s4 t2 bogs at 3700 rpm help!!
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Joined: Sep 2013
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From: Perth Australia
I mean.. spark jumping where it shouldn't be.. Arcing through insulators on the coils or out of the sides of the leads..
Sorry I wasn't clearer..
Full load or WOT is harder on ignition systems than light throttle or idle.
Sorry I wasn't clearer..
Full load or WOT is harder on ignition systems than light throttle or idle.
Joined: Dec 2001
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From: NY, MA, MI, OR, TX, and now LA or AZ!
So, your secondary injectors aren't firing.
1) Verify the impedance of the secondary injectors
2) Verify your harness matches the impedance of the injectors, or has been modified appropriately
3) Measure the impedance of the injectors AT the ECU harness
1) Verify the impedance of the secondary injectors
2) Verify your harness matches the impedance of the injectors, or has been modified appropriately
3) Measure the impedance of the injectors AT the ECU harness
He also reports of bogging while free reving, which doesn't involve the secondary injectors, so there appears to be another cause.
Thread Starter
Joined: Feb 2013
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From: West Pasco Washington
Could it be the fuel pump it self I got it used off a friend of mine and like I said sometimes when I would do the fuel test when I would pull off the gauge it didn't seem like much fuel bled off sometimes would only get a dribble not pressurized like it should be
Joined: Dec 2001
Posts: 10,630
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From: NY, MA, MI, OR, TX, and now LA or AZ!
The secondaries can be triggered in neutral -- it's mostly a matter of the pressure sensor and rpm. Given the RPM it happens at, I'd say it's more than likely a secondaries issue -- unless he has a S5 or something.
Thread Starter
Joined: Feb 2013
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From: West Pasco Washington
Its an s4 will recheck to see if there firing with the new ecu I put in
Thread Starter
Joined: Feb 2013
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From: West Pasco Washington
So today driving it it started to sputter at lower rpms so I suspect its the fuel pump ordered a walbro 255 the other day and a sard fpr so we'll see what happens
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Joined: Feb 2013
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From: West Pasco Washington
There are 4 wires at the boost sensor. Only one of them is a ground wire. Some people choose the wrong wire as the ground wire. Make sure you did not select the wrong wire to ground.
The plugs to the secondary injectors might not be secure or the two wires in each plug might not be making good contact w/the injector.
There are 4 Green wires grouped together at the ECU (they should register 12 volts w/key to on). Two of them are for the secondary injectors. The voltage should drop to about 6 volts when the secondary injectors are triggered. To recreate load on the engine while idling you can unplug the TPS and remove the vacuum line from the boost sensor. Then you can free rev the engine above 3800 rpm and the secondaries should fire.
The plugs to the secondary injectors might not be secure or the two wires in each plug might not be making good contact w/the injector.
There are 4 Green wires grouped together at the ECU (they should register 12 volts w/key to on). Two of them are for the secondary injectors. The voltage should drop to about 6 volts when the secondary injectors are triggered. To recreate load on the engine while idling you can unplug the TPS and remove the vacuum line from the boost sensor. Then you can free rev the engine above 3800 rpm and the secondaries should fire.
When testing the injectors do you also unplug the connector going to the boost sensor or just the vaccum line?
Thread Starter
Joined: Feb 2013
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From: West Pasco Washington
Nothing tells you they are firing unless you removed the rail and tied them to the rail and then provided a flashing ground signal to the injector ECU wiring (this applies to the secondary injectors. Primary injectors you can basically do the same but you use the CAS to trigger these two injectors. You can tell by the voltage at the injector ECU wires to tell if the ECU is sending a signal to the injectors but it does not tell you that the injectors are actually firing.
Joined: Dec 2001
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From: NY, MA, MI, OR, TX, and now LA or AZ!
Checking the resistance will tell you that the wiring is fine and the injectors themselves are fine and there's no issues along the way. If the resistance is off there, it's good indication that something is whack along the way.
Thread Starter
Joined: Feb 2013
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From: West Pasco Washington
Well I finally figured it out !!!! I replaced the fuel pump with a walbro 255 and threw in the sard regulator and still had no luck so I went down to radio shack and bought myself a led to test if the ecu was sending ground signal to secondary injectors which it was so then I unplugged the injector plug at ecu and the plug that used to have the resistor box ohmed out the injectors and they were all 14 ohms but one only had .5 ohms it was just the pigtail this whole time car is running great now
Thread Starter
Joined: Feb 2013
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From: West Pasco Washington
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