S4 T2 Dies when hot
#1
S4 T2 Dies when hot
Gentlemen! I hope all is well with everyone. Hoping to get some help and insight. I've searched and searched for answers but I'm getting nothing that's definitive.
My wifes S4 T2 has been having this issue where the car runs fine on startup but then when you drive it for about 20 minutes or so it just decides to buck and try to stay alive but then eventually dies.
I've replaced the fuel pump with an Aeromotive 340 and I've added an Aeromotive A1000 FPR. When I installed the FPR everything seemed fine and my wife even drove the car for a good cruise for at least an hour around the city without any issues.
The very next day it starts doing the very same thing.
I haven't done any solid electrical diagnosis but I'm guessing its either improper voltage going to the pump which indicates a bad fuel pump resistor, or just ollld corroded wiring. OR a bad AFM since those two parts work hand in hand.
I'll be doing some electrical diag sometime this week but I'd like to know if you guys have had any similar experiences that could point me in the right direction before i start doing the whole fuel pump rewire that I've stumbled across in my research.
THANKS GUYS!
My wifes S4 T2 has been having this issue where the car runs fine on startup but then when you drive it for about 20 minutes or so it just decides to buck and try to stay alive but then eventually dies.
I've replaced the fuel pump with an Aeromotive 340 and I've added an Aeromotive A1000 FPR. When I installed the FPR everything seemed fine and my wife even drove the car for a good cruise for at least an hour around the city without any issues.
The very next day it starts doing the very same thing.
I haven't done any solid electrical diagnosis but I'm guessing its either improper voltage going to the pump which indicates a bad fuel pump resistor, or just ollld corroded wiring. OR a bad AFM since those two parts work hand in hand.
I'll be doing some electrical diag sometime this week but I'd like to know if you guys have had any similar experiences that could point me in the right direction before i start doing the whole fuel pump rewire that I've stumbled across in my research.
THANKS GUYS!
#3
I forgot to add that when this problem last happened, I pinched the fuel return line after the FPR and the pressure was not going up on the gauge while trying to start it up afyer it's died. But the car still fired revved up - barely - and dies again.
#4
*update*
This thread title should be changed now lol. Turns out that the car being hot has nothing to do with this problem.
After about an hour of electrical diag and more research I'm still at the same spot. Car has been sitting for a week and I tried to start it. Car starts for 5 seconds and dies. I've seen some other threads about this problem but I get no conclusive answer as to what the culprit actually is.
I tested the circuit opening relay (yellow and black relay to the right of the steering column) and it tested good.
Fuel pressure is at 40psi and holding.
There's nothing else in the fuel system that i can test.
Any help would be appreciated
This thread title should be changed now lol. Turns out that the car being hot has nothing to do with this problem.
After about an hour of electrical diag and more research I'm still at the same spot. Car has been sitting for a week and I tried to start it. Car starts for 5 seconds and dies. I've seen some other threads about this problem but I get no conclusive answer as to what the culprit actually is.
I tested the circuit opening relay (yellow and black relay to the right of the steering column) and it tested good.
Fuel pressure is at 40psi and holding.
There's nothing else in the fuel system that i can test.
Any help would be appreciated
Last edited by misterstyx69; 05-19-17 at 12:53 PM. Reason: don't need profanity to explain a problem.
#7
Rotary Freak
iTrader: (10)
Yes, should be a two pin connector (I think yellow), and the wires are black and brown. This will bypass the AFM switch which triggers the fuel pump. If the car stays running with this connection jumpered you either have a discontinuity in your harness from the AFM, or more often a bad AFM.
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#8
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Stupid suggestion..but it happens.
The AFM door gets corroded and will stick..
Check the movement of the AFM door to see that it moves freely.Corrosion can get in between the aluminum and make it do funny things.
I had one that just plain stuck on me and I had to take it apart and wire brush,wheel and lube it back to operational condition.
I came across this by accident too,as you do not think that AIR would have anything to do with the problem..!
The AFM door gets corroded and will stick..
Check the movement of the AFM door to see that it moves freely.Corrosion can get in between the aluminum and make it do funny things.
I had one that just plain stuck on me and I had to take it apart and wire brush,wheel and lube it back to operational condition.
I came across this by accident too,as you do not think that AIR would have anything to do with the problem..!
#9
Stupid suggestion..but it happens.
The AFM door gets corroded and will stick..
Check the movement of the AFM door to see that it moves freely.Corrosion can get in between the aluminum and make it do funny things.
I had one that just plain stuck on me and I had to take it apart and wire brush,wheel and lube it back to operational condition.
I came across this by accident too,as you do not think that AIR would have anything to do with the problem..!
The AFM door gets corroded and will stick..
Check the movement of the AFM door to see that it moves freely.Corrosion can get in between the aluminum and make it do funny things.
I had one that just plain stuck on me and I had to take it apart and wire brush,wheel and lube it back to operational condition.
I came across this by accident too,as you do not think that AIR would have anything to do with the problem..!
The ONLY value that I tested that was a little e strange was the resistor relay. Prongs E-F tested at 1.2 ohms whereas the fsm states one single value of 0.64 ohms.
#10
This thread title needs to be changed lol...
So after some more work this weekend I've made one step forward but two steps back.
I tried to do the AFM jump with the yellow connector down by the passenger strut tower near the frame rail. I jumped the connector and the car started! Then tried to run the car normally without the jumper and lone behoid the car started, held idle at 1000 and fuel pressure was at a solid 40spi and it ran smoothly.
Here's what takes me back a few steps. I cant give the car any throttle. If i press the gas just a BIT it starts to stumble and die until i close the throttle plate and continues to idle smoothly.
I replaced the TPS sensor with a brand new unit about 2-3 years ago but its only seen about 2000 km of use.
I've re-grounded all of the common grounds except for the starter ground shared with the battery ground on the drivers side strut tower.
So after some more work this weekend I've made one step forward but two steps back.
I tried to do the AFM jump with the yellow connector down by the passenger strut tower near the frame rail. I jumped the connector and the car started! Then tried to run the car normally without the jumper and lone behoid the car started, held idle at 1000 and fuel pressure was at a solid 40spi and it ran smoothly.
Here's what takes me back a few steps. I cant give the car any throttle. If i press the gas just a BIT it starts to stumble and die until i close the throttle plate and continues to idle smoothly.
I replaced the TPS sensor with a brand new unit about 2-3 years ago but its only seen about 2000 km of use.
I've re-grounded all of the common grounds except for the starter ground shared with the battery ground on the drivers side strut tower.
#11
rotorhole
you have a bad airflow meter, because your fuel pump switch inside is making intermittent contact, which is why the initial test jumpering the test connector passed but again reverted to some original symptoms when not.
it's a common problem.
it's a common problem.
#13
rotorhole
i said what i had to say, you can believe it or not. the fuel pump switch in the AFM is a very common failure, you already proved that theory with the fuel pump test connector bypass.
i locked my old account so i could care less if you take my advice, since no one really gave a **** about me anyways.
i locked my old account so i could care less if you take my advice, since no one really gave a **** about me anyways.
Last edited by insightful; 05-29-17 at 10:21 AM.