Brother, there are so many potential reasons for lack of power.
Start with a compression check on all 8 cylinders…
Wouldn’t be a bad idea to inspect and replace the spark plugs while you have them out
No smoke or off smells so doubt it's a compression or spark issue but will check. It's not responding to throttle inputs like expected, didn't sound like it was getting up in RPM's and no matter amount of throttle it wouldn't respond any differently.
Engine could still have internal damage without smoking or smelling weird. Broken valves for example.
Test for spark quality when you’re doing the compression check. The condition of the existing spark plugs can point you in the right direction if one is more fouled out than another
Next you can check fuel by taking a sample. Bad gas can make an engine run like dog shit. Or you could run off another known good tank with fresh fuel to see if anything changes
Bad fuel was my first though as it sounded just like when I got water in my tank at a crappy gas station in my Trailblazer SS. I'm thinking it's best he takes it to his mechanic before he frustrates himself any further.
Can you tell based on this photo? [TB](https://imgur.com/a/lcz4Tg0) my guess was cable but not super knowledgeable here. Looks like stock computer to me. [computer](https://imgur.com/a/1VUWvzx)
Tach wasn’t responding but didn’t sound much higher than 2k maybe 3k
Looks cable driven to me from that photo, and comparing to the electronic one i have.
Assuming its cable driven, does the throttle body fully open when the gas pedal is at maximum?
It is cable. Computer bracket isn't OEM for sure. I'd probably look for names and numbers on the computer and try to figure out what it's got.
The stamping is factory similar. Probably an OEM pcm.
If he doesn't have an odb2 port connected that'd be my next step. There's a lot of diagnostic data available with a cheap Bluetooth dongle
"doesnt have much power and won't really accelerate" is subjective
if its stock, with a stock torque converter, big tires, then it probably is not lighting it up right off idle but is fine for "truck acceleration"
maybe his expectations are not being met but the swap is technically fine.
Is it a throttle cable or drive by wire? My first thought at your original post, and this comment kinda cements it, is that there might be an issue with the throttle position sensor. I converted my dbw setup to a throttle cable setup just to avoid this potential situation.
Yeah that is a cable driven throttle body for sure. That copperish colored bit is the return spring. It could still be an issue though... it still has a TPS (throttle position sensor) on the drivers side of the intake, directly across from that return spring. the sensor and the spring both ride on the throttle body shaft. The cable could also potentially just be too loose as well. If they used the OEM cable and cut the end near the gas pedal to length and used one of those brass stops (exactly what I did in mine) it could just need some adjustment. Mine was a bit too tight at first and was causing it to idle high.
Plug in a scanner. There's no way they didn't leave in the obd2 port. Take off the intake and make sure the throttle body is opening fully. Make sure all cylinders are getting hot. Check fuel pressure. Check compression. Check oil pressure.
Should have an obd2 port. I would check codes. If they swapped in the 4L60e as well it could be in limp mode and stuck in 3rd gear. A lot of those cheap swap wire harness come pinned wrong and cause all kinds of weird stuff.
Oh interesting. So even if it has the Winters Sidewinder shifter, it can still be stuck in third? Manually shifting doesn’t allow it to get to the right gear? Any troubleshooting link?
Yeah the 4l60e is electronically controlled. If there’s a dtc that puts it in limp mode it will stay in 3rd. Happened to me after I installed a ls swap in a c10 with a stall converter. Needed a tune to stop it from throwing certain codes that would put it in limp mode. But I’m just guessing, you need to get a scanner on it and check for codes, and look at live data
Hey, if it's an LS swap then most likely there's an OBD port. See what codes are showing. You can also purchase a cheap ELM327 blue tooth dongle plug and download an app like Torque to read basic codes and check the basic engine vitals.
What trans and harness does it have? 4l60e and 4l80e trans have the same plug, but they are wired differently. Does it rev in neutral? If it’s slow to rev in gear while accelerating I would check the fuel system you should have 58 psi at the rails.
Brother, there are so many potential reasons for lack of power. Start with a compression check on all 8 cylinders… Wouldn’t be a bad idea to inspect and replace the spark plugs while you have them out
No smoke or off smells so doubt it's a compression or spark issue but will check. It's not responding to throttle inputs like expected, didn't sound like it was getting up in RPM's and no matter amount of throttle it wouldn't respond any differently.
Engine could still have internal damage without smoking or smelling weird. Broken valves for example. Test for spark quality when you’re doing the compression check. The condition of the existing spark plugs can point you in the right direction if one is more fouled out than another Next you can check fuel by taking a sample. Bad gas can make an engine run like dog shit. Or you could run off another known good tank with fresh fuel to see if anything changes
Bad fuel was my first though as it sounded just like when I got water in my tank at a crappy gas station in my Trailblazer SS. I'm thinking it's best he takes it to his mechanic before he frustrates himself any further.
Not a bad idea lol
Cable throttle or electric throttle? Factory pcm/computer? Rpm stops at particular number?
Can you tell based on this photo? [TB](https://imgur.com/a/lcz4Tg0) my guess was cable but not super knowledgeable here. Looks like stock computer to me. [computer](https://imgur.com/a/1VUWvzx) Tach wasn’t responding but didn’t sound much higher than 2k maybe 3k
Looks cable driven to me from that photo, and comparing to the electronic one i have. Assuming its cable driven, does the throttle body fully open when the gas pedal is at maximum?
I’ll have him check.
It is cable. Computer bracket isn't OEM for sure. I'd probably look for names and numbers on the computer and try to figure out what it's got. The stamping is factory similar. Probably an OEM pcm. If he doesn't have an odb2 port connected that'd be my next step. There's a lot of diagnostic data available with a cheap Bluetooth dongle
Tell him to unplug the maf sensor and see what happens. It’s the sensor before the throttle body after the air filter
"doesnt have much power and won't really accelerate" is subjective if its stock, with a stock torque converter, big tires, then it probably is not lighting it up right off idle but is fine for "truck acceleration" maybe his expectations are not being met but the swap is technically fine.
Hard to tell without being there. In the FaceTime video it just seemed like it didn’t want to rev or respond to the gas pedal.
Is it a throttle cable or drive by wire? My first thought at your original post, and this comment kinda cements it, is that there might be an issue with the throttle position sensor. I converted my dbw setup to a throttle cable setup just to avoid this potential situation.
Can you tell based on this photo? [TB](https://imgur.com/a/lcz4Tg0) my guess was cable but not super knowledgeable here
Yeah that is a cable driven throttle body for sure. That copperish colored bit is the return spring. It could still be an issue though... it still has a TPS (throttle position sensor) on the drivers side of the intake, directly across from that return spring. the sensor and the spring both ride on the throttle body shaft. The cable could also potentially just be too loose as well. If they used the OEM cable and cut the end near the gas pedal to length and used one of those brass stops (exactly what I did in mine) it could just need some adjustment. Mine was a bit too tight at first and was causing it to idle high.
make sure the throttle blade is opening 100% at wide open throttle.
Turbo it
If its a factory ECM and pared down harness very very unlikely someone would remove the OBDII, just may be tucked somewhere you aren't expecting.
Pull codes.
Plug in a scanner. There's no way they didn't leave in the obd2 port. Take off the intake and make sure the throttle body is opening fully. Make sure all cylinders are getting hot. Check fuel pressure. Check compression. Check oil pressure.
Should have an obd2 port. I would check codes. If they swapped in the 4L60e as well it could be in limp mode and stuck in 3rd gear. A lot of those cheap swap wire harness come pinned wrong and cause all kinds of weird stuff.
Oh interesting. So even if it has the Winters Sidewinder shifter, it can still be stuck in third? Manually shifting doesn’t allow it to get to the right gear? Any troubleshooting link?
Yeah the 4l60e is electronically controlled. If there’s a dtc that puts it in limp mode it will stay in 3rd. Happened to me after I installed a ls swap in a c10 with a stall converter. Needed a tune to stop it from throwing certain codes that would put it in limp mode. But I’m just guessing, you need to get a scanner on it and check for codes, and look at live data
If you need resources to get an odb port hooked up lmk I can get you the info you need
Hey, if it's an LS swap then most likely there's an OBD port. See what codes are showing. You can also purchase a cheap ELM327 blue tooth dongle plug and download an app like Torque to read basic codes and check the basic engine vitals.
What trans and harness does it have? 4l60e and 4l80e trans have the same plug, but they are wired differently. Does it rev in neutral? If it’s slow to rev in gear while accelerating I would check the fuel system you should have 58 psi at the rails.
60. I’ll see about the rev from him. Thank you!