# Engine Shaking at idle



## idrivea2002golf (Sep 19, 2003)

I need some help figuring out a problem. My engine is bouncing around pretty badly when at idle. Any load, A/C or pressing the gas a little, will make it go away. I've spoken to a mechanic briefly and he seems to think it's a misfire. I will say the bounce isn't cyclical so it's not something out of balance. It seems to occur at random although I'm sure there's a root cause. 

So far this is what i've done:
1. had the throttle body adapted to the ECU, after I cleaned the oil/buildup out from inside. All this coincided with the head gasket replacement below
2. replaced the spark plugs with the OEM model with a gap of 1.0mm per the bentley, i used proper feeler gauges not that silly circle thing with the incline.
3. the compression reads 190,185,180,190 PSI from 1-4, all at the high end of the range from the bentley
4. the head was machined with new valves about 2 years ago, i replaced (obviously) the head gasket at this time
5. I borrowed a smoke tester and didn't find any vacuum leaks
6. the fuel pump was replaced a few years ago with an OEM model (those ****ers are expensive)
7. the injectors were replaced as the factory ones were ticking really badly (this was a recommendation)
8. the timing belt, water pump, and tensioner pulley were replaced at 110K give or take. 
9. OEM replaced ignition block

I think that's most of it. Now here's the kicker, the bouncing was at a certain level. Along with the bouncing I noticed a pinging under heavy acceleration. I checked the timing belt tensioner yesterday and found the tension wasn't right. Thinking this was the cause of both problems I retarded the timing one notch and fixed the tensioner. After doing so the pinging is gone but the bouncing level easily doubled. 

I'm lost as to what would cause this in the first place. The only that I haven't really focused any energy on (yet) is the fuel system. I think the pressures may be low. I'm not sure.

Engine is a bone standard 2.0 AVH model, currently at 130K miles. manual transmission so no chance of a bad torque converter (i only mention this as it was a problem on another car). 

Any thoughts? Ideas?

Thank you,
Spencer


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## Anony00GT (Mar 6, 2002)

Firstly, set the timing belt where it belongs. TDC mark on flywheel and camshaft gear. Advancing/retarding the cam is only going to complicate things. Line up the marks, tension it, and that's good.

Then scan the car for faults, regardless if the CEL is on or not. If you have VCDS, post an auto-scan. How was the TB adapted, was it done properly through VCDS?

Also post fuel trim numbers (MB 032).

Can you take a quick video and post it to youtube so we can see exactly what you mean by "bouncing"?


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## idrivea2002golf (Sep 19, 2003)

The timing retard lined up the marks. Either when the belt was installed or because the tensioner lost tension the cam jumped a tooth.

I do not have a VCDS, I do have a little plug in one that will tell me whatever codes are posted. I will see if I can track down a real VCDS and get an autoscan. The adaptation was done with my mechanic using his VCDS. 

Bouncing is the wrong word. It is near impossible to actually see the engine move when it shakes. You can feel it if you're sitting in the car or if you hold the intake manifold. I wonder if it can be heard in a video. I'll get a link up this evening.

Thank you.


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## idrivea2002golf (Sep 19, 2003)

I have access to an inexpensive OBD 2 reader. I took the car for a drive with the data logger running and came back with the following graphs.

This is the RPM against the Lambda readings:
http://s25.photobucket.com/user/idrivea2002golf/media/RPMwithLambda.png

This is engine load, MAF (lb/min), Thottle position, and Lambda reading.
http://i25.photobucket.com/albums/c54/idrivea2002golf/LoadvMAFvTPvLambda.png

They all look normal to me except those spikes where the Lambda reads 2.0. No idea what causes it, doesn't seem to correspond to anything I do while driving.


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## Anony00GT (Mar 6, 2002)

Not live Lambda readings. Short Term and Long Term fuel trim numbers, your scanner should display them at idle.

Also, doesn't look like you ran it all the way to redline on the graph, but it's hard to read. Set the scanner to metric so you get a g/s instead of lb/hr unit on the MAF, then run it WOT to redline. See what's the highest number achieved.


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## pporcelana (Feb 10, 2015)

*I've the same problem with my passat 2.0 FSI*

Dear Spencer I've the same problem.
I've changed the spark plugs and the fuel.
I will try using some injector cleaner. Also I've connected to VAG COM and no faults.

Do you hace solved the problem??

BR
Pablo


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## idrivea2002golf (Sep 19, 2003)

Hi Pablo,

I have narrowed my problem down. I'm going fix the problem some time next month. 

Check the spark wires for resistance. The manual for the 2.0 states the wires should read between 6.000 and 8.000 ohms. 

Next, do what's called a Leak down test. It will check the piston rings, the head gasket, the Intake and exhaust valves. My problem ended up being a leaky exhaust valve on cylinder number 2. There are several great walk through videos on YouTube. 

If the leak down test comes back negative there's a good chance the ignition coil pack could be bad. See if you can borrow a buddies and try it in your car. 

have you performed the other tests I mentioned in my first post?


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## roadsterred (Feb 25, 2010)

My sister's 2000 2.0 with automatic transmission has the same problem e.g. rough idle. The engine starts perfectly when cold and hot, and runs smooth on the streets, highways, and freeways. Using a Vag Com, the DTC stored was 17990 - Idle Adaptation Limit Reached.

At the Ross-Tech Wiki web site, it lists the following solutions:

Check Fuel Pressure
Check Intake System for Leaks (False Air)
Check Fuel Injector(s)
Check Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80)
Check Exhaust System for Leaks
Check Secondary Air Injection (AIR) for Leaks
Check Vacuum Lines for Leaks
Check Throttle Body

Before accessing the Ross-Tech web site, I treated the Throttle Body with cleaner but the problem was not corrected. After Ross-Tech I checked the fuel system pressure at idle and with the vacuum line to the Fuel Pressure Regulator disconnected. The fuel system pressure met specifications.

After adding Techron to a full tank of gas, I drove the car 60+ miles today. At the end of the drive, the rough idle disappeared even when using the AC.

Will be driving the car again tomorrow to see if the problem has been corrected.


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## Anony00GT (Mar 6, 2002)

You guys should start your own threads for these issues, instead of hijacking the OP's. This one is already getting confusing.

Roadsterred, check values in measuring block 032. If both fields are +/- 5%, your problem is fixed.

Pablo, start your own thread. Include the complete auto-scan from VCDS and values in measuring block 032. DO NOT clear any faults.


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## Gary_98Cabrio (Sep 4, 2009)

that happened to me. std OBD2 meter did not catch it nor the check engine light. hooked up a $20M? Snap On analyzer and it id'd an intermittant mass air flow sensor and downstream o2 sensor ..good to go.


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