# Misfire across all cylinders



## jon-vw (May 25, 2011)

Logged my engine at idle for about 5 minutes:
Missfire Counter:
Cyl1: 1
Cyl2: 0
Cyl3: 1
Cyl4: 2

I'm sure if I had let it run longer they would've kept rising. Swapped all coil, dropped in fresh plugs ([email protected]") and am still seeing the missfires. Kinda lost and need some help.

Also, received an n249 mechanical malfunction error. Impossible cause I just replaced my n249 yesterday due to having this code prior, the f$%ker is brand new! :banghead:


----------



## AmIdYfReAk (Nov 8, 2006)

i get some misfires on my 1.8T, can you fell them? or does the CEL blink?


----------



## jon-vw (May 25, 2011)

No CEL, and you can't feel them.

I logged my car on the way to work today. It appears the engine is only misfiring at idle. Does that make any sense?


----------



## Downeywu (Apr 27, 2005)

possible problems....

Vac leak, perform pressure test to check for leaks.

Clean your TB, perform TB alignment

Clean/replace MAF

inspect wire harness

possible o2 sensor causing issue

when was the last fuel filter?


----------



## jon-vw (May 25, 2011)

Downeywu said:


> possible problems....
> 
> Vac leak, perform pressure test to check for leaks.
> 
> ...


MAF is two weeks new. Performed a TB alignment this morning. Fuel filter has about 10,000km's on it.

I'll see if I can't borrow a smoke tester and replace the primary o2 and post back. ty


----------



## Imola Yellow GTi (Oct 27, 2000)

Rubber hose tween pancake pipe and hard charge pipe leaking?


----------



## Yosh_Cupra (Jun 28, 2008)

Check torque setting on knock sensor bolts?
Otherwise maybe bent rods...


----------



## jon-vw (May 25, 2011)

Wasn't able to get to the knock sensor yet. My boost piping is custom for my front mount. I removed the pancake pipe and all that oem stuff a while back. I check all piping/couplers from the turbo all the way to the intake manifold and then pressure tested. Looks good.

Also checked the o-rings on my injectors for tears.

Any more ideas? I hope I didnt bent rods, I'm running 25psi, but no meth. I doubt my car busts the 270whp barrier...


----------



## Imola Yellow GTi (Oct 27, 2000)

jon-vw said:


> Any more ideas?


the lovely ignition harness... speaking of which i need to get that done


----------



## jon-vw (May 25, 2011)

Imola Yellow GTi said:


> the lovely ignition harness... speaking of which i need to get that done


Sheeeiiit. I despise wiring. I have the diagrams for the pinouts. Anyone have a clue what I can use to insert/remove the wiring pins out of the harness?

Found a new coilpack harness for $50, also gonna buy some beer and advil to boot.


----------



## MNShortBus (Mar 14, 2008)

jon-vw said:


> Sheeeiiit. I despise wiring. I have the diagrams for the pinouts. Anyone have a clue what I can use to insert/remove the wiring pins out of the harness?
> 
> Found a new coilpack harness for $50, also gonna buy some beer and advil to boot.



You can try and find the correct tool. Or use paper clips 

They take a little bit of moving around, but get the job done.


----------



## simonjosVW (Feb 1, 2009)

such a broad range of ideas everyone throws out there... but nothing is really being narrowed down.

You described your problem as misfiring when at idle? does the misfiring stop on throttle? Most of these problems are result of a boost leak from your PCV system hoses connecting at the end of your intake manifold... To further explain, your PCV is pushing air back into your intake during idle because you're not making any boost, so basically your not getting any air. 

You could check your plugs and see if they're fouled. You are running the hotter plugs available from these cars, so i would imagine they're going to look cleaner that normal. 

Other issues could be your ignition coil packs which are such a common issue on this motor, granted you're getting random miss fires, so its possible all 4 didn't go out at once, but depending on the mileage you never know. Theres been A TON of revisions on these, I believe revision D is the latest, and the price has actually gone down since the revision R coils. 

Think of it like this, if you spend $100 bucks replacing ignition coils you can rule out that issue, plus you'll have new coils, and thats always good :beer:


----------



## Zneith (Jan 4, 2010)

simonjosVW said:


> such a broad range of ideas everyone throws out there... but nothing is really being narrowed down.
> 
> You described your problem as misfiring when at idle? does the misfiring stop on throttle? Most of these problems are result of a boost leak from your PCV system hoses connecting at the end of your intake manifold... To further explain, your PCV is pushing air back into your intake during idle because you're not making any boost, so basically your not getting any air.
> 
> ...


Your best bet to start is to call the stealership and ask them if there are any recalls for you vw. They will ask for your vin number so have that handy. If there are any recalls (usually atleast coils), they will take care of it free of charge. Just an idea to get you a set of 4 new coil packs. 

Also, your knock sensors should be torqued to 20ft/lbs. 

Take a very close look at the wiring harness. The heat is known to crack these. If any type of moisture got there, that could be your issue as well. For a temporary solution, Id tape the harness in exposed areas.

And as always for safe measure, do a leak down test with a compressor and if you feel spunky, do a smoke test as well.


----------



## Slimjimmn (Apr 8, 2006)

there is a reflash available for cold start misfires due to the ecm opening the evap valve on cold starts. Its for 02-03 1.8t cars

Also if you have a faulty check valve for the n249 vacuum hoses it will set a mechanical malfunction code. 
:thumbup:


----------



## jon-vw (May 25, 2011)

Slimjimmn said:


> there is a reflash available for cold start misfires due to the ecm opening the evap valve on cold starts. Its for 02-03 1.8t cars
> 
> Also if you have a faulty check valve for the n249 vacuum hoses it will set a mechanical malfunction code.
> :thumbup:


Confirmed: faulty check valve on the n249 vacuum circuit. That explains why it wasn't misfiring under boost. Thanks everyone for your input and help  Beers on me :beer:


----------



## Slimjimmn (Apr 8, 2006)

goal this weekend is to fix my n249 stuff. pretty sure my check valve is bad. Just been too lazy this winter to fix it.


----------



## jon-vw (May 25, 2011)

Also, I found a hose 1" in length coming directly off the manifold that connects into that vacuum circuit. The damn thing was torn in half. Crazyness.


----------



## Slimjimmn (Apr 8, 2006)

was it that 90 degree looking check valve on the end of the bracket?


----------



## jon-vw (May 25, 2011)

Yeah, the 90degree closest to the manifold.

Unfortunately that only solved part of the problem. Misfires have progressively gotten worse over the past 2 weeks. My car is undrivable 

Misfiring at idle, misfiring under boost, and even when I get on it a little. The whole car will buck if I try and boost past 5 psi, yikes. I'm leaning towards the botched ignition harness job I had done last year. The mechanic cut the original harness halfway and soldered the new one on, lolwtf :thumbdown:

I'm really hoping it's the issue. My fueling and lamba looks good. I'm not hearing any knocking or pinging from the motor, but I'm going to perform a compression test (before I waste anymore money/time) this weekend and post back.

I should also add, there are no check engine lights, no codes, and I'm running fresh plugs and coilpacks.


----------



## groggory (Apr 21, 2003)

I had similar problems and it ended up being a collapsed cat. You can check for that with an exhaust backpressure tester.


----------



## jon-vw (May 25, 2011)

Would using a vacuum gauge at idle suffice? If so, what readings are norm? -15 psi + ?


----------



## groggory (Apr 21, 2003)

jon-vw said:


> Would using a vacuum gauge at idle suffice? If so, what readings are norm? -15 psi + ?


Sorta....

a healthy stock cams 1.8t at sea level at idle will read 20-22 in Hg. (yes, vacuum is measured in inches of mercury, not PSI. ).

If you are seeing numbers below that that means that there is a load on your engine. Less vacuum means more load on the engine. Positive pressure means even more load on engine. makes sense, right? 

Misfires count as additional load. The other cylinders have to work harder to keep the car spinning at say 850 RPMs now that one of the cylinders is missing now and again. Exhaust back pressure counts as a load because now it takes more energy to push exhaust out the tail pipe. etc etc etc.

So in short, no. An intake vac/ boost gauge is not equivalent to an exhaust back pressure tester...but it can give overlapping results depending on the conditions.


----------



## BassNotes (Mar 16, 2005)

jon-vw said:


> Anyone have a clue what I can use to insert/remove the wiring pins out of the harness?


ECS Tuning sells a Schwaben kit. It's not cheap but it sure beats breaking the pins. I've found that removing them is fairly easy, but getting them to insert fully is tough!


----------



## jon-vw (May 25, 2011)

Compression Test Results

Cyl1: 185psi
Cyl2: 184.5psi
Cyl3: 178psi
Cyl4: 185psi

:thumbup::thumbup:

My harness came in this morning, and I also snagged some new "R" revision coilpacks from the dealership. Before I replace the harness, I'm going to swap in the newest coils to see if the problem still exists. One question: If the current ignition harness is damaged/faulty, is it possible I could write off these new coils? Don't wanna waste'm..


----------



## groggory (Apr 21, 2003)

jon-vw said:


> Compression Test Results
> 
> Cyl1: 185psi
> Cyl2: 184.5psi
> ...



Awesome numbers.

If you want to be 110% sure about your engine you can get the engine hot, then do a 100 PSI leak down test too.


----------



## jon-vw (May 25, 2011)

Wasn't able to perform a leakdown nor had access to a backpressure tester. However, my vacuum readings at idle are a steady -20psi with no fluctuation.


----------



## groggory (Apr 21, 2003)

jon-vw said:


> Wasn't able to perform a leakdown nor had access to a backpressure tester. However, my vacuum readings at idle are a steady -20psi with no fluctuation.


----------



## redefine6 (Jun 24, 2009)

I hear ya. Just workin' with what's available 

I'm outside in the garage atm. I will be arranging for a backpressure test shortly. One person mentioned tapping gently on the catalytic converter to listen for any debris rattling around in there, I shall try that. Just wish I had some spare gaskets so I could take the whole downpipe off for inspection. It's a 3" BillyBoat Turbo Back and seems to be of very decent craftsmanship, but you never know.

The schwaben electrical terminal toolkit hasn't arrived yet, so I'm testing everything I can imaginable. Thanks again for your correspondence :beer:


----------



## jon-vw (May 25, 2011)

Status update. Work done as of yesterday: 

-New MAF 
-Replaced ENTIRE ignition harness 
-New 'R' revision coilpacks 
-New NGK BKR7E @ 0.028" gap 
-Fuel Filter is 1 year old 
-Bosch 440cc's are 6months old 
-Cleaned IAT 
-Compression test looked great 

Lots of work done here these past two weeks. I still don't have access to a backpressure tester. I'm hoping it's a leak from the Combi or Brake booster, but I don't know if they could cause misfires this badly.


----------



## Slimjimmn (Apr 8, 2006)

I had a bad check valve for my secondary air solenoid (under that metal bracket by the dipstick tube). I also had a leaky gasket from my combi-valve to the head. Its why I deleted it all. Not needed w/o a cat.


----------



## jon-vw (May 25, 2011)

Could a leaky/fault EGR (combi) cause a performance/misfire hit like this? I should also point out that my exhaust note has changed significantly. The misfires/rough running seem to be more persistent when the car has been warmed up/driven.


----------



## jon-vw (May 25, 2011)

Again, no error codes/CEL's of any kind :banghead:


----------



## jbutlertelecom (Aug 12, 2009)

Misfires @ idle only is a sure sign of bent rods when all other variables have been ruled out FIRST. 

Since you have replaced plugs, coils, wiring, did a vacuum test and verified no leaks, replaced vacuum check valves, MAF, etc. I would say you have pretty much narrowed it down to VERY few possibilities. If you feel you have a sound vacuum system, sound fuel system and sound wiring, plugs and coils; I would suggest you prepare yourself for bad news, you have bent rods. You are on a stock bottom end with Uni2+ boosting 25 psi on a Frankenturbo F4H? Yeah, bent rods.

Easiest way to check without opening the engine is to get a friend's car (obviously ANY 1.8T engine will work) and compare depth of piston @ TDC #1 cylinder. Use a 3/8" long extension (it will just fit the spark plug hole) and mark it with a straight edge in known good car, repeat the process on your car for each cylinder when @ TDC of the respective piston. Compare measurements with a micrometer. ALL measurements should be identical, if there is a bent rod it will be shorter (longer measurement= bent rod since rod will be shorter thus increasing the distance between the piston top and the point of measurement) by a few hundredths or more but it will be a pretty small amount.

Alternatively, if you have the budget, a depth gauge would be ideal as it would be a lot easier and more accurate than having to measure by hand but they are pricey.

If you don't have access to another engine to compare with and you can't budget (or stomach) the cost of a depth gauge setup you could pull the head and check against the deck of the block with a straight edge and feeler gauges.


----------



## jon-vw (May 25, 2011)

Yeah, I was hoping it wouldn't come to this, but dropping in new rods affords for interesting opportunities with this car 

By the way, the car misfires more frequently when warm, and I was wondering if I could still drive back and forth to work (no getting on it hard) without doing anymore damage to the motor?

I will still do tests to verify, but the engine isn't knocking at all..


----------



## Slimjimmn (Apr 8, 2006)

compression test will tell if rods are bent. 
It will usually be 10-12% less if the rod are slightly bent. Seen this with diesel engines, they run rough cold and smoke a bunch but still run.


----------



## jon-vw (May 25, 2011)

Compression Test Results

Cyl1: 185psi
Cyl2: 184.5psi
Cyl3: 178psi
Cyl4: 185psi

To clear things up. The ignition system is now sound. On to the other possibilities. My FPR is the original, I will attempt to get a fuel pressure gauge. Would a dying pump cause this, or more importantly, what causes misfires when the engine is warm? Readiness showing on both o2's, sai, combi.


----------



## jon-vw (May 25, 2011)

bump


----------



## demonbug (Apr 19, 2012)

*Long shot*

Randomly came across this thread while searching for something else...

I was having an issue with occasional misfires being reported on all cylinders, between my mechanic and I spent quite some time trying to figure it out. Eventually gave up since the car seemed to be running fine for the most part. About 1-2 months later had a full engine cut-out at a stop light; turned out I had a bad crank position sensor (this is an '01 Golf 1.8T w/ only 110,000 miles). I can't say for sure that it was directly related, but after replacing the sensor the phantom misfires went away. If anyone can come up with a theory why this would be it might be worth looking into...


----------



## jbutlertelecom (Aug 12, 2009)

demonbug said:


> Randomly came across this thread while searching for something else...
> 
> I was having an issue with occasional misfires being reported on all cylinders, between my mechanic and I spent quite some time trying to figure it out. Eventually gave up since the car seemed to be running fine for the most part. About 1-2 months later had a full engine cut-out at a stop light; turned out I had a bad crank position sensor (this is an '01 Golf 1.8T w/ only 110,000 miles). I can't say for sure that it was directly related, but after replacing the sensor the phantom misfires went away. If anyone can come up with a theory why this would be it might be worth looking into...


If this doesn't fix it, check for bent valves or burnt valve seats by performing a leak down test. Cyl. #3 was a little low on the compression test compared to the other cylinders, could be valves like I said or rings. Most likely a single valve is leaking/bent/burnt.


----------



## jon-vw (May 25, 2011)

demonbug said:


> Randomly came across this thread while searching for something else...
> 
> I was having an issue with occasional misfires being reported on all cylinders, between my mechanic and I spent quite some time trying to figure it out. Eventually gave up since the car seemed to be running fine for the most part. About 1-2 months later had a full engine cut-out at a stop light; turned out I had a bad crank position sensor (this is an '01 Golf 1.8T w/ only 110,000 miles). I can't say for sure that it was directly related, but after replacing the sensor the phantom misfires went away. If anyone can come up with a theory why this would be it might be worth looking into...


 I will most surely have a look into this. Quick question, what tune were you running, if any? And, did your car throw any codes related to the crank sensor, cause I'm still getting none. 

Again, my car is throwing no codes at all. The car occasionally makes a popping sound from the exhaust when shifting gears, no sure what that is. 

Also, for the past 6 months, the engine will completely cut out (stall) while doing a WOT 3rd gear pull.. :thumbdown: 

I'm getting a backpressure and leakdown test done at a local shop early next week and will post back.


----------



## Slimjimmn (Apr 8, 2006)

sounds like a mad vacuum leak to me.. 

did you ever clean your throttle body?


----------



## sxpilot (Apr 9, 2019)

*Sorry to dig up this old thread*

But did you ever Figure out the cause of your random misfires?
I’m having the same issues with my mk4 BT full build, 

I started with my car with a broken timing belt, bent valves ext...and then the person decided to start taking bits and pieces off of it, so when I got it, it was a basket case. What started out as a project to just get it running and get it on the road I ended up turning it into a work of art, a masterpiece if you will and I’ve been working through all sorts of issues with it. 
I had it running pretty good I thought and then like an idiot I failed to put the radiator cap on completely and correctly and it blew it drenched the entire engine compartment with the pink stuff! Since then I started developing misfires. I tried to dry it out as best as I could but, I was thinking it could’ve soaked into the harness? I ended up replacing the ignition harness with a 034 motorsports Version and initially I thought I had cured everything but as soon as I ran it a while it started miss firing again so either I have water that’s past the new harness deep down inside or something else is going on? I’ve change the crank position sensor the cam sensor I’ve checked my timing belt, I’ve replaced the maf, map, it has brand new fuel pumps x2, Coils, plugs gaped at .28. I’ve checked all of my ground straps throughout the vehicle, it’s got new O2 sensors I double checked the front O2 and it’s goo the ECU is good, my A/F is on target at 14.5-ish, I’m just at a loss at the moment.
I’m going to try a new set of spark plugs and the only reason I say this is because before I got my engine tuned it was running very rich. To the point when I would pull the plug zero dripping so I could’ve filed the plug but Teufel all four plugs to me is just nonsense and I’m having misfires and 123 and four cylinders. If anybody has any direction I should be looking I’m all ears thank you 

Also I’m not able to post any pictures yet for some reason but I sure would like to show what I built


----------



## Vegeta Gti (Feb 13, 2003)

All that.. and no posted logs? No compression test numbers, etc??

Sent from my SM-N950U using Tapatalk


----------

