Skip to content
Gold Hills Posse 4×4 Club · Folsom, CA

Arm Chair Mechanics Unite!

  1. Guest former user
    #113 Feb 2008, 12:58 PM

    As some of you know, Eric and I spent the better part of the last few days driving to Chicago. Along the way we had some car trouble. We’re not real sure what is going on. Here are the symptoms, some of our theories, and a few random thoughts. Eric’s car is a 93 Honda Prelude. Any advice on what to check next would be appreciated.



    1. Gas mileage dropped quickly. Eric’s car normally gets about 27-28 mpg. We started at 21 and dropped from there. We noticed a substantial drop east of the Rockies where we started getting 18 mpg which eventually dropped to 17 mpg. The car was loaded and there was a bike on the roof rack which explains some of the drop, but not all (in our mind). One theory for the quick drop after the Rockies is a higher ethanol content in the gas. We changed the spark plugs in Des Moines. The gaps were big, but they were not fouled. The new plugs resulted in the 18 to 17 drop in gas mileage. Between the first and second tanks we made an effort to lower our speed by about 10 mph. There wasn’t really any change in the mileage.



    2. We noticed the car was burning oil at gas stop number two in Austin, NV. Overall, we were averaging a quart of oil per thousand miles. Before the trip Eric switched to synthetic motor oil. There was no evidence of leaking oil. Prior to the trip, the car had not used oil.



    3. The Cruise control stopped working in the cold parts of the trip. The only reason I mention that is because my understanding is that the cruise is vacuum controlled. We figured a vacuum leak might explain some of the mileage problems. We tried to locate a leak but were not able to.



    Overall, the car ran great. We didn’t notice any change in performance and the car had plenty of power. We never had a check engine or oil pressure light.



    Our theories center around the switch in oil. We figure the synthetic oil is getting past the rings, changing how the fuel burns which the computer is compensating for so we didn’t notice any loss in power, just a change in mileage.



    I’m home now and Eric is with some family in Illinois for a few days. Based on how the car is running, he shouldn’t have any problems with the last 1000 miles, but with gas mileage that bad, he might as well drive a Jeep. 🙂

  2. Fred Subscriber
    #213 Feb 2008, 1:19 PM

    I'd look into #3.



    It could also have something to do with the change in altitude.

  3. Justin Subscriber
    #313 Feb 2008, 1:23 PM

    How many miles are on the car?

  4. Guest former user
    #413 Feb 2008, 1:33 PM
    "Justin" wrote: How many miles are on the car?



    About 150,000.

  5. BKGM Jeepers President Joined: June 2003
    #513 Feb 2008, 1:51 PM

    My guess would be to investigate a cracked head.



    I suffered similar symptoms (decreased MPG and "burning" oil). I ended up with some oil burning and some oil in the coolent.



    My head cracked after driving across the Sierras at night in winter, and through Nevada when the temp was in the 10's and 20's. It was a road trip to Utah, so I was also doing long distance continuous driving.



    You could try a quick pressure check to rule it out?

    Kathleen and Brad
  6. Guest former user
    #613 Feb 2008, 1:56 PM

    good to have you back. these yahoo's keep making fun of toyotas. there's just to many of them!!!!! Lets get em!

    "To the pain."

  7. Guest former user
    #713 Feb 2008, 2:19 PM
    "BKGM Jeepers" wrote: My guess would be to investigate a cracked head.

    I suffered similar symptoms (decreased MPG and "burning" oil). I ended up with some oil burning and some oil in the coolent.

    My head cracked after driving across the Sierras at night in winter, and through Nevada when the temp was in the 10's and 20's. It was a road trip to Utah, so I was also doing long distance continuous driving.

    You could try a quick pressure check to rule it out?



    There's no oil in the coolant which doesn't rule out a cracked head but it doesn't make the diagnosis any easier. We talked about doing a compression test and Eric will do it when he gets to CT, but to be honest it was too cold. When we changed the plugs it was 0 degrees with a substantially negative wind chill (rumored at -20). By the time we were done I had icicles in my beard.

  8. Guest former user
    #813 Feb 2008, 3:10 PM
    "FAM" wrote: I'd look into #3.

    It could also have something to do with the change in altitude.



    We kind of leaned away from #3 because the idle is fine. A vaccum leak should also show up in the idle right?

  9. JohnDF Subscriber
    #913 Feb 2008, 3:12 PM
    "lowrider" wrote: these yahoo's keep making fun of toyotas.



    I made this just for you guys, to make you feel better about your vehicle choice 😉

    Attached files

    I used to wheel a lot. . .
  10. Fred Subscriber
    #1013 Feb 2008, 3:20 PM
    "Bender" wrote: [quote="FAM"]I'd look into #3.

    It could also have something to do with the change in altitude.



    We kind of leaned away from #3 because the idle is fine. A vaccum leak should also show up in the idle right?



    We had a Camaro that developed a vacuum leak. The only indication was the a/c vents kept opening and closing at random (not good crossing the desert to Vegas in July). The car seem to run fine on the highway or at idle though.

  11. RobD Subscriber
    #1113 Feb 2008, 3:35 PM
    "JohnDF" wrote: [quote="lowrider"]these yahoo's keep making fun of toyotas.



    I made this just for you guys, to make you feel better about your vehicle choice 😉



    We need to find you a job where you don't have so much time on your hands 😉

    __________________ 'If we ever forget that we're one nation under God, then we will be a nation gone under."- Ronald Reagan
  12. Guest former user
    #1213 Feb 2008, 3:48 PM
    "JohnDF" wrote: [quote="lowrider"]these yahoo's keep making fun of toyotas.



    I made this just for you guys, to make you feel better about your vehicle choice 😉



    Did you seriously make that? You have much talent grasshopper.

  13. JohnDF Subscriber
    #1313 Feb 2008, 4:16 PM

    No I didn't make it. But, I did stay at a Holiday Inn, and I added the text. Still funny though 😀

    I used to wheel a lot. . .
  14. Dan-H Subscriber
    #1413 Feb 2008, 5:08 PM

    Has the cam timing belt been replaced?

    Closed Mondays.
  15. Guest former user
    #1513 Feb 2008, 7:08 PM
    "Dan-H" wrote: Has the cam timing belt been replaced?



    Funny you should ask...that's one thing I left off the list. 😳 The timing belt was changed roughly a month before the trip. Eric didn't notice anything odd between the time the belt was replaced and the trip.

  16. JohnDF Subscriber
    #1613 Feb 2008, 7:12 PM

    I think the car didn't want to leave California

    I used to wheel a lot. . .
  17. Guest former user
    #1714 Feb 2008, 8:48 AM

    quick update....I have lots of posts to read



    On the next two tanks I got 21.5 one of those was after raising air pressure in the rear tires which I didn't check before. The current tank appears to be much better I have 288 miles on it without the bike up top.



    Over all I'm still leaning towards the oil...the research I've done leads me to believe this has happened when switching to synthetic after runing the whole life on mineral oil.



    Will update again in CT

  18. Justin Subscriber
    #1814 Feb 2008, 9:14 AM

    I would never recommend switching to synthetic oil on any engine which has over 100K miles with regular oil. I have seen undesirable things happen.

  19. Fred Subscriber
    #1914 Feb 2008, 9:25 AM
    "e_rubs" wrote: On the next two tanks I got 21.5



    So let's see, your gas mileage started off fine. The longer you were on the road the worse your gas mileage got. Then you drop off Keane at the airport and your gas mileage improves. Could it be that Keane was just eating too much during the road trip? 😂

  20. Guest former user
    #2014 Feb 2008, 9:33 AM
    "FAM" wrote: Could it be that Keane was just eating too much during the road trip? 😂



    It wasn't the eating that was the problem. It was the drinking. :badidea:

  21. JohnDF Subscriber
    #2114 Feb 2008, 9:34 AM

    Fred, you know Keane doesn't eat. That boy needs a CHEESEBURGER 😏

    I used to wheel a lot. . .
  22. Fred Subscriber
    #2214 Feb 2008, 9:37 AM

    Maybe he just wasn't going to the bathroom. He probably didn't want to use the yucky gas station potties. He should have packed the Pett.

  23. Guest former user
    #2314 Feb 2008, 9:39 AM
    "JohnDF" wrote: [quote="lowrider"]these yahoo's keep making fun of toyotas.



    I made this just for you guys, to make you feel better about your vehicle choice 😉



    OMG to funny..... 😂 😂

  24. Guest former user
    #2414 Feb 2008, 11:03 AM
    "FAM" wrote: Maybe he just wasn't going to the bathroom. He probably didn't want to use the yucky gas station potties. He should have packed the Pett.

    or flip flops.

  25. Guest former user
    #2514 Feb 2008, 2:37 PM
    "Justin" wrote: I would never recommend switching to synthetic oil on any engine which has over 100K miles with regular oil. I have seen undesirable things happen.



    Any specifics? Would you expect more oil burning than before? I have read conflicting things about going back to mineral...any opinion?

Sign in to post here.