That thing must be real finicky if the jumper itself was all it took to cause a problem.
CK5
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'89 R3500 Crew Cab 2wd to 4wd conversion & beyond
- Thread starter mrk5
- Start date
Started out with 2wd TBI350 with SM465 to current 4wd with 454, 700r4, NP241
sucks about the TPS
Can you feed out tps from the pcm? Have a scope? Hows the reference?
I have only questions... lol
I have only questions... lol
No, everything is all right there on the throttle body.
Apparently this is a Sniper only issue as people don't have a problem with the upscaled Holley efi units.
I don't get a TPS voltage on the Sniper handheld, just a percentage. But the percentage doesn't jump around. Also I can see TPS voltage on the trans controller (in between error messages since it's not connected to the trans) and those numbers seem fine. It must damn touchy about the voltage.
It makes me curious why it's so touchy and what about the Sniper is different than other Holley EFI.
Apparently this is a Sniper only issue as people don't have a problem with the upscaled Holley efi units.
I don't get a TPS voltage on the Sniper handheld, just a percentage. But the percentage doesn't jump around. Also I can see TPS voltage on the trans controller (in between error messages since it's not connected to the trans) and those numbers seem fine. It must damn touchy about the voltage.
It makes me curious why it's so touchy and what about the Sniper is different than other Holley EFI.
The scope would show you possible interference which you won't see on a scan tool. You need a more accurate view to figure out what is happening.
I.E. a lab scope, a Modis/Verus with scope. I've never compared my new Solus graph to an actual lab scope but i was taught never trust it over a true scope. Granted I was taught that stuff over 15 yrs ago... lol.
This can be common. In fact some sensors can require entire new circuit runs instead of splice during repair procedures. Solder used can affect this. But tapping in a new component can bring serious headaches and interference to the line.
Is there any ability for the ecm on the holley unit to output sensor data?
I.E. a lab scope, a Modis/Verus with scope. I've never compared my new Solus graph to an actual lab scope but i was taught never trust it over a true scope. Granted I was taught that stuff over 15 yrs ago... lol.
This can be common. In fact some sensors can require entire new circuit runs instead of splice during repair procedures. Solder used can affect this. But tapping in a new component can bring serious headaches and interference to the line.
Is there any ability for the ecm on the holley unit to output sensor data?
Been a busy day. The goal is to find out if there is interference, which there most likely is, coming from the trans pcm to the holley ecm through the circuit.
It could be as easy as changing ground placement or rerunning the circuit, or as hard as running a separate TPS for the trans. Either way what the holley is seeing it does not like for some reason. Without scoping it, it is hard to say.
These are just places to start.
It could be as easy as changing ground placement or rerunning the circuit, or as hard as running a separate TPS for the trans. Either way what the holley is seeing it does not like for some reason. Without scoping it, it is hard to say.
These are just places to start.
Lol on the probe caps. 
I don't have the first clue how to scope. LOL. I can data log tho.
It did occur to me that I did run the new wire for the trans controller right behind the alternator which is a high output Powermaster unit. So that could be throwing some interference in there. I'm thinking I can try moving the wire further away from the alternator. Otherwise it is a good distance from the spark plug wires.
I could also try some braided sleeve that is made with tinned copper to shield wires from EMI and RFI. It will stay in closed loop for a few seconds before going open and keeps going back and forth so maybe the interference isn't horrible.
It did occur to me that I did run the new wire for the trans controller right behind the alternator which is a high output Powermaster unit. So that could be throwing some interference in there. I'm thinking I can try moving the wire further away from the alternator. Otherwise it is a good distance from the spark plug wires.
I could also try some braided sleeve that is made with tinned copper to shield wires from EMI and RFI. It will stay in closed loop for a few seconds before going open and keeps going back and forth so maybe the interference isn't horrible.
couldn't we just add in a diode to make it a 1 way flow only on the signal wire ?
gm had to do something like this back in the old days on the a/c clutch 2 plug wire .
gm had to do something like this back in the old days on the a/c clutch 2 plug wire .
So to test if the "noise" is from the controller or the jumper lead, I could start by disconnecting the sensor wire from the controller. That wouldn't be hard to do.
I have not followed the wiring page by page... so I'm assuming it didn't throw a code before the TCM upgrade. First do a simple resistance test pin to pin on that TPS wire. Make sure its unfucked. Do the same on your new grounds.
Then unplug the tps wire from the TCM. See if it stops throwing a code. If not I'd work back and rerun a new tps sensor circuit. Then check for codes. If still codes start looking at grounds etc..
Just for shits and giggles do a slow multimeter sweep on the tps, just to make sure it didn't decide to fubar itself in the middle of you changing all sorts of stuff, without scope though you can miss it.
Isolate the changes that happened after it started throwing a code and try to narrow it down. Its gonna be shooting in the dark but hopefully you can hit something.
I'm in the middle of trimming 4k screws to length... so my brain is fried and may just be talking gibberish
Then unplug the tps wire from the TCM. See if it stops throwing a code. If not I'd work back and rerun a new tps sensor circuit. Then check for codes. If still codes start looking at grounds etc..
Just for shits and giggles do a slow multimeter sweep on the tps, just to make sure it didn't decide to fubar itself in the middle of you changing all sorts of stuff, without scope though you can miss it.
Isolate the changes that happened after it started throwing a code and try to narrow it down. Its gonna be shooting in the dark but hopefully you can hit something.
I'm in the middle of trimming 4k screws to length... so my brain is fried and may just be talking gibberish
Just catching up. Great detailed work!
I had a similar problem with my 4L80E separating from the magnum. I noticed it because the magnum was popping out of gear on the highway, which was unsettling. Blue locktite and external tooth lock washers on 4 of the 6 pieces of hardware (what I could easily reach while in camp) solved that for me.
Also, my magnum vented a bit while on the highway, but I didn’t want to reduce to fill for the same reasons noted earlier. I combined the venting with the 205 and routed to a “catch can”. I check it regularly, and have only ever seen a few drops in the bottom. Your single can routing should do fine.
Again, very great looking work.
David
I had a similar problem with my 4L80E separating from the magnum. I noticed it because the magnum was popping out of gear on the highway, which was unsettling. Blue locktite and external tooth lock washers on 4 of the 6 pieces of hardware (what I could easily reach while in camp) solved that for me.
Also, my magnum vented a bit while on the highway, but I didn’t want to reduce to fill for the same reasons noted earlier. I combined the venting with the 205 and routed to a “catch can”. I check it regularly, and have only ever seen a few drops in the bottom. Your single can routing should do fine.
Again, very great looking work.
David
Was it loosening up between the adapter and trans or the Magnum and the adapter?
Magnum and the adapter. I have not yet observed any looseness between the trans and the adapter.
David
I went ahead and ordered new serrated flange bolts for the adapter to transmission. I noticed it had 2 different bolt types; 1 flange head bolt that required a 14mm wrench and the rest standard bolts that use 15mm wrench. There was also 1 bolt that was shorter than the others. Don't like the idea of having mis-matched hardware. I'm sure when this "new" transmission was installed in the 95 donor truck a couple years ago the mechanics couldn't find all the original bolts.
For future reference the 4l80e adapter to transmission bolts are M10x1.5 with length of 30mm. There are 6. Of course McMaster sold the bolts in packages of 5 so I had to order 10. I think I will be able to use 2 to thread into the mounting feet on the adapter. IIRC those are the same threads.
I also ordered a new rubber oring ACDelco 8681168. Figure if the mechanics couldn't be bothered to match the bolts, they probably didn't replace the original oring seal either.
Did some fiddling with the TPS jumper. With the jumper removed, Sniper goes closed loop and stays. Plugged the jumper back in and moved the wire further from the alternator and the Sniper wouldn't stay in closed loop. Next I unplugged the TPS sensor wire to the controller under the dash and the Sniper would go into closed loop and stay.
Per @sweetk30's thought, I ordered a diode and I'm going to put it in the line where I have the plug under the dash. Interested to see if this will work as it does seem that maybe the controller is the problem. I would think if it was picking up interference on the wire it would have shown up even with it unplugged under the dash. But who knows with this stuff.
For future reference the 4l80e adapter to transmission bolts are M10x1.5 with length of 30mm. There are 6. Of course McMaster sold the bolts in packages of 5 so I had to order 10. I think I will be able to use 2 to thread into the mounting feet on the adapter. IIRC those are the same threads.
I also ordered a new rubber oring ACDelco 8681168. Figure if the mechanics couldn't be bothered to match the bolts, they probably didn't replace the original oring seal either.
Did some fiddling with the TPS jumper. With the jumper removed, Sniper goes closed loop and stays. Plugged the jumper back in and moved the wire further from the alternator and the Sniper wouldn't stay in closed loop. Next I unplugged the TPS sensor wire to the controller under the dash and the Sniper would go into closed loop and stay.
Per @sweetk30's thought, I ordered a diode and I'm going to put it in the line where I have the plug under the dash. Interested to see if this will work as it does seem that maybe the controller is the problem. I would think if it was picking up interference on the wire it would have shown up even with it unplugged under the dash. But who knows with this stuff.
yearsssss ago when I was in school the diode was the great little flow control valve for electricity . 1 way only depending on the way its installed.
for sure keep us updated on this trick .
also I would report your findings to both holley and us shift . so they can make updates and or info available to others .
for sure keep us updated on this trick .
also I would report your findings to both holley and us shift . so they can make updates and or info available to others .
Yeah, I think there's lots of people that could use the information. I wonder how many have used the same TPS jumper and don't even realize the Sniper isn't staying in closed loop. I know a lot of people don't keep the handheld in a visible location all the time and aside from not getting the "green light" for closed loop I wouldn't have known it was an issue. The truck seemed to be running fine.
a lot of guys run open loop after it's tuned.
Because the base mapping is good enough it doesn't need to adjust on the fly anymore? (I may not be using correct terminology, just trying to sound EFI smart)
I believe so, I haven't messed with that function. I skimmed over some posts about it on the FiTech page.
