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96' Procharged Cobra "Casper" Build

Discussion in 'SN95 Cobras' started by 01silverstang, Feb 24, 2021.

  1. SecondhandSnake

    SecondhandSnake Well-Known Member Established Member

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    It will take it a little while to warm up enough to use the upstream sensors for feedback. A couple minutes would be a good guess.

    This part here made me wonder. I know old EECIV foxes and EECV new edges, but the SN cars I'm not as well versed with. Generally "idle" is a unique operating mode for the engine. If it thinks the throttle is cracked, it won't operate in idle mode, which means no benefits like using spark to keep a steady idle. On the old foxes you had to adjust the TPS to get the right voltages. On the later EECV cars the EEC does an auto learn on startup to determine what closed is. I know even though mine registers as something like 200 counts with the throttle closed (EEC using an A-D converter to turn volts to discrete counts), it actually interprets that as "0% throttle- throttle closed." I would make sure your scan tool isn't doing it's own interpretation based on raw voltage or something of that nature. What matters is if the EEC thinks it's closed, and sets the idle flag.

    If you have a datalogger I would check to see if the idle flag is set, what spark/fuel sources are, and when you go monkeying around with the throttle, keep in mind that's going to change the IAC behavior. If it logs IAC integrator you want that to be zero.

    Could have been something that was intermittent or just bordering on faulty, and you managed to dislodge it all the way. Sometimes you just get lucky.

    There's really only a couple manufacturers of those sensors, basically just NTK and Bosch. You can find knock off ones on places like Alibaba, but I sure as hell wouldn't trust those. You definitely want a genuine part- just a matter of shopping around to see who has the best price.
     
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  2. 01silverstang

    01silverstang Well-Known Member Established Member

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    My research has found that 99+ cars do not have to be adjusted, the EEC-V automatically checks and calibrates the TPS voltage when the key is turned on. However, on my car I do need to make sure that the sensor is in the correct range with the voltmeter. If it is... I don't know, the throttle is clearly closed. The stop has been unscrewed to the point it doesn't even touch and it's still reading high. I have tried searching for similar problems and haven't found anything conclusive. The car idles high, and when driving and letting off the gas has a hanging idle (which would make sense if the PCM thinks the throttle is roughly 20% more open than it is. It gets tricky however due to overlap, a lot of people have the handing idle with the 4V and use an IAC restrictor to solve it.
     
  3. DSG2003Mach1

    DSG2003Mach1 Premium Member Premium Member Established Member Single Barrel Sirs

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    Ive never hard to do it but I thought on those cars there was some slop in the TPS mounting and you could actually move it around a little bit. You leave the screws tight enough to have some tension but loose enough you can move it a tad. Move it, check voltage and repeat until you get it to the right reading. Once snugged down check voltage again to be sure it didn't move from tightening the screws
     
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  4. 01silverstang

    01silverstang Well-Known Member Established Member

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    So I think I found something that could potentially explain part of the issue. I have an Autel Autolink AL319 scanner, on another forum someone mentioned that perhaps the (%) isn't percentage of throttle, but percentage of supply voltage so 18-19% of 5V would be .9V which is within the range you should see at idle?

    That being said, with the screw completely back off so the throttle is closed, idle is around 1k rpm. Not sure what else could impact the idle like that?
     
  5. DSG2003Mach1

    DSG2003Mach1 Premium Member Premium Member Established Member Single Barrel Sirs

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    again Im a little unfamiliar with these but the throttle blade screw and TPS voltage reading aren't one and the same. If you're sure the TB blades are closed, put the set screw back so it holds that way. At this point Id get a fine prong/lead for my voltmeter and go direct to the wire on the TPMS for voltage. If it's not the correct voltage youd loosen the TPS itself and wiggle it around until you get correct voltage then snug it back down (this is done Key on, Engine off)

    TPS Voltage Adjustment Video | 86-04 Mustang - LMR.com
     
  6. 01silverstang

    01silverstang Well-Known Member Established Member

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    So this is the confusing thing, the screw can slightly open the throttle position but can't hold it... if that makes sense. The screw meets the cable retainer on the lower portion and depending on how far out you adjust it you can raise the retainer and slightly open the throttle blades, but when you back it off it has a natural stop.

    I will double check with voltmeter, but further research is saying my scan tool reads straight voltage and converts it to a percentage based on 0V to 5V, so 19.2 % would equal 5 x .19 = 0.95V which is within the correct range for the TPS at idle. So if the throttle body is completely closed and the TPS is within range, why would it idle at 1k... maybe it hasn't idled long enough for the PCM to "learn" it's normal idle?
     
  7. DSG2003Mach1

    DSG2003Mach1 Premium Member Premium Member Established Member Single Barrel Sirs

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    that sounds reasonable then in which case Id try letting it idle (AC off) for a solid 10 minutes and DONT TOUCH ANYTHING. Even after my car sits for a couple weeks sometimes the idle is a little off for whatever reason, I let it sit for a few and warm up and it smooths out. If thats not it then you probably need to do some actual data logging - as mentioned previously looking at idle flag, closed/open loop flag, what its seeing from the front O2s, tps, IAC etc...
     
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  8. 01silverstang

    01silverstang Well-Known Member Established Member

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    I'm going to have to bite the bullet and buy and SCT tuner... as my scan tool is pretty decent for $35 but I need to be able to generate more robust data logs and will need it for future retunes, etc.
     
  9. SecondhandSnake

    SecondhandSnake Well-Known Member Established Member

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    If it's idling at 1000 RPM with the throttle stop completely backed off, then you've got excess air getting in somewhere. It could be a vacuum leak, bad IAC, or even if the throttle body/blade itself is hanging up.

    For the throttle it might take a unique approach somewhere between the fox and new edge set procedures. You obviously need it to meet the voltage spec. You may need to slot the bolt holes, or get a new TPS sensor. For the idle I don't know if the old "set hot idle to ___ with IAC unplugged" procedure works, or if you need the newer one to verify IAC duty cycle is >25%, and idle air integrator is 0.

    Also I wouldn't bother with an SCT handheld. For the price you can get a Quarterhorse that will also let you tune it yourself, and doesn't glitch out as much as the SCT. Mine is older but it would drop data, or cause my dash to drop out randomly.
     
  10. 01silverstang

    01silverstang Well-Known Member Established Member

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    I mean I wish I knew the first thing about tuning, but with the car being Procharged... I'm not sure if it's the best vehicle to learn on. I basically need something that my local shop can tune through, and I can data log to make sure everything is safe.
     
  11. SecondhandSnake

    SecondhandSnake Well-Known Member Established Member

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    I cut my teeth on my compound boosted car, because other tuners couldn't do it. Just giving you my experience with it. I went SCT first since that's what my previous tuner used, but I wished I would have went QH from the get go.

    But I get it- if you've got a good tuner, you've got to use what they want.
     
  12. jman37

    jman37 Active Member Established Member

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    Don't buy an SCT to read codes, even that's limited. Best thing to do is buy an Bafx bluetooth dongle and download Forscan, the best Ford PID applicaiton there. If you have an iphone then you need the WiFi one I believe.

     
  13. 01silverstang

    01silverstang Well-Known Member Established Member

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    I didn't realize Forscan was compatible with SN95's... If I can datalog with Forscan and a Bluetooth dongle that would be great.
     
  14. DSG2003Mach1

    DSG2003Mach1 Premium Member Premium Member Established Member Single Barrel Sirs

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    what you can log on the device out of the box is limited but hooked up to a laptop you can see all the PIDs
     
  15. 01silverstang

    01silverstang Well-Known Member Established Member

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    So just checked TPS voltage and it measured .94V at closed, and smoothly went up to a max of 4.75V which from my understanding is the correct reading for WOT. I'll fire it up this afternoon and let it idle for awhile and check the live data.
     
  16. jman37

    jman37 Active Member Established Member

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    Right, just saying that's a far better tool and cheaper than an SCT will be. Just trying to help, if you want to spend 400 on an x4 that will have even less PIDs then that be my guest.
     
  17. 01silverstang

    01silverstang Well-Known Member Established Member

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    I had been looking at Forscan when I was considering buying a newer F150 over the summer, I haven't seen anything about it being used extensively on SN95's. If I could download Forscan and buy a cheap dongle to datal og that would be great. My car appears to have been tuned by Mike Post of Dynotune MP here in Illinois, since the origina handheld tuner is long gone and I don't know the owner's name who had it tuned I can't verify. If data logs shows issues that may be tune related I would pay to have it tuned again, if data logs look good... then I don't want to waste $1k.
     
  18. DSG2003Mach1

    DSG2003Mach1 Premium Member Premium Member Established Member Single Barrel Sirs

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    you should be able to verify on the site about using it to log, its not discussed much because theres not much if anything can be changed in the modules with it. I use a ~$30 module w/ a cable from amazon
     
  19. jman37

    jman37 Active Member Established Member

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    The laptop version is free, the $5 one on the appstore is great too but limited in functions.
     

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  20. 01silverstang

    01silverstang Well-Known Member Established Member

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    Small update:

    Didn't think I would have time to get much of anything done on Mother's Day weekend, but the wife gave me the go ahead yesterday afternoon to do what I could while our youngest was napping. Got the new Bosch LSU 4.2 sensor installed, which was a little dicey for a bit. The BBK off-road H-pipe had a plug in the driver's side rear 02 bung that was Allen bolt and even after spraying it with PB Blaster it just didn't want to budge at all. Finally got out the breaker bar, and after gently asking it to cooperate I heard a loud pop which I assumed was something breaking... but was lucky that the plug easily unthreaded and was removed.

    While I did this I tried to do the PCM idle learn procedure, but disconnecting the battery while I installed the sensor, and then once everything was done letting it idle 5-10 min with the accessories off and then another 5-10 minutes with AC set to full blast. It did idle smooth, but it still idles around 1k rpm. My AFR fluctuated between 13.4-14.8 at idle, and when given a rev went richer... so it would appear the sensor is working correctly.

    Due to how long the sensor install went due to the Allen bolt plug I couldn't mess with it longer, but in the time it idled the fan never came on... so that's something to monitor. I'm also debating if I should take it to the local Mustang shop to have the adjustable clutch cable professionally adjusted, or if I should just buy an OEM non-adjustable clutch cable and use that. I can still adjust it at the firewall, but wouldn't have to adjust it at the clutch fork.
     

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