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Thread: Random Engine Stalling

  1. #11
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    Quote Originally Posted by activethunder32guy View Post
    First, one of my engines is now idling much better and is now running to the point I would consider better than carbureted. This engine is running the full sequential setup with my magnetic pickup cam sync and the Holley 60-2 crank trigger.

    More importantly, I see a small area less than .01 seconds from the shutdown where the crank trigger seemed to have missed a beat. Its a gap where I'd expect the missing teeth to read, but it's reading more like double the normal missing teeth gap. Thoughts? I would think this is the issue!
    The only change I'd make at this point, would be to swap the crank sensors (without changing anything else) to see if the problem follows to the good running engine.

    I set my 60-2 wheels to read 11 teeth BTDC compression stroke. However, during timing synchronization, I did have to move the wheel 6 degrees to get a good sync. I wasn't sure why I had to move it this much, but the timing light and program agreed after that throughout the rpm range... The other engine didn't require nearly that much adjustment.
    If the ECU (software) timing matches the engine (timing light), it should be OK. However, the only thing that concerns me is 6° being one full tooth on a 60-2 trigger wheel (360° circumference ÷ 60 teeth = 6° each tooth). Perhaps you should use the 10th tooth on both engines. (I use the 10th "TDC Tooth Number" on my engine.)

    In reviewing the system log, interestingly enough, the cam sync was still reading... I never unplugged the harness, I just set the cam sync to "not used" in the software and switched strategy to paired. I assume the datalog was just monitoring it since the sensor was connected. Is there any way this would still cause an engine shutdown when not part of the engine strategy?
    No, that shouldn't matter.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  2. #12

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    I just checked the crank sensor to wheel gap, it may have been slightly over the .030 specified max. The problematic engine seems to have a slightly larger gap. I noticed you posted on a gap slightly over .040 causing timing issues. Could my gap being slightly high cause this shutdown issue? I shimmed my sensors to be perfectly centered on the wheel, I also checked the runout to ensure I was on center, it is within .001" on the indicator.

    I will try swapping sensors after I try correcting the gap to the .025-.030 range. That is definitely one advantage to running 2 engines.

    Based on the system log issue noted above... would you tend to agree that the crank sensor is my source of issue?

  3. #13
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    Quote Originally Posted by activethunder32guy View Post
    Could my gap being slightly high cause this shutdown issue?
    If the sensor air gap is too large, it will cause the ECU to momentarily "reset" itself while the engine is running. This can cause stumbling and/or stalling.

    I will try swapping sensors after I try correcting the gap to the .025-.030 range.
    That's a good range for engines that don't produce high enough horsepower to flex the crankshaft. I run a .028" sensor air gap.

    Based on the system log issue noted above...would you tend to agree that the crank sensor is my source of issue?
    Yes, if that's what the datalog indicated.
    Here's more info on crank & cam sensor diagnostics:
    http://forums.holley.com/showthread....mp-SL-Datalogs (Datalogs & Sensor Diagnostics)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  4. #14

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    Made a few more steps of good progress...

    I made another run on the lake having corrected the crank trigger to wheel gaps. Very frustrated with myself to have mistakenly set them wrong - I believe I messed the gap up when adjusting belt tension on a pump. Boat ran very well on plane, never missed a beat. I ran long enough to break in my piston rings... varying my rpm.

    Lingering issues that I need to address:
    1. I believe I have a vacuum leak, maybe on both engines.
    -One idles great right down to 850 rpm, if I shift it there, I have to watch it - the load of shifting seems to be stalling it out almost instantly if I don't jab a little throttle. This is more temperamental than with carburetors. On that same engine (I believe), I'm hearing a slight whistle under load around 1300 rpm.
    -Other engine starts great and then will stall almost instantly as soon as the coolant temp/idle speed hits 1000 rpm. I had to idle this engine out of gear around 1100 to be sure it would stay running. Then drop it down, shift it with a jab of throttle, then let the rpm come back up where it would stay running. I am almost sure this is a vacuum leak issue. Especially since the engines are a matched pair and act so differently with pretty much the same settings and fuel amounts.
    2. Probably related to the vacuum issue... I still haven't gotten the right amount of fuel while cranking. One engine fires with good authority, goes right to target rpm based on coolant temp. The other engine just doesn't want to start (oddly this is the one that idles better). Having looked at the custom configs, I'm surprised to see that most of the big block type engines that are similar tend to use 2-3x as much cranking fuel as I am getting the one engine to start... Typically the engine just stumbles and never has a good solid initial fire. I have been making small increases (2-3 lbs/hr at a time), but maybe I need to just give it a bunch more and see what that does... Obviously I won't put a lot of thought into this until I confirm I don't have vacuum issues.

    Thanks again for the help!

  5. #15

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    Update:
    1. No vacuum leaks... this is not the issue.
    2. Had one engine cutout several times again. Other engine continues to run well. The crank sensor gap theory is definitely not the issue now. I talked with Holley tech about gaps, they actually had me set them a little closer yet (.015"), did not help. I also swapped crank triggers and had no change. With new bearings/double checking crank thrust, there is no way I have any of the typical crank trigger alignment/run-out issues.
    3. I stumbled onto this thread, sounds familiar:
    http://forums.holley.com/showthread....mp-Spark/page2

    This is a boater that has very similar setups to mine. MSD ignition, crank trigger (although mine is the Holley 60-2). After checking voltages, my fuel pump signal IS cutting out, on/off/on... etc... the datalog does show RPM going straight to 0, (the engine physically shuts down very quickly - so I thought that was expected, but if the crank trigger signal was interfered with, causing the engine to stall, then this makes sense. Right now, my ignition connector on my shielded Holley crank trigger/cam sync harness is about 12" away from the distributor and any other hot wires. That's as far away from trouble as I can get it. Eliminated the cam sync portion, running paired strategy for now.

    The fuel pump also sounds very weak during the 5 second prime. However, I checked the voltage during that prime and found a consistent 12.4V. In an effort to pursue this further:
    A. When I attempt to start the engine, the engine fires then immediately dies. I noticed fuel pressure drops (definitely due to the on/off/on issue mentioned above. So it may be that the relay is working fine when on, but the signal side could be fluttering.
    B. My fuel pump is currently wired where the Holley loose green wire is running a secondary fuel pump relay (as required per the instructions). This relay checks out. I have NOT checked out the main Holley fuel pump/injector relay, I know the wiring is solid. The weak sound before the engine is started during the 5 second prime, but still getting 12V doesn't make any sense to me - can't blame rpm signal loss on this...
    C. I wired the fuel pump directly to the battery. The fuel pump sounds much stronger (leading me to believe there's a relay issue). The engine now starts right up and will stay running. Data logging is confirming the fuel pump/pressure is holding pressure running 100% (as it obviously should being hot wired).
    D. Then engine seems to stall any time it idles under 1000 rpm (no sputtering, just immediately drops to 0 rpm like it's losing the rpm signal, I can occasionally restart without turning the key by jabbing the throttle).
    -According to the data logs, the computer continues to log through the error, the only thing I notice is rpm dropping off (which is physically happening as well).
    -That battery runs around 14V due to alternator help while running - no variation on the data log.
    E. The engine will periodically stall in the 2500-3000 rpm range - runs anywhere from 2-10 minutes without an issue, then the rpm drop to 0, the computer remains on.
    -With the opposite engine still roaring, it's hard to hear, but I believe the engine stumbles at very low rpm (not actually shutting down 100%).
    -I can sometimes even get it running again without turning the key by backing the throttle back and then giving it 20-50% throttle.
    -I just got a system log of this whole process last night (huge file - 400Mb - not sure if I can do anything with it).

    Moving forward:
    ―I don't know if I can link the weak fuel pump issue with the rest of the problems.
    ―I plan to put swap Holley fuel pump and injector relays from engine to engine.
    ―It's starting to be more clear that the 1000 rpm issue and 2500-3000 rpm issue may be linked.
    ―I swapped all the ignition components (including MSD box) to confirm I'm not having issues there.
    ―I reviewed my engine grounds and wiring connections, no issues here.
    ―When laying out the EFI harness wiring, I payed specific attention to planning the layout such that the ECM and all harnesses avoid power wires/coil/distributor/spark plug wires. They run very separately from the original engine harnesses as well.
    ―The injector harness runs by the base of the distributor - this is the only EFI harness that gets close. I assume this is OK, I don't really have a choice based on the stock wire length.

  6. #16
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    Quote Originally Posted by activethunder32guy View Post
    I talked with Holley tech about gaps, they actually had me set them a little closer yet (.015"), did not help.
    That's dangerously too close. Adjust the sensor gap back to .025".

    I also swapped crank triggers and had no change.
    As a troubleshooting measure, have you tried swapped the ECUs? Maybe one is programmed wrong.

    This is a boater that has very similar setups to mine. MSD ignition, crank trigger (although mine is the Holley 60-2).
    Holley's DIS crank trigger kit & coil pack, with an MSD magnetic 1x cam sync, correct? Is this how your EFI software is setup?

    Ignition Parameters:
    Ignition Type - "Custom"
    Crank Sensor Type - "60-2"
    Sensor Type - "Digital Falling"
    Inductive Delay - "adjusted per application"
    Timing Offset - "0°"
    TDC Tooth Number - "9, 10, 11 or 12"
    Cam Sensor Type - "Single Pulse"
    Sensor Type - "Magnetic"
    Output Setup Type - "DIS Waste Fire"
    Dwell Time - "1.8 msec" (early coils) "2.4 msec" (late coils)

    After checking voltages, my fuel pump signal IS cutting out, on/off/on... etc... the datalog does show RPM going straight to 0...
    If you're referring to the ECU signal, this could be due to losing the RPM signal.
    I would temporarily disable any safety outputs you've created.

    Eliminated the cam sync portion, running paired strategy for now.
    This is a key troubleshooting detail. Does the engine still stall in non-sequential mode?

    The fuel pump also sounds very weak during the 5 second prime.
    I think that's just because it isn't under charging system voltage at the time.
    However, check the power and ground directly at the fuel pump terminals.
    You may want to swap the fuel pumps to rule that out.

    So it may be that the relay is working fine when on, but the signal side could be fluttering.
    At this point, you need to perform these two separate troubleshooting tests:
    1) Temporarily bypass the ECU signal wire (+12V) at relay terminal #86 (wire from + battery terminal).
    2) Temporarily install a jumper wire between relay terminals #30 & #87 (relay removed - 87a isn't used).
    Does the engine still stall while under either of these two separate test conditions?
    We need to determine if this is an ECU signal problem (1) or a relay/wiring problem (2).

    C. I wired the fuel pump directly to the battery. The fuel pump sounds much stronger (leading me to believe there's a relay issue). The engine now starts right up and will stay running.
    "Stay running", meaning it solves the problem? If so, you definitely have a wiring, relay or ECU signal problem.


    EDIT: I moved these posts to a new thread because we got way off track with the original thread topic: EFI Warning - Rev Limit vs. Timing Offset
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  7. #17

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    Quote Originally Posted by Danny Cabral View Post
    That's dangerously too close. Adjust the sensor gap back to .025".
    I was just doing what I was told (I only went to .020" for fear of that issue), but I agree that since it hasn't helped, no reason to be that close.

    As a troubleshooting measure, have you tried swapped the ECUs? Maybe one is programmed wrong.
    No - that was one of my next changes. Too easy not to try the ECU swap. I copied the 2 programs from the same base. I have even tried just syncing the other engine's program with no improvement.

    Holley's DIS crank trigger kit & coil pack, with an MSD magnetic 1x cam sync, correct? Is this how your EFI software is setup?
    Not quite - running Holley's crank trigger, but with an MSD distributor (Accel high vibration coil) with a modified 1x magnetic cam sync.

    Ignition Parameters:
    Ignition Type - "Custom"
    Crank Sensor Type - "60-2"
    Sensor Type - "Digital Falling"
    Inductive Delay - "adjusted per application"
    Timing Offset - "0°"
    TDC Tooth Number - "9, 10, 11 or 12"
    Cam Sensor Type - "Single Pulse"
    Sensor Type - "Magnetic"
    Output Setup Type - "DIS Waste Fire"
    Dwell Time - "1.8 msec" (early coils) "2.4 msec" (late coils)
    Yes EXCEPT:
    Output Setup Type is "Points Output" (triggers MSD ignition points input)
    Dwell Time = 1.5 msec (Holley default) - COULD THIS BE A PROBLEM?
    And I eliminated the cam sync for the past few weeks to eliminate any additional possible issues from the MSD magnetic pickup - running "paired".

    This is a key troubleshooting detail. Does the engine still stall in non-sequential mode?
    -No it didn't change anything...

    I think that's just because it isn't under charging system voltage at the time.
    However, check the power and ground directly at the fuel pump terminals.
    You may want to swap the fuel pumps to rule that out.
    -I checked the system voltage at the leads coming out of the pump. After hot wiring the fuel pump, I have data logs that show constant fuel pressure right through a stall (the computer doesn't lose power). So I at least know the fuel pump itself is capable.

    At this point, you need to perform these two separate troubleshooting tests:
    1) Temporarily bypass the ECU signal wire (+12V) at relay terminal #86 (wire from + battery terminal).
    2) Temporarily install a jumper wire between relay terminals #30 & #87 (relay removed - 87a isn't used).
    Does the engine still stall while under either of these two separate test conditions?
    We need to determine if this is an ECU signal problem (1) or a relay/wiring problem (2).
    Just to confirm, you are now referring to the main harness relay (not the secondary fuel pump relay) -

    TEST #1: Take "ECM fuel pump relay out" (#86) directly connecting to fuel pump green AND injector plug red (#30). This test eliminates the relay, making it directly power the injector harness and fuel pump secondary fuel pump relay (with a 22 gauge wire :\).

    TEST #2: I would be sending fused battery +12V (#87) directly to fuel pump green AND injector plug red (#30). This test eliminates the ECM from controlling the fuel pump and injector harness.

    "Stay running", meaning it solves the problem? If so, you definitely have a wiring, relay or ECU signal problem.
    It will stay running (as in not die immediately after firing) as long as I keep the engine above 1000 rpms, but it still will cut out while in cruise rpm periodically.

    EDIT: I moved these posts to a new thread because we got way off track with the original thread topic: EFI Warning - Rev Limit vs. Timing Offset
    I'm glad you moved this thread, should help others better with the new topic. Thanks for the help...

  8. #18
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    Quote Originally Posted by activethunder32guy View Post
    Not quite - running Holley's crank trigger, but with an MSD distributor (Accel high vibration coil) with a modified 1x magnetic cam sync.
    OH...that's not good! I thought you were running Holley's DIS system (coil pack).

    Excerpt from Holley EFI manual:
    NOTE - It is not advised to use a magnetic pickup distributor to directly feed the magnetic trigger input of the ECU. If the
    magnetic pickup distributor is connected to the ECU via the inductive pickup trigger wires, the pickup/rotor/cap phasing
    must be corrected. This operation may require a phaseable cap or rotor or possibly machining to the distributor and is
    therefore beyond the scope of most users. Even with the phasing corrected, the electrical noise inside the cap
    (due to the high voltage cap & rotor terminals) may be strong enough to cause electrical noise interference.
    It is advised to use a crank trigger system or a computer-controlled distributor.

    Yes EXCEPT: Dwell Time = 1.5 msec (Holley default) - COULD THIS BE A PROBLEM?
    For the Points Output Type, the Dwell Time should be 2.0 msec to avoid lost triggers.

    EFI Software Help Information/Instructions:
    - On the top Toolbar, click "Help" & "Contents". This opens all Help topics.
    - When navigating the software, click "Help ?", drag it to any parameter and click again.
    ..This automatically opens the definitions for that specific parameter.
    - Tuning information can be read by clicking the F1 key, when you're viewing any screen.

    Just to confirm, you are now referring to the main harness relay (not the secondary fuel pump relay) -
    Yes, the main system relay.

    TEST #1: Take "ECM fuel pump relay out" (#86) directly connecting to fuel pump green AND injector plug red (#30). This test eliminates the relay, making it directly power the injector harness and fuel pump secondary fuel pump relay (with a 22 gauge wire :\).
    Test #1 doesn't involve removing the relay...that's not what I said.
    Just probe relay terminal #86 with a wire directly from the + battery terminal.

    TEST #2: I would be sending fused battery +12V (#87) directly to fuel pump green AND injector plug red (#30). This test eliminates the ECM from controlling the fuel pump and injector harness.
    Test #2 just requires a short 3" jumper wire with two spade connectors.
    Correct, this test eliminates the ECU signal wire from energizing the relay.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  9. #19

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    Quote Originally Posted by Danny Cabral View Post
    OH...that's not good! I thought you were running Holley's DIS system (coil pack).
    Excerpt from Holley EFI manual:
    NOTE - It is not advised to use a magnetic pickup distributor to directly feed the magnetic trigger input of the ECU. If the
    magnetic pickup distributor is connected to the ECU via the inductive pickup trigger wires, the pickup/rotor/cap phasing
    must be corrected. This operation may require a phaseable cap or rotor or possibly machining to the distributor and is
    therefore beyond the scope of most users. Even with the phasing corrected, the electrical noise inside the cap
    (due to the high voltage cap & rotor terminals) may be strong enough to cause electrical noise interference.
    It is advised to use a crank trigger system or a computer-controlled distributor.
    Well, I'm not using the magnetic pickup on the distributor for anything but a cam sync (and I've eliminated that for now on the bad engine). I'm using the Holley crank trigger kit instead. I did correct the phasing, but that's easy to do with the crank trigger, since turning the distributor only adjusts rotor phasing. So that leaves the high voltage cap and rotor which is within the scope of many Holley HP EFI users (I should hope).

    Quote Originally Posted by Danny Cabral View Post
    For the Points Output Type, the Dwell Time should be 2.0 msec to avoid lost triggers.
    EFI Software Help Information/Instructions:
    - On the top Toolbar, click "Help" & "Contents". This opens all Help topics.
    - When navigating the software, click "Help ?", drag it to any parameter and click again.
    ..This automatically opens the definitions for that specific parameter.
    - Tuning information can be read by clicking the F1 key, when you're viewing any screen.
    So setting the dwell at 1.5 could be a problem... And yes, I have used the help section extensively - that's where I was advised to use the 1.5 (now I see there is a state to change to 2.0 if missing triggers). Missing triggers could be my cruise RPM engine stall, correct? Could this also affect idle stalling?

    Quote Originally Posted by Danny Cabral View Post
    Test #1 doesn't involve removing the relay...that's not what I said.
    Just probe relay terminal #86 with a wire directly from the + battery terminal.

    Test #2 just requires a short 3" jumper wire with two spade connectors.
    Correct, this test eliminates the ECU signal wire from energizing the relay.
    Now I understand.

  10. #20
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    Quote Originally Posted by activethunder32guy View Post
    Well, I'm not using the magnetic pickup on the distributor for anything but a cam sync (and I've eliminated that for now on the bad engine).
    I hope the magnetic cam sync is at least disconnected from the ECU.

    So that leaves the high voltage cap and rotor which is within the scope of many Holley HP EFI users (I should hope).
    I don't think you fully understand. When you convert to sequential injection, you should not use a magnetic cam sync sensor inside a distributor.
    For actual distributor applications (high voltage cap & rotor), a Hall-Effect cam sync sensor must be used.
    For a DIS conversion (cap & rotor eliminated), it's permissible to use a magnetic cam sync, but I still wouldn't do it.

    So setting the dwell at 1.5 could be a problem...Missing triggers could be my cruise RPM engine stall, correct? Could this also affect idle stalling?
    Yes, it can. Always enter 2.0 msec for the Points Output Type.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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