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Old 05-03-2015, 12:57 PM   #1
mcgawn
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Unhappy help :-(

been trying to find the dreaded cause of P0174 & P0171 codes.

I have tried

Cleaning maf (looks pretty new anyways)
Checked disa and is working properly and o-ring looks good
Checked intake boots for cracks/holes etc...
Checked for leaks with spray and listened for engine changes.
Checked cover gasket and seems new and not brittle

The car drives fine and if i clear the codes and only drive about town they don't come back, but when i drive over 30 miles in one go they come back

I also have a P1620 code which is thermostat but seem to be working fine, could this be a cause of the other two codes or am i being silly?

The car is also weird as when i floor it from cold (i know its bad) it doesn't move like it should, until it is up to full temp and even at that the low end doesn't pick up quick like it should it just bogs down till over 3k revs

Anything i could now try would be a great help as it is starting to drive me insane trying to solve it :-)
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Old 05-04-2015, 06:27 AM   #2
markusmarkus
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The P0171/174 codes are classic intake leak indicators. I bet the 2 large hoses need to be replaced, along with the "F" connector on the upper hose. Your best bet is to have the intake smoke tested. The other code indicates that the thermostat is failing. As a result the engine never reaches its proper operating temperature of between 95*C and 100*C. This can be verified by using the dash's hidden functions. Google "E46 hidden OBC functions." Test 7 will show the engine temperature that the ECU sees.
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Old 05-04-2015, 08:05 AM   #3
BaliDawg
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Do a smoke test on the intske and crankcase. You will find vacuum leaks.

How old is the fuel pump?
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Old 05-04-2015, 12:36 PM   #4
mcgawn
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Originally Posted by BaliDawg View Post
Do a smoke test on the intske and crankcase. You will find vacuum leaks.

How old is the fuel pump?
Dont know about the fuel pump i was suspecting that could be a cause as well
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Old 05-04-2015, 12:38 PM   #5
mcgawn
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Originally Posted by markusmarkus View Post
The P0171/174 codes are classic intake leak indicators. I bet the 2 large hoses need to be replaced, along with the "F" connector on the upper hose. Your best bet is to have the intake smoke tested. The other code indicates that the thermostat is failing. As a result the engine never reaches its proper operating temperature of between 95*C and 100*C. This can be verified by using the dash's hidden functions. Google "E46 hidden OBC functions." Test 7 will show the engine temperature that the ECU sees.
I have checked the intake hoses and there is no rips etc...

I know the thermostat is working to the correct temp but as i use the real-time view on the torque app to measure this from the ECU by Bluetooth OBD2
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Old 05-04-2015, 08:47 PM   #6
tony
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I finally found a leak in the vacuum hose that goes from one of the intake boots to the fuel filter/pressure regulator. Was leaking at the connection on the fuel filter/regulator.
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Old 05-04-2015, 08:57 PM   #7
BaliDawg
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Do a quickie smoke test, you may have other leaks.
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Old 05-06-2015, 01:52 PM   #8
mcgawn
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Originally Posted by BaliDawg View Post
Do a quickie smoke test, you may have other leaks.
will give that a go at the weekend, one other quick question the car is in for an mot tommorow will it pass of i clear the faults as i know the light wont come back on for 30 miles or so driving?
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Old 05-06-2015, 01:57 PM   #9
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Originally Posted by BaliDawg View Post
Do a quickie smoke test, you may have other leaks.
Need to do a smoke test myself. Seen this video several times. My question is where do I attach the hose so that smoke is entering the engine? Sorry, if this is a dumb question.
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Old 05-06-2015, 02:00 PM   #10
mcgawn
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Need to do a smoke test myself. Seen this video several times. My question is where do I attach the hose so that smoke is entering the engine? Sorry, if this is a dumb question.
I would say the intake would be the best, thats where i am going to do it, just going to take my airbox and maf off and make a cover for the intake boot with a small enough hole for a bit of hose to fit through, probably not going to use a cigar but will use a few cigs lol
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Old 05-06-2015, 02:01 PM   #11
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Originally Posted by mcgawn View Post
I would say the intake would be the best, thats where i am going to do it, just going to take my airbox and maf off and make a cover for the intake boot with a small enough hole for a bit of hose to fit through, probably not going to use a cigar but will use a few cigs lol
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Old 05-06-2015, 02:05 PM   #12
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How do you know the thermostat is working properly?

See the first 3 links in my signature.

If the MAF looks new, it may be a counterfeit Asian unit.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 05-06-2015, 02:07 PM   #13
mcgawn
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Originally Posted by jfoj View Post
How do you know the thermostat is working properly?

See the first 3 links in my signature.

If the MAF looks new, it may be a counterfeit Asian unit.
1, its getting to the correct temp of between 95.c and 99.c is this not correct? that is the reading from the ecu

2 i wouldnt say new as in brand new i mean clean :-)
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Old 05-06-2015, 03:40 PM   #14
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I dont know if this helps any but you can see from the image below i have a pretty high long term fuel trim is this a good indication of a vacum leak? i tried a smoke test tonight quickyl as it is driving me insane, but couldnt see any thing where it could be leaking. Im going to have to try get a real smoke machine and do it properly.

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Old 05-06-2015, 04:05 PM   #15
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Originally Posted by mcgawn View Post
I dont know if this helps any but you can see from the image below i have a pretty high long term fuel trim is this a good indication of a vacum leak? i tried a smoke test tonight quickyl as it is driving me insane, but couldnt see any thing where it could be leaking. Im going to have to try get a real smoke machine and do it properly.


You really need to give the LTFT with a fully warmed up engine. According to your screenshot the coolant temp is 52C.
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Old 05-06-2015, 04:07 PM   #16
mcgawn
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Originally Posted by Yewzer B Lewzer View Post
You really need to give the LTFT with a fully warmed up engine. According to your screenshot the coolant temp is 52C.
it was the exact same value as last night after a 200 miles drive :-)
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Old 05-06-2015, 04:43 PM   #17
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When doing the smoke test and pushing in smoke through the intake boots, right after the MAF. The way I see it; the smoke has nowhere to go on the M54 when the engine is shut off. Both the ICV and the Throttle Body are fully closed with the engine off. Pushing in smoke that way will tell you if your intake boots are leaky and thats about it. If you have an old M54 with a cable throttle you can pull it to open it, but for those of us with an electronic throttle - there has got to be another way of pushing in smoke. prehaps through one of the capped off vacuum ports on the back side of the intake manifold, facing the driver.
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Old 05-06-2015, 04:44 PM   #18
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Is there a way to activate the electronic throttle with INPA while the car is off?
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Old 05-06-2015, 04:47 PM   #19
mcgawn
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When doing the smoke test and pushing in smoke through the intake boots, right after the MAF. The way I see it; the smoke has nowhere to go on the M54 when the engine is shut off. Both the ICV and the Throttle Body are fully closed with the engine off. Pushing in smoke that way will tell you if your intake boots are leaky and thats about it. If you have an old M54 with a cable throttle you can pull it to open it, but for those of us with an electronic throttle - there has got to be another way of pushing in smoke. prehaps through one of the capped off vacuum ports on the back side of the intake manifold, facing the driver.
this just doesn't seem to be the case as there should still be air able to get through as the throttle will be shut in idle and the engine still needs air to idle through small channel which is regulated by the icv or I may be wrong and the icv shuts fully when the engine is off but this didn't happen in my case and smoke did pass through but then again that wasn't an actual machine smoke :-)
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Old 05-06-2015, 07:56 PM   #20
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This is how the ICV and the Throttle work on a BMW:

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