Pinging 1.8T

[Cadburry]

Looking for ideas among specialists!

My 03 B6 1.8T with 150,000 miles is running great but the engine pings (sometimes badly) and I'm trying to source the problem. The pinging occurs at around 1,500-2,000rpm on very light throttle application and stops when I give it more throttle input. The pinging never occurs under boost.

My local mechanic first diagnosed a bad MAF since the readings were too low. The MAF was replaced with a new item but the pinging still occurs.

Both air and fuel filters were replaced in the past year.

As far as I know, the motor is running the factory tune.

VAG COM reveals no error codes.

Any ideas?

[MetalMan]

You can use VAG-COM to measure & log timing pull and/or knock sensor activity.

Is your ECU stock or tuned?

[BARRY]

vacuum leak. MAF will die if issue. also you'd get some form of engine code, so your mechanic is rather not well versed.

[Cadburry]

vacuum leak. MAF will die if issue. also you'd get some form of engine code, so your mechanic is rather not well versed.

Actually, I double checked myself a few times over the past few weeks: no engine codes in VAG COM.

I can't tell whether the car was ever tuned, I highly doubt it.

There may be a related issue: oil consumption. Also I found some oil around the ignition coils on the two front cylinders, either a bad valve cover gasket or perhaps due to a small mess I made while filling up oil a few weeks back. Anyway, oil consumption is definitely high, about 1 quart every 1500 miles. PCV issues? EGR?

Oh my...! Strange cause the car otherwise starts, idles, runs and drives great, just worried it's just about to go bust on me!

[BARRY]

so your saying you have oil in your spark plug galleys? that would be the issue if so. leaking valve cover gasket if so. if there is any oil in the plug galleys this would prevent your ignition coils from sending correct spark. could be consistent or could be random as far as the dropping or missing spark.

best way to single this out is to clean the spark plug galleys, plug ends, and ignition coil end. use brake cleaner to clean each. I just spray brake cleaner down the plug galleys as this will burn off during engine run. one thing to note is if you do this you will initially have trouble cranking your motor until it has all burnt off. you might even have a real rough idle until all has been cleared from the combustion chamber. this is just what I do...otherwise sticking thin cloth down to soak up the oil would be safest.

[Cadburry]

so your saying you have oil in your spark plug galleys? that would be the issue if so. leaking valve cover gasket if so. if there is any oil in the plug galleys this would prevent your ignition coils from sending correct spark. could be consistent or could be random as far as the dropping or missing spark.

best way to single this out is to clean the spark plug galleys, plug ends, and ignition coil end. use brake cleaner to clean each. I just spray brake cleaner down the plug galleys as this will burn off during engine run. one thing to note is if you do this you will initially have trouble cranking your motor until it has all burnt off. you might even have a real rough idle until all has been cleared from the combustion chamber. this is just what I do...otherwise sticking thin cloth down to soak up the oil would be safest.

I will try pulling the two affected coils and clean as much as I can and see where this takes me. I'm not sure I'm too keen on removing the plugs, for now anyway. If oil returns to these galleries after cleaning, I will conclude it is the VC gasket rather than my oil fill mishap of a few weeks ago.

Will report back. Thank you!

[Kevin C]

A bad injector can cause one cylinder to run leaner and can contribute to pinging.

[EuroxS4]

My pinging you mean misfiring??or engine knock??I would check spark plug condition and make sure you have a good quality plug in the engine.BTW autolite is not a quality plug brand!!!I cant tell you how much they suck!!If spark plugs look good.You can try changing the coils to different cylinder to see if that will make a difference.Also if you have access to a vagcom or vcds you can look at measure value blocks 014,015,016 when the issue occurs. MVB 014 will tell you if its misfiring or not. MVB 015 shows misfires on cylinders 1-3 and MVB015 shows misfires on cylinders 4-6.

You can also check MVB 032.This will show you the reading from the 02 sensor.Should show 1-4 fields. 2 fields should read a percentage.Both fieldss with a percentage should be below 5.0% anything above is considered lean and you most likely have a vacuum leaks somewhere.


BTW no such thing as a low reading on a maf.Unless its reading zero.If the readings where high lets just say pinned at 25% then you can say yes its got a bad maf.When mafs fail on these cars they always read the max allowable percentage.But other than that I wouldnt consider that to be a correct diagnosis because if you clear faults out of the car the readings reset to 0.0% and go up as you drive.Healthy engine staying below 5.0%.

[old guy]

It would also be a good idea to monitor MVB 20 to confirm that the noise you are hearing is actually pinging. MVB 20 will show you the timing pull on the individual cylinders. The maximum pull is 12°. If one cylinder has excessive pull it may be a clogged injector as Kevin has suggested. If the pull is across all four cylinders it may be fuel related such as low fuel pressure or something else causing an unusually high A/F ratio under those conditions.

[diagnosticator]

It is only possible for the engine to ping if the ignition timing pull back is already at -12 degrees crankshaft. If the advanced ignition is not corrected by -12 degrees timing correction, then the ignition is occuring from some other hot glowing ignition source in the cylinder separate from the spark timing, like a carbon whisker or the plug tip is to hot due to a lean air fuel ratio. If the ignition timing correction is less than -12 degrees, then it is unlikely that pinging is actually happening. Otherwise, any pre ignition occuring is from some source other than ignition spark. Also, true pinging typically only occurs at higher loads with the throttle open, the cylinder charge density is usually to low at light loads for pinging to occur.

[old guy]

Thanks for the clarification. That is what I meant by excessive pull but I wasn't very precise with my explanation.

[Cadburry]

First, many thanks to all posters for detailed and very very useful help.

Regarding the oil I saw around the coils, it wasn't actually touching the coils but was rather found in the 4 galleries that surround the coils. With the coils in place it was easy to conclude oil was in the actual cylinder where the coil slips into. I cleaned the oil with a rag. I'm pretty sure it got there when I spilled some oil on the cover.

I will attempt to do the VAG COM tests you guys recommended and report back my findings.

[Kevin C]

Also, bad detonation sensors and or combustion chamber deposits can cause problems. This post might be worth considering:

The issue, it pings under light acceleration, very light acceleration like grandma driving, its consistent at around 1800 rpm. If im crusing and it hits that RPM and ive got little load on it, it will rattle like crazy. Tip in a bit it goes away immediately. Moderate, heavy, WOT no pinging. I literally just started to drive it after all the work and it had a full tank of fuel in it when I picked it up, im running it low as I can to fill it with premium. I dont know whats in it, but even if it was regular I wouldn't think it would ping at light loads. No codes no missfires no check lamp nothing.

I stopped by a local I know shop to borrow their scanner today to check the cylinder retard and check the knock voltages. You can sit there with your foot on the brake and bring it up to 1100ish rpm, about the same load im guessing if you were rolling and it will start to ping, it will sorta start to retard the timing but not really (8deg-11 deg). Sometimes it would ping really bad and it wasn't retarding the timing (0 deg), then it would back off the timing a bit and it would subside a little (still no more than 8-11 deg). The voltages for all 4 cylinders from the knock readings seemed to be a little over 1v when it would start to ping, if it pinged harder they would hit 2 or 3 volts, so I assume they are working. Fuel trim is good, its not showing its lean, Ive gone over the PCV and vacuum systems, the car starts right up, idles fine, good power, just pings at low loads. The plugs are single electrode platinum with a heat range of 7, NGK I think I put in, they are stock plugs and stock heat range. The ping did not change after I put plugs in it, infact none of the maintenance Ive done has changed the ping.

So WTF, hah. I read somewhere on some forum last week a guy had a 1.8t GTI and described exactly the same issue. Put 2 knock sensors on it and it went away. Im hesitant to go shell out another $100 or so as a hunch. (ive dumped a ton of $$ into everything else so far) What are peoples thoughts? I don't wanna give it to her till I have this fixed, cause ill end up with a melted piston or burned valve.

Mark

The Fix:

Well hate reading threads that don't have solutions so Ill put my fix here, as I have fixed the issue. New knock sensor didnt do anything. MAF looked good, O2 looked good, fuel trims dead on. I decided to pull the head assuming Id find pretty sizable deposits on everything causing the issue, as Ive had similar problems on other cars (not VW) My suspensions were correct. Chock full of crap, valves were not too dirty, but the combustion chambers had buildup on the flat parts, the pistons didn't have a single clean spot anywhere, and there was even buildup on the cylinder bore ridge. THe head is worn out, the valves that were held open by the cam moved more than im comfortable with, but since I just need to get it on the road I cleaned it all and reassembeled.

Fixed, no pings anywhere in the RPM range or load, runs much smoother

http://forums.vwvortex.com/showthrea...ght-loads-only

[Bische]

The knock control function is not active under 50% relative load, so if it's really is pinging on light throttle - the knock control will not pull any timing. Log the MV block with knock sensor voltage, it will tell if there is excessive noise regardless of engine relative load.

[old guy]

The knock control function is not active under 50% relative load, so if it's really is pinging on light throttle - the knock control will not pull any timing. Log the MV block with knock sensor voltage, it will tell if there is excessive noise regardless of engine relative load.

[Kevin C]

Agreed, very good info!

[Cadburry]

It would also be a good idea to monitor MVB 20 to confirm that the noise you are hearing is actually pinging. MVB 20 will show you the timing pull on the individual cylinders. The maximum pull is 12°. If one cylinder has excessive pull it may be a clogged injector as Kevin has suggested. If the pull is across all four cylinders it may be fuel related such as low fuel pressure or something else causing an unusually high A/F ratio under those conditions.

MVB 20 on my software measured "idle stabilization" and results showed values in CF, never above 12 though a few times it went over 11 while accelerating, not sure whether this is useful?

Carbon deposits are totally plausible. Would running gaz with higher octane than the specified 91 prove this theory?

[old guy]

12° of CF is the maximum so you will never see a value above 12°. That is an extreme amount of correction. Have you checked your LTFT (long term fuel trim) and A/F ratio to see if to see if you are running extremely lean? Maximum LTFT adjustment is +25%
Higher octane should also help a little.