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Thread: This idle...killing me.

  1. #1

    Default This idle...killing me.

    Could one of you lay eyes on this datalog? The 555 came up to temp and that's when I'm trying to adjust the IAC. I cannot get the idle to play nice. It'll be good for a while, then it will stay high. I've checked for vacuum leaks as well as reset throttle blades.

    It'll eventually stall out if I don't play with the throttle. That's the datalog I've attached. I had to zip it, hope that's correct. Is there a setting I have out of sorts? Thanks Dave
    Attached Files Attached Files

  2. #2


    Thanks for the datalog, but that's only half the story. Need the Config File as well. I used a base calibration just so I could look at the datalog and you have some glaring wiring issues. Is this datalog, all just idling in the garage? I assume so because the TPS stays at 0%. If that is the case, then it should stay in Closed Loop all of the datalog, but if you look, Closed Loop status in your datalog is all over the place in the middle. In one spot it jumps in & out of Closed Loop six times in one second! Again, at steady state idle when warm, it should stay in Closed Loop.

    Also, right click on the Graph and select "Mark Data Points". You should have 60ish data points per second. At the beginning of the datalog it's not too bad at about 55. Later in the datalog it plummets to 12. But interestingly enough, it goes back up near the end. Think about it like this, when the ECU has 1/4th the data points that it should have, it starts to do crazy things.

    I had this problem at first too. The biggest things that helped it were re-doing my ground wiring properly and getting clean relay power for the switched 12V power wires. I watched the attached video about six times. Each time you pickup something new. You can skip the first five minutes about crimping tools if you want, but definitely pay attention to the discussion about grounds. You must have a high quality ground cable from the battery to the engine. I tried to get away without that because my battery is in the trunk and it cost me. Once I redid the grounds like in the video my data points cleaned up. Do exactly as this guys shortcuts. You will be rewarded with a much better running system.

  3. #3
    Join Date
    Nov 2014
    Ont. Canada


    Always post a current copy of your Config File with any datalogs you post.

  4. #4


    The Sniper is a low voltage digital device so the wiring needs to be done properly. Without seeing some pictures of the installation, I can't tell you what to fix other than just tell you to go double check your wiring.

  5. #5


    Great video, thank you all! I'd post the Config File, but instead I'm going to go back through wiring. Pretty sure my grounds are good, but going to double check. Going to add a relay on the Switched 12V. I may take it straight from battery and switch it, instead of using preexisting switched. Thanks again!

  6. #6


    OK, a little closer I think! Gregs69rs and others, I'm not ashamed to say, I overlooked something, maybe major. Did not have engine grounded to battery. Wire was there, forgot I was sourcing a connector for the 00 wire. I've posted both DL & GCF files. I seem to be rich at idle, yes still just in garage. I can take it out and run a DL if that would be better? Any pointers? Thanks again!

  7. #7


    Wow! That IAC graph is crazy looking. Your IAC looks like a very smooth roller coaster. It very gradually goes from 0% to 60%+, then back to 0% but the RPM barely changes. I have no idea what might cause that, but hopefully some of the more experienced guys will chime in. Maybe a vacuum leak? The IAC is definitely not affecting RPM like it should be.

  8. #8


    Are any spark plug wires near IAC? First check that. Next check AFR. It almost sounds like it's too rich so you have to keep cracking the blades to stop it from stalling the engine due to over fueling. Next question is timing. What are you running? Is it controlled by the EFI?

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