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Thread: Why wont my car run longer the 5 seconds.

  1. #1
    Junior Member
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    Default Why wont my car run longer the 5 seconds.

    Im very new to tuning and im trying to get a head start for my tuner. My problem is my car only runs for a couple seconds then stalls. Sometimes it wont start at all. What I have is a 97 corvette forged 6.0, 8.5:1 comp, ported 317's with patriot extreme springs, ported polished ls2 tb, vic jr intake, Aarons elbow, 83 siemons injectors, RSI Dual fuel pump set up with return and boost referenced reg, alky control with a 10,15 nozzle, comp cam 227-223 on 115 lsr lobe, Hinson front mount turbo with 76mm precision, all hot side swain tec coated, ecs intercooler, dry nitrous setup, ls3 slot style maf (unplugged) with 4" pipe from cooler to tb relocated iat sensor, f.a.s.t 3 bar map, msd 2 step, Dewits rad and fan 160 stat, flt level 4 trans with a super yank 3500 stall, dte diff with 3:90's.

    Sorry for it being so long but im trying to give as much info for the tune. Most recent mods were I repined my ecu to 02, took out 60lb and put 83lb injectors, relolcated coils to fenders, went from snow to alky control. My concern is it ran fine before these mods and im hoping its in the tune and not rewiring it wrong. Im thinking its the tune because it does start a run for a bit. Any help or guidance would be appreciated. Thanks, EricUntitled_0001.tun

  2. #2
    Lifetime Member darcy's Avatar
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    Start by fixing the Out Of Range cells in the tune. Not sure how these could have gone OOR..... Were they are problem in the tune you had in before?

    I know you said it ran ok before, but your VE table looks low everywhere to me....

    Do you have a log of it not staying running?

  3. #3
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    I will do that and get a log. This is a totally different tune then before. Before it was a 97 operating system in hp tuners with a 2 bar map. Now the car has been repined for the new pcm 99+ for better tuning abilities and 3 bar. Also that is a totally different ve table then my old tune. Thanks for your help I will give it a shot. Eric

  4. #4
    Joe (Moderator) joecar's Avatar
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    Do you get any DTC's...?

    What MAP sensor do you have...?

  5. #5
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    I have a fast 3 bar map I believe, I bought it from speed inc about a year and a half ago. I was able to use it as my operating system wouldn't allow 3 bar. It didn't come with any data so I have the scaler set to 288 and 1.5 offset. With key on engine off it read 101 kpa. I'm not sure of any other way to calibrate it. The only dtc I'm getting is crank relearn which I can't do until it runs longer. Also some abs dtc probably from installing line lock and larger rear calipers which shouldn't effect start up, I don't think. I'm thinking maybe map sensor info is off. Idk maybe I could put a stock map in with known values.

  6. #6
    Joe (Moderator) joecar's Avatar
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    When you applied the COS, you did not edit B3647 (it looks just like the the old B3605)...

    in B3647 take a look at the commanded EQR at 400 and 800 rpm in the idle MAP range (say 40-50 kPa), it is commanding overfuel, fuel is pooling in the intake maanifold causing your engine to stall a few seconds after starting.

    Also, fix the OOR cells that Darcy pointed out, see here:


  7. #7
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    I never touched the ve table. What I did was I paid for a mail order tune, then its suppose to get tuned my me logging it. I just wanted a start up tune for now just to verify the mechanical aspect of it, then when weather get better finish the tune. Well here I am so far I had to change, injector data, map, vehicle parameters, disable vats, fix oor cells, now ve and other things also. The person tuning my car is a very reputable tuner and is very good at what he does. I'm not happy with the tune I was sent at all, Im guessing it was just a random saved one he had. Also I am not pushing the issue to much to him as I'm learning along the way which is good. I just cant believe the tune I was sent, just want a decent tune to start to eliminate anything else. So now here I am here is the new updated tune and a couple try to start logs. Im not sure why it wont go into sd, maybe just not running long enough?

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  9. #9
    Joe (Moderator) joecar's Avatar
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    B3647 is not the VE table... it is the OL commanded fuel table... when you start the enoine, it runs in OL until CL conditions are met... B3647 commands fuel during OL.

    The COS introduces B3647 (EQR by RPM x MAP) which replaces OEM B3605 (EQR by ECT x MAP)... your _0001 tune file shows B3647 having the original contents of B3605.

    Many people overlook editing B3647 after applying the COS.

    I'll take a look at your_0002 tune file shortly...

  10. #10
    Joe (Moderator) joecar's Avatar
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    To go into SD you have to get an immdiate MAF DTC... without a MAF DTC the PCM is still trying to use the MAF table (even if the MAF is physically removed).

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