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Thread: Gen 3 LQ9 Timing Mess

  1. #1

    Default Gen 3 LQ9 Timing Mess

    What I have:
    LQ9 Gen III, stock bottom end, 24x & 1x mild Bullet Racing cam, Morel lifters, AFR heads, fresh build by a respectable machinist. Reluctor on crank never came off. It was verified in correct position. Engine is N/A. EFI is Holley Terminator X, brand new, with new harness. Cam sensor - new ACDelco was used and tried the OEM one that came off the engine that worked for 70K miles. Cam sensor wiring was verified and it has 12V. Cam and crank pulses datalogging OK.

    > Verified #1 ignition timing with new timing light that works with DIS. Made a pointer and marked the balancer. Verified TDC on #1 compression stroke, making the mark on the balancer.

    > If I crank the engine, it stalls the starter engine from having way too much advance.

    > Ignition timing comes up as WAY off my TDC mark - 84° retard. I offset it -84° in the software and up loaded to my ECU. Verified at -84° it is spot on my TDC mark. I added 15° advance for Crank Timing. Timing tape says yes, it's cranking at 15°. It will not start, but it pulses like it would almost start.

    > I then place the ECU in Bank-To-Bank mode which is crude, but ignores the cam sensor signal, and it ran briefly and rough. Would not stay running.

    Mechanically and electronically everything checks out. If my cam gear was back 80°, I'm sure I wouldn't build enough compression to run at all. Seems to me that the firing order is off by 1, then I'd only have to offset by 6°. The cam manufacturer verified it's not and the reluctor cast into the cam core is clocked right.

    At this point I have exhausted mechanical, sensor, and electrical investigation. Holley Tech line is out of ideas. When in sequential mode, I get a cam error on the ECU. It goes red after 2 cranks and stays red until key cycle. I have a datalog if anyone is interested.
    Your thoughts please.

  2. #2
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    1,593

    Default

    I commend you on a comprehensive writeup of your issue, a breath of fresh air, but I don't see any mention of verification of injector pulse.
    I'll assume from your technical description, you have checked fuel pressure.
    My question is if the ignition timing shows as 15° BTDC, then this must be a fueling issue.
    So will the engine cough to life with a fog of carb cleaner etc., in the intake manifold? Gary
    Regards, Gary

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,113

    Default

    I don't know why you started a second thread about this, but here's the original thread: LINK.
    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. #4
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,457

    Default

    Did you degree the cam? For the Cam Sensor Type, did you try Digital Falling as well as Digital Rising to see if it puts the spark in the right location?

  5. #5

    Default

    I went point-by-point yesterday. I'm getting a cam signal. I rotated the engine by hand, key-on/engine-off, and watched the cam change from high to low at my TDC mark on the balancer. I changed the cam operator to Digital Falling from Digital Rising, and it starts and runs poorly. It backfires if I add more throttle. Feels like it's running on 4 cylinder.

    I verified every harness injector and coil wire is going to the correct place too. With my massive Offset of -84° every cylinder fires in the correct order according to my timing light and four marks on the balancer. My question is: Should the cam reluctor from low to high occur at 0° on the crank? Or is it supposed to be elsewhere?

  6. #6

    Default

    Have you tried setting the Timing Offset back to 0° after flipping the coil pack wires?

  7. #7

    Default

    I didnt flip the coil wires, just the cam logic. Reverting the timing to 0° with logic on “Falling”. Still results in the starter motor stalling as there is too much advance in. (84° worth). I took the starter out, borrowing a borescope today to look at crank reluctor index. Something is telling my ignition to fire at a wrong time. The crank reluctor is the boss best l can tell. The cam sensor is part of “and” logic, so if it's high the ECU knows which of the two crank rotations the state is in.

  8. #8

    Default

    Quote Originally Posted by ac delco View Post
    UPDATE: Passenger side coil harness was backwards, jumbling up the firing order. I found TDC and retarded the spark 84° to line up. I put the 15° of crank advance in and it tried to run, but would not stay running. Cranks like it wants to idle. Very close.
    Did you correct the coil wires? Just wondering it you ever tried to run it, without the Timing Offset, after correcting the coil harness? Do you have a link to the Holley YouTube video on timing an LS?
    Last edited by AmateurTouring; 12-01-2019 at 11:04 AM.

  9. #9

    Default

    Yes, coil sub-harness was corrected and verified. That only affected the even bank. My #1 followed by the rest of order are 84° advanced. It stalls the starter motor if I don't put in the 84° Retard. I can feel the clocking hole for 0° at crank reluctor when I remove the sensor.

  10. #10

    Default

    Yes, I watched that video. I even bought the same timing light he was using. That's how I arrived at 84° retard offset.

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