Driveability for the experienced., Diag codes 35, 42. Options

[ScottDavid]

Hello Toyota enthusiasts.

Well Long story short Im obviously new here. Not to working on cars....New to Toyota though.

I swapped a 93 jap spec 3sgte into a 96 gt celica. Runs great but after a la hot of test driving and quality checking I had only two diag codes.

35 - Turbo Charging pressure sensor signal
42 - Vehicle speed sensor signal.

As far as the T/C pres sensor. I have a steady 4.98v reference while idling, cruising and boosting.
I have a varying signal voltage with is .1682v @ light throttle which will increase with load to WOT @ 4.97v
The ground circuit is always grounded.

Now, as far as driveability, I noticed that while the engine is normal operating temp its boosting fin, 7-10 psi.
Great performance!

After the engine is fully warm....I was WOT and felt a slight loss of acceleration along with a slight drop in boost. And after the check engine light. max boost 6-7 psi.

Now, The wiring is all cherry, because I did it. My continuity checks are fine from sensor to ecm.

Ok, so the stock 3sgte jap spec vehicle has a turbo gauge built into the cluster....I dont have the stock cluster, I have an aftermarket gauge.

As far as code 42.....Have not tested yet.

Has anyone had this issue or has info on my driveability issue? I will appreciate it.

-Scott

[hongkongnerdboy]

are you ornag county such as california?

[ScottDavid]

Yes.

[lagos]

As far as the T/C pres sensor. I have a steady 4.98v reference while idling, cruising and boosting.
I have a varying signal voltage with is .1682v @ light throttle which will increase with load to WOT @ 4.97v
The ground circuit is always grounded.

Hahaha a fellow nerd.
Your overthinking this. The Tc code just means you hit fuel cut at 12psi. Disconnect and cap the vac line going to the turbo pressure sensor, but keep the harness plugged in.

After the engine is fully warm....I was WOT and felt a slight loss of acceleration along with a slight drop in boost. And after the check engine light. max boost 6-7 psi.

Yep, because you hit fuel cut.

42 - Vehicle speed sensor signal.

Is your speedo working? Sounds like you didnt wire it up correctly.

This post has been edited by lagos: Jun 16, 2008 - 10:00 PM

[hongkongnerdboy]

go to our meet!

[celicaGT96]

i believe i might know already but what exactly causes fuel cut? is this something all 3sgte swappers experience?

[ScottDavid]

I dont now if I am complimented or insulted. Non the less, if I remove operating vacuum I loose all funcitonality of the sensor. That doesnt make any logic sense. It just doesnt.

Yes the speedo is working fine. Although cruise capability is no longer available. Non the less not necessary.

I could make an appearance at a meet. Ill roll up in the E34 though.


Thanks for the response all..

-Scott

[lagos]

That sensor is ONLY used for fuel cut. By disconnecting the vac line, all you are doing is eliminating fuel cut. You could also BUY a fuel cut defender, that lets you keep your fuel cut, but just raise it.

i believe i might know already but what exactly causes fuel cut? is this something all 3sgte swappers experience?

Fuel cut is a safety feature that cuts off the fuel once you boost over 12psi.

[hongkongnerdboy]

well let me know if you want to come or not so if you do decide to hit me up xD

[ScottDavid]

Lagos, I understand that part. But boost gauge never rose above 10psi. Im thinking into it too much! This is just a very well built engine by myself....

Im going to miss it, leaving this week:(

HongKonger, Im busy for the next 3 mo...Maybe some later date. Thanks for the invite. If you need any rebuild, elec, work done let me know.

-Scott

[lagos]

Lagos, I understand that part. But boost gauge never rose above 10psi. Im thinking into it too much! This is just a very well built engine by myself....

Actually ... your right. Code 34 is fuel cut, not code 35.
Code 35 happens when you forget to plug the map sensor into the harness plug. So check that. If its fine, then inspect the wiring.

As for code 42, you need to check your swap wiring. It looks like your not sending the spd signal back to the ecu from the gauge cluster. If you do a search, I wrote up a detailed HowTo in someones thread on the speedo wiring a while back.

[ScottDavid]

Youre suppose to plug it in?

Inspect the wiring for?? Clearance specs

[lagos]

Youre suppose to plug it in?

Inspect the wiring for?? Clearance specs

You should have something called Turbo Pressure Sensor (map sensor) in your engine bay. Make sure its plugged in. If it is, make sure the wiring isn't damaged and check your voltage with whats in the bgb (repair manual) to make sure everything is right.

[DEATH]

Lagos, I understand that part. But boost gauge never rose above 10psi. Im thinking into it too much! This is just a very well built engine by myself....

Actually ... your right. Code 34 is fuel cut, not code 35.
Code 35 happens when you forget to plug the map sensor into the harness plug. So check that. If its fine, then inspect the wiring.

As for code 42, you need to check your swap wiring. It looks like your not sending the spd signal back to the ecu from the gauge cluster. If you do a search, I wrote up a detailed HowTo in someones thread on the speedo wiring a while back.

My thread [I also have a code 42 showing]. Here you go [Little over halfway down]:
http://www.6gc.net/forums/index.php?showto...57042&st=40
Courtesy of Lagos . Wiring diagrams on page two for your convenience.

[ScottDavid]

Sorry being sarcastic...I posted my volt readings already.....Dont worry Ill take care of it, I just thought I would try here.


Thanks for the link... A lot of OT talk in it though.

[lagos]

As far as the T/C pres sensor. I have a steady 4.98v reference while idling, cruising and boosting.

Then your either not testing the right wire, or your map is not plugged in.
The map should have 3 wires. One sends a constant 5v, one is ground, and one is signal going back from the map to the ecu. That wire should have voltage on a 0-5v scale that varies with boost/vac. The ecu is trying to tell you that its not seeing that signal back from the map by throwing code 42.

Thanks for the link... A lot of OT talk in it though.

If you scroll down, you would see how to do the wiring for the speedo.

This post has been edited by lagos: Jun 18, 2008 - 10:44 PM

[ScottDavid]

As far as the T/C pres sensor. I have a steady 4.98v reference while idling, cruising and boosting.

Then your either not testing the right wire, or your map is not plugged in.
The map should have 3 wires. One sends a constant 5v, one is ground, and one is signal going back from the map to the ecu. That wire should have voltage on a 0-5v scale that varies with boost/vac. The ecu is trying to tell you that its not seeing that signal back from the map by throwing code 42.

Thanks for the link... A lot of OT talk in it though.

If you scroll down, you would see how to do the wiring for the speedo.

I already posted my measurements, and I do know what the t/c pres. sensor looks like, where it is, and its connected. Code 42 is for the speedo circuit, 35 is the code to turbo pressure sensor signal wire.
Thanks though.