2005 Audi S4 lost power while driving and won’t start

[HudsonBarrett]

Hey Guys! Looking for some guidance on my s4.

The first issue I’m looking for help on is the car is (bucking/jerking/almost stalling) really hard in first, second, and third gear (manual) when medium to heavy throttle is applied.

I replaced the transmission, clutch, flywheel, speed sensor, motor mounts, pcv, maf, spark plugs, fuel injectors, coil packs, and all the abs lines.
I was hoping one of these would fix the issue but I cannot seem to find out why it is jerking.

Second issue came up when going down the highway at about 70 mph in 6th gear. While driving I heard something pop and then their was a low hum and I lost any sort of power in any gear. Thankfully I got off to the side safely and got it towed back to my house. When I went to try and start the car, all I hear is a click from the starter but it won’t turn over. I scanned the codes and came up with this:

P0102: MAF signal to low
P0113: Intake air temp sensor signal to low
P0301: Cylinder 1 misfire
P0302: Cylinder 2 misfire
P0303: Cylinder 3 misfire
P0304: Cylinder 4 misfire
P0300: Random/Multiple Cylinder misfire
P3081: Engine Temp to low
P0021: Camshaft A (intake) over advanced

I’ve been reading a lot about it on here and I think I have narrowed it down to 2 options: Timing, or Fuel Pump. I am leaning towards the fuel pump because I don’t hear it prime when I got to turn the key but I wanted to see what opinions others had.

[Toronto5.5]

Bad fuel pump won't keep it from turning over...
Pull the plugs and see if it will turn over freely by hand. How many miles and has timing been done?

[HudsonBarrett]

Will do.
It has 164k miles and no timing has not been done.

[Atomic Avant]

Also the fuel pump doesn't always prime when you turn the key.

I agree with what was said prior, if you can turn the engine over by hand that is a good start.

[Zolli]

Would timing affect the intake air temp, MAF, and engine temp sensors? No, right? All that stuff is on the passenger side (bank 1), so could it be a wire harness? The camshaft over advanced is troubling, though.

[Rol-co]

Looks something elektrical, i would start at the ecu box.

[HudsonBarrett]

I will look into all the harnesses and also check the ECU.

[HudsonBarrett]

I will try to start it by hand and let you guys know what happens.

[HudsonBarrett]

I looked at the ecu box and instinctively pulled out the40 amp fuse to the left of the ecu. Turn out it’s gone bad. Do you know what this fuse is?

[Atomic Avant]

I looked at the ecu box and instinctively pulled out the40 amp fuse to the left of the ecu. Turn out it’s gone bad. Do you know what this fuse is?

Off the top of my head I think it's for the SAI pump.

[HudsonBarrett]

Thank you. I’m going to go through all the fuses and replace them

[HudsonBarrett]

Do you know where the main fuse is?

[HudsonBarrett]

I checked the input power continuity for the fuel pump and it read 1.5 at the highest when the key is turned to the on position. The fuse obviously read 0 and I am going to get the relay tested.
I cannot figure out hot to manually turn the main crank pulley because there is no nut to latch onto?? Any advice?
I checked ground connection for the ground wire coming out of one of the wiring harnesses from the ecu but to no avail. Car still won’t crank. All I hear is the starter click.
All the electrical for the ecu and sensors seem to be in order.
I will check spark and maybe I’m simply out of fuel, I read that the reading from the fuel gauge can be faulty.
Would the wrong amount of air cause the engine temp to be to low?
So far it seems as if air and fuel are both incorrect but what would cause them both to be incorrect?

[Toronto5.5]

I cannot figure out hot to manually turn the main crank pulley because there is no nut to latch onto?? Any advice?

https://www.audizine.com/forum/showt...turn-the-crank

[HudsonBarrett]

Thank you.

[Rol-co]

I checked the input power continuity for the fuel pump and it read 1.5 at the highest when the key is turned to the on position. The fuse obviously read 0 and I am going to get the relay tested.
Would the wrong amount of air cause the engine temp to be to low?
So far it seems as if air and fuel are both incorrect but what would cause them both to be incorrect?

Maybe you can disconnect the fuel hose and check if there is fuel when the key is at the on position. If engine temp to low i would suggest there is a problem with the temp sensor g62.

[HudsonBarrett]

Will do.

[Dondbg]

I had similar issue with different codes



Ended up being the SAI wires, very common, all S4 B6/7 I owned or worked on suffered from the same




The big orange fuse is for the SAI and when this happened, it took the fuel pump with it, car was cranking at that stage but no start

I cut open the engine loom next to the ground connection at the at the firewall next to the coolant tank, cut the positive and pulled the naked SAI wire pair out.



Heat shrink and ran them back inside fibre glass tubing





If doesn’t start check this little wire is not damaged, it’s the starter signal, brown white or yellow can’t remember

[HudsonBarrett]

Hey! Thanks so much for all the info and pictures included! I checked the ground wire and it was cracked just like the picture you sent. I will cut open the fiberglass tubing and look for the SAI wires. Will get back to you later on! I’m really busy and haven’t had any time to work on it but I appreciate your help greatly!

[Rol-co]

They are all cracked, mine too but the car won’t stop at that only codes about insufficiënt flow.

If you start to dig at the protection hose you have to go all the way to renew. If the fuse is good and no codes leave it, thats not the problem.

Al lot of cars have sai deleted.

[Atomic Avant]

They are all cracked, mine too but the car won’t stop at that only codes about insufficiënt flow.

If you start to dig at the protection hose you have to go all the way to renew. If the fuse is good and no codes leave it, thats not the problem.

Al lot of cars have sai deleted.

Can confirm all this.

I went through the hassle of making a new harness for my SAI. Fixed everything up and made it look clean as hell. (wiring is my thing)

Did all that only to find out one of the combi valves was stuck open/closed.

Said screw it and got a tune and pulled the SAI out.

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[HudsonBarrett]

The SAI fuse is bad.
I’ll check all the wiring hopefully tonight.
If the SAI crapped out why would it take out the fuel pump?

[Zolli]

Could be concurrent problems, not causation problems, between the SAI and fuel pump

[HudsonBarrett]

Hey Guys, I found this issues. Pulled the spark plugs and 2 of them were smashed in. All the debris went into the valves and scraped the cylinder walls. Getting a new engine tonight.
Anyone have any idea why the cam over advanced?

[Rol-co]

Hey Guys, I found this issues. Pulled the spark plugs and 2 of them were smashed in. All the debris went into the valves and scraped the cylinder walls. Getting a new engine tonight.
Anyone have any idea why the cam over advanced?

Sounds like something got in the engine, pieces of the im maybe? Did you do anything before this happend?

[HudsonBarrett]

I put a new engine and transmission in the car.
It’s running good, but it is still jerking when accelerating and letting off the gas. Any ideas?

[Atomic Avant]

Motor and transmission mounts?

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[Rol-co]

More interesting, did you open up the old one?

[HudsonBarrett]

Both brand new

[HudsonBarrett]

Haven’t had the chance yet. I scanned it tonight and got 4 codes. Misfire on 3 and 5 and the speed sensor. As far as I know the 4.2 v8 doesn’t have a “speed sensor” but instead it’s the crank position sensor. Am I correct on that?

[HudsonBarrett]

I replaced the crank pos sensor, and all abs wheel speed sensors. I am still getting an ABS light, Traction control light, and the Speedometer isn’t working.

I also have a CEL: P0501 for implausible signal from Speed Sensor.

Today when I went to drive it, Both lights were not on and the speedometer was working. The car ran Perfectly for the 1st time. The. Then…lights came back on.

I don’t think it could be anything to do with my new sensors and im starting to think it’s my ABS module. I’ve done research about how aftermarket HID can affect the module and the previous owner did have the ballast mounted right next to the module. I can’t find any info on how to test the module. Does anyone have any ideas or dealt with a similar issue?

[Rol-co]

Maybe disconnect the hid and drive again ?

[ak-s4]

I have issues with my aftermarket HID interfering with the ABS module as well. Once it triggers the fault, you have to turn the car off and on twice to get it to go away (actual start, not just accessory mode). Some things I've done to help are to turn the lights on before starting the car and wrapping the HID modules in some of the foil bubble wrap (it's what I had handy).

To test, just keep the lights off and drive the car to see if the ABS module behaves?

[CONative]

The 4.2 does have a speed sensor. I apparently damaged mine in the process of putting the car back together (as I did not remove it prior to marrying the engine/trans). The car would turn over but not start. The tech who worked on my car said some B7’s have a spacer for the sensor but couldn’t confirm based on VIN. Now I’m not sure if a missing spacer is the cause behind the jerking you are experiencing, but my shop added one when they replaced the sensor and the car’s been running good.


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[Old_skool]

I replaced the crank pos sensor, and all abs wheel speed sensors. I am still getting an ABS light, Traction control light, and the Speedometer isn’t working.

I also have a CEL: P0501 for implausible signal from Speed Sensor.

Today when I went to drive it, Both lights were not on and the speedometer was working. The car ran Perfectly for the 1st time. The. Then…lights came back on.

I don’t think it could be anything to do with my new sensors and im starting to think it’s my ABS module. I’ve done research about how aftermarket HID can affect the module and the previous owner did have the ballast mounted right next to the module. I can’t find any info on how to test the module. Does anyone have any ideas or dealt with a similar issue?

I had the same issue... speedometer was intermittently not working (showing 0 during driving) which progressively got worse... not showing speed more frequently, plus ABS and 'traction-control' lights... scanned and got the same code 'implausible signal from speed sensor' on left side (maybe right side... but it was definitely one side only).

Originally thought i would swap the speed sensors between left and right to confirm that it was definitely the actual wheel speed sensor, but started googling prior to doing anything and a few threads on other forums came up with those exact, very specific symptoms (speedo stopping working, plus ABS and 'traction-control' lights, plus wheel speed sensor code) and in every case they replaced wheel speed sensors etc without any symptoms being fixed, and then replaced the abs module, which DID fix their issues.

also was stated in some thread by people in the know that what the actual cause of this is an internal connection inside the electronics-portion of the abs module breaks but still sometimes physically connects (hence the intermittent speedo etc). apparently this is repairable but not easy to do, however, the electronics-section of the module can be unscrewed and removed/swapped out for a working electronics-section while keeping the aluminium-block in the car with brake-lines all attached(ie not undoing any brake-lines).

so my options were either to unbolt the plastic electronic-portion (which has a rubber seal and can be re-installed etc) on the abs unit and bolt-in a working, used, electronics-section... or... remove entire abs unit (undo all brake lines etc) and fit used, working entire abs unit.

i did the whole unit (electronics-section and mechanical pump) and all symptoms resolved, without touching/replacing any wheel speed sensors (or any other parts).

once installed, either option needs to be re-coded to the car which is apparently always a pain and takes a few attempts... the workshop that re-coded mine said it took 3 tries and was by far what took the most time. If coding yourself then apparently a code (5 or 6 digits... unsure) must be obtained in vag-com from the original abs-unit before it is removed from the car as this is apparently crucial to being able to re-code the new unit.

[HudsonBarrett]

Rol-co I tried doing that but with no success.

[HudsonBarrett]

I will try this tomorrow! @ak-s4

- - - Updated - - -

@CONative
Where is the speed sensor located?

[HudsonBarrett]

@oldskool
I’m starting to think it is the abs module as well.
I am going to try a few things tomorrow but if I can’t fix it I will repair the module.

[Old_skool]

@oldskool
I’m starting to think it is the abs module as well.
I am going to try a few things tomorrow but if I can’t fix it I will repair the module.

Check these out before you spend any more money on anything besides replacing the abs module:

https://www.audizine.com/forum/showt...ol-light/page2

https://www.audizine.com/forum/showt...ntly-no-speedo

https://www.audizine.com/forum/showt...light-flashing


The ABS module internal cause (of those very specific, combined symptoms... no speedo, abs & esp lights, left wheel speed sensor error code) and DIY fix for ABS module internal cracked solid wire/connection:

https://www.audizine.com/forum/showt...d-sensor-codes


Good luck and hope you resolve it either way

[Rol-co]

And