would require someone with intricate knowledge of the PCM and I can't even find a schematic for one, so I never got very far on that one.

Its discussions like these that make me wish for a separate DB2 conversion forum.
 
Last edited:
Why can't you just use a computer from a 1993 4L80E 4x4 pickup? Mod the harness as needed perhaps? It will shift the trans and that is it's only function. Cruise is a separate box and you may need the harness etc for it. Aftermarket cruise may be cheaper.
 
WarWagon said:
Why can't you just use a computer from a 1993 4L80E 4x4 pickup? Mod the harness as needed perhaps? It will shift the trans and that is it's only function. Cruise is a separate box and you may need the harness etc for it. Aftermarket cruise may be cheaper.
Click to expand...

93 is not the best year, but you can and that is what I do. Its 4X4 trucks that are the problem. Its hard to get much cheaper than the factory cruise.
 
Then you also need the RPM sensor for that TCM, not a big deal I guess, to get that distributor like area sensor. Do they use the same VSSB/DRAC for VSS input and speedo?
 
buddy said:
Then you also need the RPM sensor for that TCM, not a big deal I guess, to get that distributor like area sensor. Do they use the same VSSB/DRAC for VSS input and speedo?
Click to expand...

Yes, with the GM standalone TCM you use an engine speed sensor, which is a bolt in replacement. Needs a TPS as well. On 2WD, you use the same DRAC and VSS. Really, you use all the same trans sensors. Just some rewiring, as you retain the PCM as it still handles some functions. Glow plugs for instance.

If you use the TCM on a 4X4, I would use another DRAC with the rear trans sensor. That way the speedo (and I think the ABS) will work properly.
 
Its been a while back and I don't remember exactly, but I did a lot of experimenting with various configurations when I did my conversion. I did try using the TPS to replace the APP inputs. I bought a PROM burner and the software from Westers and made lots of different PROMs to try and get it to work with the PCM. I couldn't get it sorted and then decided on going the standalone PCM route. I think the missing APP input causing limp home is in the PCM, not the PROM. Again, I could be wrong and its certainly worth a try. You are going to need someone that is willing to do all the mechanical part and then do some experiments with the wiring, PROM replacement, etc., knowing they may fail and have to get a trans computer. But if anyone is willing, I would do what I can to help.

It would be nice to find someone that had the knowledge of the PCMs. I'm sure it would be easy to get around the APP input problem, if you knew where it was.
 
ak diesel driver said:
couldn't you just split the signal to feed 2 paths
Click to expand...

Not easily. I think GM was worried that the APP failed, someone would just jump the wires and be able to use a defective APP. My guess is they were worried about runaway acceleration. Anyway, it uses 3 differently scaled APP inputs. They must match or it sets a code. So that is why you would need some sort of circuit to split the signal into the 3 different APP signals. There really is no easy way to use 1 APP signal on the PCM.
 
You must log in or register to reply here.
Back
Top