Inspection Due! Intermittent misfire on start-up.

[vwGLI]

Hi you all,

This really stressed me out. I searched and read for days but still have no idea about how to deal with it. See if you guys have any idea. Thanks in advance here!

I have my 06 vw GLI with 68K mi. The CEL came on once in September for misfire in cylinder #4. I swapped out the coil on #4 and all spark plugs, cleared the code. The light stays off for two month.

But recently, I got the same code three times in the last two weeks. I could tell the slightly shaking after start up for a few times (not always), but it only lasted for about 30 seconds (which is enough to light my CEL). Then the car runs smooth and powerful, idles smooth, no abnormal sound or smell from exhaust. IMO there was no misfire at all!

The car was normally driven for short trips in low speed in the last three month

. I also have a 15 miles hwy trip every weekend. After read a lot, IMO my issue might be caused by sticking intake valve or leaky injector, since the coil and plug are almost new. But the car starts very quick, mostly takes half second only. I never experienced 2 seconds or more. Another thing I noticed is that there was a 1 second of knocking sound right after start up for a couple times (very rare). My question is if it's possible to star that quick for a engine has stuck valve or leaky injector? I was confused.

Today the code came back again. I want to start sth. cheap before throwing new parts. I took the car to do a Italian tuneup after I checked everything works fine there. Then poured a bottle of Techron in the tank. The car now idles even more smooth and quiet. Of course, the CEL won't go off until some driving cycles are done(if it fixed). I hope it will!

Honestly, I can stop caring the intermittent 30s misfire after start up. But state inspector won't! I knew Texas allows my car with 1 code of "not ready" to pass. But I guess those auto parts stores can only clear all the codes on their device, that way I will fail.

Dun know what to do now. Should I take the car to dealership? When can I get it inspected...

 

[LeakySeals]

I say wait out the techron. I've seen it solve mis-fires more than once. In a few days if it doesn't clear but feels better, give it some help. Disconnect the battery for a few mins. reconnect. Let the ECU relearn with its nice clean injectors.

 

[vwGLI]

Originally Posted By: LeakySeals
I say wait out the techron. I've seen it solve mis-fires more than once. In a few days if it doesn't clear but feels better, give it some help. Disconnect the battery for a few mins. reconnect. Let the ECU relearn with its nice clean injectors.

Thanks.

I saw some ppl cleared CEL by techron too. That's why I used it. If so, that's a clogged injector in #4. I hope!

But I'm not sure about the disconnection part, since i have to do the inspection this month. VW's driving cycle seems so obscure...

 

[JimPghPA]

I would run two bottles of the techron in one tank of gas and run that tank until it is down to about 1/8 of a tank.

You can clear the CEL if you go to Advance Auto and borrow a scan tool. You will have to let them hold onto your drivers license while you borrow the scan and clear tool.

 

[eljefino]

It's possible the misfire I/M precludes most of the others from running. I know it will on my domestic stuff. For example there's no sense checking the catalytic converter if the computer knows it's missing.

You have to have a pretty good miss to fail a cold start misfire; the computer is set up to ignore a few isolated misses. You can start pretty easily with three working cylinders.

This is a little harsh sounding but I think for a week you should rev it up to 2500-3000 RPM immediately after starting and hold it there for half a minute. I just have a hunch that this will help somehow.

 

[Hirev]

A leaky or bad injector is a possibility. A stuck intake not so much. If a valve sticks at the very least you will have broken valve train parts. Were the replacement plugs exactly the same brand and number?

 

[vwGLI]

Originally Posted By: JimPghPA
I would run two bottles of the techron in one tank of gas and run that tank until it is down to about 1/8 of a tank.

You can clear the CEL if you go to Advance Auto and borrow a scan tool. You will have to let them hold onto your drivers license while you borrow the scan and clear tool.


Thanks. Two bottles in one tank sounds a bit much. But anyway I will try this when I have chance to do so. My tank is already full now.

Autozone also can clear CEL for me. But my question is if this will lead everything "not ready" on OBD II when doing inspection. Or just simply the misfire section (this way I may pass)?

 

[HerrStig]

Why not BUY an OBDII scanner. It'll save you many times the cost in parts you don't need.

 

[vwGLI]

Originally Posted By: eljefino
It's possible the misfire I/M precludes most of the others from running. I know it will on my domestic stuff. For example there's no sense checking the catalytic converter if the computer knows it's missing.

You have to have a pretty good miss to fail a cold start misfire; the computer is set up to ignore a few isolated misses. You can start pretty easily with three working cylinders.

This is a little harsh sounding but I think for a week you should rev it up to 2500-3000 RPM immediately after starting and hold it there for half a minute. I just have a hunch that this will help somehow.


Thanks I'll try this.

Quick Q~ Is it possible a vacuum leak causing misfire in one particular cylinder? I heard a hissing noise under acceleration with my window down last night. I didn't notice this before. Not sure if Techron in fuel makes engine sounds different~

 

[vwGLI]

Originally Posted By: HerrStig
Why not BUY an OBDII scanner. It'll save you many times the cost in parts you don't need.

Many local stores nearby provide it for free. I would save the money for potential repairing

 

[supton]

But you can use it to find stuff that needs repairing!

On my VW, for years it was slow to warm up. Fine, it's a diesel: they do that. In response to a thread here about how fast do engines today warm up, I hooked up my Scangauge and watched. Turns out, I have a bum thermostat. It opens up too early. Can't tell from the idiot gauge on the dash.

 

[Vikas]

Order a bloody cheap code reader which tells you the I/M monitors, so you will know when to go to the inspection station. I am sure you can afford $25-$30 price tag.

You are already talking about visiting the dealer. Do you have any idea how much it will cost you?

I mean what is this business about saving money but having to borrow (or not able to) tools which are essential??

As soon as I become moderator of this forum, I will not allow anybody to register unless they own a scan tool

 

[antiqueshell]

Originally Posted By: vwGLI
[ Two bottles in one tank sounds a bit much. But anyway I will try this when I have chance to do so. My tank is already full now.



DO NOT put TWO bottles of techron in the tank to treat the fuel!

It will not help and although unlikely could cause more problems.

Follow the Chevron's directions when using the product.

Make sure you get the high PEA formula
Fuel System Cleaner.

NOT THE INJECTOR CLEANER!

 

[mattd]

these engines have had some problems with cam lobe for high pressure fuel pump wearing out, causing misfires/rough running.

 

[yonyon]

Originally Posted By: vwGLI

Quick Q~ Is it possible a vacuum leak causing misfire in one particular cylinder? I heard a hissing noise under acceleration with my window down last night. I didn't notice this before.


Typically a vacuum leak that goes away as the engine warms up is small enough that is can only cause a misfire at or near idle - not the problem you're having.

 

[vwGLI]

Originally Posted By: mattd
these engines have had some problems with cam lobe for high pressure fuel pump wearing out, causing misfires/rough running.

If it's sth related to fuel pump, the misfire should be in all cylinders not in a certain one, at least should be random? Correct me plz.

 

[vwGLI]

UPDATE: Since I opened this thread, I'm gonna finish it to help some late comers, hopefully.

PROBLEM SOLVED! Crazy, it's just a bad coil. A coil couldn't last 1500 miles or 2 month so that I even never considered it. I know coil should be the first thing to think about when coming to misfire. But never expected it dies that early!

The coil on #4 is from Autozone two months ago, branded as Duralast. Some say they're Bremi coils, which are OE of early AUDIs and BMWs. But I found the stamp on the coil are exactly same as my OE ones

Who knows... The good thing is they have 2yr warranty so I can always swap new for free. Since I'm not gonna keep this car very long, Duralast is fairly good choice for me. I'll be well prepared for next misfire and change it again

Also recommend everyone has recurring misfire problem change coils no matter how "NEW" they are! Just try it before spending large $$$.

Many thanks to you all.