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1998 ML320 (W163)
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Discussion Starter #61
FWIW the area circled on the back of your manifold is the port that the vacuum assist line on the brake booster attaches on my 112 engine in my ‘99 ML 320.
I know on the old intake this port was plugged and then there's two other vacuum hoses, presumably for the brake booster, and another for the EGR valve.


I tried the throttle relearn to no avail.
 

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2003 ml500, 2004 ml350
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923 Posts
Lee
Have you confirmed that every vacuum hose is hooked correctly as per the vacuum diagram under the hood, should be on the fuse box lid.?

Are any issues you are having now the same as before the manifold swap?
When you installed the replacement did you follow the correct torquing sequence?

I have never replaced an Ml intake manifold so I don’t know if there is one, I have done others; Ford,Jeep they all had a stepped sequence.
 

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w163 02 ML500 W210 97 E50Amg w202 99 C230K w124 - need more space, time to build again
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Lee
Have you confirmed that every vacuum hose is hooked correctly as per the vacuum diagram under the hood, should be on the fuse box lid.?

Are any issues you are having now the same as before the manifold swap?
When you installed the replacement did you follow the correct torquing sequence?

I have never replaced an Ml intake manifold so I don’t know if there is one, I have done others; Ford,Jeep they all had a stepped sequence.
post#3
 

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1998 ML320 (W163)
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130 Posts
Discussion Starter #64
Lee
Have you confirmed that every vacuum hose is hooked correctly as per the vacuum diagram under the hood, should be on the fuse box lid.?

Are any issues you are having now the same as before the manifold swap?
When you installed the replacement did you follow the correct torquing sequence?

I have never replaced an Ml intake manifold so I don’t know if there is one, I have done others; Ford,Jeep they all had a stepped sequence.
I have checked but I can always double check. No, I'm having more issues now then I was before, at least it was drivable before. I did follow the sequence, overtightening may be possible but I don't know how likely. Before it would idle rough when cold then once it warmed up it'd smooth out, had 35% LTFT on both banks, and no power if pushing the throttle more than halfway down (random/multiple misfire codes and misfire on all cylinders), regular stops on side of the interstate due to cylinder shut-down (before of misfires). As of now though I can't even get it to move in my driveway. When it revs itself up it sounds great, like it does in the video, any other time though it sounds awful and is entirely undrivable.
 

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2003 ml500, 2004 ml350
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If the initial problem was a lean issue that can be various causes or a combination of them.
  • Dirty or faulty mass airflow sensor
  • Vacuum leaks – PCV hoses, vacuum hoses, intake manifold gasket.
  • Weak fuel pump
  • Clogged or dirty fuel injectors
  • Clogged fuel filter
  • Exhaust leak
  • Faulty oxygen sensor
  • Faulty air-fuel ratio sensor
What I am trying to get at is let’s assume nothing was wrong with the first set of injectors and nothing is wrong with the second.

Then what else is causing the issue?

You can start by testing that each injector is getting power by using a noid tester. Most part stores have one to loan. Harbor frieght sells one for 40.00.

Vac leaks are a PITA. Once read of an issue that would come and go. Turned out it was a cracked TEE fitting that would open and close due to a crack at the 90 degree corner.

Just hang in there you will find the issue. I can tell you are like me, I only go in for service on tires, transmission rebuild, engine rebuild, and alignment. Everything else I handle. Beacause I say “you want 65.00 per shop hour for Doing that, (oil pressure sensor for example)”!
 

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I have checked but I can always double check. No, I'm having more issues now then I was before, at least it was drivable before. I did follow the sequence, overtightening may be possible but I don't know how likely.
I almost hate to ask did you use a torque wrench, and not swap Newtons and foot pounds?

Witek do you have the torque sequence for those bolts.

Drum Roll please....
 

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1998 ML320 (W163)
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Discussion Starter #67
If the initial problem was a lean issue that can be various causes or a combination of them.
  • Dirty or faulty mass airflow sensor
  • Vacuum leaks – PCV hoses, vacuum hoses, intake manifold gasket.
  • Weak fuel pump
  • Clogged or dirty fuel injectors
  • Clogged fuel filter
  • Exhaust leak
  • Faulty oxygen sensor
  • Faulty air-fuel ratio sensor
What I am trying to get at is let’s assume nothing was wrong with the first set of injectors and nothing is wrong with the second.

Then what else is causing the issue?

You can start by testing that each injector is getting power by using a noid tester. Most part stores have one to loan. Harbor frieght sells one for 40.00.

Vac leaks are a PITA. Once read of an issue that would come and go. Turned out it was a cracked TEE fitting that would open and close due to a crack at the 90 degree corner.

Just hang in there you will find the issue. I can tell you are like me, I only go in for service on tires, transmission rebuild, engine rebuild, and alignment. Everything else I handle. Beacause I say “you want 65.00 per shop hour for Doing that, (oil pressure sensor for example)”!
I agree with that, there's someone who lives about a mile from me that works solely on German vehicles, and he suggested changing the fuel injectors, so I bought the intake because it had injectors in it and it was cheaper than buying them individually, now I realize I should've only changed the injectors instead of doing all the extra work I did. But I digress, the brake pedal hardness and the throttle is what trips me up more than anything, before the plug was on I didn't notice the brake hardness, I don't think I tried to press the brake though. And as long as it idles itself higher it's fine, just I can't make it idle higher because any throttle input stalls it out immediately.

Things I did in January of this year: New Fuel Pump and filter, new spark plugs and coil packs, cleaned MAF. When I checked for engine codes I didn't get any injector power codes. I'm still leaning towards a vacuum problem, I will check all the hoses again and make sure they're properly connected but I'm 99% it's correct.


I almost hate to ask did you use a torque wrench, and not swap Newtons and foot pounds?
It's possible that I may have, I'm not 100% sure if I accidentally switched Newton's and foot pounds.
 

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1998 ML320 (W163)
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Discussion Starter #69
You can loosen them say a quarter turn
And retorque.
It may be a few days before I can try that, I'll have to either loan one from AutoZone or borrow one (will be next tool purchase 😂). Anything else other than checking the vacuum routing in the meantime?
 

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The one that comes to mind for me i already mentioned is to check wiring to each injector with a node test light (auto zone loaner) to be sure you are getting a electric pulse to each injector. But I am not sure that’s what’s going on ( an injector not opening at all).
 

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1998 ML320 (W163)
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Discussion Starter #71
The one that comes to mind for me i already mentioned is to check wiring to each injector with a node test light (auto zone loaner) to be sure you are getting a electric pulse to each injector. But I am not sure that’s what’s going on ( an injector not opening at all).
I will definitely see about loaning one, wouldn't that cause the ECU to illuminate the check engine light due to misfiring?
 

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That’s why I said I am not sure it is your issue, not sure if a misfire would show as a fuel not delivered issue. But it really would not be a misfire, I am thinking the plugs are sparking there is just no fuel to burn at all in a cylinder. It’s not that the plugs are firing at the wrong time due to a position sensor.


Don’t know if you got it to run long enough to even throw a code. I thought Witek had something when he mentioned the throttle position needed relearning, but you tried that.

All I am getting at is a node tester is one way to confirm the the wiring on the replacement manifold is ok and the controller is ok.
 

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1998 ML320 (W163)
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Discussion Starter #73
That’s why I said I am not sure it is your issue, not sure if a misfire would show as a fuel not delivered issue. But it really would not be a misfire, I am thinking the plugs are sparking there is just no fuel to burn at all in a cylinder. It’s not that the plugs are firing at the wrong time due to a position sensor.


Don’t know if you got it to run long enough to even throw a code. I thought Witek had something when he mentioned the throttle position needed relearning, but you tried that.

All I am getting at is a node tester is one way to confirm the the wiring on the replacement manifold is ok and the controller is ok.
I'll see about loaning one and go from there, just for reference, I used the wiring that was already on mine, I didn't use the wiring harness from the replacement manifold.
 

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I'll see about loaning one and go from there, just for reference, I used the wiring that was already on mine, I didn't use the wiring harness from the replacement manifold.
Back in a day you have started thread about random misfire. Never finished it with fix or lack thereof.

Until you have smoke test done on air intake system I am out off this thread.
 

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Discussion Starter #75
IT LIVES!!! Turns out the T-Connector on top of the secondary air pump that goes to the combination valves wasn't fully connected at the air pump. I did get a misfire code on the initial test drive last night but none during my commute this morning. So far so good
 

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Discussion Starter #77
No check engine light, however if I press my foot more than halfway down I loose all power. From a completely cold start (letting it sit overnight) I have to start it twice, the first time it revs up, then dies. The second start is usually fine. I have to wait at least 5 minutes to push the throttle or the RPMs go too low. Performance is atrocious when the engine is cold, it's better when it completely warms up, but it's still pretty bad. It's no worse than it was before though. I have noticed that my brakes work significantly better since I changed the intake (maybe I had a small vacuum leak or something) and the pedal is much more firm. I'm kinda leaning towards a bad MAF sensor but I don't want to just throw more parts at it. Any suggestions?
 

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1999 ML 320
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Have you checked the pressure in the fuel rail? Sounds like some of the symptoms I had when the dealer sent my ML home to die 2000 miles ago with a list of 5 things that COULD be done ( totaling $10,000) but with no assurance any of them would fix it. After I personally did new plugs/wires, new valve cover gaskets and cleared the EGR code by cleaning out the 100% occlusion of the pipe to the intake manifold it was no better. Finally checked fuel rail pressure and it was only 25 lbs. A new fuel filter fixed it.
 

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Discussion Starter #79
Have you checked the pressure in the fuel rail? Sounds like some of the symptoms I had when the dealer sent my ML home to die 2000 miles ago with a list of 5 things that COULD be done ( totaling $10,000) but with no assurance any of them would fix it. After I personally did new plugs/wires, new valve cover gaskets and cleared the EGR code by cleaning out the 100% occlusion of the pipe to the intake manifold it was no better. Finally checked fuel rail pressure and it was only 25 lbs. A new fuel filter fixed it.
I had a new fuel filter installed in February so I'm not sure if that's it. I can try to find someone who has a pressure gauge and check it though.
 
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