w210 td not boosting - Page 2 - PeachParts Mercedes-Benz Forum

KarTek · #16 09-03-2011, 08:00 AM

When you swap transducers you're getting MAF/Wastegate codes which is confusing me.

Good thought on the plugged line to the MAP sensor. Do you have a mity-vac? you can connect it to the MAP line and see if it pulls a vacuum.

More back to basics, make sure the vacuum in, out and dump lines are connected to the proper ports on the transducers.

speednjay · #17 09-03-2011, 12:07 PM

Quote:

Originally Posted by KarTek

When you swap transducers you're getting MAF/Wastegate codes which is confusing me.

Good thought on the plugged line to the MAP sensor. Do you have a mity-vac? you can connect it to the MAP line and see if it pulls a vacuum.

More back to basics, make sure the vacuum in, out and dump lines are connected to the proper ports on the transducers.

i just got a hand vacuum pump. so connnect the vac pump to the map and see if it holds vac?

i teed a vac/boost guage into the boost sensor line and im getting nothing at the intake nipple going to the sensor. nipple at intake doesnt seem to be plugged. i can blow into it without too much resistance. im not too sure what to look at next..is there a valve inside the intake that controls the vacuum/boost to the boost sensor? im gonna pull the intake off next weekend to check things out and replace some misc parts.

KarTek · #18 09-03-2011, 10:17 PM

OK, so the path to the MAP sensor is OK and you're not reading any boost at the MAP line. That tells me that either the ECU is not commanding the turbo to boost, or the command isn't getting there.

Try this: Hook your vac/boost gauge to the vacuum line going to the wastegate. Which is to say, remove the line from the wastegate and connect the gauge to it. Even at idle, there should be vacuum present. If there is no vacuum present, try unhooking the vacuum supply line from the transducer and hooking it directly to the wastegate. You'll get a code while driving but it will at least tell you if you have boost or not.

speednjay · #19 09-05-2011, 02:30 PM

Quote:

Originally Posted by KarTek

OK, so the path to the MAP sensor is OK and you're not reading any boost at the MAP line. That tells me that either the ECU is not commanding the turbo to boost, or the command isn't getting there.

Try this: Hook your vac/boost gauge to the vacuum line going to the wastegate. Which is to say, remove the line from the wastegate and connect the gauge to it. Even at idle, there should be vacuum present. If there is no vacuum present, try unhooking the vacuum supply line from the transducer and hooking it directly to the wastegate. You'll get a code while driving but it will at least tell you if you have boost or not.

teed the vac/boost guage into the wastegate line and i have vac there. about 10hg at idle.

i hooked the transducer vac hose to the wastegate line and it gave me boost but no codes popped up.

KarTek · #20 09-05-2011, 09:02 PM

OK, seems like we're getting somewhere now. Have you swapped transducers back the way they were initially? So, you got full boost back and the car drove normally when you connected the vac line directly to the wastegate?

If so, it's sounding more and more like the transducer is goofed up. It's a shame you don't have a loaner part that you can swap in to test it out. You can leave the vacuum line directly connected to the wastegate but you'll get worse fuel mileage and you'll eventually get a code once you get out on to the interstate and settle down to a constant speed.

The ECU tries to pull boost when cruising to improve mileage and when it commands zero boost and nothing happens, it sets a code. This is a shame since the car drives much better with full boost all the time.

speednjay · #21 09-05-2011, 10:16 PM

Quote:

Originally Posted by KarTek

OK, seems like we're getting somewhere now. Have you swapped transducers back the way they were initially? So, you got full boost back and the car drove normally when you connected the vac line directly to the wastegate?

If so, it's sounding more and more like the transducer is goofed up. It's a shame you don't have a loaner part that you can swap in to test it out. You can leave the vacuum line directly connected to the wastegate but you'll get worse fuel mileage and you'll eventually get a code once you get out on to the interstate and settle down to a constant speed.

The ECU tries to pull boost when cruising to improve mileage and when it commands zero boost and nothing happens, it sets a code. This is a shame since the car drives much better with full boost all the time.

i just got back from a 300 mile trip and found some wierd things . i had the odb2 scanner hooked up the whole time. so apparently i have boost still 5psi then after 5psi it'll instantly go to cel 0243 and limp mode. also it still seems to be sluggish before any codes pop up. i had to reset the codes about a dozen of times to get over a hill.

when i put the vac line to the wastegate it had boost but it didnt seem to rev up like it was normal.

why is there no intake vacuum on the guage that i teed into the boost line? i show 0 vac at idle and actually never goes into the vac side of the guage.

Olivier · #22 09-05-2011, 11:00 PM

Dunno if this has been said but I had a leaking intercooler that was messing with my boost. It was buggering the ECU.

KarTek · #23 09-06-2011, 07:44 AM

This is starting to sound like there may be a combination of factors. When you have boost available (vacuum line hooked directly to wastegate) but no acceleration, then the ECU is not seeing that boost, possibly due to a faulty MAP sensor.

The way it works is that the ECU looks for a couple pounds of boost before giving more fuel in order to reduce pre-boost smoke. If there's no output from the MAP (or just low) you'll never get the fuel even if you have plenty of boost.

Do you have any way of monitoring the MAP output? Does your OBDII scanner have sensor output monitoring? If so, I would hook the pressure side of your vacuum tool to the input of the MAP and with the car idling, give it a couple squeezes and see if the output increases. This will tell you for sure that the MAP is working.

That's also in interesting idea brought up by Olivier. You can check for a split IC hose.

To answer your other question, diesels don't typically have throttle plates (except for some older engines that use vacuum based governors) so you'll never see a vacuum on the intake.

speednjay · #24 09-06-2011, 08:31 PM

Quote:

Originally Posted by KarTek

This is starting to sound like there may be a combination of factors. When you have boost available (vacuum line hooked directly to wastegate) but no acceleration, then the ECU is not seeing that boost, possibly due to a faulty MAP sensor.

The way it works is that the ECU looks for a couple pounds of boost before giving more fuel in order to reduce pre-boost smoke. If there's no output from the MAP (or just low) you'll never get the fuel even if you have plenty of boost.

Do you have any way of monitoring the MAP output? Does your OBDII scanner have sensor output monitoring? If so, I would hook the pressure side of your vacuum tool to the input of the MAP and with the car idling, give it a couple squeezes and see if the output increases. This will tell you for sure that the MAP is working.
That's also in interesting idea brought up by Olivier. You can check for a split IC hose.

To answer your other question, diesels don't typically have throttle plates (except for some older engines that use vacuum based governors) so you'll never see a vacuum on the intake.

i think i may have a small leak the intake manifold to intake plenum gasket. the i/c hoses got changed 6 months ago but i'l check them again.

i'll give the map test a try

i still get the 0243 code after 5lbs of boost with the transducers getting swapped back and forth. its hard to say that theres a collective of problems causing my issues..the car ran fine and stout one day..then the next it had zero power

edit: ok my mighty vac doesnt have a pressure option. i'l rig up something to my bike pump and give that a try.
i pumped some pressure into the map line and there was zero change with the idle.

KarTek · #25 09-06-2011, 09:31 PM

If you have a genuine Mityvac, the pressure port is on top, next to the gauge. It has a cap on it that you have to twist and pull off to reveal the port.

speednjay · #26 09-06-2011, 10:57 PM

Quote:

Originally Posted by KarTek

If you have a genuine Mityvac, the pressure port is on top, next to the gauge. It has a cap on it that you have to twist and pull off to reveal the port.

it says mityvac but i guess i got the ghetto one. so you think that the map sensor is bad? i pressured it up with the engine running and it had zero effect. i'll add it to the parts list for this weekend.

KarTek · #27 09-07-2011, 06:59 AM

Monitoring the output of the MAP sensor while applying pressure is the only definitive way to tell if it's bad. Do you have the OBDII read out of this in real time?

What worries me is that you get different codes when you swap transducers and I don't want to be suggesting you spend good money on parts if that's not the problem.

speednjay · #28 09-07-2011, 09:42 PM

Quote:

Originally Posted by KarTek

Monitoring the output of the MAP sensor while applying pressure is the only definitive way to tell if it's bad. Do you have the OBDII read out of this in real time?

What worries me is that you get different codes when you swap transducers and I don't want to be suggesting you spend good money on parts if that's not the problem.

i have live readout on my scanner..i dont get how a boost sensor that monitors boost reads as vacuum.
i get a reading anywhere from 28inhg at idle to 35inhg if im driving and i have a lil boost. for the most part the more throttle i gave the more inhg there was. but it was inconsistant..it was all over the board. i have no idea how to read this.