Misfiring 2.8 Quattro. (URGENT)

[rookie_vag<3]

Greetings fellow members. I would like to skip the basics and get straight into the matter.

I drive a 2.8 B5 Quattro, I got it from my cousin who didn't need it anymore. It was leaking oil from everywhere but I drove it anyway for almost 4 months now and recently it started making all these tapping noises while I drove it for another week and I tried to diagnose the the problem by pulling out each spark plug wire while the engine idling, now, I am not a pro but I like to DIY and Im a Automobile major. I thought it was one of the cylinders causing the noise but it ended up being lack of engine oil. the oil level was so low that it wasn't even touching the dipstick. Topped up the oil level and the noise was gone, what I noticed while pulling out the spark plug wire is that there was a lot of oil on the wire itself and around the spark plug (a whole lot), few days later the CEL/MIL starts blinking and I have misfires on Cylinder 1,2 & 3. Changed the spark plug wires, spark plugs, replaced the valve cover gasket and the misfire is still on. the vehicle is lacking on power and it feels horrible to drive the car.

the reason i've been avoiding the oil leaks is because Im a student and I dont have a bunch of money to spend on, local mechanics say it needs a new timing belt but carrying out that job will cost more than the car itself.

this is a list of codes its currently dealing with.

P 1338 Camshaft Position Sensor Open or Short to Plus
P 1300 Random Misfire: Fuel Level Too Low
P 1130 Fuel System Too Lean
P 1250 Fuel Level Too Low
P 1127 Fuel Trim Bank 1 System Too Rich
P 0300 Random Misfire
P 0301 Cylinder 1 Misfire
P 0302 Cylinder 2 Misfire
P 0303 Cylinder 3 Misfire

Could it be the timing belt? or the fuel injectors? does this car use a ignition control module or a coilpack? is it the camshaft position sensor.

anyone ever dealt with this before? also anyone know a good samaritan who can fix it without burning a hole into my pocket? I live in San Jose, California.

sorry for the bad english, apologies for too many questions. apart from everything, its a great car and I would like to keep it for lifetime.

[imnuts]

If it needs a timing belt, and your current belt breaks, you'll be out a lot more than the cost of a timing belt change. It would probably solve the oil issue too, as you probably need new valve cover gaskets, which should get changed with the timing belt. The cheapest option would be to clean up all the oil and change the gaskets.

Sent from my DROID Turbo 2

[rookie_vag<3]

But I already got my valve cover gaskets replaced, if it still leaks oil then my instructor said it may be the Camshaft Chain tensioner gasket (half moon seal). Does this engine use separate timing belts for each camshaft? I was wondering why only cylinder 1,2 and 3 while cylinder 4,5 and 6 are fine. does a bad camshaft position sensor cause misfires?

[PZ.]

Actually it's not the belt. It's the lack of oil that was the problem. If you are lucky, the cam chain only skipped a tooth (or two) while it lost pressure to the tensioner. It may have worn through the plastic chain guides and they broke (also common on engines that use dino oil). If you are unlucky, the chain skipped more that 2 teeth and the valves are bent.

Remove the valve cover and check the alignment marks on the cams by the chain. With the engine at TDC, there should be 2 notches that line up with marks on the cam bearing caps.

http://ww2.justanswer.com/uploads/rs...mageaction.png

[rookie_vag<3]

You sound so sure, Hmm, I'll check it and get back to you soon. Thanks anyway.

Whats "dino" oil though?

[rookie_vag<3]

So, an update on this situation.

I drove the car with misfires all the way upto August 2017 when I finally gave it to repair and I told the mechanic Im guilty of not putting oil in the right time and as the PZ. suggested, it may have mechanical damage and the cam chain may have skipped a tooth or so but to my suprise he took his time and got back to me saying that the engine is fine and its an electrical problem, at this point I was super happy as the engine being in shape was important to me. The mechanic claims he checked all the wirings, put a new cam position sensor, did all he could but the fault still persisted and told me the ECM was bad. I got a new ECM and he suggested taking it to the dealership to get it programed for the immobilizer but to my knowledge theres no immobilizer for this car as its 1998 make and he agreed with me and replaced the ECM by himself. New ECM also did not fix the car.

At this point I feel like giving up on the vehicle but I recently had the CV axles done and the body is in good shape including the transmission. Any suggestions? What could be causing the misfire?

[95blkmax]

Do you still have the same exact codes as listed in the first post? The following is just my brainstorming process so I apologize if it sounds like gibberish.

If so, something doesn't add up here.
1- Timing being off on one side of the engine would cause misfires on that side AND it would give a code for the cam pos sensor (which P1138 is for Bank1). So that is consistent, BUT your mechanic says that the engine is mechanically fine. No disrespect to the mechanic but how sure are you with his determination of the engine's condition? It could sound just fine and idle smoothly and still be off timing. But like PZ said last year, you'd have to remove the VCs and check the timing marks with the engine at TDC to determine that).
2- P1127 is bank 1 being too rich, that's your cyl 1 2 3. P1130 is bank 2 being too lean.

ECM detects misfires on one bank so it richens the fuel on that side to save the engine (normal safety protocol). What's odd to me is that the other bank is showing too lean. So, the B1=Rich situation is explained by the misfires detected and the computer trying to save the engine. So more fuel is being dumped in one bank and there's too much of a pressure drop there for the fuel pump to also feed B2 (hense it being lean). HOWEVER, this would not explain why the cam pos sensor is giving a code. So I wonder if you have two unrelated problems going on simultaneously.

Also, are you sure that the affected bank's CPS (bank1) was replaced and not the good side? I know it sounds silly, but at this point it's worth asking being that it could have been an honest mistake.

// End brainstorming //

My recommendation, double check the timing marks are you were previously advised. Get a second opinion from another mechanic if you don't want to check it yourself. The fact that the cam pos sensor was replaced, yet the code and misfires are STILL present would justify the work to me. Also, make sure that the CPS replaced was in fact Bank1's CPS.

Additionally, based on my brainstorming above, have you ever changed the fuel filter (it's still possible to have timing off one one bank and it being rich... but for the other bank to be lean isn't normal if things are well there)? It points to me as not enough fuel pressure somehow. One more for you as I'm thinking; you mentioned you got this car from your cousin. To your knowledge, did this engine ever overheat?

[rookie_vag<3]

Hi, firstly, thanks for stopping by and giving your valuable feedback.

Lets get talking now, No I haven't checked what the codes are in a long time. (I should do that) and No your brainstorming made a lot of sense so it didnt sound gibberish.

Honestly, I am not sure what this guy has been doing. I found this place on Yelp and read more than a dozen of his reviews. He was quick to respond thru Yelp and took the car within a couple of days. Since then Its been hard to reach him over the phone but when I do he does apologize and reassure me on the work being done. So, dont wanna bore you guys with the anecdotes but I am pretty confused why this guy cant figure out whats wrong with my car. I've seen R8's(not that an R8 in a shop instantly makes the owner a pro) driving into this place and trust me this guy isn't a amigo with a backyard (no offense). He claims to have worked at the Audi Dealership before this shop. Long story short. I don't know if I trust this guy or not. He has been mentioned in this forum a couple of times.

I also haven't asked him to remove the VC's and check. I just wanted him to do his own thing and assumed he would know if he had to.

HOWEVER, this would not explain why the cam pos sensor is giving a code. So I wonder if you have two unrelated problems going on simultaneously.

This could be a possibility. :( I would definitely NOT hesitate to ask any kind of silly question now so yeah I will make sure if the CPS has been changed on Bank 1. (fingers crossed on that)

Nope, don't remember changing the fuel filter and the enginer never over heated in my possession will have to consider both these possibilites too.

Thank you so much. Will work on your advice and PZ's long forgotten suggestion.
Peace

[95blkmax]

Yea dude check the current codes on it. My brainstorming was based on what we had at the time of the first post. Waiting to see what list you come back with! (Hopefully shorter list too)

[95blkmax]

And thats great about no history of overheating. I was doodling if that bank1 head had warped and was loosing enough compression that the computer detected misfires.

Definitely change the fuel filter. If you havent done it i bet that sucker is clogged up. This piece of normal (and cheap) maintenance (depending on how bad it is) could explain that bank2 lean condition.

The closer you get the engine to OE status by eliminating little gremlins, the easier it is to figure out the problem(s). ... This is the reason why some shops are scared to work on souped up cars lol

[PZ.]

Sorry, I don't get on here too often. As a poor student, you need to do some basic work yourself. Pulling a valve cover is pretty easy and you will notice if the cam chain marks do not line up. It is also possible that the plastic shoe that the chain rides on has disintegrated (either the upper or lower shoe) and that has caused the chain to skip. I worked as a mechanic about 35 years ago and started working on B5 Passats and Audis as a side job about 15 years ago after I purchased one.

[rookie_vag<3]

Had a good 20 minute audit session with the work that he has done on the vehicle so far.
He claims to have checked timing marks by opening the VC gaskets. (everything was fine) Doesn't really agree on the fuel filter problem cos he was like if thats the case it would affect all the cylinders and not just one bank. (he didnt say this but he was maybe hinting that the rich condition on the bank 1 wouldn't exist if the filter was clogged)
The reason he is so sure that its an electrical fault is that he did a voltage check on the CPS wiring to the ECM and the fault(less voltage) would come on with just the key in the "ON" position.
I'm not sure what he thought about the lean condition on Bank 2 (I think I forgot what he said or maybe he didn't talk about it at all i dont remember sorry)
He also claims to have done a continuity test(if thats not the same thing as what I mentioned above) on the wire that connects CPS to ECM.

At this point the vehicle is in the dealership and I have authorized them for the diagnosis. Got a little adjustment on the price as my mechanic was a former tech at Audi.
Fingers crossed on what they come up with.

Thanks PZ for ur inputs. will also speak to the mechanic about the plastic shoe thingy.

[rookie_vag<3]

Just got a call from the dealership, they claim that the fault is a weak cam chain tensioner and the timing is off. (Why are the alignment marks still on point then?)
Mechanic says he can replace it for ~$700 including labor. Any inputs on that?
At this point I am worried if It is a good idea to spend ~$700 on a almost 20 year old car with 190k+ miles on it. :(
More inputs please!!

[95blkmax]

Conflicting diagnosis from two sources.

You asked for input: When I was a poor student, I saved a TON of money doing the work myself (and still do). But if this project is out of your comfort level, then you have to weigh your options (as you're doing already). As long as you're in school with limited income, you need a reliable car. On one hand, you can sell this car and get a car that is much simpler to work on and very reliable (Toyota Corolla/ Camry 4cyl) to get you through your school days. The problem with jumping on to another car is that you don't know it's history. You don't know if it was abused and you just purchased a ticking time-bomb. On the other hand, you have a car you've owned over a year, and you have the benefit of being close to the previous owner. So you know exactly what's been done to the car. If these $700 fix the problems with the car and you can get another year or 2 out of it, it would be money well spent.

Personally, I would replace the tensioner and chain guides (along the recommendations of PZ above). ECS and other vendors sell timing chain service kits. If you can do this yourself with a buddy that is more familiar and comfortable with this project, you can take it as a weekend project and save yourself money in labor. But this is your decision to make

[rookie_vag<3]

woaaaah. been over a month now since this happened. sorry guys . got the tensioner replaced and it fixed the problem. the mechanic was explaining that the tensioner was fully expanded and seized when adjusting. the fully expanded tensioner resulted in the cam chain being over streched which caused the timing to be off. labor was expensive but i finally have it running properly. normal wear and tear was described as the cause of the problem. thank you PZ and 95blkmax for your time and inputs. :) peace

[warrenzo]

Great you got it fixed! Misfires are almost always the timing belt tensioner with these cars. Lots of people replace the timing belt and skip the tensioner, but they should be replaced together. I've also seen people who replace the timing belt after it's snapped, and inevitably your valves will be bent, so that'll make it misfire, too

[95blkmax]

Heyhey! Glad to hear rookie! Thanks for followng up with a final outcome