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Thread: No idle closed loop 7427 $0D

  1. #1
    EFI tuning addict 96lt4c4's Avatar
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    No idle closed loop 7427 $0D

    Tuning a truck for a friend of mine, having problems with closed loop idle. The truck will go into closed loop while driving, then when you come to a stop it goes in and out from opened to closed, then stays open. I noticed in the log that for some resaon AE is going active at idle for no reason. Here is a short log at idle.
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    -1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
    -2002 Cavalier, Tuned with HP Tuners
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    EFI GearHead ! EagleMark's Avatar
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    Couple things that stand out is low vacuum/higher MAP at idle, 104 BLM so is that the bottom of your bin? and not much timing?

    So big cam?

    Raise idle, lower VE and increase timing at idle. This will get things hot for O2 sensor and increase MAP so AE does not come in at idle.

    There's so many settings for AE in $0D, one flag for Sync fuel at idle, look at others to increase MAP AE qualifiers. Looks like the higher MAP at idle could be causing the Sync AE Flag which is making it even richer.

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    Fuel Injected! pmkls1's Avatar
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    Just took a quick look at the log and did notice a few things. First, is this a stock engine or does it have an aggressive cam ? If it is anywhere near stock the MAP readings at idle are way too high. The MAP pressure shouldn't be above 40kpa at idle in gear. I suspect that the AE is going active because the MAP readings are bouncing around enough to trigger AE. Was the A/C on and possibly cycling during the log ? The idle was also a little high as well which could explain the MAP readings. Another thing I noticed was the coolant temp. I know that 188 degrees isn't very low, but depending on what the starter bin was, closed loop idle temps are kind of high in some of the stock bins I have noticed. I had a similar issue after swapping a 427 PCM into my firebird and finally noticed some of the closed loop qualifiers in the BJYL bin. The car could go into closed loop pretty easy while driving, but would have issues with going into open loop at idle. I'm sure others will chime in too, but those were a couple of things I noticed.
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    EFI tuning addict 96lt4c4's Avatar
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    Min temp for closed loop is 2*C. The truck has a small cam in it, its a rebuilt 350 TBI, with TBI heads. Could there be a vaccum leak? So if I give it more timing at idle it will bring the MAP down? I thought around 20 degrees at idle was good. Idle is set to 700 RPM in the warmer temps. My plan was to emulate and tune the idle VE table while in closed loop. My wide band is in my truck right now so I could not tune it in open loop.

    At one point iin the log the truck was in gear, no AC on.

    His IAC counts were up around 63 at idle no load, so I cracked the throttle blades open some to get them down, then reset the PCM.

    Its one of those deals where he is always busy and in a hurry so I do not have much time to tune on it. Plus he is standing over my back asking 1000 questions making it hard to concentrate...I told him he is going to have to leave it with me for a day.

    Here is the bin he is running now

    The 104 BLM means nothing in open loop right? It needs to be in closed loop for that to update?
    Last edited by 96lt4c4; 10-15-2012 at 09:00 AM.

    -1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
    -2002 Cavalier, Tuned with HP Tuners
    -1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)

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    EFI GearHead ! EagleMark's Avatar
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    Like we both saw, the low vacuum/higher MAP so thought it was a bigger cam. But if small cam then yes it could be a vacuum leak. But IAC count of 63 does not indicate vacuum leak? Yes more timing with large cams will increase vacuum/lower MAP.

    Beginning of that log was dead? Took awhile to get going then was short.

    Your right about open loop, but if OL BLM should be 128? So I'm confused...

    What is that bin based off?

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    Fuel Injected! jameslleary's Avatar
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    Hey Mark, dont forget about my supposedly small cam, and the problems it caused here. Seems to be an epidemic. 104 is way pig rich though, I have seen 108 on mine in drive.

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    EFI tuning addict 96lt4c4's Avatar
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    Quote Originally Posted by EagleMark View Post
    Like we both saw, the low vacuum/higher MAP so thought it was a bigger cam. But if small cam then yes it could be a vacuum leak. But IAC count of 63 does not indicate vacuum leak? Yes more timing with large cams will increase vacuum/lower MAP.

    Beginning of that log was dead? Took awhile to get going then was short.

    Your right about open loop, but if OL BLM should be 128? So I'm confused...

    What is that bin based off?
    Yeah I dont know why the log did that. He is going to check for vaccum leaks. I think the BLM'S were at 104 after a drive. When we came to a stop it went back into open loop which is when I restarted a new log to capture what it was doing. I know the thing is really rich. I am thinking that he may have pretty crappy cam as well. He is trying to dig up the cam card, but said it was recomended to him by this guy who said this guy....so I dont know yet. I do know its flat tappet, I mentioned the "RV CAM" he said that sounded right. Anyway, I am going to try and get cam specs, he is going to look for leaks. The motor is only about a year old.

    I used the stock bin from my 94 Blazer, this truck used to have a 6 cyl. in it and its a 93 so we swapped in a 7427 when he went V8. Here is the stock bin I used for a starting point.

    Also here is another log while driving, if anyone wants to look, like I said, I know its rich.
    Attached Files Attached Files

    -1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
    -2002 Cavalier, Tuned with HP Tuners
    -1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)

  8. #8
    EFI tuning addict 96lt4c4's Avatar
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    Quote Originally Posted by jameslleary View Post
    Hey Mark, dont forget about my supposedly small cam, and the problems it caused here. Seems to be an epidemic. 104 is way pig rich though, I have seen 108 on mine in drive.
    What kind of problems were you having? What cam do you have?

    -1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
    -2002 Cavalier, Tuned with HP Tuners
    -1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)

  9. #9
    Fuel Injected! jameslleary's Avatar
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    Comp 12-388-4
    Surging idle, constantly low BLM's....always 118 or below.
    I am still having some issues every now and then, vac in drive, per the data dash, is 15"
    But comp swears up and down its not the cam.

  10. #10
    EFI GearHead ! EagleMark's Avatar
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    I'd like to see both the cam cards if you can?

    A vacuum gauge, mechanical! Is also a useful tool to look for shake in reading. Won't find it in a log... is vacuum steady at idle? No shake in reading? Accelerate and differences should be smooth, no shake.

    There was or still is a 290 HP 350 Chevy engine that just sucked for idle and by specs should not been that bad. There's always a degree issue when installing a cam, or at least check and see how far it's off? Push the cam specs to .224 duration @ .050 and this degree is more crucial with idle!

    Or who adjusted the rockers?

    15" of vacuum is easily tunable if it's a steady vacuum. But 15" of vacuum could be 17 or 13 depending on elevation.

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  11. #11
    EFI tuning addict 96lt4c4's Avatar
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    Quote Originally Posted by EagleMark View Post
    I'd like to see both the cam cards if you can?

    A vacuum gauge, mechanical! Is also a useful tool to look for shake in reading. Won't find it in a log... is vacuum steady at idle? No shake in reading? Accelerate and differences should be smooth, no shake.

    There was or still is a 290 HP 350 Chevy engine that just sucked for idle and by specs should not been that bad. There's always a degree issue when installing a cam, or at least check and see how far it's off? Push the cam specs to .224 duration @ .050 and this degree is more crucial with idle!

    Or who adjusted the rockers?

    15" of vacuum is easily tunable if it's a steady vacuum. But 15" of vacuum could be 17 or 13 depending on elevation.
    I am working on getting the cam card, I did not build this motor, it was built by a machine shop. As far as adjusting the rockers, I always 1/2 to 3/4 turn past zero lash.

    I have a mechanical vaccum gauge, so I will stick it on the truck next time he brings it by. I am also going to lower the idle speed and raise the timing at idle to see if it helps. If everything else comes out OK.

    -1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
    -2002 Cavalier, Tuned with HP Tuners
    -1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)

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    Fuel Injected! woody80z28's Avatar
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    I turned closed loop idle off with my built 350 running $0D. For some reason while sitting idling it would cut the BLM all the way down to 90 and stall. You could see my wideband going way lean as it was cutting the BLM but it continued to lean it out anyway. Open loop idle has been fine and the wideband shows the a/f is good.
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    EFI GearHead ! EagleMark's Avatar
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    I'd be interested in seeing your cam card too! I was watching this happen here to in last log but not convinced it is the cam yet, I think there are other issues.

    What your describing is to much cam for EFI CL Idle, either duration or overlap and your getting reversion/EGR at idle. there's a point where you can't raise idle, advance timing and lean fuel enough to get good exhaust to O2 sensor. The Narrow Band O2 sensor is lieing, or more acuratly being lied to. When that happens Open Loop Idle is the answer! As you found.

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    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  14. #14
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by 96lt4c4 View Post
    Yeah I dont know why the log did that. He is going to check for vaccum leaks. I think the BLM'S were at 104 after a drive. When we came to a stop it went back into open loop which is when I restarted a new log to capture what it was doing. I know the thing is really rich. I am thinking that he may have pretty crappy cam as well. He is trying to dig up the cam card, but said it was recomended to him by this guy who said this guy....so I dont know yet. I do know its flat tappet, I mentioned the "RV CAM" he said that sounded right. Anyway, I am going to try and get cam specs, he is going to look for leaks. The motor is only about a year old.

    I used the stock bin from my 94 Blazer, this truck used to have a 6 cyl. in it and its a 93 so we swapped in a 7427 when he went V8. Here is the stock bin I used for a starting point.

    Also here is another log while driving, if anyone wants to look, like I said, I know its rich.
    An RV cam will not cause this. But a vacuum leak will, just a little vacuum leak to one cylinder on O2 sensor side and POOF! Data is wrong!

    I looked at the bin and log. Couple things I didn't like was Max Timing increased past 41.8, not good to go past a built in fail safe of firing wrong cylinder. Then Main Spark Bias of this bin is 9.8. Your's is 0? But your timing table is about the same around idle, way more other areas. I never change this in bin because there's to many other things that could be affected. The $0D XDF says this bias is built into mask, that said timing table should be actual. Now without bias where is it? I don't know, it's just something I was taught to leave alone, do leave alone and work on bin as is. You definatly can change bias if you know how it affects every other spark setting. But that's to much work for me... KISS works well here and you don't find an extra 9.8 degrees somewhere!

    "So where do you say your timing is?" Check with a timing light and compare to data.

    Idle does not look steady? Timing and cells are constantly changing, timing is varying a few degrees, so flatening timing at idle could help.

    But that is not what I found that could be affecting this. You've changed a lot! All I saw was good tuning. Except some of the 02 settings I don't understand, like Mean/Rich, Proportional and Lean limits. Some are same both ends? I started looking closer at these differences from stock bin when I saw cross counts stop while still Closed Loop. Also saw INT of 128 and BLM of 99 and stay there with no cross counts, still Closed Loop... I'd copy in stock 02 settings for now and see what happens. Also pull power and clear BLM learn, it's probably a disaster at this point.

    HTH!

    I'm curios and would be intrested in hearing results of timing at timing marks as is. Then with Main Spark Bias back in place as well.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    Fuel Injected! woody80z28's Avatar
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    Cam in my truck is actually very mild. It's a stock F-body LT1 cam (204/207@.050). If the cam was the problem, then the wideband would also be reading incorrectly. My wideband read it fine, and I could see watch the AFR spike lean before it stalled. FWIW, closed loop idle was unchecked in my factory bin. I turned it on to help band aid any issues with my VE tuning, but disabled it since it caused problems.
    80 Camaro Z28 - 500hp+ AFR 383 / T56 6spd (Accel DFI)
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

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