Code P301-304

It seems that I have a misfire in EVERY cylider!! Any ideas what can be causing this???

I have a 1999 Passat. When I start the car it barley starts. Then I have to let it idle (very rough) before I can start driving it. When I first start driving it It will bog down even if I have it at full throttle. It sits there for like 3 seconds or so then it takes off and runs fine until I come to a stop again. Then the same thing happens. After I have driven it for awhile it doesn't do this anymore.

I had the diagnostic done and they told me that I am misfirring in every cylider. They suggested the timing belt skipped. Any other ideas?

Which engine? In addition to ignition problems I'd also look at the mass air flow sensor. It can get out of calibration & cause all sorts of codes. You need a scanner that can view the datastream of the sensors & ECM.

Which engine? In addition to ignition problems I'd also look at the mass air flow sensor. It can get out of calibration & cause all sorts of codes. You need a scanner that can view the datastream of the sensors & ECM.

It is the 1.8T. I just had the diagnostic and the only codes that they pulled was the misfire in each sensor. I believe they said that it was the P301-304. Other than that they didn't pull anything else.

The 1.8 had a problem with the ignition "module" but it usually just causes a miss on #2 cylinder. I'd look for a non-ignition cause such as the MAF or a vacuum leak.

OK so the shop checked the timing and it was perfect. The mechanic said that he thinks it is the fuel system... Well somewhere in it. What do you guys think of this? Could the injectors be faulty?

Were there any other codes in there?

If its a 1.8t it could possibly be the POS (power output stage) on top of the air cleaner box. It controls spark on all cylinders and usually goes bad arround 80-100K miles. Unfortunately its a $450 part. You can check it with a test light- Unplug the engine side connector then have someone try to start the car. Try each terminal with the test light while trying to start the car, each terminal should flash.

The car is in the shop right now. I'll call my mechanic and have him test for that. Would this throw it's own code or do you just have to know to check that? I have 90k on the car.

I didn't get any other codes from the mechanic. He just told me that he got some fuel systems hits on his scanner.

I have never seen an injector or fuel related part go bad on a vw. The fuel filter could be a problem if it is too clogged and is a cheap repair (also helps on gas mileage and power alot). The POS wont set a code for the unit itsself, you just have to find it as the culprit as per the testing i had before. Also a faulty MAF sensor or ECT could cause misfires in all cyl. if they were very bad. Also large vacuum leaks could cause misfires in all cyl.

Man... There are a lot of posibilities aren't there.... It is going to cost me like $500 to just figure out what is wrong with it.

OK so before I had my timing belt and turbo replaced I didn't have this problem. What could they have messed up while replacing those parts that could cause this? I wonder if they just didn't hook something back up right. I have already had the timing check and it was perfect. Wouldn't the MAF or ECT throw a code that could easily be tracked if they were bad?

OK so I got the car back from the mechanic. He did pull a 17708 code. What is that?? He did replace the clogged fuel filter, but that didn't fix the problem. Any ideas besides the POS?

I found that the code 17708 is a misfire because the fuel is too low. The tank is full.... Could at one time this have happened and it has fixed itself or something?

Fuel to low sounds like the clogged fuel filter. I have seen codes for misfires and a code for low fuel at the same time. Check the ECT (at the rear of the engine between the engine and firewall. If its not green then replace it- only $7.00 worth of parts and u problably need it neway)

When you fix a car with lots of miles things tend to break. An engine that has not had full boost pressure now is. Your MAF might be faulty now because of the boost pressure. Also they should check to see if all the vacuum lines and hoses are correctly installed on the turbo and intake pipe. There are alot... ALOT of vacuum lines and rubber hoses that need to be removed and installed when doing a turbo on a passat and I am sure they might have forgot one or two or possibly one hose may have cracked.

OK So after the fuel filter was replaced the check engine light hasn't came on. It starts a bit easier now, but still bad. I'll replace the ECT this weekend and see what happens. If the MAF bad wouldn't throw a code? Maybe it is just out of calibration. If it is is there anyway to recalibrate it? When the trubo was replaced they did replace a couple of vacuum line that were cracked. I'll try and case them all down to make sure that the hooked them back up right.

There is no way to (calibrate) a MAF sensor, but you can clean it with some 99% alcohol. You might also have some carboning of the valves. Try a full can of "seafoam" $8.99 at checker auto parts in a 1/2 tank of gas. That should more than blast your injectors and valves and pistons clear of any carbon or residue buildup.!

I have the same problem with my 99 passat 1.8T. The check engine light came on last week and the dealer pulled misfire codes, said it was likely a tank of bad gas. I ran the tank out and filled with new but the car still is not running right. Dealer pulled codes again and still had misfire codes P0301, 0302. There was also a P1300, and said fuel level too low. They suggested replacing the spark plugs, checking all vacuum hoses first, as they were the least expensive items. If after that it does not run right, it may be the MAF sensor.
From reading posts on misfire codes, there were several solutions/fixes that came up I would like more information on.

1. Is the MAF sensor in the airbox?
2. Does anybody know where wiring diagrams and vacuum line diagrams can be found online?
3. What is the ECT? Do you run test on it or is it just a replaceable item(cheap)?
4. The Power Output Stage test says to pull the engine side wire and put a test light on each terminal of the module as engine is cranked to see pulse. Which is the engine side? The wires enter a sleeve immediately and both run into a secondary sleeve at the rear of the engine, that lead to the ECM?
Short of these tests which I can perform, it will have to go to the dealer if nothing works. Anything else on the P1300 code Fuel Level Too Low or any other suggestions? Thanks.

1. yes have to remove the top portion of airbox to remove sensor
2. no
3. replace the ect (coolant temp sensor 10.00 in parts sensor/oring) look for previous posts on ect
4. if your engine is misfire on cyl 2 replace the pos "power output stage or ignition module" (reccomend one from a aftermarket parts warehouse and save 2-300.00 its on top of the intake box)

Looked up posts on ECT, sounds like they are junk, just replace.
Will a faulty ECT cause the car to run slightly rough and store misfire codes P0301, p0302, and p1300(fuel level too low)?
I just topped up the coolant overflow reservoir over the weekend because it was below the low level line. Could this have any effect on the ECT or how it operates?