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Old 06-14-2014, 05:35 PM   #1
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Default Higher than normal load to maintain speed = bad MPGs

So the car is back on the road and I noticed something pretty quickly today. While driving at highway speeds, 60mph+, it seems my load required to maintain a constant speed is higher than it should be. Normally, I'd be looking at 16-12mmHg of vac. while holding speed. Now I'm in the 11-9mmHg range on the gauge. This might not sound too bad.... or maybe it does. It has also caused me to go through 1/2 a tank of gas in about 100mi. of highway cruising, far more than normal.

Car holds normal vac. at idle/decel.
AFRs are good (dither between 14.6-15.2 when crusing).
No obvious problems anywhere else.
Not leaking fuel anywhere.

Halp?
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Old 06-14-2014, 05:59 PM   #2
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Did you do anything else to the car around the same time? Did it sit for very long? Stuck brake caliper?
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Old 06-15-2014, 01:41 AM   #3
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Timing is sync'd properly?
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Old 06-15-2014, 01:57 AM   #4
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Quote:
Originally Posted by Fireindc View Post
Did you do anything else to the car around the same time? Did it sit for very long? Stuck brake caliper?
It did sit while the engine was being replaced- but in a garage. See detailed reply below.

Quote:
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Timing is sync'd properly?
IIRC we checked that before installing the engine and all was well.


I've noticed that pretty much under 3k RPMs in any gear, that holding 10mmHg causes me to accelerate- as seems correct- while 18-16mmHg would hold a steady speed. But on the highway, anything above that RPM level, 10mmHg is holding a steady speed. Might this come down to ignition advance timing? Might more timing help with this?
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Old 06-15-2014, 02:10 AM   #5
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Sync timing as in the engine with the ecu, not the timing belt

or does the faghydra not do that?
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Old 06-15-2014, 03:30 AM   #6
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Very true, you have to sync to the hydra. But I have no idea how unless it's a MS.
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Old 06-15-2014, 10:27 AM   #7
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is the new motor a different compression ratio?
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Old 06-15-2014, 03:22 PM   #8
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Negative- its still 10:1
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Old 06-15-2014, 04:31 PM   #9
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First thing I would do is double-check the timing belt alignment.

--Ian
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Old 06-15-2014, 04:45 PM   #10
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I will be doing that this upcoming week when I go in to check/adjust the valve lash.


I'll look into the Hydra stuff...perhaps even get some logs and post them up.
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