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With Xentry and a 4 channels pico automotive scope + 2 low current clamps and some hard work because of your airbox, you can see which one went "bad" first, Ignition or Fueling.
I don't envy M276.9 3.5NA air box when doing troubleshooting ignition, fuel injectors and engine breathing.
It is so pain in the azz by design for us to troubleshoot ( based on photos if for me ), as no M276.9 was introduced in my local market, they jump to M276.8 3.0 Turbo from M272 3.5 or 3.0
For my country, in 2009, engine with higher than 3.0 liter displacement, there will be luxury sales tax like 40% or so , hence that strategy of engine choice MB took.
Mine is easier M276.8 3.0 Turbo as my air box is purely airbox and not part of intake manifold like M276.9 3.5NA
I feel your pain
M276.9 being a MAF engine, the airbox vacuum hoses & PCV hoses and if one get loose ENOUGH, it will cause bad idle and distract you from your initial troubleshooting
Mine because of a turbo version, uses MAP ( speed density as US tech likes to call ).
You suggesting replacing the alternator?
Or first battery?
Audit/test them first before deciding anything.
I am sure you have DC current clamp right ?
Use your Xentry to monitor B95 Battery Sensor, or your Instrument Cluster can do that too. Better use Xentry.
Get a DMM as a volt meter to monitor at F32 copper bar, that small bar where you charge the battery.
The current clamp will read Gross amperage out of the alternator, before power consumers consume them and surplus is given to battery.
B95 sensor or battery, gets NET power or sometimes battery MUST give power to F32 ( devices ) when and if the dumb-azz yoyo voltage at alternator falls below 12.6V causing a deficit.
B95 will show positive or negative amperage and the actual voltage at battery terminals.
Load the car with HVAC maximum blower speed and heater core activated to heat up evaporator and hence run compressor more and the radiator fan faster.
High beam ON, if you have electrical based heater on the car, turn them all.
Do not play with your electric power steering for the time being...YET, this is the biggest sudden power sucker of them all.
Having engine at proper operating temperature would be good as the hotter the engine bay gets, the possibility of electrical gremlins appearing is higher.
Share your findings.
===================
Next test, remove the single LIN cable connector to your alternator and do the same test.
Removing LIN will make alternator revert back to its original setting without engine ECU intervention, expect to see awesome 13.6 to 13.9V all the time and very nice precise low amperage
charging at B95 sensor when and if the battery is already starting to be fully charged.
Now play with your ELECTRIC power steering, lock to lock L to R but do it slowly and not too fast.
Here you can see how fast a non ECU intervention alternator response to the EPS demand.
Share your findings.
By then you can tell if your alternator can actually supply enough current/power or not ?
I think your alternator is easy 180A, mine is 200A and I am not a winter car with any electric heaters except the rear windshield defroster..
========
The voltage reading at F32 copper bar is to make sure there is no significant voltage drop between your F32 to Battery.
The ground of your DMM for F32 voltage reading , use the engine lift hook. This way we can also see if the un-documented W-TF ground cable from car under carriage to the
engine's block near starter motor is decent or not.
ADD : You are probably in winter now, so your radiator fan may not run fast. Use your Xentry to maximize M4/7 radiator fan, to 90% ( maximum ) when your engine already hot.
This one is 600 - 800 watts of power sucker.
===========
After all these test, cleaning your car grounds ( a few important ones) connection is a must do, after all the car is 10 years old at least...right ?
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by Dave Backmarker
JettaRed, Without a doubt, a bad battery will kill the alternator as the battery is putting a large constant current draw the alternator must produce. I liked your checklist above. The flickering dome lights indicated to me an alternator - vol at age regulator issue.
My son had a 1998 Red Jetta. We pulled the engine five times. He had the car for seven years and won a second place at Water Fest. He learned a lot about working on cars with that car and he and I spent countless and precious father-son hours under his red Jetta. Whenever I see a red Jetta, Imthink back to those days.
My first new VW was a 2000 red Jetta (hence the alias). It was a 2.0 liter that I supercharged with a Neuspeed supercharger. I think I have one of the longest running threads on VWVortex about the supercharger and all the mods I made. I, too, learn a lot with that car.
Use your Xentry to monitor B95 Battery Sensor, or your Instrument Cluster can do that too. Better use Xentry.
Get a DMM as a volt meter to monitor at F32 copper bar, that small bar where you charge the battery.
The current clamp will read Gross amperage out of the alternator, before power consumers consume them and surplus is given to battery.
B95 sensor or battery, gets NET power or sometimes battery MUST give power to F32 ( devices ) when and if the dumb-azz yoyo voltage at alternator falls below 12.6V causing a deficit.
B95 will show positive or negative amperage and the actual voltage at battery terminals.
Load the car with HVAC maximum blower speed and heater core activated to heat up evaporator and hence run compressor more and the radiator fan faster.
High beam ON, if you have electrical based heater on the car, turn them all.
Do not play with your electric power steering for the time being...YET, this is the biggest sudden power sucker of them all.
Having engine at proper operating temperature would be good as the hotter the engine bay gets, the possibility of electrical gremlins appearing is higher.
Share your findings.
===================
Next test, remove the single LIN cable connector to your alternator and do the same test.
Removing LIN will make alternator revert back to its original setting without engine ECU intervention, expect to see awesome 13.6 to 13.9V all the time and very nice precise low amperage
charging at B95 sensor when and if the battery is already starting to be fully charged.
Now play with your ELECTRIC power steering, lock to lock L to R but do it slowly and not too fast.
Here you can see how fast a non ECU intervention alternator response to the EPS demand.
Share your findings.
By then you can tell if your alternator can actually supply enough current/power or not ?
I think your alternator is easy 180A, mine is 200A and I am not a winter car with any electric heaters except the rear windshield defroster..
========
The voltage reading at F32 copper bar is to make sure there is no significant voltage drop between your F32 to Battery.
The ground of your DMM for F32 voltage reading , use the engine lift hook. This way we can also see if the un-documented W-TF ground cable from car under carriage to the
engine's block near starter motor is decent or not.
ADD : You are probably in winter now, so your radiator fan may not run fast. Use your Xentry to maximize M4/7 radiator fan, to 90% ( maximum ) when your engine already hot.
This one is 600 - 800 watts of power sucker.
===========
After all these test, cleaning your car grounds ( a few important ones) connection is a must do, after all the car is 10 years old at least...right ?
Have fun.
Thanks for the guide I appreciate it!
So far I did test the voltage on the cooper bar and rest of the ports on the F32 and wile engine running I have 14.4 V I use Matco voltmeter.
i will do your advice and use clamp and check the amps and also I will check the undercarriage ground point.
ill let you know the findings
keep it in mind I work after hours on this car
Nobody wants to touch it anymore I am trying to save it from junking it (it’s nice car overall)
Which data of the scanner or test instrument tells you that ?
I plug coil with spark plug and leave it on the side and watch it with my eyes
Start engine and leave it running spark never goes out
I know it’s funny 😆 don’t laugh please but it’s truth!
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Everything looked good until that last pic. It does appear you are running a little rich on the right bank, but not outside permissible limits (0.782v). Cylinder 1 is right bank.
Maybe someone smarter than I can explain the high misfire count.
I plug coil with spark plug and leave it on the side and watch it with my eyes
Start engine and leave it running spark never goes out
I know it’s funny 😆 don’t laugh please but it’s truth!
Its normal to do that, as long as you add ground wire from engine block to the s-plugs metal thread to let it fire to its L tip and not to send "Zeus" to other components...
Since cylinder 1 belongs to Bank 1 or Right Bank , you see a bit rich Lambda at 0.923.
.
Mild rich.
.
The RIGHT / BANK 1 rear narrow band oxygen sensor after CAT also confirms a rich condition.
But for rear oxygen sensor, you need to graph it overtime , a single look short duration does not tell the whole story as this sensor is for CAT and not for engine per se.
================
It is actually easier to understand fuel mix with AFR value than a Lambda value.
If we use 0.92 Lambda, we see 13.52 AFR
So 1 part fuel only get 13.52 air, short of the target stoich of 14.7 air.
So lack of air it is.....if based on how the front / upstream wideband oxygen sensor is seeing.
Let say we have bad injector spraying more fuel than intended due to a mechanical problem, would the result be also RICH, .......yes.
3 things can cause a misfire.
AA. Injector - fueling, can be spray pattern, spray quanity, delayed spray timing
BB. COP - Weak firing due to few reasons.
CC. Breathing air into the cylinder and its timing.
What Mak did :
01. Injector was swap with new one. I hope it is coded to tell ECU the "metering & inductance" value of the new injector. That 6-8 or so digits on the injectors.
Have you coded the new injector ?
and others below.....
VVT issue is not likely as only cylinder 1 is the issue.
Mak,
Did you check the condition of the hydraulic lifter tappet ( #60) and roller cam follower (#50) of intake and exhaust valves cylinder 1 ? and the intake and exhaust lobe on the camshafts of Cylinder 1 ?
If item #60 goes bad, the valve opening can be bad or not open enough.
Even on manual adjusted valve clearance engine, if left un-check , this can cause misfire.
Your M276.9 of 145,000 miles is a lot of miles .
I think unless the #60 is really bad, it might not show when visually inspected because we can't tell if it leaks enough oil to collapsed itself and be out of spec.
==============
In-cylinder pressure waveform testing can show breathing problem in a cylinder.
This is a 2 hour long video but its a good watch if you want to see what In-cylinder pressure waveform testing can do without engine tear down and in fact sometime the only way to see minor issues where we need
a running engine to see the actual fault occuring.
Question?
if the issue is the hydraulic liffter/cam lobe or follower it will show low compression or leakage in the cylinder?
If the valve is broken off at its sealing side and not sealing, YES, you loose compression tested using mechanical gauge.
If say inlet valve never opened enough due to hydraulic lifter issue and let say only 50% of regular air intake happen, your testing of compression using mechanical gauge
which has check valve and is reading peak pressure only, does not tell the story per 1 event of compression in a full picture of the 720 degrees crank.
The manual gauge compression test is cranking for a few seconds and that cylinder get a few compression events, so that is accumulated peak pressure-s and held in place by check valve.
200 RPM crankshaft cranking speed typical of a starter, for say 3 seconds is approx 4.5 compression events per cylinder.
So your compression testing is by-product of that many air intake events being compressed to represent a single reading. I hope that make sense.
In-cylinder waveform engine cranking only or engine idling and with fast throttle when using scope and pressure transducer,
we can see per 1 compression event and hundreds of them. Exactly as how a combustion should happen, 1 event at a time.
Try and use Xentry Compression Test under N3/10 engine computer.
See how much slower or faster is cylinder 1 compared to other cylinders.
I think Xentry uses averaging, because we need like 7 seconds cranking before it is completed.
The averaging would still show some differences...I am hoping.
At least do the Xentry compression test twice, to be certain.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Maybe a leak-down test for cylinder 1 is in order. As @S-Prihadi said, a mechanical compression test is showing peak values. A lead-down will show whether the cylinder chamber is tight or not. Bad rings, scored cylinder walls, cracked head, torn/blown head gasket, etc. may not show with a mechanical compression test if they are minor deformities, but would certainly cause a leak-down test to fail.
If the valve is broken off at its sealing side and not sealing, YES, you loose compression tested using mechanical gauge.
If say inlet valve never opened enough due to hydraulic lifter issue and let say only 50% of regular air intake happen, your testing of compression using mechanical gauge
which has check valve and is reading peak pressure only, does not tell the story per 1 event of compression in a full picture of the 720 degrees crank.
The manual gauge compression test is cranking for a few seconds and that cylinder get a few compression events, so that is accumulated peak pressure-s and held in place by check valve.
200 RPM crankshaft cranking speed typical of a starter, for say 3 seconds is approx 4.5 compression events per cylinder.
So your compression testing is by-product of that many air intake events being compressed to represent a single reading. I hope that make sense.
In-cylinder waveform engine cranking only or engine idling and with fast throttle when using scope and pressure transducer,
we can see per 1 compression event and hundreds of them. Exactly as how a combustion should happen, 1 event at a time.
Try and use Xentry Compression Test under N3/10 engine computer.
See how much slower or faster is cylinder 1 compared to other cylinders.
I think Xentry uses averaging, because we need like 7 seconds cranking before it is completed.
The averaging would still show some differences...I am hoping.
At least do the Xentry compression test twice, to be certain.
Today after 5 pm I will do one more Xentry compression test and post results
And also I will do leak down test and post the results.
Thanks guys
Maybe a leak-down test for cylinder 1 is in order. As @S-Prihadi said, a mechanical compression test is showing peak values. A lead-down will show whether the cylinder chamber is tight or not. Bad rings, scored cylinder walls, cracked head, torn/blown head gasket, etc. may not show with a mechanical compression test if they are minor deformities, but would certainly cause a leak-down test to fail.
Have you scoped the cylinder?
I will do leak down test today after 5 pm and scope the cylinder
I will post the results
Thanks
If the valve is broken off at its sealing side and not sealing, YES, you loose compression tested using mechanical gauge.
If say inlet valve never opened enough due to hydraulic lifter issue and let say only 50% of regular air intake happen, your testing of compression using mechanical gauge
which has check valve and is reading peak pressure only, does not tell the story per 1 event of compression in a full picture of the 720 degrees crank.
The manual gauge compression test is cranking for a few seconds and that cylinder get a few compression events, so that is accumulated peak pressure-s and held in place by check valve.
200 RPM crankshaft cranking speed typical of a starter, for say 3 seconds is approx 4.5 compression events per cylinder.
So your compression testing is by-product of that many air intake events being compressed to represent a single reading. I hope that make sense.
In-cylinder waveform engine cranking only or engine idling and with fast throttle when using scope and pressure transducer,
we can see per 1 compression event and hundreds of them. Exactly as how a combustion should happen, 1 event at a time.
Try and use Xentry Compression Test under N3/10 engine computer.
See how much slower or faster is cylinder 1 compared to other cylinders.
I think Xentry uses averaging, because we need like 7 seconds cranking before it is completed.
The averaging would still show some differences...I am hoping.
At least do the Xentry compression test twice, to be certain.
I will do Xentry compression test today after 5 pm and post the screenshot
If the valve is broken off at its sealing side and not sealing, YES, you loose compression tested using mechanical gauge.
If say inlet valve never opened enough due to hydraulic lifter issue and let say only 50% of regular air intake happen, your testing of compression using mechanical gauge
which has check valve and is reading peak pressure only, does not tell the story per 1 event of compression in a full picture of the 720 degrees crank.
The manual gauge compression test is cranking for a few seconds and that cylinder get a few compression events, so that is accumulated peak pressure-s and held in place by check valve.
200 RPM crankshaft cranking speed typical of a starter, for say 3 seconds is approx 4.5 compression events per cylinder.
So your compression testing is by-product of that many air intake events being compressed to represent a single reading. I hope that make sense.
In-cylinder waveform engine cranking only or engine idling and with fast throttle when using scope and pressure transducer,
we can see per 1 compression event and hundreds of them. Exactly as how a combustion should happen, 1 event at a time.
Try and use Xentry Compression Test under N3/10 engine computer.
See how much slower or faster is cylinder 1 compared to other cylinders.
I think Xentry uses averaging, because we need like 7 seconds cranking before it is completed.
The averaging would still show some differences...I am hoping.
At least do the Xentry compression test twice, to be certain.
02-19-2024, 07:14 AM
Maybe MS Visio for your Birthday
