All this work to get it right and it's still a work in progress....What's next?

[GoToGuy]

Sure, the intake was pulled for a gasket replacement, water leaking. So did it then, took to work, plastic bead blasted the EGR passages. And mating surfaces all cleaned up.

 

[Dajain]

Is the QD actually in the intake or does yours have the spreadbore adapter/riser under the TB?

The QD for the heater core hose is between the TBI and the distributor and is threaded into the intake manifold.
This video is the 5.7 but it is in almost the same location on the 7.4. Again, I just replaced it with a kings nipple and did away with the problematic QD.

xc_hide_links_from_guests_guests_error_hide_media

 

[Dajain]

I'm not quite sure how the coolant leak, which I fixed, is giving me any ideas on the shifting issue with the 4L80e.

 

[Dajain]

Going to put the scan tool on it today. Maybe get a better insight as to what we are actually dealing with. I'll post the numbers later.

 

[Dajain]

OK, put the scan tool on it and here are most of the results at operating temp, at idle and in park. I see one issue is the vehicle speed.
Here we go!!!

Idle - 800 rpm
O2 - bouncing between 350-400
Intergratr - 128
Open/closed loop - Open
Exhaust O2 - bouncing between rich & lean
TPS - .46 @ 800 rpm's
1.00 @ 2500 rpm's
Throttle % - Changes with acceleration. I seen 30% at 2500 rpm
Desired Idle - 750 rpm
Block learn - 134
O2 cross counts - 25
FT cell - 4
IAC Position - 34
IAC coil A - on
IAC coil enable - yes
IAC coil B - On
IAC direction - Fwd
PROM Id - 4261
MAP (inHg) - 8.5
MAP (volts) 1.00
Baro (inHg) - 25.3
Baro (volts) 4.08
Coolant (F°) - 192
Start Coolant - 41°
EGR duty - 0%
Air control solenoid - Norm
Asynch PW (ms) - 1.3
Air/fuel learned - bouncing between yes & no
Air/fuel ratio - 14.7:1
Vehicle speed (mph) - 14 thru 30 depending in throttle position. (I was in park and stationary!)
Knock - 0
Clear flood - No
Spark Advance - 20°
D cell fuel - No
Safety fuel C/O - No
Battery 13.6
Fuel Pump - 13.5

Also looked up the codes and here is what it is currently showing:
22 - TPS too low
42 - EST Problem
87 - Shift solenoid B stuck off
86 - Shift solenoid B stuck on
85 - Gear ratio problem

So, time for some brain storming.
If anyone sees another problem that I am missing, please let me know so we can get this thing up and running great again.

What I see is a vehicle speed sensor that is faulty.
-Being in idle and seeing a vehicle speed if 14 mph tells me that sensor is putting out too much/little signal and throwing everything else off under acceleration.
-This could also throw off the EST and cause the code 42, correct? My brain says the computer is advancing the timing too far based on the heightened mph reading which would make it "Doggish" from having too much timing advance.
-The incorrect mph reading would also throw a gear ratio code (85). The ecm knows how fast it should be moving, A speed rating of 14 mph faster than it should be, would show as a gear ratio issue.
-And code 22, basically saying not enough throttle is being given to move that fast.

Am I thinking right on this?

Any other thoughts or problems from the data?

 

[1998_K1500_Sub]

Check your TPS more closely...

TPS:

- Turn off the engine
- Turn on the ignition
- Start the scan too
- Look at the TPS readings
- Slowly move the accelerator to WOT and back, and do it a couple of times while WATCHING the TPS numbers; they should increase and decrease smoothly. If they ever jump, there's a problem.

Your min TPS looks OK. Max should be around 4.5V, give or take.

Baro reading... you said "Baro (inHg) - 25.3". What's your elevation, 4000-5000ft? Near sea level BARO would read ~30.

MAP: At idle, I might expect to see the MAP at around 10"Hg. Let's see what others say.

You can test the MAP sensor akin to how the TPS is tested.

- Put a vacuum pump on the MAP sensor's input port/hose, then
- start with igntion off
- Pump to a target value
- Turn ignition on
- Check the BARO reading with the scan too; the reading should jibe with the vacuum applied by the pump (taking into account the difference b/t "vacuum" and absolute pressure of course)
- Repeat this process, starting with ignition off, for as many different vacuum settings as you like.

Example: Assuming you're really at 4000-5000ft like your stated BARO reading in your original post suggested:

- Apply 0 vacuum to MAP; BARO reads 25.3
- Apply 5" of vacuum; BARO reads 20.3
-Apply 10" of vacuum; BARO reads 15.3
- Apply 15" of vacuum; BARO reads 10.3
(you get the idea)

 

[Dajain]

Check your TPS more closely...

TPS:

- Turn off the engine
- Turn on the ignition
- Start the scan too
- Look at the TPS readings
- Slowly move the accelerator to WOT and back, and do it a couple of times while WATCHING the TPS numbers; they should increase and decrease smoothly. If they ever jump, there's a problem.

Your min TPS looks OK. Max should be around 4.5V, give or take.

Baro reading... you said "Baro (inHg) - 25.3". What's your elevation, 4000-5000ft? Near sea level BARO would read ~30.

MAP: At idle, I might expect to see the MAP at around 10"Hg. Let's see what others say.

You can test the MAP sensor akin to how the TPS is tested.

- Put a vacuum pump on the MAP sensor's input port/hose, then
- start with igntion off
- Pump to a target value
- Turn ignition on
- Check the BARO reading with the scan too; the reading should jibe with the vacuum applied by the pump (taking into account the difference b/t "vacuum" and absolute pressure of course)
- Repeat this process, starting with ignition off, for as many different vacuum settings as you like.

Example: Assuming you're really at 4000-5000ft like your stated BARO reading in your original post suggested:

- Apply 0 vacuum to MAP; BARO reads 25.3
- Apply 5" of vacuum; BARO reads 20.3
-Apply 10" of vacuum; BARO reads 15.3
- Apply 15" of vacuum; BARO reads 10.3
(you get the idea)

I will do that test with the TPS and see what it reads.

The Barometer seems to be accurate judging what you have stated. We are at 4250' elevation where I live. Right where you guessed (which I'm sure was an educated guess. )

But I'll do the vacuum test and see what it reads. See if the numbers change like they should.

While I'm there, I'll also unplug the VS sensor and start the truck and see if I am still moving at 14 mph while stationary. If so, I'll be looking for a shorted wire. If not, I'll be ordering an OEM sensor. I did replace the old one, but this new one was from Oreillys. Tried to save a few bucks. dohh!

 

[1998_K1500_Sub]

But I'll do the vacuum test and see what it reads. See if the numbers change like they should.

I suspect you may have a TPS problem. It’s easy to check.

I don’t suspect a MAP problem but since you’re testing…

VSS provides, IIRC, a time varying voltage whose frequency corresponds to the speed. The voltage may increase with speed as well, but it’s the frequency that’s measured by the ECU.

I’m curious to learn why the ECU reads non-zero when you’re stationary. Others may comment.

Methods for testing the VSS are given in the FSM, I’m quite certain. Go that route.

 

[1998_K1500_Sub]

Good VSS stuff here, perhaps you’ve seen:

Post in thread '700r4 VSS and speedometer'
https://www.gmt400.com/threads/700r4-vss-and-speedometer.65554/post-1374569

 

[Dajain]

I suspect you may have a TPS problem. It’s easy to check.

I don’t suspect a MAP problem but since you’re testing…

VSS provides, IIRC, a time varying voltage whose frequency corresponds to the speed. The voltage may increase with speed as well, but it’s the frequency that’s measured by the ECU.

I’m curious to learn why the ECU reads non-zero when you’re stationary. Others may comment.

Methods for testing the VSS are given in the FSM, I’m quite certain. Go that route.

I will check the TPS. That is code 22 which is one that is current.

Since the Barometer seems to be working and somewhat accurate for elevation I'll keep trying to figure on what the codes are leading us to.

I did unplug the VSS and the reading showed I was doing 11 mph at first but them climbed up to 13 mph while testing.
I know a test will show if the TPS is bad, but would a faulty sensor tell the ecm that the vehicle "should' be moving that fast?

And according to the service manual, the VSS being faulty should throw a code 24. It's doesn't have that code stored.

Now, another thing i should mention. I didn't erase the codes from when I drove it. But if I have a faulty TPS, that will show up again.

But, I agree, Why would I not be getting a zero reading while stationary? I think that might be causing the timing issue?