polo 1.4 bby misfire

[witblitz]

Hi, I need to know if a faulty evap solenoid can cause a misfire on a specific cyclinder only. I qm getting an intermitent misfire on cylinder 2 and have done the following:
replaced ignition solenoid
cleaned and swapped the injectors
replaced plugs
checked for leaks
Cleaned TB (it was very black)

The only other symptoms are a sligtly uneaven idle (sometimes). The car sems to run fine but every now and then normaly after a 20km motorway run in the morning at almost the same spot at the lights I get a little shudder and then a misfire which goes aways after restart. I get a evap code and a misfire code on vagcom. Anybody know how to test the evap solenoid/purge valve?

[witblitz]

Well I have now replaced the evap purge solenoid, cleaned all the sensors and the egr valve. Ran like a dream for about 20 min then the dreaded shudder and misfire on number 2. Could this be mechanical???

[witblitz]

I have now blocked off the egr flow and disconnected the valve. so far no misfire although i do get a change in the idle at the same place every morning where the misfire happened. I guess I will have to replace the egr valve.

[witblitz]

Replaced egr valve, the misfire seems to be gone but the idling is still a little rough at certain times. So the search continues.

[-M-]

Replaced egr valve, the misfire seems to be gone but the idling is still a little rough at certain times. So the search continues.

You say you cleaned the throttle body as it was carbonized/black - did you carry out basic settings on this and the egr valve when they were replaced ? This needs doing to setup the ecu properly to the new/cleaned componants

[witblitz]

Thanks adaptions were done yes. 060 and 074 on vagcom

[witblitz]

Strange thing, the engine light did not come on but got a misfire on 2 plus an error message that saying too much flow on the egr!!! I have now set 060 on 074 to basic settings, this seems to have done the trick, lets hold thumbs...

Aah crap, I spoke too soon. The Misfire is back with a vengeance....

[witblitz]

Very frustrating. Yesterday on the way home I had a constant misfire for 20km on the motorway. This morning I clear errors and change channel 3 from 103 to 200. I then drove 40 km in heavy traffic, no misfire and slight shudder at idle. I then drive the same distance home at normal motorway speeds, no errors but channel 3 is back to 103. Another thing is that the all systems under readiness test show as passed, which is a first.

[witblitz]

I've decided to run the car with egr unplugged at least it drives ok and does not misfire at odd times.

[witblitz]

Unfortunately I just can't leave this problem alone. The latest update is that I have reconnected the EGR but am riding with the aircon on (whenever I am not on the motorway). This sorts out the misfire and stops the car from running on 3 cylinders (once the misfire starts the number 2 cylinder does not work until after switching off for a few minutes). Yesterday I had the air intake manifold off, there was not an excessive build up of carbon on any of the cylinders intake ports but I did notice a little bit of oil around number two and the one valve had a quite a bad build of sticky carbon. I tried to clean it up as best as possible but it does not seem to have made any difference.

[Crasher]

The BBY ECU is very powerful and can detect a slight variation in the time the crank takes to travel on each firing pulse. If it detects one cylinder is slower and it sees a rise in emissions it will shut down the offending cylinders injector to reduce emissions. The clue to this is deleting the fault code with the engine running, if the misfire disappears only to return a few minutes later you should carry out a compression test which will show the offending cylinder is low on compression, usually due to a burnt out exhaust valve.

[witblitz]

Thanks crasher, i should have mentioned that i did a compression test as well. There is only a very small difference between the cylinders, less than 50 kpa.

[Crasher]

Half a bar isn't much. Do you have a code reader so you could do the test I mentioned?

[witblitz]

Yip you are correct the minute you clear the fault the misfire goes away until you sit at the traffic lights again...

[Crasher]

That means the offending cylinder has poor combustion, I suggest a compression re-check with a different gauge.

[witblitz]

Well now I am really stumped.On the off chance that injector cleaner might help to clean any residual carbon off the intake valves, I put in a bottle when there was only a quarter tank of fuel, I also decided to drive hard with exteneded periods of high revs (probablem not the best idea). Needless to say, I then had to use the aircon and back window heater to avoid misfire..... until yesterday. I noticed that idle was very smooth with aircon running so took a chance and switched it off. Since then it still has a very slight vibration at idle and I sometimes get the feeling that it is going to give that little shudder just before the misfire but has not missed or given signs of very poor combustion on 2. Now my hope is that it lasts and that some other electrical fault is making the cpu change the mixture. To scared to plug in vagcom and check.....

[Crasher]

Giving it a good thrashing will have reseated the offending valve a little.

[Audijimmer]

Hi All,
Read with interest this posting! We have a misfire problem with a BBY coded engine in a Lupo! Car is a 2004 MY and has only done 17k miles from new! We have the usual codes, " Random Misfire, Misfire Cylinder1, etc. nothing else. We scoped the output from the ECM to the injectors and found that the ECM cut the signal to random injects. ECM has been away for testing and has come back faultless. I'm now looking at inputs to the ECM starting with crank sensor. The scoped signal from the crank sensor is not what I would expect from a Hall sensor, castellated trace, its more saw tooth and very random extended castellation for TDC!

Crasher, are you saying that the compression needs to be spot on with what the ECM is looking for or you get problems?


Cheers
Jim.

[Crasher]

You wasted your money sending the ECU away for testing, it was doing its job. If the ECU detects a reduction in crank speed and can tie that into an increase in emissions, it will shut down the cylinder as dictated by EU4 emissions standards. If the compression is any more than approx 2 bar adrift the ECU will shut that cylinder down.

[Audijimmer]

Mmmm, tell me about it!!
If we had a genuine misfire as in plugcoil going down i would expect to see lambda faults, lambda is switching fine hence the scoping of the injectors.

[witblitz]

Just a quick update on mine. It is still running well, every now and again (usually after town driving) it seems to want to slip back into its old habits but I just red line it a few times and all good again...I think it likes a good beating from time to time.

[witblitz]

Update on this issue. So the miss came back (not surprising). My next course of action was an engine flush to see if maybe there was some internal grime that was affecting the valve performance, plus valve lifter fluid in the new oil. To my surprise this made a huge difference for about 2 weeks until going back to normal. This leads me to think that maybe its the valve lifter.....I probably should just bite the bullet and get the head reconditioned.

[Crasher]

Have you had a proper and accurate compression test done yet? Remember the throttle has to be wide open for this test.

[witblitz]

Had a professional compression test done which matches my home test. i.e. no problems with compression and therefore not an issue with valve seating but maybe and exhaust valve not lifting properly.

[Crasher]

What were the compression figures?

[witblitz]

Ok so stupid me did not think to ask them for the actual figures so have redone the test (engine hot) with my home gauge, here is what I found (in KPA) across a number of tests.
Cylinder 1: 1250, 1050, 1150, 1080
Cylinder 2: 1000, 1200, 1100, 1100, 1200
Cylinder 3: 1150, 1150, 1150, 1150
Cylinder 4: 1150, 1200, 1150, 1150

[Crasher]

So roughly 11.5 bar give or take a smidgen therefore that is acceptable as it should be between 10 and 15 bar.

Soooooo.....we could do with a bit of Measuring blocks misfire information, you have full VCDS don't you?

[witblitz]

Not sure if this is what you mean. There are no misfires on the other cylinders.


TIME
Group 15 - Field 1
Group 22 - Field 0
TIME
Group 22 - Field 1


STAMP
Misfire - Cylinder 2
Engine Speed
STAMP
Engine Load




/min

%


1.03
22
680
0.53
19.3


2.57
31
660
2.05
19.7


4.1
40
675
3.59
19


5.65
48
697
5.13
19.1


7.17
57
689
6.65
19.2


8.71
66
663
8.19
19.2


10.24
74
700
9.73
18.8


11.77
82
672
11.26
18.9


13.22
90
660
12.79
18.9


14.76
0
675
14.24
18.9


16.3
6
720
15.78
21.5

[Crasher]

So 14/3 (total misfires) will show the same number as Group 15/2 (individual cylinder 2). With the compression as good as it is and IF the plug and coil pack are correct (moving them around will prove this) then the next thing is either an air leak into the intake tract of cylinder 2 or a faulty injector 036 906 031 M and the cheapest I can find these for is £145.20 inc. VAT from ECP, from VW they are only about £15 more! If you have moved the injectors around and the misfire did not move then it is going to be wiring or engine output ECU driver IF it is not an air leak.

http://i222.photobucket.com/albums/dd20/Crasher1964/Injector036906031M_zps535361d3.jpg (http://s222.photobucket.com/user/Crasher1964/media/Injector036906031M_zps535361d3.jpg.html)

[witblitz]

Thanks crasher but I have my doubts. 1. This issue is definitely confined to no. 2 (have tested injectors and coils), 2. If it was wiring why would this only be apparent at idle and not at higher revs, 3. why would revving the engine high in the past have made the problem less of a problem for so long, 4. why would engine flush and new oil make the problem less of a problem for a few days and 5. other than idle issue car runs normal with normal to good fuel consumption. All of this leads me to think mechanical.

[Crasher]

Well I have thought it was mechanical from the start but valve related so the oil aspect could mean a faulty hydraulic tappet, more likely if they were not replaced when the head was rebuilt.

[witblitz]

Thanks Crasher, I am going to be replacing the the hydraulic tappets in the next few weeks and will report back (for clarity as far as I am aware the head has never been off).

[Crasher]

How many miles has it done? Make sure that the lifters/tappets (called equaliser elements by VW) are made by INA (Febi supply these) and no one else or you will probably have problems. You should also replace the followers but if not be extremely careful to keep them in the correct order.

I do the Febi lifters for £5.55 and the rollers for £9.64, the latter not being a very big saving over genuine.

[witblitz]

Ok so lifters and rockers replaced with quite a bit of improvement in that the misfire is now not enough to through up a code but is still there. Also it seems now that number 1 (which I have seen a miss on in the past but only once in a while is now also playing up a little more). 3 and 4 are good.....

[Crasher]

It would have been nice to do a cylinder pressurised leak down test with the cams out but you probably don't have access to a blow by gauge and decent sized compressor.

[witblitz]

Ok, time to trader her in..... out of the blue I got a multi cylinder missfire error in addition to a misfire code on 1,2 and 4 and this on the pull away whilst stuck in traffic rather than whilst idling. Then no start (I assume flooded) as I got a strong smell of fuel. Once I got her going continued on the motorway as if nothing had happened...time for a new problem.

[seer]

Did you get it solved, or did you send her to lost graveyard where other 1,4 16v's Lay to rest?;)...


Sent from my iPhone using Tapatalk

[witblitz]

Nope, the next move would have required me to open the engine and I do not have the facilities. The service station wanted to charge almost as much as what I traded her in for just to open and re-assemble (excluding replacement parts). That will definitely be the last 1.4 16 valve VW product that I buy. I now drive a B5 Passat 2.0 20 valve (lets hold thumbs that there are no issues with any of the 20 valves).

[Crasher]

The ALT engine.....good unit until they have problems which is usually with, the valves.....