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Question Sluggish Acceleration - am at a loss

Any help/ideas would appreciated as I am basically at that point where I don't know where to go with this problem.

1972 911T 2.4L with about 105K on it. MFI. Car runs exceptionally well except when accelerating through higher RPMs above 4000 in all gears. After 4000 rpm, things get sluggish, like the car wants to go but just can't and has trouble pushing through. Additionally, when neutral cruising (ie not accelerating or decelerating), I get what I can only describe as a gurgling sound from the engine, almost like a soft popping. Disappears when accelerating/decelerating.

Had a bad alternator and thought that might have been the issue (ie not enough juice at higher revs). Changed it out but nope. Fuel pump crapped out about the same time. Thought perhaps. Changed it out but nope. Coil going on me? Temp change out with a good one. Problem still there. Thought I was VERY close to figuring it out after bench testing the injectors and found a bad one with very poor spray pattern. Changed it out and, you guessed it, problem still there. Distributor cap, rotor, plugs and fuel filter also all changed out and have used injector and fuel cleaner over the summer.

I'm at a loss as to where to go next. ANY ideas, no matter how out to left field would be appreciated.

Last edited by 1972RSR; 09-13-2017 at 03:50 PM..
Old 09-12-2017, 05:05 PM
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buy some fuel cleaner additive... put a couple bottles in your tank and use up your gas about 2 fill ups...
Change your fuel filter... change your rotor and cap... I'd start with those first.

Change your spark plugs and wires.

I had a similar problem as you have... I did all that... even did a valve adjustment.
Car runs ALOT better than it did before all of that...
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Old 09-13-2017, 12:29 PM
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Sounds like a fuel delivery issue. As stated above, check your fuel system, specifically the filter, for blockage.
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Old 09-13-2017, 01:08 PM
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What induction are you running?....From what I can read based on vintage and injectors, you are running MFI??...though very robust when tuned correctly they can fall out of adjustment or require tweaking if/when components are changed/replaced.

When ever trouble shooting MFI you have to look at the entire delivery system as a whole or you'll be chasing your tail to no avail (hey that rhymes). Grab the CMA and go through the checklist in order and properly. It's a finicky system, hence why so many were replaced with carbs in the earlier year but so rewarding when it runs properly.
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Old 09-13-2017, 01:21 PM
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MFI or carbs? What is your battery voltage under load?
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Old 09-13-2017, 01:26 PM
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My 2 cents... If there's mechanical advance in distrib, might not be working.
Old 09-13-2017, 01:55 PM
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Quote:
Originally Posted by Discseven View Post
My 2 cents... If there's mechanical advance in distrib, might not be working.
++++ This is the first thing I would do... clean and lube.

How about a couple of pictures
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Old 09-13-2017, 02:43 PM
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