1997 engine swap into a 1995 5sd setting DTC Codes

[mrbornery21]

I recently put an engine that came out of a 1997 6.5 turbo 1ton 4x4 automatic trans dually. In a 1995 6.5 turbo 1ton 4x4 crewcab 5spd dually.

when installing the engine all electronics pluged right in, But when I drive the truck down the freeway the "service engine soon" light comes on the codes I pulled are,


DTC 78 Turbo wastegate solenoid fault.

DTC 84 Accelerator pedal position circuit fault.

DTC 99 Accelerator pedal position 2 ( 5 volt Reference fault)

Going to try switching the the waste gate solenoid with the one that came off the old engine and see if code 78 clears as for the other codes I have no idea what to do. Except switch the injection pumps, but there has to be a better way. Maybe a sensor swap of the old injection pump might work but which one .

[DmaxMaverick]

Check all the grounds. Battery to block. Battery to frame. Block to firewall. Frame to firewall. Strange as it may sound, any one of these in less than optimal condition can cause what you are seeing, and more. Also, clean the APP connector and make sure it is bolted tight. The wastegate code could be reversed vacuum lines, as well. Check your vacuum pump to ensure more than 25"hg at the pump, and ~15"hg at the wastegate actuator, all at idle.

[Robyn]

The 97 engine had OBD II controls where the 95 had OBD I
I dont know if that would have any bearing on this but??????

I agree with maverick though on the grounds.
There are several grounds that are bundled at the passenger side rear of the engine as well as a ground strap to the body from the back of the head.
Be sure all these are intact and connected to the engine.
We assume you had no issues prior to the swap????

With the electronic controls came a whole new set of issues.
Grounds are always critical for the electrical system to work right but these new electronic controls will go absolutely bonkers if there is a ground issue.

My first stop would be the bundle of ground wires that comes from the main harness at the pass rear of the engine.

When a gound is poor or not connected the system wil lsearch for a ground and this can make all sorts of stuff do goofy things.
I had a ground wire in the HEI on my 86 GMC 454 break and when it happened the wipers would cylcle on intermitent and the faster the engine was reved the more the wipers would cycle. :eek:

let us know

Robyn

[mrbornery21]

Checked vacuum at the waste gaste solenoid got 9inches from pump line, and 8inches at the wastegate on turbo. wastegate is working, closes when vacuum line is attached and opens when line is removed. But is 8inches of vacuum enough to keep the waste gate closed on hard acceleration.

And could the computer be sensing not enough or to much boost causing it to throw the TPS DTC codes.

symtoms are lots off power going down the freeway then when I shift into fifth gear truck accelerates almost to 70-75 then the "service engine soon" light comes on and I only have power in the first 1/4 of the gas pedal but thats it I can push accelerator to the floor and nothing no more fuel & power, just in the first 1/4 of the pedal is power & fuel. Is this some kind of limp mode because the computer is sensing a problem.

As for the grounds they all were replaced on the passenger side with new connectors on install but that doesnt mean the wires are good. The battery grounds are still original. I will check them all again and make sure they are good.

As for no prior issues I have no idea didnt own it with the 1995 motor running bought it blown, previous owner is no help doesnt remember any service engine soon light coming on.

[Robyn]

Vacuum at the pump should be 26 Inches and the same at the Actuator with engine at idle.

[gmctd]

PCM regulates Boost by modulating WG solenoid, varying vacuum to the WG actuator.

Should be 26"hg from vac pump to WG solenoid, and 15"hg from there to the WG actuator at idle and 2000rpm.

Check at both conditions, as vac pump sometimes fails as rpm increases.

8-9"hg is not enough vac for even limited functionality

[mrbornery21]

will this cause the truck to go into limp mode, and also set dtc 84 & 99

[gmctd]

Low vacuum will seldom cause DTC78, but will cause black smoke - the other two are likely wiring, as suggested, with two APP DTC's causing limp mode - the 5v error mostly causes other DTC's as well, as that reference is used for the OS, CPS, IAT, ECT, etc..

However, limp mode won't give black smoke, as PCM is in programmed fuel mode with no power as main symptom.

[mrbornery21]

at 2000rpm vacuum at pump increases to 15inches, Went to get new one from Autozone called was instock, dude even went to check and see if its on the shelf said he had it in hand and it was the last one, so I had him put it on hold, Drove the 15miles to pick it up and guess what they couldnt find it any where. So I guess the guy was scared that they might give it to the wrong person, He must of hid it real well or took it home.

As for smoke there is damn near none even in limp mode, I wish I had a boost and egts gage.

As for the pump probably have to order it at another parts house

[gmctd]

Did you test vacuum right at the pump, or via the vacuum harness - the oem plastic tubing is prone to crumbling and the not-quite-rubber nipples are prone to soften and dissolve into holes.

[mrbornery21]

Yes I tested vacuum off the back of the pump, Recieved new vacuum pump today put it on and at idle I get 20" at pump and 20'' at wastedgate. Cleared all codes and went for a drive at 73mph SES light came on went home pulled code 78 But there was no APP codes, 84 & 99 were gone. I will switch my wastegate solenoid back to the 1997 one and see what happens.

[mrbornery21]

Problem solved for now,Went to switch out wastegate solenoid , Figured I would check the connector pluged up and unpluged to test for proper wastegate opration again. And when I unpluged the connector the wastegate remained closed, Vacuum lines were crossed at the solenoid. The reason I missed this is because the old vacuum pump would bleed of when I unpluged the connector to try this test acting as if the lines were hooked right and the wastegate was working properly.

Moral of the story is
Bad vacuum pump and crossed lines caused codes 78,84,99 at 70mph
After new vacuum pump crossed lines caused code 78. at 70mph

I thank all of you guys and gals for you help and responses, For this is the first 6.5 diesel I have worked on. Thanks Again !!!!