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Thread: MAP & CTS sensor questions

  1. #1
    boostaholic Turbo Mopar Contributor
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    MAP & CTS sensor questions

    OK all you tuning guru's out there, I need some guidance with my setup.

    I'm having a sensor issue on my 2.5 TII setup. I'm running a custom tune by Rob M.(2.5, +40's, 52mm TB, ported head, FMIC), but I have an issue with two sensors. Overall, it runs like a scalded dog, but I occasionally get a MAP sensor fault on deceleration. After logging a couple runs, what we figured out is, the MAP sensor is reading way too much vacuum. At idle it's showing -28" hg, and during a couple logs, it shows -34" on decel. Obviously that's impossible, hence the code being set... It runs like crap for a few seconds until I blip the throttle 3 times so it sees a "good" vacuum signal again, then the CEL shuts off, and it runs fine. I assumed it was a bad MAP sensor, but I've installed 3 different ones(none of them cheap ebay versions), and I get the same results. By my mechanical gauge, I'm running about -20" at idle. I've checked the tune, and it's set up for the 3 bar sensor that I'm using. I'm not sure what else it could be.

    Also, my CTS is reading way off. Like right now, my garage is about 50 degrees, and per MPScan, the ECU is reading 100 degrees, and it climbs to 230 really quick once the engine is running. Again, by my mechanical gauge, it's only running about 180-190 when the ECU says 230. Not sure what else to do about this. The radiator fan kicks in while the engine is still relatively cool, and basically never shut off because the ECU thinks it's getting hot. I'm going to back probe the CTS sensor, and document the readings as soon as I can. The sensor is new. I guess I could have just gotten a bad one???

    Also, after looking at the logs, Rob made a couple tweaks to the tune, and the new tune does the same thing.

    Any suggestions or help on this would be appreciated.

    Thanks

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: MAP & CTS sensor questions

    Code 13, or code 14 for the MAP? What brand of MAP sensor is it?

    For the coolant temp sensor, have you ohmed it out to see what it's reading at room temp when cold?

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    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: MAP & CTS sensor questions

    You might want to try logging map volts, and trying to get readings with a mityvac vacuum pump at the highest vacuum it can achieve for reference.
    Also try getting a map volt reading at 29.2 psi which should be 5v.
    Maybe there is a issue with that wire circuit, or the computer?

    You could try getting some info for the coolant sensor too.

    You somehow could have corrupted RAM setup info for those gauge points? I would be sure you have updated all those MPScan lists and tables.

    Which 3bar map are you using? Some were known to not be scaled correctly iirc.
    Wayne H.

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    Re: MAP & CTS sensor questions

    I did add MAP volts to my MPScan screen. I haven't had the chance to do another log yet. I'm hoping to do a log this afternoon.

    As far as MAP sensors, I've been running the one DIY Autotune sells. I've also tried a factory GM sensor I borrowed from a friend, and the last one was from an instrumentation place recommended on here. I'll have to find the name. None of them came from ebay. I know about the issues with those.

    I'll get some readings later today and post back.

    Thanks

    Sent from my LG-H900 using Tapatalk
    Last edited by 83scamp; 04-02-2018 at 09:57 AM.

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    Re: MAP & CTS sensor questions

    Quote Originally Posted by cordes View Post
    Code 13, or code 14 for the MAP? What brand of MAP sensor is it?

    For the coolant temp sensor, have you ohmed it out to see what it's reading at room temp when cold?
    I'll Ohm it out today. It was a code 13 for reading not changing. Like I said, after getting it, if I blipped the throttle 3 times, it would clear, and it would run fine until I hit another high vacuum/deceleration event. And it doesn't always do it every time, but it's often enough to be a correlation... I found I could avoid it by pressing in the clutch as soon as I got off the gas coming to a stop. When it would happen, it was when I was coasting to a stop, had to be in high vacuum for about 10+ seconds.

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: MAP & CTS sensor questions

    Quote Originally Posted by 83scamp View Post
    I'll Ohm it out today. It was a code 13 for reading not changing. Like I said, after getting it, if I blipped the throttle 3 times, it would clear, and it would run fine until I hit another high vacuum/deceleration event. And it doesn't always do it every time, but it's often enough to be a correlation... I found I could avoid it by pressing in the clutch as soon as I got off the gas coming to a stop. When it would happen, it was when I was coasting to a stop, had to be in high vacuum for about 10+ seconds.
    I had the same problem in my CSX. What type of vac line are you using on the way from the manifold to the solenoid/MAP sensor? My line was getting hot enough to become soft and collapse under the vacuum when at idle.

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    Re: MAP & CTS sensor questions

    Quote Originally Posted by cordes View Post
    I had the same problem in my CSX. What type of vac line are you using on the way from the manifold to the solenoid/MAP sensor? My line was getting hot enough to become soft and collapse under the vacuum when at idle.
    I'm running rubber line line from the intake over to the MAP and fpr. It's good thick hose from the auto parts store. Not cheap thin stuff. It T's off the back of the manifold. One side goes to the fpr and MAP, the other side goes to the BOV and boost gauge inside. Kept them as short as possible.

    Did some logging. My mityvac will only generate -24" vacuum. At that point MAP voltage is .39v. But MPScan was showing -31". At atmospheric, it's at 1.59 volts, and -2" on MPscan. Both MAP and cts are showing 5v feeding them, so that is good.

    I may have to pull the cts sensor to read it. I can't get my probes in it to measure resistance.

    Sent from my LG-H900 using Tapatalk

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    Re: MAP & CTS sensor questions

    Good luck,
    At times it can be something other than the code. In my case, two years ago I was getting a few different error codes but mostly MAP. What was my issue? A faulty O2 Sensor, WTF. Problem never returned. Is your TPS OK?
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
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    Re: MAP & CTS sensor questions

    Quote Originally Posted by chromguy View Post
    Good luck,
    At times it can be something other than the code. In my case, two years ago I was getting a few different error codes but mostly MAP. What was my issue? A faulty O2 Sensor, WTF. Problem never returned. Is your TPS OK?
    I think so. Getting good reading from it. When I built the motor last year I installed all new sensors. I'm running the O2 off the wideband sensor I'm using. Using the narrowband lead off the gauge. It's an AEM unit.

    Sent from my LG-H900 using Tapatalk

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    Re: MAP & CTS sensor questions

    Quote Originally Posted by chromguy View Post
    Good luck,
    At times it can be something other than the code. In my case, two years ago I was getting a few different error codes but mostly MAP. What was my issue? A faulty O2 Sensor, WTF. Problem never returned. Is your TPS OK?
    Good point. Maybe something skewing the reference voltage?
    Wayne H.

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  11. #11
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    Re: MAP & CTS sensor questions

    OK, to update, I ordered new MAP & CTS sensors from Cindy. They arrived today, and seem to have fixed my readings according to MPscan. Got 50 degrees on the CTS cold, and I was getting about 15" hg at idle at first start-up.

    Now the bad news. Since changing these two sensors, it is now running pig rich at idle. I mean O2 pegged at 10.0, and black smoke rolling out the exhaust, plus it idles like crap(which is why I think I'm only showing 15" vacuum). Before, the injector PW was running about 1.6 ms, now it doesn't go below 5 ms. Is that strictly due to the warmup programming? I can't drive it like this. Not sure what to adjust to make it better?

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: MAP & CTS sensor questions

    It's not just the cal trying to learn. That's a problem. I would put a known good 3 bar cal in there, or attempt to go back to stock to see if you can solve the problem.

  13. #13
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    Re: MAP & CTS sensor questions

    I'll try a standard BB Stage IV cal in it and see what happens...

  14. #14
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    Re: MAP & CTS sensor questions

    Loaded a BB stage IV cal, and it's still pig rich cold. So, I went in and cut cold fuel enrichment curves A, B, and C in half. Still pig rich. The good news is my injector PW dropped from 8 to about 3.5, but before it was at about 1.6 to hold a 14.7 AFR at idle, so I'm still dumping twice as much fuel in it as it needs... Now the bad news is it's now hunting at idle. Won't hold steady. The IAS is moving, so the computer is compensating, but it's like it's over shooting and won't settle down. I have no idea what to do to correct that...

    What am I missing? I guess I need help from one of you tuning guru's who is much smarter than I am. I'm not even sure I'm doing it correctly. After making changes to the .tpl file don't I have to re-compile? It won't let me. I burn the chip, using the file I just changed, it says it's successful. I install it in my SMEC, and it runs, but nothing gets any better. Before I burn a chip, don't I have to erase it? It won't let me do that either.

    Maybe I just need to leave this to the pros... Anybody have a good online how-to I can read to show me how this is supposed to work? I've read the BB wiki a dozen times, and it's no help to me....

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: MAP & CTS sensor questions

    Yes. You need to erase the chip. What chip are you using? Where did you get it from? What are you using to burn and erase the chips?

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    Re: MAP & CTS sensor questions

    Harry recommended to me to cut the reported injector size to get the unit working at idle first.
    Worked well for me and makes sense
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    '87 CSX #432

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    Re: MAP & CTS sensor questions

    Quote Originally Posted by cordes View Post
    Yes. You need to erase the chip. What chip are you using? Where did you get it from? What are you using to burn and erase the chips?
    Moates Burn 2 and 27SF512 chips bought from Moates as well. Using MPtune to edit & flash chips.

    - - - Updated - - -

    Quote Originally Posted by chromguy View Post
    Harry recommended to me to cut the reported injector size to get the unit working at idle first.
    Worked well for me and makes sense
    Wouldn't you want to say they are larger? Seems like if you tell them they are smaller, it will add injector PW, not take it away??? Maybe I'm looking at it wrong...

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    Re: MAP & CTS sensor questions

    And why will MPtune let me edit a .tpl file, but not flash it? If I edit a .bin file I can flash that... Shoot, maybe I'm not flashing anything. MPtune tells me I am, but nothing seems to be changing. I can't erase anything, so maybe I'm not flashing anything either...

    Maybe I'm just not understanding any of this.... Guess I'm way in over my head. I don't understand how a proven tune that hundreds of guys have used is total crap in my setup???

    Starting to wish I'd left this truck carbed...

  19. #19
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    Re: MAP & CTS sensor questions

    a .tpl file is a human readable (text) file that displays the table data. the .asm file is a human readable (text) file that contains the operating code. for the ecu to run it needs to have a machine readable file, i.e. the compiled binary (.bin) file that is created when you "compile" the tpl/asm. the .bin is what is downloaded to the ecu.

    when you edit the .bin file you are directly modifying the bytes in the file. mptune uses the .mpt file to tell it where the table bytes are located (similar to the old dcal .tbl file). the downside to modifying the bin is if changes are made to the code (i.e. the asm file) for new features/etc. that is why editing the tpl file and recompiling is/was the best way. since rob L is no longer actively supporting the turbonator code it may not be quite as necessary to work with the tpl files. also, the turbonator cals used a common code base (asm) and different (tpl) files so users could easily start with a compatible system (e.g. manual vs auto, stage 1 vs stage 4).
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    Re: MAP & CTS sensor questions

    OK, playing around a little last night, I decided to download Moates' burning software. It read the chip, and erases the chip. So I know that's working. After erasing it, I went back into MPtune and burnt the chip using the edited .bin file I made. Checked it with Moates program, and it verified the chip was not empty. So I guess I am able to burn the chip. Just don't know why MPtune won't erase it...

    Tonight I will install this chip, and see if it makes any difference.

    It's just really frustrating because I know what's wrong, just not sure how to fix it. It's feeding way too much fuel at idle. I can see it from the injector pulse width. Before, it was running about 14.7 AFR at idle and the PW was about 1.6. Now it's buried on 10.0 AFR, and the PW is still around 3.2-3.5. Obviously I need to cut fuel at idle when cold. I assumed trimming the A, B, & C curves would do that. Maybe this new burn will make a difference....

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