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Thread: My Dual TBI Camaro Project

  1. #46
    EFI GearHead ! EagleMark's Avatar
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    Re: My project

    Some day when you have time would you do a write up on changes needed for the wideband ?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  2. #47
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    As far as the wideband goes I just used the Advaneced_$0E_TP5_v250.xdf and .ads. these are already set up with the parameters written to insert the WBO2 into the datastream. You just have to follow the read_me directions at the top. You can also datalog commanded AFR (in place of Battery V) from the PCM by changing a couple of bits in the .ads I just inserted a scalar to make it easy to change. I can upload my current files later when I get home.

    Also here are some very helpful tuning notes that I gathered from several post by HaulnA$$ on the FSC site. These really got me going in the right direction.
    Attached Files Attached Files
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  3. #48
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    So BJDR 0E-1 is what I have loaded now, and 1.1 has the transmission line pressure changes to try this week, with a gauge on the trans obviously. I found that the acceptable pressure ranges are 37-171 for drive gears and since I didn't put a shift kit in it or drill any feed holes then I figure what pressure changes I do make shouldn't be as harsh. It was set to 90psi max allowed line pressure, so I am going to work up little by little to see if I can get this thing shifting a bit firmer. Running it in $0D it had set a transmission error which defaulted to full line pressure and the shifts were nothing short of BRUTAL, it shifted so hard I didn't even dare try it at WOT. So I know it can get better, I am just going to take my time and sneak up on it. I increased the Load based Pressure offset vs. TPS, PE line pressure vs. Input speed, and max allowed line pressure to 125. I will run it on -1.bin to get a current baseline and if it does max out at 90 psi, then I will try the -1.1.bin version and post back with the results.
    Attached Files Attached Files
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  4. #49
    EFI GearHead ! EagleMark's Avatar
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    Re: My project

    Hey did you go to Car dAlene? Or going tonight?

    Thanks for documenting this tranny stuff I'm sure it will help others!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  5. #50
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    No, I didn't make it to Car d'alene. I usually don't get to because of the hours I work. But the up side is I have lots of time during the week to work on my stuff. Those line pressure changes seem to have made a big difference. I also modified the kickdown stuff so it drives much better. I made some VE changes thursday night and have been datalogging my drive back and forth to work. It's kind of neat that the engine likes the fuel curve a certain way whether it's EFI or carbed. It's just much quicker and easier with EFI. It doesn't need a lot fuel for cruising, but the instant you start to open the throttle it wants LOTS of fuel and it wants it NOW. I still don't know how WOT really shifts because all it does is spin the tires in 1st (basically bald 295/50-15 Cooper Cobras)

    My next step. After driving it a few days ago and idling up my half mile driveway as usual I got out and the TBI adapter was so cold it had moisture condensing on it when it was about 70 outside and the engine fully up to temp. I then let it idle while looking over the DL and making a few changes and the idle started to creep up with the IAC completely closed. Got out and the adapter had warmed up from the fan blowing on it. So after reading a bit on FSC I decided I am going to put a MAT sensor in the RPM Air Gap manifold. From looking thorugh it the PCM already has the code for it and I still have a couple of extra wires in the harness so it shouldn't be that hard.

    I am also trying to fix a small issue with the 60mph cruise. It is kind of wierd. At 55 and 65 the engine sounds happy, runs great. But right at 60 it just feels rough. I added more timing and that seems to have helped a little but I am almost maxed out in those cells and I don't think it will completely get rid of it if I do go to 41.2 degrees SA.

    And the last issue is that while going through town @35 or 45mph, it requires so little throttle like 2.4 -3.1% that I thought I was bouncing off the DFCO or Decel Enleanment threashold. I was looking through the DL from my drive to work Friday and could see the lean spike (20:1 AFR) as TPS (2.4%) and MAP (28.1) remained completely steady. I changed the TPS for DFCO down from 3.9% to 0.4% and no luck. I have the "time before DFCO" set to 1 second so I will try up-ing that and see what it does. I don't know if anyone is still watching this thread, but any advice would be welcomed. I can go out and get the laptop if anyone wants to see the log.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  6. #51
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    Also one question for you guys with a test bench. I know that the injectors alternate firing with DRPs, but does each one always fire on the same DRP, from one engine start to the next? Or when going from Asynch back to Synch fire?
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  7. #52
    EFI GearHead ! EagleMark's Avatar
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    Re: My project

    I don't know?

    Just pulled the harness and ECM from my bench as it was done for a freind. Next time I get one on there we can look into that.

    If your ever down to CDA stop by and we will try it out?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  8. #53
    EFI GearHead ! EagleMark's Avatar
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    Re: My project

    Wish I had some earth shattering news for you but sounds like your heading the right direction. You sure it's not hitting lean cruise?

    Have you thought of a hot air intake? When I installed one on my otherwise stock 1990 TBI Blazer , that someone put an open element on, it made the world of difference in anything below totally warmed up on an 80 degree day. GM has so many available from factory that need no hoses or lines. Closed and draws heated air off headers when cold. Open to all cool air when warm.
    Quote Originally Posted by gregs78cam
    No, I didn't make it to Car d'alene. I usually don't get to because of the hours I work. But the up side is I have lots of time during the week to work on my stuff. Those line pressure changes seem to have made a big difference. I also modified the kickdown stuff so it drives much better. I made some VE changes thursday night and have been datalogging my drive back and forth to work. It's kind of neat that the engine likes the fuel curve a certain way whether it's EFI or carbed. It's just much quicker and easier with EFI. It doesn't need a lot fuel for cruising, but the instant you start to open the throttle it wants LOTS of fuel and it wants it NOW. I still don't know how WOT really shifts because all it does is spin the tires in 1st (basically bald 295/50-15 Cooper Cobras)

    My next step. After driving it a few days ago and idling up my half mile driveway as usual I got out and the TBI adapter was so cold it had moisture condensing on it when it was about 70 outside and the engine fully up to temp. I then let it idle while looking over the DL and making a few changes and the idle started to creep up with the IAC completely closed. Got out and the adapter had warmed up from the fan blowing on it. So after reading a bit on FSC I decided I am going to put a MAT sensor in the RPM Air Gap manifold. From looking thorugh it the PCM already has the code for it and I still have a couple of extra wires in the harness so it shouldn't be that hard.

    I am also trying to fix a small issue with the 60mph cruise. It is kind of wierd. At 55 and 65 the engine sounds happy, runs great. But right at 60 it just feels rough. I added more timing and that seems to have helped a little but I am almost maxed out in those cells and I don't think it will completely get rid of it if I do go to 41.2 degrees SA.

    And the last issue is that while going through town @35 or 45mph, it requires so little throttle like 2.4 -3.1% that I thought I was bouncing off the DFCO or Decel Enleanment threashold. I was looking through the DL from my drive to work Friday and could see the lean spike (20:1 AFR) as TPS (2.4%) and MAP (28.1) remained completely steady. I changed the TPS for DFCO down from 3.9% to 0.4% and no luck. I have the "time before DFCO" set to 1 second so I will try up-ing that and see what it does. I don't know if anyone is still watching this thread, but any advice would be welcomed. I can go out and get the laptop if anyone wants to see the log.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  9. #54
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    Well from looking at this morning's log, it seems that while cruising @33mph, 3.9%TPS, 34.7Kpa, I have the Synchronous AE flag ON. Then just as the lean spike is starting the Asynch pulse flag goes ON, Synch AE goes off for one sample while the Asynch remains on for another 5 samples.

    But now my question is why is Synch AE on all the time? Is it the lower vacuum that my cam makes.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  10. #55
    EFI GearHead ! EagleMark's Avatar
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    Re: My project

    Saw you on TGO, what was it?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  11. #56
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    Well after looking at the datalog for a couple of hours, it looks as if the synch AE flag in on whether AE is in effect or not. That would be the default AE mode. Then if more AE is called for it switches to Asynch AE. Who knows maybe the "Synchronous AE" flag should really just be labeled "Synchronous Mode"?
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  12. #57
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    AS far as the lean spike goes, I still have no idea. I was wondering if I was at such a low TPS that maybe PCM thought I was trying to idle, and because RPM was too high for an idle maybe it was cutting fuel. IDK. Interesting thing though, when I put the TBI engine in my '74 truck, I had the power to the ECM running off the resistor wire from the original points ignition, It showed 12+V with engine off, but then dropped to 5V when started. This naturally set off the LOW BATTERY code and opened the IAC all the way. Engine would Idle very high, and to keep RPM down the ECM would cut fuel completely until RPM dropped low enough. Now that is the '7747. I will have to look at the log again and see if the "Idle Flag" is set when the lean spike occurs. I'll check it when I get back.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  13. #58
    Fuel Injected! gregs78cam's Avatar
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    Re: My project

    UPDATE:

    Lean spike only occurs in closed loop. That is not such a bad thing though. I have the VE tables set pretty well (rich enough@WOT) so that I don't have to worry. It drives so much better in open loop. One thing I don't quite understand is, correct me if I am wrong, but when in closed loop as you get into WOT doesn't the PCM basically go open loop and ignore the O2 sensor and meter fuel strictly off the VE table and associated adders? I ask because WOT is actually richer in OPEN loop than it is in Closed loop. I always figured they would be practically the same.

    Also, trans tuning is coming along slowly. It takes a lot of time to get the shift points(up and down) and TCC to happen when what you want is far from stock. One more ?. How do I set this thing up to keep the TCC locked while decelerating?
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  14. #59
    EFI GearHead ! EagleMark's Avatar
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    Re: My project

    Not sure the exact procedure that your ECM follows but yes open loop like when you enter PE is by fuel tables. Some guys on TGO say yes others say there are still some O2 feedback? Some of the best tuners I have worked with in person tune totally open loop. When done switch on closed loop and all data is spot on and your back to 14.7 to 1. Enter PE and goes to that fuel ratio. There are always little checks in stock bins to check PE has not been entered to long to overheat cat. Sounds like you got er close?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  15. #60
    Super Moderator Six_Shooter's Avatar
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    Re: My project

    At WOT, the O2 feedback is not applied, but if the BLM is below 128 before entering WOT, that value is used for WOT fueling.
    The man who says something is impossible, is usually interrupted by the man doing it.

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