3 Bar Map sensor on 1kzte

[Lomoski]

Hi Gang,

I have a 95 1kzte. I have been having some issues with my turbo pressure sensor. I have plans to add power as I add mods to my truck. So I decided to order a 3 bar map sensor as I will be going above 1 bar eventually. (with the supporting mods). Wired it in correctly to the best of me belief. However now I have a 35 code and my check engine light comes on while accelerating. It seems to be running fine otherwise but the CEL light is on and the code 35 keeps popping up. Do I just live with the CEL on all the time now? It's a generic GM 3 bar sensor with Red, Blue, Black as inputs.

Thanks in advance

Marc

 

[Lomoski]

To add some more context. I was having a surging/fuel cut issue at 9psi of boost (measured at the manifold and at the wastegate) which was worse at sea level then at altitude where I live (1954m ASL). My ECU has been rebuilt and I trust is working properly. With the new 3 bar in the surging is gone, the motor runs better and accelerates a lot more cleanly. Other than the ECU light being on when I am on the accelerator it is running better. If I get a toyota specific 3 bar will I still have the ECU confused? I don't mind the light being on if it means my truck can actually accelerate and drive up hills. Thanks friends!

 

[TheBussman]

If you just change the sensor and nothing else your computer is going to think your at even lower boost then your really are. What was the factory sensor? 2 bar? computer is going to add less fuel with a bigger sensor. Will not matter if you use a Toyota 3 bar sensor or GM 3 bar sensor. Completely possible your old sensor was bad or plugged.

 

[Lomoski]

If you just change the sensor and nothing else your computer is going to think your at even lower boost then your really are. What was the factory sensor? 2 bar? computer is going to add less fuel with a bigger sensor. Will not matter if you use a Toyota 3 bar sensor or GM 3 bar sensor. Completely possible your old sensor was bad or plugged.

Factory sensor was a 1 bar factory that was very old. The surging problem I had under load is gone now with the new sensor. I have adjusted the spill control valve previously when I replaced it as well to get fueling closer. I have a EGT and Boost gauge. I can now mat it without my motor surging, EGT climbing rapidly and keep the accelerator at WOT which I couldn't do before. So I have no doubt the old sensor was bad. However it runs substantially better now with the 3 bar. So can I just keep running the 3 bar and ignore the CEL? When my exhaust and AW intercooler are done I intend to add above 1 bar, hence the 3 bar. I have read that you can also do voltage clamps with some trickery but this seemed the easiest place to start knowing it was likely the sensor. Also the 3 bar was 30 dollars vs hundred plus for a factory. Cheaper diagnostics for a poor bloke. I just checked voltage and I have 5 volts on wire 3 and 2. I thought just 3 was supposed to have voltage and 2 was signal. (as labeled in the FSM)

Bit of rambling but just wanted to let you know what I've done and what my thought process has been. Injectors are clean and pop tested, valves have been checked and re-shimmed withing that last year and compression is within spec.

Thanks kindly,

Marc

 

[gnob]

you definitely should not have 5v on 2 wires.
test the wires unplugged from the sensor, what do you have ?

 

[TheBussman]

Factory sensor was a 1 bar factory that was very old. The surging problem I had under load is gone now with the new sensor. I have adjusted the spill control valve previously when I replaced it as well to get fueling closer. I have a EGT and Boost gauge. I can now mat it without my motor surging, EGT climbing rapidly and keep the accelerator at WOT which I couldn't do before. So I have no doubt the old sensor was bad. However it runs substantially better now with the 3 bar. So can I just keep running the 3 bar and ignore the CEL? When my exhaust and AW intercooler are done I intend to add above 1 bar, hence the 3 bar. I have read that you can also do voltage clamps with some trickery but this seemed the easiest place to start knowing it was likely the sensor. Also the 3 bar was 30 dollars vs hundred plus for a factory. Cheaper diagnostics for a poor bloke. I just checked voltage and I have 5 volts on wire 3 and 2. I thought just 3 was supposed to have voltage and 2 was signal. (as labeled in the FSM)

Bit of rambling but just wanted to let you know what I've done and what my thought process has been. Injectors are clean and pop tested, valves have been checked and re-shimmed withing that last year and compression is within spec.

Thanks kindly,

Marc

of course you can just leave it alone if you don't mind the check engine light. But the ECU might be pulling back fuel if it thinks there is any issue. I would try a 2 bar sensor or resistor mods assuming you don't want a standalone ECU.

 

[Lomoski]

you definitely should not have 5v on 2 wires.
test the wires unplugged from the sensor, what do you have ?

I have 5 v to ground from both 3 and 2 wires. 3 is supposed to be the 5v, 2 is supposed to be the sensor wire and 1 is earth. I don’t have an exact FSM for my year but that’s what the FSM seems to say for the wire orientation as the colours of wire vary year to year,which is also labele. I didn’t have the check engine light before with the stock sensor, but it was almost undrivable for the reasons previously stated. I’m going to swap the stock sensor back in tomorrow to confirm the check engine light goes out. Other than wiring the new 3 bar in I haven’t changed anything so far so it would be strange for my ecu to decide to crap out at the exact same time. My ecu was rebuilt by a member here and I trust it’s been done properly as it hasn’t had any issues otherwise since. I took it for a good drive today and it’s got much better power, lower egt and I’m up to stock boost again. So colour me confused.

Appreciate everyone!

 

[Lomoski]

of course you can just leave it alone if you don't mind the check engine light. But the ECU might be pulling back fuel if it thinks there is any issue. I would try a 2 bar sensor or resistor mods assuming you don't want a standalone ECU.

Yeah, as much as I would love a standalone ecu, I’ve got other things to do before then and if I do I think I’ll put a 1kd in instead of the 1kz..
. I’ll order a 2 bar and see if that helps. The truck drives a LOT better with the 3 bar sensor so I think I’ll just continue to drive it with the 3 bar until I can get a 2 bar.

Thanks for your suggestions and help! Still learning new things about this ol’’girl after 7 years of ownership haha. Love it.