2G 2g TPS cause P0340?

[frosty3156]

HI. I have a 98 GST that came with a 1g throttle body when I bought it. Ran fine until I broke the CAS while working on it one day. I pulled the connector off the TPS and noticed it had a 1g tps.

I bought a new 2g TPS, new CAS along with a new crank sensor and igniter. Since I live in Nicaragua, can't get parts down here. Shipping takes over a month so I figured I'd change all the sensors.

I installed everything and it cranks, tries to start and backfires out the tail pipe. I scanned for error codes and P0340 popped up. I put the 1g TPS back in and did the same thing but when I scanned for errors, a large laundry list of errors popped up. It ran before with the 1g TPS (for many years) now it won't.

I am seriously stumped. Timing is good, spark and compression also. Has fuel pressure. Thank you for your time.

 

[o0GuitarKid0o]

That happends alot when the ecu is fried (capacitors or various other things ) does your check engine light come on when you turn the key?

Have you looked inside your ECU at all yet? Take some pics

 

[AllanL]

HI. I have a 98 GST that came with a 1g throttle body when I bought it. Ran fine until I broke the CAS while working on it one day. I pulled the connector off the TPS and noticed it had a 1g tps. I bought a new 2g TPS, new CAS along with a new crank sensor and igniter. Since I live in Nicaragua, can't get parts down here. Shipping takes over a month so I figured I'd change all the sensors. I installed everything and it cranks, tries to start and backfires out the tail pipe. I scanned for error codes and P0340 popped up. I put the 1g TPS back in and did the same thing but when I scanned for errors, a large laundry list of errors popped up. It ran before with the 1g TPS (for many years) now it won't. I am seriously stumped. Timing is good, spark and compression also. Has fuel pressure. Thank you for your time.

is there no way that the CAS was installed incorrectly?

tps miss-installation would not do those things...

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[frosty3156]

That happends alot when the ecu is fried (capacitors or various other things ) does your check engine light come on when you turn the key?

Have you looked inside your ECU at all yet? Take some pics

I looked at the ecu and everything looked fine. I even found someone with the same year eclipse and tried his ecu, nothing.

is there no way that the CAS was installed incorrectly?

tps miss-installation would not do those things...

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I did not check that because I never removed any of those parts.

I believe it has something to do with the TPS wiring or CAS sensor because someone must have done some re-wiring to get a 1G TPS to work in a 2G.

 

[o0GuitarKid0o]

I believe it has something to do with the TPS wiring or CAS sensor because someone must have done some re-wiring to get a 1G TPS to work in a 2G.

1g tps is a 3 wire plug and the 2g tps has 4 wire plug (an extra for the ips ) as far as I know . Is there a wire hidden in the harness ? You might have to remove some of the wire cover to see.

Are you running a 1g throttle body?

What kind of Cas is on your car ?

Ahh just re read your first post .

Can you post some pictures of your throttle body and cas ? And of the wiring

 

[frosty3156]

1G throttle body. The TPS that was on the car when I bought it was a 3 pin. (I installed a 4 pin) I do not have the wires connected to the CAS. I saw inside the wireloom that someone had soldered extensions onto the wires and the pigtail wires did not match. The pigtail broke and I do not remember which wire goes where. I thought is was (top of pigtail working down) black, then blue, then red. If the 1G sensor worked, someone swapped some wires somewhere. I just need to figure it out. Not too thrilled about opening up the whole wiring harness.

 

[o0GuitarKid0o]

I dont own any 2gs so I cant help with wire colouring but I'd keep this in mind of you had a 1g cas on the car

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If this is the case and was wired up properly I would just throw the 1g cas back in as you can get rid of the crank sensor .

This picture has some colors so wire it back up accordingly.
Does your car have a crank sensor ? If it doesnt the 2g cas will not work without it as the ECU uses both crank and cam sensors

Open up the harness fix the crappy wireing using a soldering gun and heat shrink. It shouldn't of fallen apart on you .

 

[frosty3156]

It does have the crank sensor. The plastic connector fell apart because the previous owner must have broken it and super glued it back together. I haven't had time to work on it but I will make some time tomorrow. I did solder up the wires correctly and shrink wrapped them.

I am just stumped on how it ran for so many years with the 1g TPS sensor. I am probably going to just pull the wiring harness apart and do some detective work. Thank you for your time, I really appreciate it.

 

[dustyboner]

1G

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2G

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[frosty3156]

Update: Got the wiring sorted out. Tried to start it and it tries to run but sputters and back fires.

I use the Torque app to read error codes but my new phone will not connect. Prior to trying to start it, I cleaned the plugs. After trying to turn it over twice, backfired out the exhaust and intake. Pulled the plugs and they are all wet. (I know the coil packs are good so there is spark)

1G

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2G

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Not sure what your point is. Are you saying that my 2g will work with a 1g TPS and have no issue?

That happends alot when the ecu is fried (capacitors or various other things ) does your check engine light come on when you turn the key?

Have you looked inside your ECU at all yet? Take some pics

I pulled my ECU again. What area should I be looking at for any problems. I will try and get some pics posted soon.

 

[dustyboner]

on the 2g harness the (yellow/red) wire going to pin 3 if for the closed throttle switch which is built in to the sensor.
the 1g doesn't have a built in switch, it has it on the throttle body. that is the only difference. they both read the same range of resistance.

If i remember correctly, all that needs to be done to get a 1g sensor (on 1g TB) to work on a 2g is connect the wire at pin 3 to the idle switch on the 1g throttlebody.

 

[frosty3156]

on the 2g harness the (yellow/red) wire going to pin 3 if for the closed throttle switch which is built in to the sensor.
the 1g doesn't have a built in switch, it has it on the throttle body. that is the only difference. they both read the same range of resistance.

If i remember correctly, all that needs to be done to get a 1g sensor (on 1g TB) to work on a 2g is connect the wire at pin 3 to the idle switch on the 1g throttlebody.

It's strange, the TPS connector has all four wires going to the TPS. So the pin 3 wire wasn't removed and the idle switch on the throttle body is missing. It ran for 5 years like this. And checking error codes prior to my electrical problems did not show anything. Could something have been changed at the wiring connecting to the ecu?

When I checked for error codes after installing the 2G TPS, no errors except for the cam sensor. I thought that putting the 1G TPS in would solve my problems but when I checked for error codes, every code imaginable popped up.

 

[dustyboner]

on the ecu, you want to look for any burnt traces on the board, leaking capacitors, or damaged components.

so what is the exact code your getting now?

 

[rabenne]

Popping and back firing during cranking? Did you have the plug wires off? Verify you firing order.
Maybe the plugs are firing at the wrong time, like when you have a distributor 180° out?

Unless there is a bigger wiring issue ie short, the car should run with tps disconnected. Why would TPS cause a no start?

.

 

[frosty3156]

on the ecu, you want to look for any burnt traces on the board, leaking capacitors, or damaged components.

so what is the exact code your getting now?

I tried to pull some error codes before removing the ecu but my new cel phone would not connect to the adapter. Since it is still doing the same thing as before, I am going to assume it is still pulling up a P0340 error code. After installing a new cam sensor, crank sensor and TPS.

 

[frosty3156]

Popping and back firing during cranking? Did you have the plug wires off? Verify you firing order.
Maybe the plugs are firing at the wrong time, like when you have a distributor 180° out?

Unless there is a bigger wiring issue ie short, the car should run with tps disconnected. Why would TPS cause a no start?

.

I had the plug wires on. The firing order is correct and I even tried changing the firing order as if the crank signal was 180 off (friends suggestion) I think I am going to have to just pull the wiring harness apart and see if there is something wrong inside the looms. Everything I have tried up to now hasn't changed a thing so it's either the ecu (which shows no sign of damage) or the wiring harness.

 

[rabenne]

Okay so you swapped 1&4 with 2&3? No change?
If you have truly done everything suggested above, I am not sure what to try next...

 

[frosty3156]

Okay so you swapped 1&4 with 2&3? No change?
If you have truly done everything suggested above, I am not sure what to try next...

Yeah, I think the last thing to try is pulling the wiring harness. Should be a ton of fun :0 Thank you for your time.

 

[rabenne]

Please report back your findings, I am very curious. Good luck.

 

[dustyboner]

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ECU pinouts are HERE if you need them

 

[ist dwa]

Check the wiring for all the sensors at the ECU, I bet the sensors grounds or powers are screwed up.

 

[o0GuitarKid0o]

Clearer pictures would help but can you get a close up of here:

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This looks to be the power transistor circuit although it's hard to see anything
.
That's either pin 10 or pin 23.

Anything look bad in the area I circled ?
Blown sensor grounds are a possibility.
What ecu is that? Black box?

 

[frosty3156]

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ECU pinouts are HERE if you need them

Thank you!!

 

[rabenne]

If the sensor ground trace is broken you will see -55 or something crazy like that for ECT and other parameters. Can you view live data on your scanner setup? or does it just read out fault codes?

 

[frosty3156]

Clearer pictures would help but can you get a close up of here:

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This looks to be the power transistor circuit although it's hard to see anything
.
That's either pin 10 or pin 23.

Anything look bad in the area I circled ?
Blown sensor grounds are a possibility.
What ecu is that? Black box?

Something does look a little strange next to the numbers D150, on the black part. It is a black box.