Hi guys/gals,

Wanted to post here for more visibility in regards to an issue I have been having with my 2007 SL55 93k miles. Car is very rough on cold starts and idles almost perfectly when warmed up. Always had symptoms of a small vacuum leak where when decelerating at around 2k RPM the rpm would slightly bounce between 2k-2200 then go down and same with around 1k-1200 then go down smooth. I tried getting a Eurocharged tune and the CEL would pop up within 10 miles for p0505. Jerry tried sending multiple files and the issue would come up right away (same code). I have since had no tune and I just got the same CEL pop up. The car sometimes has a whining noise at low RPMs then goes away when you turn it off and restart. I completely removed the intake manifolds to verify all the hoses are plugged in and nothing is loose and all is good. Lately, I have heard a very loud constant whistle come from the TB and it will go away when accelerating or tapping the gas pedal and sometimes come back. There has been two times where the car would just crank and not start, but doing attempting to start it the second time starts it up right away (bad crank sensor?)


Just now, I used the iCarsoft and did the ETC (Electronic throttle control system) reset and the CEL went away on its own. This leads me to believe it is TB related? I have noticed absolute throttle position in drive goes from 1.6 to .8 and occasionally will even dip to .4

Here are the freeze frames from the CEL with vehicle in Drive:
short term fuel trim b1= .8%
long term fuel trim b1= 5.5%
short term fuel trim b2= 1.6%
long term fuel trim b2= 6.3%
intake manifold absolute pressure= 38 kPa
engine speed 450 rpm (looks low car usually idles at around 550)
ignition timing advance for #1 cylinder= -9.0
Intake air temp= 36C
Absolute Throttle position= 1.2%


Here were live frames I captured for a few seconds each: (first shown in park // followed by drive)
short term fuel trim b1= -4.7 to 3 // -3 to .8
long term fuel trim b1= 7% this was constant
short term fuel trim b2= -25% to -11% // -16.4% to -11.7%
long term fuel trim b2= 7% this was constant
intake manifold absolute pressure= 32-33 kPa // 37-38 kPa
engine speed 640-680rpm // 540-556rpm
ignition timing advance for #1 cylinder= -13 to -9 // -13.5 to -9
Absolute Throttle position= .8% // .8%
Oxygen sensor output voltage (b1-s1) -.8 to 1.6 // .080 to .78
short term fuel trim(b1-s1) -3.1 to 2.3 // -2.3 to .8
oxygen sensor output voltage (b1-s2) .075v to .175v // .090 to .170
short term fuel trim (b1-s2) 99.2% this stayed constant
oxygen sensor output voltage (b2-s1) .070 to .735v // .095 to .745
short term fuel trim (b2-s1) -11.6 to 1.6 // -14.7 to -10.9
oxygen sensor output voltage (b2-s2) .38 to .545v // .740 to .750


Bought the car 4 months ago so far I have done:

new engine + trans mounts
new plugs and valve cover gaskets
new breather hoses
new IC pump
fuel filter
fuel pressure sensor+ upgraded harness
new y pipe (mine was zip tied on) car has 80mm TB stock
new (used) pedal
cleaned TB (did not remove)
diff service
trans service
rear main seal
PLM XL heat exchanger
5 piece aluminum pulleys
83mm SC pulley


For maintenance sake, I will be changing the MAP sensor and IAT sensor and replacing the gaskets under the intake manifolds (getting them powdercoated). I dont think any of this will have any effect on my issues. I am hoping it is not a bad TB, but I am leading to believe that is the case. I will probably have to do a smoke test once I get the MAP and IAT sensor in just to be safe. Are there any other ideas based on what you guys are seeing?


Thank you very much for your time, any help or ideas are greatly appreciated.

 

Here are some videos of the very loud noise coming from the TB area...



any help is appreciated. Thank you