help identifying connector

[FFRWRX]

I bought a partially built 818C recently. It used a 2006 Impreza WRX donor. It starts, sometimes, and runs, sometimes, but very poorly. I've checked the basics. It has secondary air system codes since the air pump was removed, but no other serious codes. I pulled the intercooler and checked for throttle movement....seems OK. It cranks a lot and will start with the gas pedal floored, then I can back it off but hold some throttle. It will run, but poorly with no power. In poking around the engine I found this connector near the throttle body. I didn't see any connector in the area that it should be mated with. I don't know if this is important or not.

Thank you for any help,

Rick


128314128315

[Ajzride]

I believe that is the secondary air valve, which was probably also removed. I can see the plug on my engine, but can't trace it without removing the intercooler, which is a bigger job than I can sneak away for during work hours. I'll try to pull it tonight and trace it out for you to confirm. Is the motor Turbo or NA? I would check to ensure the MAF is installed and wired correctly. I've heard it is easy to install the MAF backwards.

[FFRWRX]

It’s a turbo. I’ll check the MAF. Thank you.

Forgot to mention that the oxygen sensor is just hanging in the breeze; no place for it with the temporary exhaust that the car has. Maybe I should install it?

[Ajzride]

It’s a turbo. I’ll check the MAF. Thank you.

Forgot to mention that the oxygen sensor is just hanging in the breeze; no place for it with the temporary exhaust that the car has. Maybe I should install it?

umm.. yea that's kind of important to the feedback loop.

You can get a clamp O2 bung for temporary if you need.

https://www.oreillyauto.com/detail/b/hooker-header-3890/performance-16477/exhaust-16555/oxygen-sensor-flange-19095/530b9d81b369/hooker-header-oxygen-sensor-bung/71014303rhkr/4370491?pos=7

[STiPWRD]

Forgot to mention that the oxygen sensor is just hanging in the breeze; no place for it with the temporary exhaust that the car has. Maybe I should install it?

Which oxygen sensor - front or rear? The front is the important one, it measures AFR for closed loop fuel control. The rear O2 sensor doesn't need to be plugged in, it's just used for emissions.

[Ajzride]

Which oxygen sensor - front or rear? The front is the important one, it measures AFR for closed loop fuel control. The rear O2 sensor doesn't need to be plugged in, it's just used for emissions.


Yea, thanks for clarifying that, I just kind of assumed it.

[FFRWRX]

I checked the MAF sensor. Took it out and cleaned it and cleaned the connector. Didn't make any difference. The fuel pressure was maybe a little high at idle (45+ psi) so I backed it down to around 37 psi).

I was only seeing one oxygen sensor at the back (not in the exhaust) then saw the forward one under the engine; so it is in place and connected. See picture.

So the engine will start with the throttle pedal to the floor, then backing off when it fires up. But I have to keep some throttle on or it will die. And when I floor it, it doesn't make much difference. I checked the real time data with a scan tool and the throttle position wasn't changing much with pedal movement. When the engine was off I checked it again and the real time data showed it moving from around 15% to 78%, and the throttle plate was moving. Maybe something going on there with the throttle position sensor. I was getting an error code about that now and then, but not consistent.

Rick

128339

[Ajzride]

So, not to be a wise ***, but since you bought it used, have you checked the basics like making sure the wires for the injectors and coils are hooked up to the correct connector and not fueling or firing out of order?

[Ajzride]

So, not to be a wise ***, but since you bought it used, have you checked the basics like making sure the wires for the injectors and coils are hooked up to the correct connector and not fueling or firing out of order?

Wow, our forum has a bleep feature, who knew. Apparently it's set to PG too.

[Ajzride]

Okay, I went out and pulled the intercooler, and the connector I saw was for the knock sensor. Is the wire black/blue or black? If it is black/blue then it is the knock sensor, and that is probably important. If it is black then it is the secondary air valve, which is not important.


https://www.youtube.com/watch?v=zPIZwlOse6s

[FFRWRX]

So, not to be a wise ***, but since you bought it used, have you checked the basics like making sure the wires for the injectors and coils are hooked up to the correct connector and not fueling or firing out of order?

I’ll take any suggestions. I even put some gas in it when I first got it and that helped it start!

I did see a video of it running, and don’t think anything was changed after that. But there could be something hooked up wrong. I’m not familiar with these engines so am learning as fast as I can.

[FFRWRX]

Okay, I went out and pulled the intercooler, and the connector I saw was for the knock sensor. Is the wire black/blue or black? If it is black/blue then it is the knock sensor, and that is probably important. If it is black then it is the secondary air valve, which is not important.


https://www.youtube.com/watch?v=zPIZwlOse6s

I think it was a solid black wire and a white one, but I’ll check again tomorrow. I have a bunch of secondary air valve codes, so probably the whole air pump system was removed.

[fletch]

See next post.

[fletch]

It's E115 - Secondary Air Combi Cut Valve RH
Clear those codes and the ECU will be happier.

[Ajzride]

It's E115 - Secondary Air Combi Cut Valve RH
Clear those codes and the ECU will be happier.

It should run fine with those codes though, at least mine did. Something else is going on for sure. Fletch is right, if it's a solid black wire it is the secondary air valve.

[fletch]

You're right. Those codes shouldn't cause the engine to run poorly. Another thought would be to search for a vacuum leak. They can cause all kinds of havoc.

[Ajzride]

Yes, I had a hell of a time figuring out the vacuum routing on the motor with all of the secondary air stuff removed. You can find a lot of my research and Q&A here:

https://thefactoryfiveforum.com/showthread.php?31639-Aj-s-818S-in-Houston&p=378824&viewfull=1#post378824

[STiPWRD]

So the engine will start with the throttle pedal to the floor, then backing off when it fires up. But I have to keep some throttle on or it will die. And when I floor it, it doesn't make much difference. I checked the real time data with a scan tool and the throttle position wasn't changing much with pedal movement. When the engine was off I checked it again and the real time data showed it moving from around 15% to 78%, and the throttle plate was moving. Maybe something going on there with the throttle position sensor. I was getting an error code about that now and then, but not consistent.
I would think the engine is struggling to get enough air if the throttle has to be wide open (or as open as it can get). Maybe there's a restriction in your intake system? The fact that your TPS can only get between 15% to 78% and that you've had some codes from the TPS sensor leads me to suspect either the sensor or the throttle valve. I would go ahead and replace the TPS sensor with an OEM unit (not aftermarket) and see if that fixes anything. You could remove the throttle and check if it's dirty. I'd also check the AFR your ECU is reading when and your fuel trim levels. Check if the ECU is trying to add or take away a bunch of fuel (~25%).

I'm not 100% certain on this but I think once you pass a certain TPS threshold (i.e. press the throttle far enough), the ECU goes from closed loop to open loop fueling. This could be another thing to check with the scan tool depending on if the car car runs in open loop fueling but can't in closed loop.

[FFRWRX]

I did a quick smoke check the other day and didn't find any intake leak. I was expecting a large vacuum leak with these symptoms. I'll do another one and check carefully.

I think you might be right about the open loop beyond a certain throttle point. I don't recall seeing any fuel trim adjustments, long and short term were both 0 from what I remember, but I'll check again. It is running like it is not on all cylinders. Distinct banging or popping as it is trying to start. But no error code to indicate a cylinder is out (fuel or spark).

I read somewhere that the TPS on the tumble valves is the same one as the throttle body. Anyone know about this? I'll have a look and if they are the same (and I can get at one on the tumble valve) I can swap it temporarily with the throttle body one. I am tempted to start removing stuff from the top of the engine as it is so congested trying to see what goes where. I can then clean out the tumble valves and see that things looked like they are hooked up properly.

Appreciate all the help and suggestions,

Rick