jimmydanny

Hiya'll!

I got a FC3C TII, S5. Before, I got my 7-9 PSI, whatever is stock, but now I only get 4-5, which means the duty solenoid controlling the boost isn't working somehow. It is clicking, so in that manner it works.

What can cause this to happen? The possible causes that I can think of are these:
Solenoid, wastegate, MAP, vac lines to solenoid, or my intake being straight instead of the S-shaped rubber one.

Any other ideas/ways to test?

Does it matter what way the solenoid is plugged on the vac lines?

vrracing

iTrader: (1)

There is a set of tests to run on the solenoid in the FSM.

HAILERS2

Read the output of the ECU TO the solenoid with a meter while in boost and at other times and write back.

jimmydanny

Do you have any numbers I should look for?

I am struggling with the evaporator box, PO fecking glued one of the brackets to the firewall mount, so I can't get it out for ****, except maybe by taking out the dash, which I ain't doin'.

So that is first pri anyways.

HAILERS2

Get a meter and look at the voltage on pin 3R with key OFF and then key ON and compare with the jpg I attached in my other post above.

I own a series four so I can't tell you what the voltage would be. No duty solenoid on series four.

OR it occurred to me that with key ON ony , you could just unplug the duty solenoid and reconnect it again. IF it clicks it seems to me the ECU is ouputing to the solenoid. Seems the ECU would pulse a gnd to the solenoids plug since it's a 'duty cycle" thing. The black/white wire on the solenoid has 12vdc anytime the key is ON. The other wire at the solenoids plug is a gnd signal from the ECU and a pulsed gnd signal from what I read. Sucker should at least click when the plug is put on / taken off with key ON.

jimmydanny

It is clicking, also tested two solenoids, both work. The MAP is just swapped, the lines to the solenoid seems fine. Is the placement of the vac lines to pre-turbo important? In the S-bend they kinda got air forced into them I'd say, mine are now 90 degrees on, since I got a straight pipe from the turbo to the AFM and filter. Shouldn't matter as it releases the air, not sucking in, but still, gotta ask.

HAILERS2

Not an answer to your questions, but.............Since the ECU is the item that determines the duty cycle of the solenoid, it seems you need to make sure the ECU is indeed seeing the boost signal from the boost sensor.

Either backprobing the boost pin at the ECU and taking a reading with a meter is one way. You''d just put the key to ON and read the voltage on the wire at the ECU (backprobe the wire with a meter with the plugs fully connected to the ECU) and compare that reading to the one called for in the CONTROL UNIT pages in the manual (3.4 to 3.6vdc).

Then read the voltage with the engine idling and compare it with the manual. (should be a lesser number than before)..............then what one could do is backprobe the wire at the ECU with key ON only and then watch the meter as you blow as hard as you can into the nipple of the boost sensor with the connector on it. Voltage should rise as you blow into the pressure sensor. Should rise above the 3.4vdc - 3.6 vdc figure.

You determined the ECU is indeed outputting a gnd to the duty solenoid and the above would confirm that the ECU is indeed seeing the real boost from the boost sensor which determines if the ECU raises of lowers the boost via the duty solenoid.

jimmydanny

Will do when I find my multimeter :P It is kinda gone, too messy in my car to find anything. But it is 6am here, so I need to go to sleep first of all

Thanks for the tip, I will try testing like you said.

jimmydanny

Hmm, okay, I fiddled with the wires to the MAP sensor, and still running without my wastegate connected I got 1.1-1.2 bar, which is around 14-16 psi somewhere? 1.0 is 14.4 I think.

Anyways. Connected the wastegate again, 0.4 bar again.

Any good method to test the MAP sensor? Anything I can do while not driving to see what readings I get from it in volts at idle, reving, and ohms when off.

jimmydanny

I tested the MAP now, I got volts up to 4V, when I got to 14psi (yeah, Im stupid, I know), but it decreased nicely, and 7,5psi was around 2,20, so this is perfectly right. Idle vacuum was 0.9-1 volts.

Nvm, wrong connector haha

EDIT: That last part is for the solenoid testing. Tested the front connector instead of the engine connector :P

jimmydanny

Okay, weird part incoming now.

Measured over pin 3R to ground, got 3V when ign on, 2-4 on idle (jumpy idle), and 12V when over 2-3k rpm, no matter what boost/vac level.

Then I measured over the solenoid valve itself. I got 12V when idle, when reving to over 3k I got 0. How the **** is the possible?

So, I ohmed over the L/W (blue/white) wire from the ECu to the solenoid, got a beep. Ohmed the other wire on the solenoid to the plus on the battery when ign on, nothing, 91 ohms. Then I took it over to the minus, got a beep. Tell me, are both connected to the ground?

And still I am getting a voltage, inverted on one side of the cable. This doesn't make sense for ****!

RotaryEvolution

iTrader: (30)

i think you're too focused on the wastegate solenoid.

make a test cap and pressure test your intake system, i bet you either find a leak in the intake tract or a plugged cat(if you have one).

oh, and don't do the open wastegate trick again to see how high you can push the boost unless you like a driveway ornament.

jimmydanny

It's not a leak, can't be! My vacuum is way too low for that to be possible. When I had even the smallest vac leak the boost gauge went haywire. That is one 3mm vac hose makes everything go bad... there is no significant leak here.

I got no cats left, how else would I push 14psi? Now I get what, 3-5? 0,4 bar anyways.

jimmydanny

I got some error codes (which does not affect the boost solenoid (which is the only problem, face it! I get 0,4 bar which is the wastegate spring's max, a bit too obvious)).

The error codes are the following:
11 - Intake Air Thermosensor (Engine) - Intake air fixed at 68F (does not affect the boost level to that degree, I haven't had this working for one and a half year, had 0,7 bar boost after it broke)
30 - Solenoid, Split Air Valve (should not have anything to say, this one is in the rack at the oil filler neck right, with the 33 and 38? Can try to reconnect them, just to try)
33 - Solenoid, Port Air Valve
34 - Solenoid, Bypass Air Control (BAC) Valve
38 - Solenoid, Accelerated Warm-up System (AWS)

As for the duty solenoid again, did you see the numbers I posted? They went nuts, nothing as they were supposed to be?

Would it be safe to run 12V straight into the solenoid, or just connect the two hoses together? That should give me my 0,7 bar no matter what, even though it also gives me a small vac leak, it is a good test to check if that part of the boost system is failing.

jimmydanny

Bypassed the solenoid today, got my 0,7 bar then. So it is not opening like it should, so my weird numbers got a say in this after all

RotaryEvolution

iTrader: (30)

if you bypassed it and it cleared up then your solenoid is seeing 12v/ground(can't recall which it is) bleed off from a different circuit holding the solenoid open or it is naturally stuck open and not sealing. take it off and test it for leaks.

jimmydanny

Will do. However, the numbers I got, they don't make sense, but in a way they do, cause if it was shut when I needed it to be open, the output would be something else. But I'll try later.