Engine sounds like a VW bug

[Rock2610d]

Well I thought I had this issue fixed with new EGR. I go to start it today and VW bug sound is back.

History: got a random misfire code and EGR malfunction code.

Put new emission parts on and cleared codes. No new codes and no misfires yet but car sounds like a VW.

When I got random misfire all I had to do was put transmission in neutral and coast, put back in gear and misfires gone.

This has only happened at highway speeds. I think it's just a matter of time before I get another P0300 code.

Plugs are NGK brp7es with NGK plug wires and only 3000 miles on them.

7 bolt motor and head, both rebuilt 3000 miles ago. New OEM cps, cas, knock sensor with rebuild.

My fuel mileage has gone from 27 to 24 mpg.

My AFR is good at 14.5 to 14.8 normal driving, and 10.2 or so at WOT.

Also the car vibrates more now, even the steering wheel shakes.

What the heck is making my car sound like a VW bug?

Please help!

 

[the blurr]

If I were you I would start at the plugs while the car is on pull each plug wire to see if the tone of the engine changes once you know which cylinder it is then you can check compression, leak down check you could have a blown head gasket check you oil and coolant to see if it's mixing

 

[jayson427]

What are your plugs gapped to? And depending on your mods I think 10.2 at wot is a little on the rich side. Have you checked your timing?

 

[Rock2610d]

Plugs are gapped to .028 inches.....just checked them a week ago. One was gapped to .040 and I corrected that at the time the plugs were checked.

Am I wrong to assume since the VW Bug sound goes away and comes back it should not be compression?

Is it possible the timing belt slipped a tooth and my exhaust is opeining too soon causing the weird sound? Problem is the sound seems to come and go.

On a 2G I cannot adjust the timing. But my code reader/data logger shows between 4 and 5 degrees at idle.

 

[evoredy]

Sound clip? Lol J/K...but if you do have it...post it!

Have you checked for hairline cracks on the exhaust manifold and turbocharger area (specifically underneath where you can't see)? That could explain the coming and going as metal expands and contracts. Also, a loose downpipe or warped DP flange/damaged gasket would do that easily. Good luck man.

 

[Rock2610d]

The exhaust is the logical 1st step, but does it explain the loss of fuel mileage and P0300 random misfire code?

When the P0300 hits my a/f ratio gets really lean, like 18 or 19 and motor is really missing. Kinda like a rev limiter would work. Then I put in neutral and coast. Put back in 5th and miss is gone.

I guess it's time to replace the coils and power transister, I know I could test them but they are 18 yrs old and have 275k on them. Even if they do test good they are in need of R&R.

 

[PieEyedPiper]

Search for P0300, there are many many threads describing this behavior.

Have you recently installed a new clutch, flywheel or resurfaced the stock flywheel/removed it for any reason?
Testing your coils and power transistor are critical so you can cross them off the list. From my experience, this is no sort of exhaust phenomena but rather an ignition related problem.

In the past, the main culprits have been wrong year CAS (somewhat different issue but very similar), alternator/power transistor/coils and the flywheel.

 

[Rock2610d]

Yah, I searched and found a lot of posts. None were resolved except one or two. Those were a CPS and ignition transistor. None had any mention of motor sounding odd.

Stock flywheel was resurfaced 3000 miles ago when new OEM clutch was put in.

I will test the coils and transistor so I can post results here, but I will be installing new OEM units.

New alternator will be next if coil and transistor don't help.

It's the VW sound that is confusing!

 

[Timechg]

Check your Power transistor unit, that could be going faulty. You can take it out and have it tested at a part store. They will probably call it an Ignition contol module.

 

[Ghost_92TSi]

Yah, I searched and found a lot of posts. None were resolved except one or two. Those were a CPS and ignition transistor. None had any mention of motor sounding odd.

Stock flywheel was resurfaced 3000 miles ago when new OEM clutch was put in.

I will test the coils and transistor so I can post results here, but I will be installing new OEM units.

New alternator will be next if coil and transistor don't help.

It's the VW sound that is confusing!

Your car speaks German?

I don't see how the alt will make a difference. If your car is putting out the correct volts then there is no reason to change it. I wouldn't just be throwing parts are it. Everything has a way of being tested. Have you pulled the top timing cover to check if it was a tooth off?

And an exhaust leak will lower fuel economy.

 

[Rock2610d]

I've read that an alternator going out will affect sensors and ignition system.

I do wonder about the timing. It was correctly installed and ran perfect for over 2500 miles. I guess when the 1st P0300 misfire happened it could have jumped a tooth.

Would a tooth off cause my car to speak German?

 

[PieEyedPiper]

Yah, I searched and found a lot of posts. None were resolved except one or two. Those were a CPS and ignition transistor. None had any mention of motor sounding odd.

Stock flywheel was resurfaced 3000 miles ago when new OEM clutch was put in.

I will test the coils and transistor so I can post results here, but I will be installing new OEM units.

New alternator will be next if coil and transistor don't help.

It's the VW sound that is confusing!

Check your timing before moving forward.




Very few of these P0300 threads get resolved, it's the nature of the beast.

Secondly, this "VW sound" you claim isn't well documented because it's your own, personal, [un]cute way of describing what a misfire/loss of 2 cylinders sounds like. It's likely that most p0300 folks innately associate the sound with the misfire and move along. Unless you honestly believe that your engine is fubar'd then go ahead and pursue the sound, otherwise we ought not split the hairs of a singular problem.

I'm just going to go ahead and take a shot at this one.

When the shop resurfaced your flywheel they either took no notice to the locating dowel, removed it, or otherwise. Additionally the flywheel could be cut with significant runout or some other machining anomaly causing the flywheel to be out of balance with the rest of the rotating assembly.

This is a real thing, it happens. It happened to me and it's happened to others.

The p0300 likes to show up right around 3krpm (hwy cruising), putting the car into neutral, revs dropping to idle and then throw it back in gear and everything works as normal...for 30 seconds. Or an hour. Or a week.
The behavior is unlikely to "quit" on it's own, even though mine did. I should mention though, that I suffered with this sporadic p0300 code literally for years. Then one day it stopped coming around so much. I soon switched flywheels from my machined OEM flywheel to the Competition Clutch units that I prefer. I've never seen the code since.

I fear that no amount of transistor or alternator swapping will solve your problems. Let us know what you find out or decide to do, I'd be pleasantly surprised to discover that I'm just being alarmist.

 

[Ghost_92TSi]

^He has a point. The fact that a shop did it and you didn't do it yourself, there is not telling what is going on in there. I would have to take a look for myself. I still wouldn't think alternator unless you have other power issues when the "sound" occurs. Radio dying or fading lights.

 

[Rock2610d]

Only thing shop did was resurface the Flywheel. Pressure plate is new and OEM, not resurfaced. I assembled the engine.

I had the whole assembly balanced prior to putting engine together. The machine shop even marked the proper orientation for the pressure plate so it would be balanced. The Flywheel had the locator pins in it after resurface and would only go on crank 1 way.

The VW bug sound is even present when I am not getting a P0300 code. I start the car and there it is. No codes yet and car has not missed since I replaced the EGR stuff, but still sounds like a VW.

I pulled the Mdp sensor or manifold diff pressure sensor plug and no affect on motor...is this right?

I pulled the plug on the MAS sensor(next to air filter right?) and engine immediately died. I thought it should still run just not very good?

I will check the timing belt....thanks

 

[PieEyedPiper]

Only thing shop did was resurface the Flywheel. Pressure plate is new and OEM, not resurfaced. I assembled the engine.

I had the whole assembly balanced prior to putting engine together. The machine shop even marked the proper orientation for the pressure plate so it would be balanced. The Flywheel had the locator pins in it after resurface and would only go on crank 1 way.

The VW bug sound is even present when I am not getting a P0300 code. I start the car and there it is. No codes yet and car has not missed since I replaced the EGR stuff, but still sounds like a VW.

I pulled the Mdp sensor or manifold diff pressure sensor plug and no affect on motor...is this right?

I pulled the plug on the MAS sensor(next to air filter right?) and engine immediately died. I thought it should still run just not very good?

I will check the timing belt....thanks

If what you say is true, and I do believe you, then I must apologize. I did not understand that you are getting a strange sound when the car is operating "normally".
Let us know what the timing turns up.

This is a perfect hair to split and I shouldn't have been so quick to doubt.
I'm especially happy to hear that the shop you used went to such trouble for "just a 4 banger".

Where does the sound come from? What are you using to log?
Does the sound relate to engine speed or load?

I'd listen to youtube videos of a VW but I'm not sure it would help.

 

[Rock2610d]

Well no skipped timing belt. Took # 1 plug out and rotated motor until cam marks were lined up. Piston 1 at TDC and to my relief the indicator on crank pulley was on with timing tab on lower cover. 1st time I rotated engine scared me a little until I realized it must have been on exhaust stroke ### nothing lined up!

Got in car this AM and started it to warm up, and decided to check some things while waiting. Turned heater fan on and one interior light. I tapped the air peddle(throttle) several times quickly. The interior light kinda blinked dim and bright as I tapped throttle. At cold idle (900 rpm) or so interior light was dimmer than 1200 or so rpm during tapping of throttle.

Is this normal? I rarely drive car at night and would not notice this unless specifically looking for it.

Alternator issues?

I am beginning to think I may have multiple issues instead of just one.

**********************

UPDATE

OK, I have put over 300 miles on it since I have had a CEL for multiple misfires.

Its been 300 miles since I put a new EGR system in....Valves, solenoids etc. EGR code is gone along with the multiple misfires.

I am going to assume that the bad EGR valve and bad check valve caused the EGR valve to loose boost/vacuum thru exhaust causing a lean condition and multiple misfires.

Now prior to the new EGR Valve I tried to clean old EGR. Car sounded fine before I tried to clean old EGR. Put old (Cleaned) one on and that is when the VW sound started. That prompted me to buy a new EGR Valve. After testing it I found the diaphragm was toast on the old one.

New EGR gasket....not the same as the metal one I removed, was installed along with new EGR Valve. VW sound is still there. I do not see or hear any vacuum leaks around it but could a leaky EGR valve cause the VW sound?

Maybe my old one was bad for so long that I do not know what my car should sound like, is the VW sound is normal for my car.

 

[PieEyedPiper]

Well no skipped timing belt. Took # 1 plug out and rotated motor until cam marks were lined up. Piston 1 at TDC and to my relief the indicator on crank pulley was on with timing tab on lower cover. 1st time I rotated engine scared me a little until I realized it must have been on exhaust stroke ### nothing lined up!

Got in car this AM and started it to warm up, and decided to check some things while waiting. Turned heater fan on and one interior light. I tapped the air peddle(throttle) several times quickly. The interior light kinda blinked dim and bright as I tapped throttle. At cold idle (900 rpm) or so interior light was dimmer than 1200 or so rpm during tapping of throttle.

Is this normal? I rarely drive car at night and would not notice this unless specifically looking for it.

Alternator issues?

I am beginning to think I may have multiple issues instead of just one.

**********************

UPDATE

OK, I have put over 300 miles on it since I have had a CEL for multiple misfires.

Its been 300 miles since I put a new EGR system in....Valves, solenoids etc. EGR code is gone along with the multiple misfires.

I am going to assume that the bad EGR valve and bad check valve caused the EGR valve to loose boost/vacuum thru exhaust causing a lean condition and multiple misfires.

Now prior to the new EGR Valve I tried to clean old EGR. Car sounded fine before I tried to clean old EGR. Put old (Cleaned) one on and that is when the VW sound started. That prompted me to buy a new EGR Valve. After testing it I found the diaphragm was toast on the old one.

New EGR gasket....not the same as the metal one I removed, was installed along with new EGR Valve. VW sound is still there. I do not see or hear any vacuum leaks around it but could a leaky EGR valve cause the VW sound?

Maybe my old one was bad for so long that I do not know what my car should sound like, is the VW sound is normal for my car.

So now you tell us...

Kidding!

Can you take a video at all to help us understand the sound?
I've seen your other thread. Yes it sounds like your mas works and yes DSMs have horrible charging. My lights are brighter at 1200rpm than at 750rpm and my charging system is operating normally.

 

[Rock2610d]

Sorry, but since i fixed the EGR system I thought it was a non issue. But after thinking about it is odd that the droning sound started after reinstalling old EGR.

In addition it seems boost is not really helping power. Boost gauge hits 12 psi and minimal power is supplied by motor.

My obd2 scanner does not show timing pulling unless 25 degree is low at 4000 rpm and 15 psi.

Hoping it is as simple as a boost leak.

Will try to post a video

here is a video

https://www.youtube.com/watch?v=ctAyzqw0BR4

 

[PieEyedPiper]

Sorry, but since i fixed the EGR system I thought it was a non issue. But after thinking about it is odd that the droning sound started after reinstalling old EGR.

In addition it seems boost is not really helping power. Boost gauge hits 12 psi and minimal power is supplied by motor.

My obd2 scanner does not show timing pulling unless 25 degree is low at 4000 rpm and 15 psi.

Hoping it is as simple as a boost leak.

Will try to post a video

here is a video

https://www.youtube.com/watch?v=ctAyzqw0BR4

25* is what I'd call very high for 4krpm and 15psi. I'm not even sure the stock maps can attain that.

I just checked, the only way to get 25* @ 4k is to only be around 70 load. I can't tell you how much boost that is [likely not any], as every car is different, but I can tell you I easily hit loads of 140+ (I'm actually unsure how much more, but more) around 3-4k with the t-25.

Do you have a tuning/logging device other than a universal scanner?
If so, I'd be curious to see your airflow numbers to get an idea if the car really is down on power.

Anyways, I listened and watched your video and you're right - it's is really hard to hear.
When I listen to it I hear the predominance of air "wooshing". Are all of your vacuum lines connected and not ripped/torn?
I may be just because the engine [air pump] was running that I heard that.

It does seem louder near the EGR though.

 

[Rock2610d]

I have a scanner that can log MAF, TPS, speed, rpms, O2 sensors, Fuel trims, etc.

I will make a log tomorrow and post results.

***********************
UPDATE

Well....I think its fixed

Put new spark plugs in it.

Did a compression test 150 +/- 5 psi in all cylinders. Pretty sure this is good for 7000 feet of elevation.

Did a boost leak test.....no leaks cool

Turbo has oil film on intake side. There is also some oil in the intake tube that hooks to the turbo inlet. Guess I will be putting on a s16g now, the T25 must have a bad seal. The turbo shaft has a little play and I do not like that.

Did a good once over and seen that the drivers side motor mount bolt had backed out and that mount was not secured. Pretty sure this is the vibration I was feeling.

Drove it 30 miles and no VW Bug sound now. Crossing my fingers that all is good now.

I did do a scanner log, and will post if symptoms come back.