April 23, 20178 yr I just finished rebuilding the engine on my 85 GL, and noticed that the mpg is less then it was before the rebuild. Is this normal for newly rebuilt engines or is there a problem?
April 23, 20178 yr How much less? Variations could be from driving / location / route changes How long have you monitored ? Variations could be from fuel itself Rebuilds in general should make things better Run a vacuum test on your engine and see if there are any issues to be considered.
April 23, 20178 yr Depends on how tight the pistons are and how coarse the rebore/rehone was. Also valve seating, etc. Generally we see a reduction in fuel economy for a few thousand miles when we knurl the pistons on the EJ's. Were the pistons knurled? What was the ring gap and how were the cylinders setup? Have you compression tested it? GD
April 24, 20178 yr Are you wearing heavier boots? On a serious note, how did you do your rebuild? New or reused pistons? Valve job? Perfect bore and hone? Deck the block and mill the heads? Worse milage after a rebuild is not right. Check ignition timing, run higher octane fuel, check plug gap, pcv valve. If you haven't already, install new plugs, wires, cap & rotor, fuel filter, amd air filter. Give it a good oil change after 500 mile break in.
April 24, 20178 yr 1. you are comparing last summer (before you took car off road for rebuild) with summer blend gases to winter blend gas you've been running since the rebuild this winter. for the eagle eye hyper milers, it should go up any day now as stations start switching. 2 maybe it's not actually getting worse mileage - you love that new go pedal feel and can't get your foot out of it...or the old engine was such a basket case you were driving cautiously. what all did you do to the engine? post previous and current gas mileage - is this a 0.5mpg difference or 10 mpg? how many miles have you put on it? have you driven enough to get an accurate measure - consistent highway miles or inconsistent urban/mountain driving?
April 24, 20178 yr Author How much less? Variations could be from driving / location / route changes How long have you monitored ? Variations could be from fuel itself Rebuilds in general should make things better Run a vacuum test on your engine and see if there are any issues to be considered. It's like a 5-10 mpg difference
April 24, 20178 yr Author I kept the old pistons, because they were like new (.002" worn), still had hatching.
April 24, 20178 yr We need some data to help you. Vacuum test is the easiest to do and can reveal a problem in a number of possible areas, or point to best subsequent testing.
April 24, 20178 yr 5-10 MPG probably indicates problems with rich mixture or timing. It should not be that much different. GD
April 28, 20178 yr Author We need some data to help you. Vacuum test is the easiest to do and can reveal a problem in a number of possible areas, or point to best subsequent testing. Ok ill do a vacuum test next time I'm in the shop, see what it shows.
April 28, 20178 yr Author 5-10 MPG probably indicates problems with rich mixture or timing. It should not be that much different. GD What would be the proper adjustment on the fuel/air mix?
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