Does anyone know how to understand SCT logs?

Discussion in 'SN95 4.6L Mustang Tech' started by mat82284, Jul 18, 2010.

  1. Ok after being back in the car again and looking at it the "IAT sensor Tempor" is not the IAT I thought it was. I'll try to get more logs. I'm fallowing that guide with certain pids this time so there is not a whole lot. I just didnt have internet access to access that page before.
  2. Just had time to glance at them and not study them - but the first log with all that useless data wasn't good for much. The second one was OK, except you should hold the RPMs at different levels longer. Then do a 'loaded' log where you don't go to WOT, but slowly give it gas, then hold it at certain RPMs with a load on the motor , i.e. with it in gear - best done on a dyno, but CAN be done on the street if you are very careful and have a helper to either drive or run the laptop and you break no traffic laws.

    The pressure drop looked fine, so your sensor is probably OK. Your fuel trims are OK at the beginning of the log,then as you give it gas, get really far off - then the trims start varying bank to bank, as in one bank gets stuck at its limit and the other is OK. This can mean many things - the tune can be off at midrange, bad 02 sensor on one bank, wiring problem, bad 02 sensor heater ground (on the back of the head usually), stuck injector, injector not firing, bad ignition component and probably more. I'd figure out what it is exactly before I'd go to WOT with it myself or you might have major engine damage. That's a worst case scenario and 90% of the time it's something simple, but you need to figure it out.

    Hope this helps!

  3. Ok thanks. That actually does help. Yeah the first log I really didnt know what to do. The second I had access to that page you sent me.

    I'll try to do that load test you talking about. The second log I was only sitting in the parking lot. The car wasnt actually moving. At the end of the log the car died and I tried to hit the gas at the last minute but missed it so it just stayed dead lol. The car died a few times though before I stopped the log.

    When going out and doing the log do I slowly increase through the rpm range? Does it matter what gear?

    Should I try some seafoam on the car to fix test to see if if it can fix a stuck injector (that is if its even a possible cause) I guess it doesnt hurt worst case i wasted $8

    Oh. Hey Don, I just realized you work for Lasota. I was recently looking online to possible learn how to tune my own car and I searched the forum over and over and I kept getting links to your page and I was thinking of buying the pro racer package with your video. How hard is it to learn? I'm not new to computers and I understand cars up to the electronic aspect. I wouldn't be learning to save money, I just wanted to learn it myself. I think it would be easier if I had a stock car to test tune lol since my car is way different.

    Thanks again for your help.
  4. mat28824,

    Don_95Vert is none other than the erstwhile Don Lasota of Lasota Racing. You are talking to THE man. Don was involved with SCT back when it was just a few smart guys with bags of tuning experience who figured it would be good to crack open the Ford PCM codes and let us tune things for ourselves.

    IMO, you can buy with confidence from Mr. Lasota.

  5. Thanks so much Chris! As far as the PRP goes, heck, I learned how to tune - not that difficult and a lot of good people like Chris that'll provide help on the SCT PRP forum. I always give a 'starter' tune with the PRP, so you'd be 90% of the way there. The video really works well to get you started - it's an animation in the software that walks you through everything. Happy to help!
  6. That sounds good. I'm waiting on this job to go through and If I get it I'll be purchasing it soon from you. If not it might have to wait a month ish unless my current problem is tune related then i'll have to figure something out asap. I guess the first thing I need is a Wideband 02 sensor. That will tell the truth.

    I also wondered, Does the pro racer package allow you to tune for ethanol? I've been wanting to switch over to ethanol but before I do I need to find out if I have enough fuel for 500hp. That I'm sure i'll bring up on the PRP forums when i purchase it if the program works for that.

    I redid another log the way you asked. Hopefully this shows something that can best give an idea if the tune is bad or if its something else. When I first tuned the car the engine was rebuilt at and only had 2000 miles since the build. Is it possible my engine has changed over time and forced the tune to be out of sync now? I have put 15000 miles on the engine since rebuild. only 13000 since tune.

    O the log ended accidentally while driving. The usb cable popped out so if anything looks strange at the very end thats why. The car also died on me once in the beginning.

    I went in and looked at the long term fuel trims. In bank 2 there was a fluke and it showed a max of 37.0 I looked at it in excel and it only showed up twice. No other numbers went above 1.24

    Here is the edited one without that tiny glitch. That is if its a glitch or a clue about a problem? glitch).zip
  7. I was looking at the log and my car started to when slowing raising the rpms to 5k then it bogged down afterwords. If you look at the load it goes crazy. What does that mean?
  8. I re read your current post and I wanted to ask. Is there a way to check to see if an injector is firing? Would that be looking at the spark plugs? As for the 02 sensors, I had the same problem before replacing them. I only replaced the front 02 sensors. Would the rear 02's cause an issue like this?
  9. We'll here is my last log. I finally went out and did a WOT run. When I did the slow rpm run this afternoon I didnt see any smoke. This time I smashed on it and I didn't see any smoke. There is a possibility that the cats may have stored up carbon that was just pushed out making me think it was rich, or the car is still rich and I was dark enough to mix in with the darkness.

    At the end of the log I set the cruise control at 28mph and the car was very jittery. I couldn't tell why when looking at the logs.

    Don 95Vert if you happen to have free time and can look at the recent logs I posted I would greatly appreciate it. I also understand that this can be time consuming and im not trying to impede on your time. So If I'm asking to much feel free to let me know. I already really apre*****e all your help that you've given me so far. Thanks!

    This is the WOT run.

    Look at the file full throttle 2. The first log was an attempt, but I stopped at 4k to make sure there was no smoke. Then I re-logged again on the way back and took it to 6k which is in the the log called full throttle 2.

    Thanks again to anyone who has helped or can help.
  10. The first log looked OK - the problem I saw went away - which would bother me - because it's more likely a stuck injector or something like that. If it happenes in the log again, you can swap injectors bank to bank and see if the problem follows the injectors - then get someone you trust with a good Snap On scanner (and knows how to use it) and see if they can narrow down which it is. May also be ignition and/or bad 02 sensor too though. The scanner can help with those also.

    The WOT log is troubling - you are maxing the fuel pump out at 4800 RPMs - on your PCM the MAX duty cycle is 0.5 and yours hits that at about 4800 and stays there. Normally the PCM will somewhat compensate by increasing injector PW, but you can also see when this happens how the pressure drop across the injectors starts to fall off. Without a wideband, no way to tell if it's going lean, but I'd bet it is. One thing for sure I WOULD NOT do is to go to WOT anymore with the car until it's fixed - just hope you didn't hurt anything up until now.

    As far as the PRP goes, yes you can do E85 tunes with it - but since you are running out of FP with gasoline, you have a long ways to go to improve the fuel system to make it ready for E85. You can do anything in the software with your car with the PRP that most dealers can do.

    Might be time for 03 Cobra tank and pumps - or to get the fuel pump voltage table tuned if you have an adequate fuel system already.

  11. Don_95Vert:

    I wrote this up earlier today but I didn't have an Internet connection. The variable MAF counts come and go but mostly come and stay. Is this what you figured disappeared in his other logs?


    Your MAF counts are very nervous. Look at the first log around time 192 to 199 where the TP is pretty steady at 216 to 228, the RPM rises from 1970 to 2200. The MAF counts vary from 294 to 453!! The load is following the same nervous trend as that of the MAF (because load is a function of MAF counts [and RPM]). Same thing happens at 219 to 225 time, 318 to 327 time, etc. At lower RPM, say, below 1400 to 1500 RPM, the MAF and load are not jumpy.

    Having said all that, there are other places in the datalog where the same conditions (even higher RPM, TP) show a smooth MAF and load trend. Maybe there is some sort of electrical interference??

    In any case, let’s look at your MAF setup.

    Plumbing is key in a forced induction setup. If you have anything entering/returning in front of the MAF then it has to be far enough upstream so that the flow is not rough and disturbed at the MAF. Also, if you have air returning on the downstream side of the MAF, the entry point has to be far enough away so that it does not backwash the MAF element. If you can post some pictures then we can “check your plumbing”, lol.

    Next is blow-through or suck-through setup. I don’t have a supercharger so I am not speaking from my own experience so I suggest that you wait for some professional help to arrive in this thread for this matter. From what I have read, a blow-through setup is more difficult to tune so this might be part of the problem.

    Do you have a MAFia? Is it wired up OK (no flame intended – just trying to cover all the bases)?

    That’s all I can see in the datalog(s) at the moment.


  12. Thanks Don and Chris. This is very puzzling to me and I wish it wasn't happening.

    As for fuel. I am already running a cobra tank setup. I am running dual SVT focus pumps. I don't understand how I could possibly be running lean after 4k. Especially when the car pulled like crazy till 6k. I'll stay away from wot, which isnt a problem since the last time I did that was 4 months ago at least.

    As for maf setup. I'm running the BA-2400 mass air unit. I am running a suck through setup. I have an anderson power pipe and the blow of valve is after the intercooling pluming into the anderson power pipe. Then at the bottom of the Anderson powerpipe is a 4" 90" silicone bend, Then my mass air, then my air filter at the end. The mass air and basically hiding directly behind the bumper.

    I'm really stumped about the fuel pump. Is it possible one of the pumps became defective? There only a year old..... If so could I check by logging voltage or is this something I would have to drop the tank for?

    When the car was tune he told me I still hat at least 30-40 extra fuel in the system. I'm only pushing 500rwhp and my fuel setup should get me near 600 like most get out of duel focus pumps and 60lb injectors.

    As for the scanner. Is this something that can be borrowed at an auto-parts store? or will I need to see a mechanic for one?

    If my mass air unit was going bad how could one tell?
  13. The FP duty cycle is done - no question on that. Your fuel system should be fine - my guess is either the tune wasn't changed to reflect the FP change or maybe you have an in-tank leak so it's pushing fuel back into the tank and the FPs are maxing out - or a dead pump. Could also be inadequate wiring to the FPDM or you simply need a BAP - but I'd do a wiring upgrade anyway. Those are things to look at.

    The Snap-On scanners take a lot of expertise to operate - so it's no do it yourself venture - you need a good shop that has been trained in how to use it.

    As Chris said, it also looks like you have a TON of MAF noise - open your file in LiveLink and put a check next to AD counts - looks like the trace of a 9.0 earthquake - should be fairly smooth. This is caused by MAF backwash which is usually caused by a bypass problem, too small a bypass, bypass too close to the MAF, bypass not plumbed correctly. This can solved by either/or: going to a larger size bypass, moving it away from the MAF, plumbing it so the bypass blows away from the MAF (at an angle with a deflector inside the pipe, adding more air volume before the MAF by lengthening the inlet pipe. This assumes you are in draw through - blow through usually solves this but can have it's own problems especially if you run bends or reducers near the MAF. Dunno what you are running, but this should help. The best setup is an '05 style MAF - i.e. PMAS HPX MAF in blow through with a BOV ahead of the IC, if you have one. But you need a retune for that.

    Looks like your 'ro do' list just got bigger... Hang in there and good luck with it!

  14. Thanks for taking the time to help me.

    The wiring was never upgraded. I left it stock. I really didnt think that i would need to upgrade it. Users on here have been getting away with dual svt focus pumps at 600hp. I'm not even pushing alot of boost. I pretty much only wanted 500hp so i was happy to have reached that. I've actually had one of the lines come loose in the tank before and it caused my car not to run at all. So it sounds more like a clog or maybe one of the pumps went bad. I'll have to drop the tank to take a look. That'll probably be by the weekend since I have a full tank of gas :(

    As a side note I know the tuner adjusted for the pumps. If he didn't I wouldn't have been able to hit 500rwhp on a mustang dyno.

    But honestly, if one of the pumps did go out the car would be getting alot less fuel so the fuel table would be out of sync like its doing now.. hhmm. I really need to get into that tank... I'm also using the stock fpdm.

    As for the mass air. In my original tune I had used the vortech mini race. After that I was forced to swap it to the stock vortech plastic piece. I could see this causing some backwash somehow. I never changed my piping though. I'll take some photos to show you on how I could possibly fix it. I live in California and It's extremely hard to modify anything on the car. That why blow through would never work. Life would be so much easier though if i could.

    So far my parts list is getting bigger. If my pump is out, I'll probably just buy the tripple pump gt system or two GT pumps and a modified FPDM, then upgrade injectors to 80lbs, get a wide-band 02, get the pro racer package and go ethanol. I was really hoping I could wait a little longer, but time will tell.

    I e-mailed my tuner to see his response. I also asked him for the original dyno log for you guys to look it at if he still has it. So ill keep you updated.
  15. Here are the pictures. I took it off the car to clean the mass air meter with electrical cleaner and cleaning the air filter. The red line shows the path of the by pass valve flow. I did find some oil on the mass air meter. Not much but a little run off from the supercharger apparently. I'm cleaning it up and I'll test it tomorrow since I cant get the laptop back till then. Of course I'll do a slow log keeping it under 4k because of the fuel issue.

    Thanks again!

  16. Ok after you mentioned fuel pump volts I went ahead and did 2 more logs. The first was was my doing a 3rd gear pull and stopping at 4k. The log cut out and I had to make a new one. The second one was a slow to 5k pull. that was not wot like the first one. I then later on did a 4th gear wot pull after the slow to 5k pull and stopped at 4k.

    I can totally see that I'm having a huge fuel issue right now. I logged the volts to the pump this time (wish i had before) and I was hoping you can double look at it to see if it looks correct. The volts look really low to me, but im not sure. Could a bad fpdm cause bad voltage or maybe 1 dead pump? What about a clogged fuel filter?

    I'll be dropping the tank this weekend to check volts, probably upgrade wiring if i can find wires. Mostly im checking to see if both pumps will be working.

    I also reset the ecu on the these logs, which explains the car feeling slow because of the loss in fuel. Lastly I noticed one of the rear 02 sensor volts didn't show. Does that mean its dead? He turned them off in the tune i believe.

    This is my last log unless otherwise asked for another. I figured the next step it so find my fuel problem.
  17. mat82284:

    Thanks for posting up pics and for the latest datalog. I'll try to look at that today.

    What are the two small (1/2" dia.) tubes on the air intake tube across from the bypass valve? I'm thinking one is for the IAC and the other is for the PCV. Of course, these can't be open to the atmosphere since they are downstream of the MAF.

    I'll study those pictures some more but the two stubs caught my attention.


  18. Thanks Chris and Don for all your help. Hopefully when this is all good and done I'll be asking about learning to tune here soon :) I know my car has a lot of potential and I cant wait to test some ethanol on it.

    Those two small 1/2 tubes connect to the IAC and PCV on the drivers side. I had them disconnected to take the photo, but in the second photo I reconnected them. Just so you know those hoses are connected every-time I've logged.

    If the backwash is still happening after everything is fixed and im still getting backwash then I was thinking of tossing another stock bypass valve on there right after the intercooler.
  19. mat2284:

    Good work collecting more data and thanks for posting the logs.

    Slow RPM rise datalog: at time 175 and 233 the engine speed is steady at 2200 RPM but the MAF is very, very noisy. I think the problem is the MAF, not the fuel system. The MAF drives everything.

    The 3-4 WOT log is similar: at 280 to 317 time, the RPM are rock steady but the MAF is ‘not noisy’ but then gets noisy in a cycle (OK/noisy/OK/noisy/etc.). It almost looks like resonance – something happening at a regular pattern of time. Maybe the air filter is too big? Some light restriction on the filter (smaller filter or foam sleeve) might be enough to damp the resonance. (Obviously, the engine is not really drawing in air in that crazy way or the RPM would be following the same pattern and your car would be bucking badly.) No action required, just something to think about for now.

    If this is a new problem then check your MAF wiring and clean the MAF. Maybe there is something that is on the sensor that is ‘fluttering’ and causing the noisy signal problem. I really don’t see anything wrong with the fuel pump duty cycle in terms of the simple question: “does it look reasonable?”. It gets up to about 75% so that tells me that you have pump capacity available.

    I see water spots on the Power Pipe and some loose electrical tape on the MAF wires. Please recheck the wiring at the MAF and look for a loose connection (loose pin in the plug, loose splice, loose wires on the pins, corrosion of the wires, etc.). Can you ‘clock’ the MAF? I would try 90 degrees and see if that settles it down, and another 90 degrees if it doesn’t. The MAF is perpendicular to the downstream elbow but the incoming air (into the fender from under the car) might be buffeting around and causing the sensor to see pulses when there really aren’t any.

    What is the connection on the left side of the intake tube in the picture above. It is the one that is opposite from the bypass valve and near the radiator. It has a black zip tie on it.

    Your rear O2 sensor looks kaput. No impact on performance unless you are due for emissions testing soon.

    The fronts are switching nicely.

    There is a large variation in your STFT’s. This could be due, in part, to the wacky MAF signal. Let’s see about settling down the MAF signal first but keep in mind that tight fuel trims make for a better tune.

    The isc_integrator is making big corrections at idle. Once the MAF noise problem is resolved, you must tune up your isc_air functions to get the integrator corrections to be reasonable (+/- 0.05 is do-able). This will help with idle and drivability.


  20. Just about every draw through car we have seen with an IC has had a VAST improvement in the MAF signal with the addition of another bypass ahead of the IC - and keeping one after. I think that'll really help.