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Thread: Noob questions on tuning a 97 dirt track cavalier

  1. #1
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    Noob questions on tuning a 97 dirt track cavalier

    First things first. It's a 3/8 mile clay track. My father and I both race so my car will be next (98 Cav LN2).
    Little information on dads car:
    Port and Polished Shaved head (unknown amount as of right now)
    99 2.2 pistons (shallower dish)
    1.6 rockers Compcam
    Stock cam
    94 Cav port and polished manifold (Larger runners)
    MSD 8.5mm plug wires
    MSD Coils

    I currently do not know the compression of the car just yet, but I will figure it out. WE RUN 109 OCTANE IN THIS CAVALIER!

    I am apologize that the logs are so long. I have to start the scan before we race, than I have to get into my race car. As you can see there are a few things I am worried about. First off, under WOT the car runs lean (AFR in the 12-13s :/) And there is a lot of knock retard.

    Basically the car will be in WOT 90% of it's life time. Let go of the throttle through the turn than throttle through the turn.

    Now I am not the kind of person that expects people to do this for me. I still need to tune my race car and my 91 Camaro is undergoing a LS1 swap So basically I do not know where to start. What should I start playing with? Main VE tables? Main Spark Advance? Keep in mind this car does NOT have a MAF sensor!
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    Last edited by JTNKTZ; 04-22-2012 at 10:25 PM.

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    Advanced Tuner imphat0260's Avatar
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    Your VE and timing tables are all really rough! Go back to stock timing tables, get rid of your TQ management, and smooth out your VE tables... Once you get those smoothed out and your fueling where you want it, start adding some timing (keep an eye on AFR, it will change)...

    P&P Tuning

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    Quote Originally Posted by imphat0260 View Post
    Your VE and timing tables are all really rough! Go back to stock timing tables, get rid of your TQ management, and smooth out your VE tables... Once you get those smoothed out and your fueling where you want it, start adding some timing (keep an eye on AFR, it will change)...
    Huh, this is my stock tune. No modifications on it... Where can I find the correct tune for this car if possible....

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    Can anyone else chime in as to what to do here? Or point me in the right direction into tuning this thing?

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    Advanced Tuner imphat0260's Avatar
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    Quote Originally Posted by JTNKTZ View Post
    Huh, this is my stock tune. No modifications on it... Where can I find the correct tune for this car if possible....
    Let me see if I have a stock file for a 97.... You had a few changes in your file, but the history log did not show much.... Either way, it could be a lot better... I got you PM. I will try to give ya a call.

    P&P Tuning

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    Quote Originally Posted by imphat0260 View Post
    Let me see if I have a stock file for a 97.... You had a few changes in your file, but the history log did not show much.... Either way, it could be a lot better... I got you PM. I will try to give ya a call.
    Thanks, I appreciate it! I'll throw yeah some paypal cash when everything is all said and done! Fun = Time = Money

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    Can anyone help me out here? How can I begin to smooth out VE tables?
    Hypathetically, if I raise the numbers, that will put more gas in it thus higher the air fuel ratio correct?

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    Raise VE number put more gas and lower the AFR.
    Boost Lover

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    I just found this: http://www.j-body.org/forums/read.ph...&i=6694&t=6694
    Is this a valid way to do a VE table tune? It just feels to easy...

    I decided to follow what is said on the above link. I just want to make sure that I am in the right track. We are going to run the tune I have posted (Openloop with DFCO disabled) in a warm ups which is 5 laps. Can someone check over it for me just incase? More or less make sure my target AFR is okay. I didn't touch the mult vs rpm because well I don't know what it'll be running here. What should my target AFR be? Remember this car will always be for racing purposes. Would it be necessary to lower the PE enable's RPMS so it is always in PE?

    Also the above link does not have the histograms. Does anyone have the histograms I need?
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    Last edited by JTNKTZ; 04-22-2012 at 07:56 PM.

  10. #10
    Advanced Tuner Dr. Nopps's Avatar
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    This should represent a stock 97 file. I think this is the config file you need too. Without using a super or turbocharger you're only supposed to go as rich as around 13-1 AFR, but with all of that extra flow you may be able to go a little richer. Some motors however are very sensitive to over-fueling and will result in detonation/KR issues. You aren't required to be in PE all the time, but yeah you can definately set it to come on earlier. And from what I've seen, they won't command the AFR that you set in your PE tables unless they are also running in closed loop mode as well. Oh yeah, almost forgot- I've got a brand new set of Eagle H-Beam connecting rods for the old 2.2 non ecotech OHV motor if you're interested. They are very bad ass rods!
    Factory Tune 4spd automatic '97 Cavilier-2.2L.hpt
    L4VEWideband.cfg
    Last edited by Dr. Nopps; 04-23-2012 at 12:42 AM.

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    Well I compared my stock back up file to your stock file and they are pretty much the same minus the trans stuff. Do you think I am better off having the car run in open loop through out the race? Just forget about closed loop? I'll set my commanded AFR too 12.8 for now and go from there. And considering that this is a race car, should I just keep DFCO disabled rather than reenabling it after I am done tuning?

    This is what I set my commanded AFR too. Will this be alright?
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    Last edited by JTNKTZ; 04-23-2012 at 01:21 AM.

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    That looks alot safer AFR for a naturally asperated vehicle. You can disable DFCO all the time it shouldn't harm anything. You can also be in PE all the time, or just a majority of the time - if that's what you want, again no harm there. Based on my experience and testing when you look at your scanner (not just HPT, any good automotive scan tool) under commanded AFR, the numbers will be changing with throttle input. (Alpha-N settings I believe) The only way I could get the PCM to command the AFR I had requested with those tables, was while in closed loop mode and in PE mode as well with at least 1% throttle. Only then would the commanded AFR display what I wanted. (In your case 12.8 to 1) Because of this unique PITA this causes while tuning, others have been using filters to help with their histograms. Sorry but I haven't set any of those filters up or applied them yet.
    Last edited by Dr. Nopps; 04-23-2012 at 02:18 PM.

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    Quote Originally Posted by Dr. Nopps View Post
    That looks alot safer AFR for a naturally asperated vehicle. You can disable DFCO all the time it shouldn't harm anything. You can also be in PE all the time, or just a majority of the time - if that's what you want, again no harm there. Based on my experience and testing when you look at your scanner (not just HPT, any good automotive scan tool) under commanded AFR, the numbers will be changing with throttle input. (Alpha-N settings I believe) The only way I could get the PCM to command the AFR I had requested with those tables, was while in closed loop mode and in PE mode as well with at least 1% throttle. Only then would the commanded AFR display what I wanted. (In your case 12.8 to 1) Because of this unique PITA this causes while tuning, others have been using filters to help with their histograms. Sorry but I haven't set any of those filters up or applied them yet.
    Alright bare with me I am still learning but this is what I got out of this:
    It's okay to leave DFCO disabled, won't affect anything.
    Same thing with PE all the time.
    Leave it in closed loop to TRY to get the commanded AFR (Not guaranteed)
    Better off to set PE active with at least 1% throttle at all RPM's to get the best commanded AFR results.

    Now how do I know if my computer is Alpha-N based or MAP based cause I read that it could be either one? I'll do a search, but just in case, what's the difference between the 2?

    Does anyone have these filters to use with the Histogram that I could get?

  14. #14
    Advanced Tuner Dr. Nopps's Avatar
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    Yeah those cars seem to be an enigma wrapped in a mystery badged with a chevy logo to alot of people. Here's what may help: Look through your entire tune for any table that would allow you to command a specific AFR. I'm (not really) guessing the only one available to you is that one under the PE Mode tables. Set that entire table to your AFR content. (12.8 from earlier) Prevent your car from going closed loop in the tune, or physically. Perform a scan with a PID in the main table for logging commanded AFR, this is what the PCM is actually shooting for. Notice it will not be what you wanted, and may not seem consistant at times. In order to tune your car to run at 12.8 AFR I would think you should tell it to try and shoot for that, and then correct (in the tune) how far off you were from that figure. Perform the same type of scan but this time allowing the car to enter closed loop (it may take a few secconds) and running PE mode all the time any throttle 0% on up. As soon as you establish at least 1% throttle input, that PID for commanded AFR should read your desired 12.8 and stay that way untill you let off the throttle. Sorry about what you may have read but this leads me to strongly believe our cars are actually a mix of both. (Alpha-N & MAP) I don't have a backyard full of these cars of all different years to do testing on, so I really don't know about this next part but.- The cavaliers could all be like this untill they started using MAF sensors. In fact it would be hard for me to believe otherwise unless I saw a tune for one with the right tables. Even then I would still want to do a scan on it and see for myself exactly how it's thinking/functioning in regards to openloop vs. closed loop, fueling & AFR commanding.
    Last edited by Dr. Nopps; 04-24-2012 at 05:16 PM.

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    Quote Originally Posted by Dr. Nopps View Post
    Yeah those cars seem to be an enigma wrapped in a mystery badged with a chevy logo to alot of people. Here's what may help: Look through your entire tune for any table that would allow you to command a specific AFR. I'm (not really) guessing the only one available to you is that one under the PE Mode tables. Set that entire table to your AFR content. (12.8 from earlier) Prevent your car from going closed loop in the tune, or physically. Perform a scan with a PID in the main table for logging commanded AFR, this is what the PCM is actually shooting for. Notice it will not be what you wanted, and may not seem consistant at times. In order to tune your car to run at 12.8 AFR I would think you should tell it to try and shoot for that, and then correct (in the tune) how far off you were from that figure. Perform the same type of scan but this time allowing the car to enter closed loop (it may take a few secconds) and running PE mode all the time any throttle 0% on up. As soon as you establish at least 1% throttle input, that PID for commanded AFR should read your desired 12.8 and stay that way untill you let off the throttle. Sorry about what you may have read but this leads me to strongly believe our cars are actually a mix of both. (Alpha-N & MAP) I don't have a backyard full of these cars of all different years to do testing on, so I really don't know about this next part but.- The cavaliers could all be like this untill they started using MAF sensors. In fact it would be hard for me to believe otherwise unless I saw a tune for one with the right tables. Even then I would still want to do a scan on it and see for myself exactly how it's thinking/functioning in regards to openloop vs. closed loop, fueling & AFR commanding.
    Well if you are ever in VA than let me know! I have about 10-15 cavaliers/sunfires!!!!