bugblatterbeast

sounds like your tip in table is off. you can load the tip-in values from the map I sent you since we are using the same injectors. you will still need to tune a bit but the values should be close. you will need to do a base map flash for the values to take effect. once you have the data loaded, can you log tps delta, fuel trim learned, fuel trim immediate and AFR. 7-10 samples a second should do. you will need to drive in a really jerky way ie; keep getting on and off of the throttle. 20 mins worth of logs should do the trick.

Hi Christian, I was wondering if there's any way we can get access to the cold start tables? I have a bit of a hickup on cold start with 740cc injectors. The car will fire up pretty quickly, then bog (rich I'm guessing) for a few tenths of a second then ramp up to the normal cold idle speed. I've adjusted the scale and latency values at 14volts and again at 11.5 volts (actually reduced the electrical system voltage and got the value there). Since my fuel trims are within a percent or two of zero (and my idle is smooth) I'm pretty sure there isn't an error in my scale or latency values. If the cold start enrichment can't be adjusted, is there any other way to fudge the values? I was thinking of messing with the maf calibration but haven't gotten around to logging maf during cranking (I'm not even sure if our cars use the maf during cranking, or if the cranking maf voltage will be lower than idle) any insight would be appreciated thanks

we are both on the learning curve;) there are many like Christian and Edmundu with far more experience... so in comparison to them we are still noobs. my background is in electronics (mostly RF) and control. the car stuff is a hobby. the funny thing is the math is the same for many different technical subjects so it is matter of learning what things are called and getting practical experience. practical being more important (but more costly to get)

I see. Knowing the boost cut value would certainly help:lol: just for my own clarification, does our ECU cut fuel and cue the wastegate when the boost limit is exceeded, or just cue the wastegate. the reason I ask is I'm confused by the logs. I can understand if the wastegate was overridden to drop boost and the setpoint was not moved (hence the turbo dynamics value) but I can't make sense of the AFRs. It looked like the AFR went a little leaner because of the drop in load. I would have expected a much bigger change if the injectors were turned off briefly (or is the O2 sensor slow enough to smooth out the reading?)

thanks Christian. It is really nice that you take the time to help us noobs out one of the reasons I have confidence in Cobb products is that you guys are very forthcoming with information and have nothing to hide.

I'm not sure if it is boost or fuel cut. around line 130 of the second pull, there's a sudden drop in MAF flow and boost but the AFR is not comensurate with no fuel and turbo dynamics indicates that the ECU is trying to get the boost back up. Can you try decreasing the number of items logged and increasing the logging speed? maybe the BPV is leaking?

thanks the first bit actually answers a question I've had for a long time. I've been trying to figure out if our valve overlap goes to zero or goes negative when AVCS is set to 0. I wish I had access to a dyno at reasonable prices.....sigh..... I can get my paws on pressure transducers, logging equipment and almost any electronics industry related instruments for almost nothing, hence the desire to find other ways of optimizing my setup. I know I have to shell out for dyno time at some point. if you ever need something x-rayed.....

Thanks Christian. Now I'm really confused. I think we are saying essentially the same thing but are referring to different points on the turbo. By turbine inlet pressure I was referring to the pressure before the turbo on the hot side. Based on your comment about the inlet pressure being slightly below the manifold (except at idle) I'm guessing you are talking about the cold side just before the compressor. I agree that the pressure just before the compressor will drop as flow increases and level off as one near choke flow. For the hot side, I was always under the impression that the pressure was around 2x boost at stock flow levels but possibly 2-3x boost when one abuses the turbo Are we talking about different things here? Just so I'm clear (I've been trying to figure this out for a while) is this the case: at very low RPMs, the dominant effect is timing the intake valve closing so that the piston hasn't had a chance to push air back into the intake medium rpms, we are making a compromise between intake manifold resonant effects and catching the exhaust scavenging pulse with the right overlap high rpms/loads, the exhaust back pressure/turbine inlet pressure is now higher than boost so we want to minimize overlap so we don't expose the intake side to the exaust pressure during overlap

which brand header are you using? if it is gruppe-s or gt-spec, send me a PM on the weekend and I'll forward you what I have.

one more thing to keep in mind.... at very low RPMs (say sub 1600) there isn't much gas velocity in the manifolds. as a result, you can't count on the gas momentum to help fill the cylinder with a late IV closing event. you can raise the effective compression my moving the IV closing such that there's no back wash, but you need to keep an eye on timing

depends on your manifolds. if you have headers, you will loose some spool up if AVCS isn't adjusted a bit. FWIW, tuning AVCS on the street is a real PITA. I've found that you need to combine the data from 4-6 identical runs before you get data which is statistically valid.

sounds like your WGDC is not in line with the boost your are running and the boost targets. If the car is targeting less than 14 and you can't get the boost down it will probably assume that there's something wrong with the WG and cut fuel.

Can AVCS but tuned without a dyno? I was thinking of using the following procedure to dial in a new set of headers (don't have them yet and I'd like to use as little dyno time as possible): 1) adjust the boost targets to hold a constant (low) relative pressure 2) advance the intake cam timing slightly across the rev range 3) observe the MAF g/s log for increases and decreases in the flow 4) keep the more advanced settings where the flow was increased and revert to the old values where there was no change or a decrease in flow 5) pay attention to the logs to see if there are any spots where WGDC suddenly drops off to maintain boost (I'm hoping this is a good indicator that reversion is just starting to happen) and avoid advancing those areas. I'm assuming, correct me if I'm wrong, that most good aftermarket headers will improve scavenging a bit and allow the cam timing to remain advance to a slightly higher RPM before the EGBP becomes high enough to cause reversion. I'm also assuming that slightly more cam advance will likely be needed at lower engine speeds to get the turbo to spool up quickly with the headers.

It is actually closer to 1000 if you are referring to the single walled (cheap) non-halogen bulbs. Most household bulbs put out 16-20 lumens per watt when new. Much less when they are aged.

idle speed is one. so is the high detonation fuel map. I was told that the high det fuel maps are set correctly from the factory so it would be better to just leave them be. the guys at Cobb have answered all my questions so far....even the ones I should have been able to answer by going through their ST forum (just found it on the weekend)

has anyone had to rescale their load breakpoints yet? I'm finding that I'm runninng loads above the max on the tables. while this makes tuning easier as there is no doubt as to which cells to edit, I'm worried that the ecu is nolonger compensating correctly. I was thinking of just rescaling the last two columns as the car normally sees low to medium throttle, WOT, but almost never a little less than WOT. Does moving the 2.3 load point to 2.4 (populated with data interpolated from 2.3 and 2.5) and extending the 2.5 load point to 2.7- 2.9 make sense?

probably car to car variation in the MAF cal. Under light loads, the AFR is set to lambda 1 and the car can make some corrections to the fuel map using the NB o2 sensor readings. At the lower loads, only the bottom end of the maf calibration is used. As the load increases and the upper portion of the maf calibration is used and the car can not make closed loop corrections any more. The best it can do is use the corrections made to the bottom part of the maf cal curve to scale the upper portions. If the maf has different errors for the bottom and top of its calibration, you will get errors in your mixture when running open loop. it could be that the errors in your maf calibration were sufficient to make the car run a bit lean despite the map settings.

Personally I wouldn't risk road tuning without a wideband. You can get the LC-1 for $130-150 and the sensors are around $40. I have to disagree with the claimed accuracy of the narrow band sensor. Narrow band sensors have a temperature dependance which can't be easily compensated for. When I data log, I can get a few pulls where the NB and WB readings agree. If I get the sensor really hot or let it cool off enough the two disagree. Also, up here our gas is chocked full of MMT. After a few thousand km, the NB sensor will start to get an offset in its calibration due to the MnOx coatings on the sensor tip. I only install my WB sensor for tuning for this reason. There are a couple gotchas when it comes to using the LC1 with street tuner. These are the one's I've found so far: 1) make sure the usb to serial convertors go into the same slots each time so the configured com ports are correct. I've found that if they are wrong, you can't get the setup working by changing the settings in ST. It just hangs and crashes if the settings on start up don't match with what's plugged in. 2) don't insert or remove the cables after ST is running. For some reason, the SW hangs if this is done even if Live tuning is not turned on yet. 3) when setting up a dashboard in ST, I've found that I need to have some ecu logged parameter displayed in addition to the LM1/LC1 AFR trace. I don't know why this is byt the AFR trace shows nothing unless another parameter, logged through the OBDII port, is displayed. I normally use RPM 4) If you use the LC1 programmer tool to figure out which port the LC1 is on, you need to power cycle the LC1 before it will be recognised by ST or logworks. 5) Don't use the LC1 firmware upgrade. I've been told that the new firware is not compatible with ST.