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  1. #1
    FEP Supporter vdubn's Avatar
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    Default Troubleshooting Some Driveability issues after EFI Conversion

    I just finished my EFI swap a couple weeks ago, and got the car running last week. I'm running a 93 Cobra ECU, with a Pro-M 75mm MAF, 65mm throttle body, and 24# injectors.

    Car fired right up, and had some idle issues initially, so I ran through the idle setup procedure, and TPS procedure. I got it to idle, and was supposed to set the TPS to .96 to .98 volts. Only after drilling the holes out a bunch, I was able to get it from 1.14v down to 1v. Hopefully that is close enough. If not, I can drill them larger and see if I can get it to .96 to .98.

    Timing is set to about 12 degrees BTDC, and at 2500 rpm set to about 28 to 30 degrees BTDC.

    Car is idling around 900rpm, and starts pretty rough. If I try to drive around the block right away, initial take-off is pretty rough, with some occasional popping in the intake. When idling in the garage, its running rich enough that its burning my eyes.

    I pulled codes, and got the following codes:

    31 - EGR Valve Position/Pressure Feedback EGR Circuit Below Minimum Voltage. 0.24 volts (O,CM,R)
    67- Park Neutral Position Switch Circuit Open; A/C On -Manual (O), Manual Lever Position Sensor Out Of Range/A/C On (CM,O), Clutch Switch Circuit Failure (CM)
    81 - Secondary Air Diverter Circuit Failure (O)
    82 - Secondary Air Bypass Circuit Failure (O)
    84 - EGR Vacuum Regulator (EVR) Control Circuit Failure (O)

    I think all of the codes are pretty normal for my situation. The car is a 5 speed, and the clutch switch works, so not sure why I'm getting that code, but don't think it matters. I don't have a smog pump, or EGR, so I think its all good.

    My fuel pressure is set to 40psi, and I am not running cats, so maybe some smell is normal, but it doesn't seem that it should be burning my eyes.

    Any help is greatly appreciated.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  2. #2

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    For one thing - the 93 Cobra computer is designed to run with a 70 MM MAF.

    Second - the calibration on the MAF pickup used with the Cobra computer is exactly the same as the 93 GT. The computer tune is altered to compensate for the larger 70 MM MAF and the 24 lb vs 19 lb injectors.

    The first issue will give too much air vs what the MAF is telling the ECU is there.

    the second thing I believe is the issue. I suspect your running a "recalibrated" MAF "for 24lb injectors" while running 24's but with a compurt that already compensates in its tune. So now it's running pig rich

    I would get a 70MM Cobra MAF and an OE MAF sensor and give it a shot.

    The other thing you might be able to try (that won't work nearly as well) is set the calibration selector on the 75MM to 19 lb/hr.

  3. #3

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    X2.

    Get a stock maf sensor.

    Tps voltage really doesn't matter as long as its between .67 and 1.29v if I remeber correctly. This is a myth that I with would die. I had a car that read 1.27v and idled perfectly and another that was around .65, same thing.

    What's critical is the sweep voltages. Needs to raise by about 3.5 volts from the idle setting to initiate wot. Any dead spots, and it can run like crap or not want to idle.

    The way I set my idle, check tps voltage. Unplug iac with the car running. Turn idle screw down till the car starts to lug, then plug it back in. That's it.

    I've bought cars with blown out cats, they are louder but runs and smells about the same. When its running right, you won't be able to tell it doesnt have cats.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  4. #4
    FEP Power Member Ourobos's Avatar
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    ^ Agreed. And ignore all the codes except the EGR. Either plumb the EVR and EGR properly (vacuum to bottom port on EVR, then top port to EGR valve), or delete the EGR valve vacuum and leave the electronics plugged in.
    1986 CHP SSP Coupe

  5. #5

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    When the car has an egr code, the computer deletes it. You can block it off, but I've never had an issue just leaving there and deleting it.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  6. #6
    FEP Supporter vdubn's Avatar
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    Awesome info guys, I think you are correct on the MAF. I assumed 75mm was what was needed, since this MAF says calibration is for 24# injectors. Here is a pic of the MAF:

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    So, if I am hearing you right, the ECU is detecting too much air flow due to the size of the MAF housing, and due to this, setting the injector dwell much higher than it needs to be, thus causing a pig rich condition?

    Any suggestions on a good place to get a stock Cobra MAF housing and Sensor? I had a new one, and sold it to 4-Barrel Mike, I just messaged him, and hopefully he ended up not needing it and I can buy it back.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  7. #7
    FEP Supporter Broncojunkie's Avatar
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    I don't believe you need a "cobra" maf... just a regular ol 5.0 stock maf.

  8. #8
    FEP Supporter Broncojunkie's Avatar
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    ...or an aftermarket maf for 19lb injectors.

  9. #9
    FEP Supporter vdubn's Avatar
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    Right. As long as it has a 70mm housing, right?
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  10. #10
    FEP Supporter Broncojunkie's Avatar
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    I don't even think the size of the housing matters. You just get better flow through a larger one. Someone can chime in and correct me if I'm wrong.

  11. #11
    FEP Supporter vdubn's Avatar
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    It Looks like I'll be able to grab the 70mm housing that I sold Mike, so I'll try to get that installed tonight.

    I also ran into an interesting issue where the engine started making some valve noise yesterday, but only on the drivers side. I pulled the intake and drivers side valve cover to find that 2 rocker arms were loose. I'm guessing that the lifters weren't staying pumped up on the two valves. I went ahead and readjusted the poly locks and they tightened up ok, but it's strange that new lifters would do that. These are Ford Racing roller lifters, and one had the check valve upside down, and had to be warrantied by LMR. I'm hoping these aren't junk lifters. It was the two middle cylinders on the drivers side.

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    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  12. #12

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    All the stock mafs read the same. The larger housings often use the same "guts" so to speak.

    A calibrated maf changes what the computer sees to try to bandaid a tune basically.

    With the cobra computer already running 24# injectors, the calibrated tune is trying to trick the computer, assuming its a 19# tune on the computer.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  13. #13
    FEP Supporter vdubn's Avatar
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    That makes sense. I got my Cobra MAF back from Mike (thanks a bunch Mike for meeting up with me today), so hopefully I will get the engine back together tomorrow, and fire it up and see how it runs.

    Is there any reason to worry about the 67 code (neutral/park safety switch)? My clutch safety switch works, but the extra plug is just sitting up above the pedal cluster. I was told that if 67 code exists, it may cause idle issues? Doesn't make sense that it would, but just thought I would check.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  14. #14
    FEP Member Tigger's Avatar
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    My Saleen started to idle funny Friday when I drove it to work. I ran the KOEO test when I got home. I got 67 because the car was in gear when it ran the test. Put the car in neutral and ran the test again and it went away.
    67 Mustang Coupe
    96 Tangerine GT
    86 Saleen #179

  15. #15

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    The GT and Cobra use an identically calibrated MAF sensor but one MAF is 58MM while the other is 70MM. Tom Moss did a write up on the air flow differences. It's only a really problem as airflow increases - which it does when we shove our foot into these old motors

    If you use a Cobra 70MM housing with an LX/GT computer like the A9L (as I have done) and stock 19lb injectors the engine will become chronically lean at high RPM. It can be treated by bumping the fuel pressure up a little but the cure is to tune the ECU for the flow behavior of MAF meter that is installed or swap to cobra ECU and 24's.

    Likewise if you use a 58MM with a 93 Cobra ECU (there were about 2-3 different codes but they are all basically the same) and 24's the engine will start and run fine but it will run chronically rich at high RPM and it will be down on power. It can be treated by reducing fuel pressure but the cure is to put the MAF sensor in a 70MM housing. (Or swap to 19's and an A9L)

    A lot of stuff can sorta work together but not really. You can tune around a ton of problems but doing so is a bit like opening Pandora's box.

    If you want to use a factory ECU tune there are some specific things you simply must take into account or you will go to tuning jail and the only cure will be to open Pandora's box.

    Stuff like
    - MAF+housing flow curves
    - ECU code vs injector size setting in the ROM

    Etc.

    And while we are on the topic I'll say it again - there is no such thing as a properly "recalibrated" MAF. Any time you lie to the computer about airflow to make it lean up injector pulse width it has consequences. First of which is yanking a crap-load of timing out.

    Yes it will run, but will it perform?

    I cannot count the number of "head and cam and intake and throttlebody and header" cars I have ran into over the years. Back when few knew a damn thing about what they were doing so many got the butts stomped by my turned up VM1 SD car with a very slight cam and nearly all stock parts. Things have to work properly together or you go backwards very quickly and any of the potential gains are lost on lack of correct tune.

    I did rather enjoyed taking their money though..... used it for the basics. Tires and fuel and beer. Perhaps the rest I just wasted. Didn't forget about ****, those were "free" but like the cell phone commercial and sure to be trouble.

  16. #16
    FEP Supporter vdubn's Avatar
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    Excellent info Erratic, totally agree. I appreciate you making me aware of this information. Interestingly enough, the fact that the Cobra uses the same MAF as other GT cars, escapes even seasoned Mustang folks. In my brief attempt to find a 70mm housing/MAF assembly from a Cobra, every person on Ebay that had one for sale was adamant that it will only work on a car with 19# injectors. Even when presented with the idea that the Cobra ECU is where the difference lies, they still disagreed. After you mentioned this information, I did some more research on the topic, and all of the reliable sources I found confirmed what you said.

    Fortunately, I got my Cobra Mass Air Meter back yesterday, so I think I should be set. My camshaft isn't terribly radical, so running the Cobra ECU, stock Cobra MAF, and factory Cobra 24# injectors it should all run like factory (but hopefully breath a little better with my 2.02 heads, Intake, headers and exhaust).

    Tonight or tomorrow I am hopeful to get the engine back together, and see how it runs.

    The more I think about it, it makes sense that it ran so poorly when I first started the car, when I had the Pro-M MAF that was calibrated for the 24# injectors. During the cold-start period, it would load up bad, and occasionally give intake pops.... it was probably off-the-charts-rich. I had to constantly give it some gas, probably just so it could get a little more air to keep running. Once the car warmed up, it ran better, but was still rich enough to make my eyes burn, and didn't run crisp, it felt sluggish and slightly loaded up.

    Another thing I read, was something about getting the ECT and CTS (both coolant temp sensors, and they look similar) backwards. One is in the intake, and one goes in the heater tubes going back to the firewall. I think I have mine in the correct locations, but is there a way to determine which goes where?

    I honestly thought that they were the same sensors, so I want to make sure that isn't causing any issues. I wouldn't see any codes for this, if they were installed in the wrong place... would I?
    Last edited by vdubn; 01-17-2018 at 04:58 PM.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  17. #17

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    You shouldn't be able to mix those two sensors up. They are on opposite sides of the engine harness. I'm 95% sure the sensors are the same, even if you did mix them up. They both read coolant temp.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  18. #18
    FEP Supporter vdubn's Avatar
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    Quote Originally Posted by Haystack View Post
    You shouldn't be able to mix those two sensors up. They are on opposite sides of the engine harness. I'm 95% sure the sensors are the same, even if you did mix them up. They both read coolant temp.
    I thought the same thing... thanks for clarifying.

    I got the engine back together, and fired it up this morning only to find that I have 0 oil pressure. I had oil pressure that showed up at the 2/3 mark of the oil pressure gauge when I first fired it up, and when I shut it down warm the other day, it was down to 1/4 gauge warm. Today, nothing. I pulled the stock sender, connected a manual gauge, and not only 0 pressure, but no oil came into the gauge hose.

    The engine is all totally new, so I am guessing that I lost one of the galley plugs behind the timing gears, but I will know more tonight. This explains why 2 of my lifters pumped down causing lifter noise the other day. The good news is that I only ran it for a few minutes like this, and heard no bad noises.

    I pulled the distributor, and the oil pump shaft is still in place (its an ARP shaft as well, so no issue with it breaking). I'll connect a primer to my drill tonight, and see if any oil comes out of the side of the block. If not, I guess I will be pulling the front of the engine apart to see what might be causing the problem.

    I thought maybe the oil pickup might have dropped off of the oil pump, but I think its bolted on (not sure, as my engine builder assembled the bottom end).

    Not sure what else it could be.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  19. #19

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    Good luck, hopefully nothing is scorched.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  20. #20
    FEP Supporter vdubn's Avatar
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    Me too... I know it had good oil pressure, and we primed it all before we fired it up, so hoping that the film its had on all parts was protective enough to prevent the possibility of damage during the small time I had it running without pressure. What a crazy deal. My machine shop does great work, if a galley plug did come out, not sure how that would have happened.

    I drove it around the block 2 or 3 times all with oil pressure. Then today nothing.
    Last edited by vdubn; 01-18-2018 at 05:07 PM.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  21. #21
    FEP Supporter 4-barrel Mike's Avatar
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    Jeez, Dean. If it ain't one thing, it's another.

    Mike
    1985 ascMcLaren 5.0 SC Roadster
    My '78 Fairmont build - http://vb.foureyedpride.com/showthre...539-78-Big-Red

  22. #22

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    Thats some great info on the Cobra mass airs, I followed a little different rule on my 93 Cobra. Someone had already swapped in an A9L but I wanted to use the factory style mass air for originality. What I ended up doing is cutting the bridge out and buying a 24lb sample tube from C&L, adding a little spacer so the sensor was at the proper height and bolting it all together. I figured in stock form it would be close enough for a show car that saw little street use. Ended up selling it to an older guy in PA who just wanted to go to cruise nights with his kids. Good Luck chasing down the oil pressure issue.

    Mike
    1982 GT 351W, retro hyd roller, ported Pro Comp heads, Tremec, M2300K brake kit, Recaros...needs paint!
    1984 LX 5.0 Vert *SOLD*
    1993 Cobra #3971 mostly stock *SOLD*
    1966 FFR Cobra replica 383W, Vic Jr heads, Vortech YS, TFS Box intake, 652rwhp, crazy fast!
    1987 GT in MM&FF May of 97 "Not Fade Away" white and purple. Sold 1999

  23. #23
    FEP Supporter vdubn's Avatar
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    Quote Originally Posted by 4-barrel Mike View Post
    Jeez, Dean. If it ain't one thing, it's another.

    Mike
    \
    Well Mike... you know what they say... sometimes without bad luck, you wouldn't have any luck at all

    The good news is that I figured out the issue tonight, bad news is I had to tear the engine apart to get to it. I got the oil pump primer tool on the way home tonight, and was able to get about 5lbs of oil pressure with my drill running full speed in reverse... about 2000 rpm. which would be about 4000 rpm crankshaft speed. Knowing that something major changed, and suspecting that one of the cam galley plugs let loose, I set to taking the front of the engine apart.

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    I pulled all of the accessories, removed the water pump, unbolted all of the timing cover bolts, and removed all but the rear two oil pan bolts. Dropped the pan about an inch, pulled the cover, and fished around in the oil pan with my magnet.... and found this:

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    My builder says that he staked the galley plugs, after installing the new ones, so not sure why this came loose. He also put some sealant on it, from what I can see, so I would have thought it was double insured against coming out. Anyone else have any good suggestions for how to make sure it doesn't come loose again? My builder is coming over tomorrow to help me fix it, but I'd like to hear if anyone has any suggestions.
    Last edited by vdubn; 01-19-2018 at 12:06 AM.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  24. #24

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    Tapping the holes and threaded oil galley plugs are the absolute best answer, but not so much to do so after an engine is together... unless extremely careful with where the tapping operation shavings go... as in, NOT get into or remain in the engine anywhere. Years ago I removed all the pressed in rocker studs from the pair of '72 302 heads I was running, because one stud that hadn't been suspect when checking them all earlier ended up beginning to pull out later, and so I tapped for and installed 3/8 screw-in rocker studs and used Chevy rocker balls and nuts with the Ford rail rockers, after having rebuilt the engine a few thousand miles before that, and very, VERY carefully ensured that none of the iron shavings went down into the heads' coolant passages (stud rocker holes go into coolant) or were left to wander around the cylinder head tops...Good luck with it.
    Mike
    1986 Mustang convertible 3.8L ---> BUILD THREAD
    1983 Mercury Cougar 3.8L LS
    1986 Ford Thunderbird 5.0L ELAN
    1966 Ford Fairlane sedan 200-6
    1966 Ford Fairlane GT (390ci 4spd)
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang Fastback
    1974 Pontiac Luxury LeMans

  25. #25
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    TPS voltage lets computer know what load tables it needs to use when the engine is running. Idle, part throttle or WOT. If the voltage is too high at idle, the computer thinks it's in part throttle. When this happens, it will be using look up tables for that mode. So try to get it down under 1 volt.
    Trouble code 67 can be fixed easy. Are you able to do a key on engine running code test? If not, all you need to do to fix the problem is to ground that wire coming from the computer to a chassis ground. I can't remember what pin number it was. I had the same issue years ago doing a swap like that.

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