gas mileage - Monte Carlo Forum - Monte Carlo Enthusiast Forums


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Old 09-30-2010, 04:55 PM
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My jr. monte carlo is gettin bad gas mileage. i replaced the spark plugs and wires and i have a short ram intake on it and its getting bad gas mileage what could it be i am running out of ideas. if know what it could be send me a message

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Old 09-30-2010, 05:49 PM
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Did you start noticing the higher usage after you change S/P and wires, or after the switched to the ram air? After I switch to the wizair, my gas consumption went up. Tuned the PCM and no couldn't be happier.
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Old 09-30-2010, 07:42 PM
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it was after the spark plug wires and spark plugs
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Old 10-01-2010, 07:26 AM
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I would make sure the wires are not crossed and are pushed on fully on the spark plugs and coils. Also make sure you set the gap on the plugs correctly. Since it happened after the tune up I suspect somethings not quite right. Here's a link to the firing order, its says Oldsmobile, but its the same as your monte http://autorepair.about.com/library/...bl551a-lib.htm
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Old 10-01-2010, 09:36 AM
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As already mentioned, if you noticed the poor mileage after the plug / wire change, chances are it's directly related to that. Check the gap on all plugs. If you haven't already, get some dialectric grease and apply a small amount to each plug wire connection (both at the plugs and coil connections). That will help ensure good electrical contacts and prevent corrosion build-up. Make sure the plugs are properly tightened; use a torque wrench if possible (sorry, don't know the proper torque requirement off the top of my head). If no torque wrench, just hand-tight with socket wrench; don't crank down too hard. Too loose or too tight can cause problems. While you're gapping the plugs, check the color / look of each electrode. If a particular cylinder is having issues, the electrode may look different than the others.

Just in case it's not related to plugs / wires, trying to think of some other options...

Other than bad mileage, does it seem to run OK? Acceleration / power the same as it had been? If yes, then maybe it's a fueling issue, like running too rich. That could show up with fouled plugs (electrodes looking black, wet, gunky). If not fueling issue, then need to consider electrical issues, whether the plugs are getting a full-energy spark. Each plug should show a nice bright blue spark. Yellow or orangy spark could indicate it's not getting enough juice.

Let us know what happens after checking plugs / wires and running enough gas through to check the mileage again.
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Old 10-01-2010, 07:31 PM
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Quote:
Originally Posted by Sparky-88 View Post
As already mentioned, if you noticed the poor mileage after the plug / wire change, chances are it's directly related to that. Check the gap on all plugs. If you haven't already, get some dialectric grease and apply a small amount to each plug wire connection (both at the plugs and coil connections). That will help ensure good electrical contacts and prevent corrosion build-up. Make sure the plugs are properly tightened; use a torque wrench if possible (sorry, don't know the proper torque requirement off the top of my head). If no torque wrench, just hand-tight with socket wrench; don't crank down too hard. Too loose or too tight can cause problems. While you're gapping the plugs, check the color / look of each electrode. If a particular cylinder is having issues, the electrode may look different than the others.

Just in case it's not related to plugs / wires, trying to think of some other options...

Other than bad mileage, does it seem to run OK? Acceleration / power the same as it had been? If yes, then maybe it's a fueling issue, like running too rich. That could show up with fouled plugs (electrodes looking black, wet, gunky). If not fueling issue, then need to consider electrical issues, whether the plugs are getting a full-energy spark. Each plug should show a nice bright blue spark. Yellow or orangy spark could indicate it's not getting enough juice.

Let us know what happens after checking plugs / wires and running enough gas through to check the mileage again.
Its running the same as it had been before... feels like it has more power actually. My gas mileage just went down. If I have a chance this weekend I will look at the plugs and wires and see if that's what the issue is. I will deff be keeping everyone informed, and as always, thanks so much for the help!
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Old 10-23-2010, 09:07 AM
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So I started to smell a rotten egg smell and gas mileage continued to decrease. I had one of my co-workers husband look at it, he hooked up a diagnostic tool and instantly said my cat is clogged and my rear O2 sensor is basically not reading at all. We ordered a new cat from ZZP last Wednesday. I will keep everyone posted. Thanks for everything.
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Old 10-23-2010, 10:13 AM
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That makes sense. A clogged cat would give you worse mileage. At least you get to make an order to ZZP
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Old 10-23-2010, 01:26 PM
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Yeah I'm only gettin maybe 180 miles on 3/4 tank. im fillin up at least twice a week and I only work maybe 10-15 minutes from home. SUCKS... cat needs to get here soon! lol
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Old 10-23-2010, 09:43 PM
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So did you order a downpipe with a high flow cat? Be prepared to also get the PCM upgraded or you will throw a P0420 code.
 
 
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