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Thread: 88 chevy 1500 tuning issues

  1. #1
    Carb and Points! typhoonss's Avatar
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    88 chevy 1500 tuning issues

    I have had this motor for almost a year as a daily driver now. I have for the most part drivability idle to 3200rpm with out knock and seems to run pretty good. Where my main issues are is it may break the tires loose a little off the line so it seems I may not have enough something there and also after about 3/4 throttle it drops off. My idle seems a little high usually in park around 1100-1300 and in drive with brake anywhere from 800-1000. The vehicle is a 88 chevy 1500 reg cab reg bed weighs 3960lbs without me in it. here is the motor build:
    motor: ATK SP03 357 4-bolt .040 +12.3cc Dish pistons 9.7:1 w/64cc

    cam: Comp Cams 12-262-4 1,500-5,500rpm 218/224 @.050 .464in/.470exh. lift LSA114

    lifters: COMP Cams High Energy Hydraulic Lifters 812-16

    pushrods: comp cams High Energy Pushrod Set Chevy 262-400ci w/Flat Tappet Cam 5/16 7.794

    timing chain: Magnum Double Roller Timing Set 1955-91 Chevy Small Block V8 265-400

    springs: COMP Cams Valve Springs 26918-16 Beehive 372 lbs./in

    rocker arms: Competition Cams 1417-16 Magnum Self-Aligning Roller 1.52 ratio, 3/8"

    harmonic balancer: ACDelco Harmonic Balancers 12551537 6.75in cast iron, internal balance

    Flexplate: Gold Series SFI-Rated Chromoly Steel Flexplate 1986-97 Small Block Chevy 350 Gen II

    oil pump: Melling M55HV High Volume

    Gaskets all Felpro
    Bolts all ARP except mains and piston rods

    Vortec heads 062
    Edelbrouck EPS Performer for vortec heads
    TBI adaptor aluminum
    TBI bored to 50mm with tbi spacer and #80 cop car injectors adj fpr w/17-20psi (17psi at 90's F and 20psi under 65 F)
    stainless midtube headers 1 5/8 to 3in
    msd blaster coil
    electric fans
    upgraded to 3 wire o2 sensor
    I have a 700r4 trans rebuild about 3yrs ago with the extra clutch packs and upgraded valve for firmer shifts(im not a transmission person had a buddy build it who has a transmission shop)
    FTI 2,400 stall convertor
    3.42 gm posi rear
    255/60r15 tires

    I have been reading post for years learning and tweaking the setup but I am getting stuck at this point. I know I will only get 5000 rpm out of the tbi which is fine.
    I do not have a wideband o2 for testing from what I have been reading seems I might need t get one.
    I started with Dave w. Performance AMUR bin file and have gone from there. I just changed the timing a little and have a little better low end and during normal driving but still 3/4 throttle up drops on it's face. Here is the bin files and logs. Oh yeah it is a 7747 $42. The datalog .csv would not upload so I zipped it.
    Any help would be greatly appreciated. I hope I got all the info and files you need to take a look.

    Also just to make sure this is working corretly I have a raspberry pi running android connected to a 5in touch screen running aldldroid which is where I datalog from and is also a touchscreen gauge cluster when driving.
    Attached Files Attached Files

  2. #2
    Fuel Injected! CDeeZ's Avatar
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    You can tune using a NBO2 and BLMs. I like using a wideband myself. I learned on the 7747 ECM. I switched two trucks over to the 7427 PCM for a multitude of reasons.... You should look into swapping one in and consider it yourself.

    Post pics of your touchscreen setup please. I'm interested in the layout you have there.

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    Carb and Points! typhoonss's Avatar
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    off topic here is the touchscreen. I am also putting a 7in in the glovegox which will run a home automation linux system and also be a wireless router for sensors around the truck and leds. 20180212_135951404_iOS.jpg20180212_220317041_iOS.jpg

  4. #4
    Fuel Injected! CDeeZ's Avatar
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    Very cool thanks for sharing. I love the GMT400s. Have two of 'em.

    If you were to switch over to the 7427 PCM you could use Daves spreadsheet to make dialing it in easier. As far as which wideband I have an two different AEM 30-4110s installed in each of my GMT400s. The 7427 can be made to log wideband data directly in the datastream making it even easier. That's what I would do.

  5. #5
    Carb and Points! typhoonss's Avatar
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    OK I have spent about 5 hours reading posts over the past 2 days and I have changed the spark table, added a little more at idle and some to the 60-100 map in the 1800-3200 range. I also added a degree to the pe so it is at 3.52 now. I also changed the BPW from 110 to 120. I took a drive and datalogged and used the vortec ve excel sheet to correct the VE tables. It did not fall on it's face in the higher rpm but still stumbled a little. So I added a little more timing higher map and rpm then took another drive. Here is where I am at now. Idle a little high, I have been trying for a year now to get this down but nothing really seems to help, it is either high or it wants to die, maybe someone can give me a direction on what to try to change. WOT is almost perfect in first gear around 4800-5000 I get a little stumble but is good in second WOT. Just under WOT but over 3/4 throttle I get a little stumble in the higher rpm range 3000-4800. My second gear shifts in auto or D at 4800 in second. Additionally if anyone can take a look at the datalog and give any pointers if anything else looks odd or misconfigured as alot of you out there seem to know this system very well.
    It's all about learning, testing, changing and over and over again till good.

    CdeeZ - I have thought of going the route of upgrading the computer but my next step will be an after market throttle body system as this truck will eventually be for play and I would like to see 500hp, hopefully a year or 2 down the road. This is just a daily driver that I was looking for 350hp and hopefully still get decent gas mileage. At the present time I get around 14-15 depending on the driving situation.
    Attached Files Attached Files

  6. #6
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    Quote Originally Posted by typhoonss View Post
    OK I have spent about 5 hours reading posts over the past 2 days and I have changed the spark table, added a little more at idle and some to the 60-100 map in the 1800-3200 range. I also added a degree to the pe so it is at 3.52 now. I also changed the BPW from 110 to 120. I took a drive and datalogged and used the vortec ve excel sheet to correct the VE tables. It did not fall on it's face in the higher rpm but still stumbled a little. So I added a little more timing higher map and rpm then took another drive. Here is where I am at now. Idle a little high, I have been trying for a year now to get this down but nothing really seems to help, it is either high or it wants to die, maybe someone can give me a direction on what to try to change. WOT is almost perfect in first gear around 4800-5000 I get a little stumble but is good in second WOT. Just under WOT but over 3/4 throttle I get a little stumble in the higher rpm range 3000-4800. My second gear shifts in auto or D at 4800 in second. Additionally if anyone can take a look at the datalog and give any pointers if anything else looks odd or misconfigured as alot of you out there seem to know this system very well.
    It's all about learning, testing, changing and over and over again till good.

    CdeeZ - I have thought of going the route of upgrading the computer but my next step will be an after market throttle body system as this truck will eventually be for play and I would like to see 500hp, hopefully a year or 2 down the road. This is just a daily driver that I was looking for 350hp and hopefully still get decent gas mileage. At the present time I get around 14-15 depending on the driving situation.
    Up your MAP AE 25% for the stumble and see if it helps. I would also do some VE tuning in the upper MAP/RPM ranges with the PE TPS enable set to about 90%. You can watch the integrator and see if it goes higher or lower than 128 to know if you are lean or rich.

    Woth that throttle body, proper fueling and timing you should have no problem reaching 5,500-6,000 rpm with that cam and heads.
    Last edited by Fast355; 03-21-2018 at 08:02 PM.

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    Carb and Points! typhoonss's Avatar
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    ty, will test tomorrow when I get a chance and let you know.

  8. #8
    Carb and Points! typhoonss's Avatar
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    ok, I added 25% to the MAP PE at 80kpa I also added another degree to the PE - spark advance amount. The PE TPS enable I was not sure of are you talking about the "PE-Delta TPS". I also used the vortec VE excel to adj the VE table again from the last datalog, and it seems much closer. From previous experience it seems I need to datalog adj VE tables about 3 times before they get close. From the last datalog it pulls hard in the 3200 to 5000rom range but there is still a slight miss or stumble right before it switches to the next gear.

    Something I would like to straighten out is the idle. in park it runs anywhere between 1150-1400rpm once warmed up and in gear between 850-1050rpm. Any thoughts on this.

    When in park or n if I rev the motor it does not seem to come back down to idle quick, it seems to come down to say 2200 then slowly come back to idle. Is this something that can be adj in the chip?
    So far the help I have received in this forum has helped out a ton and at this point is running the best since I built the motor, thanks.

  9. #9
    Fuel Injected! CDeeZ's Avatar
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    I think you could crank out 500 HP using a stock TBI system. Would have to step up to a larger throttle body but I think everything else could definitely do it. Unless you just want to switch to an aftermarket setup.

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    Quote Originally Posted by CDeeZ View Post
    I think you could crank out 500 HP using a stock TBI system. Would have to step up to a larger throttle body but I think everything else could definitely do it. Unless you just want to switch to an aftermarket setup.
    With a single 2.00" bore 420 hp 496 TBI unit using the high pressure 61s at 32 psi for 105 lb/hr I ran out of engine before I came close to running out of air or fuel. 370 rwhp through a 4L60E, GM 12 bolt and 2 piece driveline with carrier bearing. Was making atleast 450 hp.

  11. #11
    Fuel Injected! CDeeZ's Avatar
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    Quote Originally Posted by Fast355 View Post
    With a single 2.00" bore 420 hp 496 TBI unit using the high pressure 61s at 32 psi for 105 lb/hr I ran out of engine before I came close to running out of air or fuel. 370 rwhp through a 4L60E, GM 12 bolt and 2 piece driveline with carrier bearing. Was making atleast 450 hp.
    Makes me wonder exactly how the general consensus (wrong as it is!) started among the crowd that "TBI is junk" "It can't make power" ..... Well you know how all that goes....... All the sidline shit talkers that said it couldn't be done.......

  12. #12
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    Did you raise the rev limiter ? mine was set a 4800 stock. I would hit it hard with a thm 350 in kickdown at shiftpoints instead of the4l60e. raised it to 6000. no problem

  13. #13
    Fuel Injected! woody80z28's Avatar
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    Extremely similar build to my truck. I like it.
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

  14. #14
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    Quote Originally Posted by woody80z28 View Post
    Extremely similar build to my truck. I like it.
    Very similar to what I am currently building for a 5.7 Vortec application as well.

    The engine I am building has stock 906 heads with Comp 787 retainers, .050" offset locks and GMPP Blue LS6 springs. Pushrod holes drilled out to 1/2".

    I had Comp Cams custom grind a roller cam. Using the older and milder Magnum lobes.

    270/284 @ .006
    215/223 @ .050
    .533/.533 w 1.6 rocker
    110 LSA +4* advance

    Will be running it under a stock vortec intake setup that has a ported lower intake and MFI conversion spider at 70 psi. 1 5/8" primary long tube headers with 2.5" collectors, dual 2.5" exhaust to the magnaflow di/so muffler with high flow cats and a single 3.5" tail pipe.

    The cam should sound alot like a GM Hotcam but start making power about 3-400 rpm sooner. Peak torque should happen in the 3,500 rpm range and peak HP in the 5,500 rpm range. Just a guess but the rpm effective range should be 1,500-5,500 rpm which should work very well with the factory 4.3 torque converter and 3.73 gears.

    For reference the GM Hotcam
    278/287 @ .006
    218/228 @ .050
    .525/.525 w 1.6 rocker
    112 LSA +3* advanced
    Advertised as 1,800-5,800 rpm.
    Last edited by Fast355; 03-29-2018 at 08:47 AM.

  15. #15
    Fuel Injected! CDeeZ's Avatar
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    Quote Originally Posted by woody80z28 View Post
    Extremely similar build to my truck. I like it.
    You mentioned that your fuel pressure is 20 PSI.... What did you have to do in the tune to do in the tune to make it happy down low at idle? I'm thinking transient paramters are what need adjusted but haven't been able to look around yet.
    Last edited by CDeeZ; 03-29-2018 at 01:27 PM.

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