trentster_08 0 Posted April 23, 2015 Report Share Posted April 23, 2015 I finished building my VRT last year. It's a mk4 12v AFP motor using C2 42# tune and 42# injectors. Standard compression. The car has ran rough at idle ever since, it kind of sounds like it has a big cam in it. I have ran logs in VCDS and it seems to run very rich at Idle and very lean under boost. I was hoping the fuel trims would stabilize overtime but they continued to be just as bad and eventually led to a washed piston ring. The car has two known issues. First of all, I used the stock plastic intake manifold and because it sits right above the exhaust manifold, its getting very hot. I'm sure this is contributing to the lean condition. Secondly, the shop that built my downpipe pie cut the turns instead of bending them which is probably causing an uneven flow of exhaust gas over the O2 sensor. It also has a few leaks around the cat. I am hoping this is causing my rich under idle condition. So do you believe that if I rebuild my exhaust correctly and install a short runner intake manifold the car should run at proper AFR? Thanks for your time ️https://vimeo.com/125817135 Link to post Share on other sites
vr6turbo 27 Posted April 25, 2015 Report Share Posted April 25, 2015 hicheck your coolant temp sensor using vag com its what decides the fuelling until the lambda gets hot Link to post Share on other sites
trentster_08 0 Posted April 26, 2015 Author Report Share Posted April 26, 2015 Ok I'll replace that soon thx for the advice Link to post Share on other sites
vr6turbo 27 Posted May 2, 2015 Report Share Posted May 2, 2015 any news on your car Link to post Share on other sites
Mk3highline 287 Posted May 4, 2015 Report Share Posted May 4, 2015 Id be tempted to get the software checked or a remap Have you got the correct size MAF housing for the software? Link to post Share on other sites
FishWick 21 Posted May 8, 2015 Report Share Posted May 8, 2015 (edited) Leaks upstream of the O2 sensor can cause it to over fuel, but as you're running OBD2, check the measuring blocks in VCDS to see how much the O2 is adding at idle. If it's a very small number (talking 1-2%, which is normal) then the problem is elsewhere. FWIW, I had the same tune on my UK OBD2 engine. 4" MAF, 42lb injectors, C2. I had exactly the same problem. I was seeing 14.7 AFR in boost and it didn't drop to 12-11.5 AFR until 5500ish rpm and pedal to the floor. Luckily I was running 8.5:1 forged pistons otherwise serious detonation would have occurred. Never got to the bottom of it, so went back to standalone. What are the 42lb injectors out of interest? Bosch green tops? They are notorious for having a crap spray pattern at low duty cycles and can also leak, which may also be the cause of your poor idle. Edited May 8, 2015 by FishWick Link to post Share on other sites
apollovr6 1 Posted March 30, 2016 Report Share Posted March 30, 2016 Well here's an update everyone. (I'm the OP just switched usernames) After a year of meticulous rebuilding I've finally got her fired up and running decent. If you would like to see my current thread and read what's going on here's the link: http://forums.vwvortex.com/showthread.php?7771897-VRT-Running-Very-Lean&p=94896073&posted=1#post94896073 Link to post Share on other sites
apollovr6 1 Posted March 30, 2016 Report Share Posted March 30, 2016 (edited) For those of you that would rather have the information here: Rebuilt the motor (new rings, bearings& timing chain kit and ARP head studs). Also built a full 3" exhaust, switched to a SRI and added a front mount intercooler. Fuel injection is still C2 Stage 2 with Bosch 440s & 4" MAF but added an inline Walbro 255. Also replaced the fuel filter and now have functioning wideband, boost and fuel pres. gauges. At first I was running extremely lean (17.2:1AFR with ecu adding 25% fuel) until I changed my Intake/MAF configuration. Now I'm running stoich but the ecu is cutting about 22% fuel. So it's nowhere near perfect. I havent even driven it yet so who knows what will happen then. What I've learned: the MAF condition/setup has a detrimental effect on how it runs. And the air filter needs distance from the MAF or it will throw off air speed through the housing and cause a super lean condition. Edited March 30, 2016 by apollovr6 Bealieboy 1 Link to post Share on other sites
RBPE 198 Posted March 30, 2016 Report Share Posted March 30, 2016 1. Check all hardware, could just be a faulty lambda probe or something. 2. LTFT's go out of sync due to the bank specific readings of the ecu and the adaption and learning routines the ecu has for injection - very common problem when going NA to FI on these as you change the boss placements/manifolds when adding a turbo. One way of getting around it is hack the data so that the ecu is actually reading from one bank, a number of people have done this and it works fine it seems. Otherwise, you need a proper exhaust manifold with the bosses in place that you can take the readings from - like HPA/HGP's mani's. However - I do not know what C2 have done in the ecu so the tune's are very much part's dependent unless you can go through all your ecu and mod it accordingly, they could have done the hack which would render the new mani somewhat obsolete without a re-tune? 3. The MAF/HFM is the way in which the ecu knows how much air is going into so is probably the most important part of any tune! When they max out some re-scale them and some upgrade them to larger one's - pulsations maps are also present in the ecu - easier to keep the pipe straight though really! Link to post Share on other sites
apollovr6 1 Posted April 1, 2016 Report Share Posted April 1, 2016 I've already checked the oxygen sensor and compared it to the wideband sensor and they match identically. Got the car running in and out on the road for about half an hour didn't go too crazy but noticed wideband was all over the place. It stayed stoich when cruising steadily. But anytime in and out of boost it jumped all over the place. Another problem I've noticed is low vacuum and I can't locate the problem. Have already done a compression test and boost leak test . Link to post Share on other sites
apollovr6 1 Posted April 1, 2016 Report Share Posted April 1, 2016 (edited) Is it possible cam timing is slightly off? Compression #s were from 150-170. As for the bank specific readings, all of us on c2's tune generally use the ATP style one piece cast manifold, (with O2 sensor in the mid pipe) most with success. So that's probably not the issue. AFR's are all over the place, except when idling and vac is low so I'm leaning toward a fuel system/sensor/vac leak. Edited April 1, 2016 by apollovr6 Link to post Share on other sites
RBPE 198 Posted April 2, 2016 Report Share Posted April 2, 2016 I think you misunderstood. The ME ecus take their inputs from 02, Pedal position, Eng coolant temp, air temp and cam/crank position sensors so if any of them are defective it causes all sorts of problems throughout the ecu as many maps are interconnected. Like you said, could very well be a hardware problem like a leak or those sensors, usually is, those are all what ultimately need checking if your car's running badly. What I was getting at is when you go NA to FI on these there's a fair bit of work involved in the ecu. you need to redefine the axis of maps, add boost/PID controls, change multiplicative's and so on even before you need to modify things like timing due to NA/FI differences! The main part is the injector constant, krkte, as you are going up to 440cc, 630cc, 1000cc's etc, so obviously the math has to change accordingly. A part of this is obviously the MAF/HFM as that is how the ecu actually tells the engine what air is coming in, probably pretty much the most important part alongside the injectors and you have those 2 as the absolute fundamentals, air and fuel. As you are adding boost you're obviously upping the air significantly and you can use stock maf's or it needs rescaling accordingly as it maxes out voltage wise....and of course due to high mach numbers causing turbulent instead of laminar flow - i.e. poor maf reading's due to turbulent air/high mach numbers/air speed all dictated by ultimate volume flowing through the orifice, is basically why some tuners advertise "you need a 4" maf housing" - their tunes/maps in the ecu are modified accordingly because of those factors! Because that essentially dictates the air in air/fuel it is, alongside the changing of math for bigger injectors, most important to get those right first and foremost. Say, someone buys a tune and doesn't use the advertised maf, the values in the maf maps are not correct, as such it confuses the ecu as the math doesn't add up! It's all math by the way as it is electronics. The ecu therefore tries to compensate to make it logical again. These ecu's have amazing adaptive functions, the guys and gals at Bosch really must be genii - no not the genie definition of that word that seems to be replacing the plural of genius, although a champion of that I digress... these adaptive functions are very prominent in the injection areas. In short, the ecu takes readings over periods of time and if something doesn't compute it adapts to overcome. (The more I learn about these ecu's the more I am amazed - make aftermarket systems look like children's toys if I am honest! Kudos to Bosch's white jacket wearers!). SO........ the point I was getting at, is that it MAY be a case of the ecu adapting due to some problem not entirely related to hardware or no longer the hardware shall we say. It does have the ability to adapt after some things are changed/replaced like a sensor and why 99% of the time it's usually a hardware problem and then reverts back to normal. HOWEVER, for example with the bank specific readings I mentioned, these problems were from the ecu reading 2 banks of 02 stock, you obviously change to 1 in the downpipe gong FI so you either use a mani with bosses or have to hack the ecu to compensate. I'll stick a quick screenshot of a part of how it works - diff FS for diff ecu though, you can see a flip-flop switch on the diagram and bank specific aspects and again, being electronics, it's simply math and the ecu taking inputs and calculating. Point I was making though is a lot has to be changed with these for fi and the stock ecu doesn't like certain changes without hacks, thus making them possibly more temperamental! Add to that something to throw it off and it tries to adapt to work properly again, not always with success! In summary then regarding why your car runs like a bag of spanners? Simply put - Why does it not compute? 99% of the time it's hardware specific, leak or sensor related as mentioned in the first paragraph - have to check all those sensors I'm afraid just in case as they are all inputs for the ecu, however, sometimes, something's upset the ecu and the math's changed. LTFT's on bank specific readings were a common cause on early fi tunes and as the ecu was constantly adapting for injection, they got worse and worse over time. So what started working alright became worse as the ecu adapted and no-one really knew why. Very clever these ecu's though, they do what the can to protect their systems (I bet Bosch eggheads create Skynet! ). So, if you check and replace all these inputs and still have problems, that's your answer! You may inadvertently cause this upset via moving/changing parts and as such, sensory inputs may not be as they should or possibly the ecu changed it's functional logic to compensate and it cannot go back to how it was for whatever reason. Those statements should pretty much cover everything and basically explain all running problems though! Functional logic: http://i194.photobucket.com/albums/z252/bigady69/VR6%20R32%20%20Tuning/LAKH3_zpsya9ickw2.jpg[/IMG] Some good info: http://s4wiki.com/wiki/Tuning#Idle_LTFT_and_idle_misfires Link to post Share on other sites
apollovr6 1 Posted April 2, 2016 Report Share Posted April 2, 2016 Wow, great info. Seriously, thanks for the in depth info. That is a rarity on any forum. I hardly feel worthy of such wisdom. It's going to take me some time to digest all of it. i think I understand that your saying all the proper ingredients need to be intact for the particular tune. I've already got all that covered. As for the bank specific readings, I'm still a little confused. The standard 12v vr6 only ever has 1 bank even from the factory. Both exhaust manifolds join in the downpipe and have a single pipe back with one primary and one secondary oxygen sensor. Feel free to correct me if I'm still misunderstanding. Anyhow, took the car out again and it seems to be adapting well. AFR in boost now sticks at 11.7 and cruising is 14.7. My only issue is idle where it hunts up and down. Going to check all my wiring, I'm getting a fault code now: p0116, eng coolant temp sensor- implausible signal. And the sensor is 2 days old. Because of this I had no coolant temp, coolant fan or after run pump. To sum it up, I'm going to keep messing with and/or replacing hardware components and hope for the best. If not I'm going to have to go standalone. I will report back later. Link to post Share on other sites
RBPE 198 Posted April 2, 2016 Report Share Posted April 2, 2016 I'm as fallible as the next guy sunshine but I will admit it! I have 28 years of car building and about 5 years of hacking the ME7.1.1. ecus to bits to fall back on so I do know a few things but I'll admit I still need to educate myself and always will! Ignore the bank specific readings aspects, I was merely trying to put across the point of something might change in the hardware that causes the software to change it's logic and therefore cannot re-adapt back afterwards and so even if you revert back it still doesn't work correctly! That and budding DIY tuners crave these tings! Needed to put up a simple post too, of the fact that many will have running issues and that covers all of them pretty much, you have to check all sensors as the ecu needs them right for logic, check leaks and then onto the software but if you've ever changed all inputs to the ecu, then I hope you understand that the functional logic in the ecu has changed! Link to post Share on other sites
apollovr6 1 Posted April 2, 2016 Report Share Posted April 2, 2016 i get your point then. Functional logic? A little over my head. I would love to be able to tune and understand these ecus like you do. I can't even manage to connect to one though. Would probably help me out a lot if I had that capability. Link to post Share on other sites
RBPE 198 Posted April 2, 2016 Report Share Posted April 2, 2016 Functional logic is simple - everything in the ecu has to be calculated, as such, it is always math! https://en.wikipedia.org/wiki/Functional_verification https://en.wikipedia.org/wiki/Functional_completeness https://en.wikipedia.org/wiki/Logic_gate https://en.wikipedia.org/wiki/Boolean_function Link to post Share on other sites
apollovr6 1 Posted April 3, 2016 Report Share Posted April 3, 2016 (edited) Forgot to ask, last night I did a couple pulls through first and second and shredded a brand new belt? You guys ever heard of this? The belt had a very small tear from the dog getting a hold of it but I don't think that caused this? I mixed and matched mk3 and mk4 accessories, they don't have different numbers of pulley grooves do they? The uphill battle continues... *Edit: got this sorted. Had the pulley on backwards. Edited April 3, 2016 by apollovr6 Link to post Share on other sites
apollovr6 1 Posted May 23, 2016 Report Share Posted May 23, 2016 Well, Ive got a new problem now which really has me stumped. While attempting to install a GM coil pack, I shorted the coilpack power(between ICM and coil) to ground and popped a fuse. Since then it wont stop misfiring/running like crap and knocking at idle. Ive got spark at all plugs, plugs are new and gapped at .022. Plug wires are brand new. Compression and timing is good. Pulling #2 and #6 plug wires have no effect on idle condition, but the other wires being pulled makes idle worse. Disconnecting #2 and #6 injectors makes idle better. Strange thing is, im getting spark from all 6 plugs. Seems to me that #2 and #6 spark is off-time causing the misfire and knocking. Here's where it gets stranger...I followed the Bentley's diagnosis procedure for testing the coilpack system and the signal from the ECU to the ICM isn't flickering with a test light. Instead, its solid on all 3 signal lines. So what the hell is going on here? How can I have a solid spark signal while turning over the motor but it still runs? Thanks for your help. Link to post Share on other sites
IDMR32 0 Posted March 6, 2022 Report Share Posted March 6, 2022 Im having similar issues on my boosted mkv r32. You ever figure out your problem? Link to post Share on other sites
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