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Thread: How does the self-tuning respond to engine problems?

  1. #1

    Default How does the self-tuning respond to engine problems?

    I have a '71 Mustang 302. My Holley 4 barrel needs rebuilt, so I'm using that as an excuse to buy the Sniper EFI. The problem I'm having is that my engine needs to warm up to at least 160°F or it bogs out when I put it in gear. If there's a vacuum leak I can't find it. If I install the Sniper EFI before I get it figured out, how will it react to this problem? Will it be able to do it's thing and self-tune, or should I get it figured out before I install the EFI unit. This will be my first EFI, so I'm a newbie here.

  2. #2
    Join Date
    Dec 2009
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    As I always say, the engine must be in proper working order to install any aftermarket EFI system.
    (I assume you're just being funny with your username. If not, I'd think twice before converting to EFI.)
    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.

  3. #3
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    Did you ever stop to think it may be the carb that's the problem, and by switching to EFI, it may fix the problem? Just a thought.

  4. #4
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    Yeah, I thought of that too. Especially since he claims it bogs down until the engine reaches 160°F (probably too lean).
    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.

  5. #5

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    Vacuum leaks are really bad for the Sniper EFI. Mustang is a pretty simple car with just a few vacuum lines, so they shouldn't be hard to check & fix. If the leak is in the intake or another engine part, it must be fixed. If the vacuum leak is in your carb or your carb needs rebuilding, Sniper will fix that. Sniper needs over 160°F coolant temp to run right. It will be in open loop below that. Make sure your cooling system works properly, and use the stock temp thermostat unless there a good reason not to. I think the stock temp is about 195°F on Fords.

  6. #6

    Default

    Quote Originally Posted by MechanicallyRetarded View Post
    If I install the Sniper EFI before I get it figured out, how will it react to this problem?
    For anyone else that wants to know the answer to this question, if you have a vacuum leak the Sniper will add fuel at the issue to bring the air fuel to what it's set at. It will idle and run OK and over time, the plugs will foul out from running too rich. Just had this issue.

  7. #7
    Join Date
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    Any vacuum leak is simply in parallel with the IAC. So although you may chase idle speed control issues, the fueling should not be altered. There is no MAF involved, the fueling is controlled by module programming using the wideband O2 sensor as the primary input. Gary
    Regards, Gary

  8. #8

    Default

    Use a cheap cigar to find vacuum leaks: https://www.youtube.com/watch?v=zMok2y05jNE

    Or, if you don't want to be sucking on a cigar yourself, get one of those cheap siphon pumps for $5 at Harbor Freight:
    Click image for larger version. 

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    1. Remove the air cleaner, remove the oil fill cap, prop the choke open, and back out the idle speed screw until the throttle is as closed as it goes (remember the number of turns).

    2. Hook the outlet of the pump to a vacuum port (power brake booster hose is usually good, as you *should* be able to tell if the brake booster is leaking when you have no power brakes).

    3. Light the cigar, and start pumping.

    4. Watch for smoke coming out somewhere it shouldn't, like any hoses, carb gaskets, etc. (A little smoke up past the throttle blades is usual). Smoke out of the oil fill cap means you have a leak into the crankcase, like the bottom of a V8 intake manifold.

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