VW Surging/Chugging @ Idle

Bill Owner/Technician Jackson, Michigan Posted   Latest  
Question
Driveability
Electrical
2015 Volkswagen Passat S 1.8L (CPKA) 6-spd (09G)—1VWAS7A31FC065962
Chugging/ Surging At Idle

This Passat surges or chugs at idle more so with lower engine temp. Very noticeable 700-1100 RPM bouncing Tac. 

It arrived with many faults stored! (p0300-p0304) Misfires for all cylinders, P1158 Manifold pressure, P0068 throttle correlation, P119A Fuel pressure sensor, P0111 cam position. I found engine oil did not register on dipstick 2+ qts low. 

Did a oil service, inspected and cleaned throttle body, relearn throttle adaptions and reset engine controller. Vehicle is still surging at idle. Vehicle drives down the road nice with no misfires or surging. Idles nice when at operating temp. 

I have smoke tested the crankcase and air intake i do NOT see any leakage, HP fuel pressure matches actual /expected. Boost pressure matches actual/expected at all times, crankcase pressure is -70 to -80 mbar. I dont have a know good spec for this exact engine code but see no smoke from the vent hole on the diaphragm and pressure seems in line with other late model VW..... I noticed this morning on cold start using OBD long term fuel trim was -49% unplugging the front o2 sensor did not make a difference. Using Ross Tech i see a pid for low pressure fuel (actual and expected do Not match 5 vs 11) but i do not see a low pressure senor so i dont know if i can trust it... Once the engine is at operating temperature no more surging/chugging fuel trims are good. What am I missing??

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David Diagnostician
Candler, North Carolina
David Default
 

Hi Bill, I know you smoked the crankcase, but it sounds like a typical VW crankcase ventilation problem. Remove the dipstick with the engine running. If it’s difficult to remove and makes a whooshing sound, there’s likely a PCV problem. Confirm it by connecting a manometer or simple vacuum gauge to the dipstick tube. Look for less 1 hg on a normal system.

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JB Owner/Technician
Minneapolis, Minnesota
JB Default
 

Many of the breather valves (the replacement OEM ones) are now stamped with a rating for pressure/vacuum. However, live measured values are often not super close to this value (you can use more as a ballpark).

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JB Owner/Technician
Minneapolis, Minnesota
JB Default
   

1st thing I would do if this was low on oil is check cam/crank timing. Use a lab scope to make sure the timing has not jumped. These EA888 engines DO NOT tolerate low oil level well and frequently jump time when too low. There is no low pressure fuel sensor on this vehicle. It's a calculated value. To check low pressure you can koeo and check the rail pressure before a cold start. Easy and fast…

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Bill Owner/Technician
Jackson, Michigan
Bill Default
   

JB do you have a known good cam/crank wave form for this engine code? Also strange it would run so nice at operating temp if cam timing is off??

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JB Owner/Technician
Minneapolis, Minnesota
JB Default
   

There are also some good groups on there for waveforms. One is called the Automotive Waveform Exchange.

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JB Owner/Technician
Minneapolis, Minnesota
JB Default
 

Not 100pct sure this is from the exact same engine but it's likely.

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Ray Diagnostician
North York, Ontario
Ray Default
 

This is from a 2017 Golf 1.8 cmp, ckp COP 1, but I don't know the engine code.

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Bill Owner/Technician
Jackson, Michigan
Bill Default
 

Hello Ray and Thanks for the waveform! do you recall if the cam magnet was unplugged when this was taken? my file with it unplugged looks pretty similar to yours. I do notice some thing in scan data at idle that it weird. the camshaft actual valve is erratic or cycling between 2-20 while the specified valve remains at 10 constant. ill try to post a video of it. but i see this happening when the…

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Ray Diagnostician
North York, Ontario
Ray Default
 

The cam magnet was plugged in and this capture is on start up.

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Victor Technician
Cudahy, California
Victor Default
 

you don't need it on VW... everything is in the VCDS. go to VCDS / MVB / IDE00178, 179, 182 phase adaptations should be +- 5 Degrees. thats the way you dont need scoping... it is reliable fast and right to the money,

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Bill Owner/Technician
Jackson, Michigan
Bill Default
 

diag​.​net/file/f6jez7x21… ​

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Victor Technician
Cudahy, California
Victor Default
   

Good... Check you cam actuator. You have 23 degrees out in the intake side. Also would you do a relative on cyl 4. You might have 2 issues. Since inj are ok enoug also check oil pressure.( the bridge might be also bad).

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Victor Technician
Cudahy, California
Victor Default
 

out of timing. complete timing train Job.

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Elias Owner/Technician
Poway, California
Elias Default
 

Check and make sure hpfp not leaking into crankcase. Have seen many that are rich at idle.

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Jeff Manager
Manchester, Missouri
Jeff Default
 

We have seen vacuum leaks quit often at the rear crankshaft seal. Spray some brake clean through the inspection port on the bell housing and see if your idle changes.

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Victor Technician
Cudahy, California
Victor Default
 

Hello Amigo: I would say, do a running compression test on cyl 4. also, question: go to your VCDS engine/mvb/ IDE01931 and 32 give me a reading out of that please. you CCV Valve looks ok, the specs is 90 mbars or less and based on your FT, it looks ok. this is what might be happening on cyl 4. compresion should be 140 psi (70 psi running) but after a while it will decay to less tha 40psi.

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Bill Owner/Technician
Jackson, Michigan
Bill Default
 

Victor here is VCDS engine/mvb/ IDE01931 and 32 diag​.​net/file/fmgkps42c… ​

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Victor Technician
Cudahy, California
Victor Default
 

Good... You problem is not fuel intrusión. Injector are not the problem. Do a running compresion test...

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Victor Technician
Cudahy, California
Victor Default
   

also I didn't notice something... your IDE 01932 is not mm3 but in mg/stroke you need to convert it to mm3 to be able to determinate fuel injeccio volume ( specs are +- 5 mm3 ) take a look at my vcds pic ...I just found one... PS: that pic is for a bad injector ( completely open )

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Bill Owner/Technician
Jackson, Michigan
Bill Update
 

Look at intake cam specified vs actual - it is cycling like this even when the engine is running smoothly

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Victor Technician
Cudahy, California
Victor Default
   

can you move the LOC tab to see the MVB descriptions it looks bad 10 is 2 tooth out... if 10 is IDE00182. that test is useless if you don't see it in correlations to IDE00182

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Victor Technician
Cudahy, California
Victor Default
 

can you move the Loc Tab to see which exhaust mvb are you looking at at this time.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Hey Bill,nice diag going on. If you leave the cam magnet unplugged does the problem go away?

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Bill Owner/Technician
Jackson, Michigan
Bill Default
 

Caleb - I tried unplugging the cam magnet this morning and yes the surging went away... I am investigating this further today... Seems hard to believe this engine is out of mechanical time and can run so good/smoothly at times. I'll follow up

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JB Owner/Technician
Minneapolis, Minnesota
JB Default
 

Can you do a relative compression test with a lab scope? And an intake pulse capture? Would give us some more clues. :)

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JB Owner/Technician
Minneapolis, Minnesota
JB Default
 

It's out of time. You need a chain job. And I'd also do the cam bridge and the central valve for cam phasing.

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Ray Diagnostician
North York, Ontario
Ray Default
 

These captures are from a 2014 Passat 1.8. In the first capture, CH C is the bad cam adjuster valve volts/frequency and CH D is the erratic valve current draw. The second capture shows the new cam adjust valve volts and amps.

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Richard Technician
Stony Brook, New York
Richard Default
 

I know you smoke tested it. But I would smoke test it again especially when the car is cold. Like before starting. Look from underneath at the bell housing and see if you got smoke coming out of it. If so, the rear main is leaking air. I am thinking it leaks worse cold and kind of seals back up as it warms, which is why it starts idling smoother as it warms. Best of luck with it.

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Victor Technician
Cudahy, California
Victor Default
 

This car is having a lot of fuel -49 LTFT. CCV would cause Lean mixtures....

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Victor Owner/Technician
Doral, Florida
Victor Default
 

To me it seems to be flooding like back in the old carb days.

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Victor Technician
Cudahy, California
Victor Default
   

Hello amigo Bill Kenel From Michigan. I am going to complete your training in VAG 101. take a look at this pic...? no need for scopes. what's wrong in the following pic...? sp iler alert!!! it has a lot to do with this issue of yours.

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Bill Owner/Technician
Jackson, Michigan
Bill Default
 

Victor - i see the cam adjustment on your screen shot is at 28% most likely the engine is out of mechanical time. Cam/crank timing issue.... I wont disagree with you that a scope is not necessary to see this on a VW sometimes using a scope is fun sometimes you find something you cant in scan data.... So do you still think the Passat i am working on needs a complete timing chain job?

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Victor Technician
Cudahy, California
Victor Default
 

glad you found your problem. we meant to guide you... scope is used when scan tools don't give you enough data. but most of the time people use it because they can't read/undestand scan tool data in first place. I thing the 3 dregres ok is because the cam actuator was able to handle the gap(10+3) . Thanks for answering the 28% gap trivia question, that is a perfect example of 18 degrees out…

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Bill Owner/Technician
Jackson, Michigan
Bill Default
 

Victor - you do seem to have a good understanding of VW data blocks (better than most).... I do appreciate your help, advise, and time given here. The Camshaft magnet is bolted to the outside of the upper timing cover it takes about 10 minute to R&R (pic included as you requested). Any shop looking to sell a complete timing chain job due to this failure is NOT a shop i would ever…

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Victor Technician
Cudahy, California
Victor Default
 

Well... I call that: camshaft solenoid (Intake or Exh). it is a magnet principle but in fact is a solenoid ( DC%.) I've been mistaken your "magnet " with intake camshaft sensor... ..... .... if you statement proof to be correct... (your injector number 4...is it ok? ) don't put too much brain in that, you did well. I was helping you... Don't get cocky to those who are helping you... don't…

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Bill Owner/Technician
Jackson, Michigan
Bill Resolution
 

Thanks to all who took the time to respond and offer help!! A special thanks to Ray Y. and Victor A. for your wave forms and multiple inputs. Several of you suspected this vehicle would need a timing chain replacement..... Personally i dont understand how a engine could run perfectly at times if a mechanical item is failed? This condition was intermittent and was always noticeable with low…

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Ray Diagnostician
North York, Ontario
Ray Default
 

Good work Bill! Did the cam adjuster Magnet amperage on your Passat oscillate similar to this capture?

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