So my car is a 2000 5.5 Audi S4 Tiptronic B7. I don’t really have any previous history as far as stuff that has been done to the car other than what I have done. I have lately then getting into the diagnostic part of cars. Like using the MAF sensor and the map sensor to pinpoint lean conditions like vacuum leaks, and using stuff like fuel trims…etc. Lately my car has been running a little rough here in there. The car will be at idle, and all of a sudden it feels as if one of the coils drops off for a few seconds. The engine drops in RPMs, runs a little rough and then Smooths back out. How do I go about logging with vcds? I have a Ross Tech cable but I’m not an expert on using it to do logging. I don’t drive around with it plugged in, so capturing it as live data will be hard. Would this be stored somewhere as freeze frame data?
As you said logging and vag com is helpful when you can watch the car real time. Logging works when you know you can capture the event.
I usually try to pin point an issue like your talking about. So over like a week or so I will take the time to write down notes on stuff like temp, time of day, how long driving, car warm or cold, cold start warm up, AC cycle on or off with the transmission being automatic I look at comming to a stop after a log drive.
Other wise your logging tons of data and youll have to sort though all kinds of data in a log and that is hard because you might not know where the event happened.
Thats how I do it and a lot of the time I dont have to log very much once I get a chance to single out when the event happens or how to get the car to replicate the issue. If you can kinda do that and share your thoughts on what triggers the event or when you see the event we can help tell you what to log to help you find the event or sort it out
ok thanks! i’m going to keep my eyes and ears peeled for if there is something that provokes it. The only thing off the top of my head i can think that coincides with the rough idle is when she is hot. However, every once in a while it does it when i first start it up. How do i log the car with VCDS? and one of my concerns is the timing components…i know there has to be a way to watch the live data and determine if there is something up in the timing department. I’ve watched the live data from the knock sensors (one or two have odd readings compared to the rest) and ive watched the timing. It tends to fluctuate up and down (dont know what to make of it) Anyone care to walk me through doing a logging session and what to look at to try and help narrow it down when it DOES mess up?
Thanks!!!
Lots of different points to talk about.
Knock voltage will be different in each cylinder and can wildly change depending on weather or gas or load it can wildly be different. Also when you see where your knock sensors are located it makes sense why the signals are what they are.
The timing ignition wise will always jump. The MAF and RPM will cause that to change. That is also from MAF RPM temp load the list goes on. When the car has to turn on something like fan or AC the timing will also jump around. If you were to get a constant MAF reading and a constant RPM your timing would be the same.
As for logging its really easy. Just pick the blocks you want to look at and log when you hit go look at the bottom of the screen and you will see the log tab. Just hit that and a box will pop up asking you what you want to name the log. The only thing you want to look at is at the top of the screen there is a turbo tab. that turbo tab will allow you to look at more then on block group at a faster rate of sample
Awesome. I cannot thank you enough. I will log the car over the next few days and report back what I get. Yeah the knock sensors are in a weird place. It was only like one or two that the readings were all over the place, but I’ll see what the logs say. It was running kindof rough today. Wish I had my laptop with me. I’m going on a long drive tomorrow and I’ll have my laptop so maybe I’ll do some logging then. Thanks again!
I just picked up a VAG COM as well and have NO idea how to use. is there a special site for tips or anything?
Iirc, Ross Tech has a forum about that.
They do which is great for the basics. If anybody has any questions then please ask because a lot of people here will be willing to tell you exactly which measuring value blocks, basic settings, etc to check.
Hey Jimmy, what measuring blocks would provide the best information for me to log? And by the way, the one common denominator I have noticed every time my car does this, is the car is hot and I am idling at a stoplight.
First I would like to check fault codes to see if you have any fault codes present. This may sound stupidly easy but even I have to start with the simple stuff first.
Then it should be simple to test certain things since you know that this happens when the engine is hot and idling. That sounds like a temperature related vacuum leak to me. I sound like a broken record to me at least, but please check that the 5 mm allen bolts for the intake manifold are tight.
The way that I would diagnose this issue with a vagcom is by going into measuring value blocks sections and the engine warmed up running at idle. First look at channels 15, 16, and 17 to check for misfires. There should be no misfires at all and each block is labeled for which cylinders are misfiring if they are. This gives you an idea of how your spark plugs and coil packs are working. Next go into channels 3, 32, and 33. Those channels show the MAF reading, long term fuel trims, short term fuel trims, and some other stuff. I am interested in the idle fuel trims because the partial fuel trims are anytime that the throttle is opened at all. They should be below as close to 0.0 as possible. A positive number is lean and a negative number is rich and the ECU has to see above 10% either way to set a fault code usually. With the engine running at idle and that second set of channels up, spray starter fluid or carb cleaner around the intake manifold while watching the channel 33 values to see if the idle fuel trims go really negative (like -20%).
ok so it has been a bit. stuff is crazy at home right now. so my car has been feeling like it is super sluggish (like it did when the intake flapper was stuck) so i did some logging… i think… either way here is what i found:
No misfires. there are some fault codes yes…
6 Faults Found:
18358 - Radiator Fan (V7)
P1950 - 001 - Movement Restricted / Jammed - Intermittent
17981 - Left Engine Mount Solenoid Valve (N144)
P1573 - 004 - Open Circuit
18043 - Powertrain Data Bus
P1635 - 008 - Missing Message from A/C Controller - Intermittent
19475 - Valve for Exhaust Flap 1 (N321)
P3019 - 004 - Open Circuit
18010 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
17978 - Engine Start Blocked by Immobilizer
P1570 - 008 - - Intermittent
The engine mount code has been there for a while. i’ve been told that ill need to replace that. on the list of things to get around to. The exhaust flap i know about. the tank has been removed and the hose capped. there is a possibility that it came undone while installing the sound deadening material to the trunk. The radiator fan… well i looked at it. it doesn’t come on when the passenger fan does. It moves freely so im going to have to assume it will need to be removed to check it out. Not sure where the best place to start for that will be. The other codes… not sure.
I did happen to click the log button a few times while driving. Not exactly sure how to go about decoding that or what not. i can post it or whatever i have if needed. I’m kindof in the grey area as to know what to do with it.
Ok so i had something happen that i found extremely odd… yesterday while i was idling at home, i heard a knocking sound coming from the fuel filter area. At first i thought the neighbor kid was messing with me (yes it was that loud)… then it did it again and the engine did its rough idle thing and then settled back to normal. exactly as i was describing in my first post. i have heard it do that i think a total or 3 or 4 times… but never really thought anything of it. I have read elsewhere someone having the same sound coming from there. cant remember what he found. The fuel filter is a newer filter…one of the first things i bought from ECS tuning. looks like the name brand is Hamburg-technic or something like that. lol. might be the problem there? could this really be as dumb as a bad fuel filter?
moving on… so i did some more checking. all the intake bolts are tight…however, when carb cleaner is sprayed around the drivers side of the intake manifold, the short term fuel trims go from like -7% up to -20% . Bingo. intake manifold leak. Thank you Jimmy. i actually recorded a video of it. its at night and its dark but you can clearly see what im doing and it does go into the negative pretty far. No noticeable change when the other side is sprayed or the intake elbow is sprayed. That being said… when i was sitting in my car, (before the spray test) the numbers were both in the negative sitting about -5 to -9% and then the car did its rough idle thing (had just turned the logging off ofcourse) and immediately after it did its rough idle thing, the fuel trims went positive. not a whole bunch… but both of them jumped to 6 or so percent positive (lean) and stayed there for a while.
on a side note… since im complaining about my car running slow… i was challenge to race a mk3 volkswagen jetta with what looked like the EXACT engine that came out of my GTI. I polished the upper intake manifold to a nice shine and painted the lower intake manifold white to match the oil pan and parts of the upper intake manifold. I hand assembled that engine and as the guy drove by me (at the park with no hood) i could see what looked like my old engine. i could distinctively hear supercharger whine. sure enough… the engine was now supercharged…
i guess it just wasn’t my day (had my fiancee and kids in the car. out looking at wedding venues) The guy parked next to my S4 for a minute and then proceeded to leave the park. Well as i left, he burned rubber to catch up to me. He followed me out of the park and up this long hill. The sensible adult with my children and fiancee in the car decided to not race him, but to watch him in my rear view mirror revving the engine, for about a mile or so. haha. he passed me and just for fun i decided to see if i could pull on him… im sad to say… though his car sounded nice… i could have passed him. haha. anyways…that has nothing to do with my car running like doo do… just had to pass that on to someone
The codes look like standard long term codes that if you cleared them probably wouldnt come back. I would write them down and just clear them. See what happens over the next few days. If any of the codes come back you can look further into it. The mount code will probably come right back and the exaust code seems like you know what the cause of that would be.
The intake manifold might benifit from just loosening all the bolts and re tighten down the intake. Use the X pattern and start in the middle to tighten down the intake. You might have to go back a week or two later and re tighten down the intake but if you had a leak that might be a good place to start.
I’ll just use it as an excuse to buy intake spacers lol
So now Im convinced something is up. My car is pretty darn sluggish. And it’s from idle on up to like 4 grand. With this acceleration, i Might as well go buy a Honda. I’m going to start digging In so see if anything sticks out. What would make it run rich? It has a new air filter so it’s not starving for air. . But what else? Could clogged cats cause both sluggish acceleration and rich conditions?
Since I can’t seem to figure out how to edit my post… when I say running rich…I’m taking about the readings in vcds. They were just under -10% and occasional jumping up to -12%. ( without the addition of carb cleaner)
My theory would be the oxygen sensors reading lean due to the intake leak and calling for more fuel, thus reading rich.(just my theory lol)
- Would logging some acceleration runs help?
- If I wanted to read or watch the log… how does one do that?
- I went and got gas somewhere I normally don’t go. Could that cause it?
I checked and the intake flap seems to be moving at 5000 rpms so I’d assume that is still functioning as it should be
You can check the intake flap and hardware on first key up after the car sits for a while.
Have a friend pop the hood for you you stand at the front of the car take off the cover that covers the flap and the arms of the intake flap After that have a friend key up but not start the car. The intake flap arms should move through the full range of motion.
As for the other parts. Do you still have your stock air box. Lots of guys years ago had issues with the open air kits that were out there. The open air kits actually pullled in hot air and hot air caused the tune to add more fuel.
Are you on a stock tune still
Ok I’ll check the flap this morning to make sure it is moving properly. I am sitting stock on both the air box and tune
ok then its good to check the usual and go from there. If you think the intake could still be part of the issue Remove the intake and mark what full travel is with the flap and note if the flap is wide open on the travel
You should be able to test the flaps with the VCDS Engine output tests.
Below is a video of an A6 with output test. You basically use the same method.
awesome thanks! i will check it with that method the next time i scan the car (just got inside from doing some testing) so here are a few things i saw tonight:
http://i1098.photobucket.com/albums/g361/sq5hunter/20160421_225542_zpsr7uxbfe6.jpg
http://i1098.photobucket.com/albums/g361/sq5hunter/20160421_225516_zpsqbbiot9t.jpg
i did a log for a few minutes with some acceleration runs and it’s 6.4 seconds in vcds. PaTHetic. why would the engine run so rich? wouldn’t the intake manifold leak cause it to run lean? the o2 sensors can trim the fuel for the leak but what could make it run that rich? it was pretty consistent around -10%
could this be from a faulty fuel pressure regulator inside the fuel filter? couldn’t be a stuck injector or it would be on one bank. if it was one on both banks then it probably wouldn’t be so close together in numbers between sides.
what would the effects of too much oil in an s4 engine be? not talking a huge amount, but say half a quart to a quart. (curious for other reasons. looking at cavitation and its effects on engine performance)
if there was, say a clogged cataletic converter, wouldn’t that cause the engine to run on the rich side? (backed up air has to go somewhere. Reason i ask is because for some reason i feel like my exhaust isn’t as loud. i noticed an interesting sound coming from my exhaust today. hard to describe, but i would call it a burble from the middle of the car (near the resonator) i tried to catch it on audio recording. its a short video and the video doesnt do it justice.
http://i1098.photobucket.com/albums/g361/sq5hunter/th_20160421_212638_zpsjjo9kmux.mp4
I really hope it isn’t one of those exhaust flaps. i would feel stupid. however…it wouldn’t explain both banks running rich.
You are looking at short term fuel trim in those screen shots. They jump around quite a bit and those numbers are normal.
The long term fuel trims are what you’re probably looking for and are read from group 32.