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Thread: PCM swap and DBW issue

  1. #1
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    Default PCM swap and DBW issue

    Hi, I have upgraded my LQ4 to DBW and am having some issues with getting it running. I originally had a 512kb pcm and cable TB and have swapped it out for a 1mb PCM from a 2003 Silverado. I also used the TAC and pedal from the Silverado. With the car sitting there and ignition on the throttle body and pedal position work fine all the way up to 100% so I am thinking the wiring is ok. This setup is in a landcruiser and is also turbo'd so I had to use COS3 as there is no COS5 for the 1mb PCM. I copied all the tables over from the original tune so I was hoping it would start up and run. It dosent unfortunately. It idles very rough and as soon as I tap the throttle it will stall. Could someone please have a look at my tune and see if I have missed something obvious. It is a maffless setup and I have attached a log of it idling also. It now has a LS2 90mm throttle body with X-link converter.

    Many thanks

  2. #2
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    In the Engine DTC Processing Enablers set P0101, P0102, P0103 to "C" Non-Emissions and see if that helps.

    Jeff
    98 GMC RCSB 2WD, Internally stock 305 w/Twin T-3 junkyard Turbos,4L80e,Ramjet intake,42lb.inj., 0411PCM, COS3,4675LBS w/me in it. Best Time on 5 passes-13.01@110

  3. #3
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    Thanks Jeff I tried that and I still have the problem. What I have worked out is that it is throwing P1514 code about 4 seconds after startup and this is cutting out injectors 2, 3 & 5. I have confirmed this with a test light on the injector plugs. For some reason it is going into reduced power mode straight away. How can I tell if the maf is properly disabled in the tune?

  4. #4
    Joe (Moderator) joecar's Avatar
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    MAF is properly disabled if one/any of the MAF DTC's immediately triggers.

  5. #5
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    Ok thanks Joe, p0102 always comes up so I guess it's disabled. Heres a list of the DTC's after it has been running for a few minutes.

    Click image for larger version. 

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    Click image for larger version. 

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ID:	17264
    Last edited by ttls1; August 5th, 2014 at 06:11 PM.

  6. #6
    Joe (Moderator) joecar's Avatar
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    P0106: you need to follow this up, MAP sensor is important for various subsystems, get this sorted out and see if P1514 persists.

  7. #7
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    I don't think there is anything wrong with my map sensor as it was working perfectly before the PCM swap and seems to indicate correctly once it idles. Could a tune related issue cause this DTC?

  8. #8
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    Ok I have had a chance to get back and sort this DTC issue. I had to increase C6101 by 50% and the car now runs and revs ok but I now have a new problem. I am trying to do the RAFPN idle tuning but every time the IAC long term correction just stays at 0.5 g/s. It should be 0 and the IAC short term corrections start at 4 and just count down to 0 and flatline. If anyone has ever seen this issue could they please help. I have tried disabling and enabling both long term and short term trims but it makes no difference. I have attached a log and the current tune.

    I have just spent an hour going through all 25 pages of RAFIG threads and found a couple of logs that appear to do the same as mine but never had a fix posted. I just don't know where it is getting the 0.5 g/s long term correction from.

    Cheers
    Attached Files Attached Files
    Last edited by ttls1; August 20th, 2014 at 06:46 PM.

  9. #9
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    I have persevered some more with this menace and manually set up the desired idle airflow as the fuel trims are not indicating any realistic data. In park neutral it is starting and revving nicely with good response and no delay back to idle rpm. Now I have another weird issue which is as soon as i put it into gear the max throttle position is 16%. When my actual pedal position is showing 100% the TB wont go over 16%. It remains like this even back in park until I shut down and restart.. Could this be a torque limiting thing?? Im pretty sure I have disabled all limiting? I have the tune and log attached and could really use some help nutting this out. There are no DTCs except the MAF circuit low (im running SD) after this happens. One last question, my desired idle airflow is about 10 g/s at operating temp and this seems high to most other tunes i look at. Could adding the 90mm DBW TB and new intake make this much difference? Originally it was 6.2g/s or could this indicate a vac leak or would that cause the opposite?

    Cheers
    Attached Files Attached Files
    Last edited by ttls1; August 24th, 2014 at 04:34 PM.

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