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Militant-Grunt
08-29-2009, 03:38 PM
I replaced my front suspension last night, I took the car for a drive, came back washed up, got back into the car and it just started bucking like an animal. Put the car on the lift figuring I popped off a hose. Checked everything, replaced a connector right off the turbo, and put new clamps in. Restart the car. Same issue. I scan the car, get a whole bunch of codes, including misfire cyl 1-2 and intake air temperature sensor - high interference codes. I clear them and the motor returns to normal.

I vag the car again and at idle the motor engine load is 40% and vacuum is holding at -15, instead of the previous -22. Also the car is throwing 8 degrees of btcd timing purely on idle. I drove the car (not wot) and between gear changes the vac is -20.

Any ideas what is causing this? I replaced all the coil packs, I have new F5DPOR side fire plugs, and no leaks. [headbang]

Stubek
08-29-2009, 04:23 PM
Coil? When you say you replaced all the coils, did you do it this morning or just in the past? I have seen over the 6 years I have been on here coils going in a couple hundred miles.
First time I had a coil fail, it was just a little rough and very low on power.
A few years later, I had two at once fail and it was really rough.

Militant-Grunt
08-30-2009, 02:18 PM
Coil? When you say you replaced all the coils, did you do it this morning or just in the past? I have seen over the 6 years I have been on here coils going in a couple hundred miles.
First time I had a coil fail, it was just a little rough and very low on power.
A few years later, I had two at once fail and it was really rough.

The coil packs were off another car at the shop, they all work. It was random misfires not per cylinder.

I have a feeling its the intake temp sensor Im not sure though.

Poopie
08-30-2009, 07:49 PM
check fuses?

////D
08-30-2009, 08:30 PM
40% engine load at idle seems very high

Militant-Grunt
08-30-2009, 08:56 PM
And 8 degree's of advance timing on idle...

T3hD0gg
08-31-2009, 10:07 AM
I have a feeling its the intake temp sensor Im not sure though.

Check the VAG-COM block related to the IAT sensor after the car has sat and cooled down for a few hours. It should match the outside temperature.

If you're in a hurry, just take the IAT sensor out of the intake manifold and wave it around a bit and check it then.

Militant-Grunt
08-31-2009, 04:19 PM
Checked the compression, its fine all across the board. Changed IAT sensor, still same 30-40% load and 15-18 vac at idle.

At 1500rpm the load is at 20%, so the ecu is increasing load to keep motor on I also did a boost leak check, holds 30psi / boost checker blows off. No leaks. Sprayed all lines with soapy water. Other than a very small leak on a t splitter for boost gauge there are no major leaks.

Poopie
08-31-2009, 05:24 PM
you running a mafless tune?

whoace
08-31-2009, 09:29 PM
Multi programs on ECU? Perhaps you switched programs by accident. Normally when you have high load you require less advance. I'd check throttle body and knock sensors.

Militant-Grunt
09-01-2009, 12:26 PM
you running a mafless tune?

Yeah its a Mafless tune, one of my knock sensors is on its way out, but they wouldnt cause a load issue.

I think I figured out the problem, I swapped 3 IAT sensors, in and out and all 3 are reading -45C, either there is a break in the wiring on my ECU is taking a dump on itself. We had a similar issue on a 2.7t =/.

T3hD0gg
09-01-2009, 01:08 PM
Yeah its a Mafless tune, one of my knock sensors is on its way out, but they wouldnt cause a load issue.

I think I figured out the problem, I swapped 3 IAT sensors, in and out and all 3 are reading -45C, either there is a break in the wiring on my ECU is taking a dump on itself. We had a similar issue on a 2.7t =/.

Might have crushed the wiring between something metal? That would explain the high interference that it's getting.

Militant-Grunt
09-01-2009, 04:32 PM
Might have crushed the wiring between something metal? That would explain the high interference that it's getting.

The thing is there there is nothing to squish that particular wire. It comes from the bottom by the pcv breather and the whips around the throttle body, nothing there to pin it. I'm going to strip the rubber grommet regardless to see if its stripped or cut.

ghost6303
09-01-2009, 05:20 PM
Yeah its a Mafless tune, one of my knock sensors is on its way out, but they wouldnt cause a load issue.

i dunno, when my knock sensor went out it did some weird things. it didnt fail outright but was making the ECU think the engine was knocking when it wasnt. for a few months before it finally died, it would put the car in soft limp mode randomly and every once in a while pop up a code but with no CEL. when it completely died it was as if the MAF was dead, the car would barely run.

that combined with your IAT sensor issue might be the reason. knock sensors are basically a microphone surrounded in a rigid foam, that foam breaks down over years.

Militant-Grunt
09-02-2009, 06:35 PM
So today. I checked the intake temp sensor wire for continuity, the circuit goes all the way to the ECU. I also got another ECU and had it flashed with my tune. Same issue, the bucking comes back. When I pull the throttle body plug it stops, the same low vac continues. After clearing the codes and plugging back the throttle body (and aligning it) the car runs the same as on the old ECU. The same low vac on idle is there along with the 30-40% idle engine load. The ecu reads the intake temp sensor.

This shit is really getting on my nerves =/.

Tomorrow ill be running a leak down test but honestly I'm all out of ideas, I really don't know what would cause this so suddenly.

quattro16
09-02-2009, 07:44 PM
MAP sensor!

Militant-Grunt
09-02-2009, 08:29 PM
MAP sensor!

Why would you say its the Map sensor?

I would get a code for it if it was bad, that and I wouldn't be able to hit 20psi lol..

Poopie
09-02-2009, 09:03 PM
well the map sensor is what the ecu is using to calculate load at part throttle and idle.

Militant-Grunt
09-02-2009, 09:09 PM
well the map sensor is what the ecu is using to calculate load at part throttle and idle.

Alright, you have a point there. I will try that tomorrow, got a bunch of map sensors laying around.

Militant-Grunt
09-03-2009, 02:23 PM
Not the map sensor.. Getting real sick of this shit.

Militant-Grunt
09-03-2009, 03:30 PM
Also just replaced bad knock sensor same issue continues.

Militant-Grunt
09-04-2009, 09:51 PM
Did a leak down test today, each cyl held 50psi.. Cam timing is correct.

Militant-Grunt
09-21-2009, 09:26 PM
Just to update this.

Replaced throttle body.

No dice. Going for the accelerator pedal tomorrow since its also a TPS sensor.

Oceanside
09-21-2009, 10:41 PM
good luck man

biketsai
09-21-2009, 10:59 PM
No dice. Going for the accelerator pedal tomorrow since its also a TPS sensor.

Didnt you get that memo?

Militant-Grunt
09-22-2009, 07:17 AM
Didnt you get that memo?

Que?

whoace
09-22-2009, 02:30 PM
Testing the intake temp sens for continuity only tells you that there are no broken connections between the sensor and the ecu. The sensor is a thermistor. You need to test for resistance and compare it to manufacturer's specs at specified temps.

And leak down tests normally show %. If you're only holding 50 PSI and assuming you're using shop air which is about 100 PSI, you have a leakdown of 50%. Anything over 20% is normally deemed unacceptable.

Militant-Grunt
09-22-2009, 04:34 PM
Testing the intake temp sens for continuity only tells you that there are no broken connections between the sensor and the ecu. The sensor is a thermistor. You need to test for resistance and compare it to manufacturer's specs at specified temps.

And leak down tests normally show %. If you're only holding 50 PSI and assuming you're using shop air which is about 100 PSI, you have a leakdown of 50%. Anything over 20% is normally deemed unacceptable.

I bought a new IAT. And I didnt have a real leak down tester. I have a compressor, and a compression tester. I filled each cylinder to 50psi, and it wasn't going anywhere. Ive done this on bad heads and know immediately if valves are not sealing..

I changed the gas pedal today (tps) no change [=(]