1987 Honda Prelude losing power once warm

Discussion in 'Prelude' started by zardozrocks, Dec 11, 2007.

  1. zardozrocks

    zardozrocks Guest

    I have a 1987 Honda Prelude 2.0 SI. It's the fuel-injected model. If
    the car is cold, it will start up immediately and runs great - i can
    lay a patch of rubber. It will run perfectly immediately following a
    cold start. Once the car has traveled a few miles, however it starts
    to lose power quite dramatically as I attempt to rev it up past about
    2000 RPM as though it were starving for fuel or air or something. The
    problem will happen in any gear but seems a teeny bit more pronounced
    in the higher gears. Around this time, the PGM-FI light comes on on
    the dash.

    I've been looking at this problem for some time now and I have had
    some repairs done:
    * rebuilt/replaced fuel injectors
    * new fuel pump
    * new air/fuel/oil filters
    * replaced EGR valve
    * checked main relay for broken solder - it seems fine

    After posting here previously someone told me to check the ECU codes.
    The ECU code that is blinking is code #12 which for my car means a
    problem with the EGR system. When I took the car in for repairs last
    January to a small shop, the mechanic claims he replaced the EGR valve
    so I'm inclined to rule that out.

    Any hints on what it could be? Would a clogged oxygen sensor result
    in the ECU sending code 12? Any advice would be much appreciated! I
    MUST fix this problem and simply cannot afford expensive repairs.
    zardozrocks, Dec 11, 2007
  2. zardozrocks

    Tony Hwang Guest

    Manifold vaqcuum leak?
    Tony Hwang, Dec 11, 2007
  3. zardozrocks

    motsco_ Guest


    If it's a problem when it warms up, what's your TEMP gauge showing,
    and how full is your rad and reservoir? Your engine can run like crap
    if the computer is getting wrong info from the coolant sensor(s) because
    they aren't immersed.

    motsco_, Dec 11, 2007
  4. zardozrocks

    zardozrocks Guest

    Which manifold? How does one test it? Also, sounds expensive.
    zardozrocks, Dec 11, 2007
  5. zardozrocks

    zardozrocks Guest

    If it's a problem when it warms up, what's your TEMP gauge showing,
    When I say 'warms up' I didn't mean to imply anything at all about the
    temperature. I was only trying to imply that the problem happens once
    the car has been running awhile...like after 20 minutes/5 miles or
    so. The temp gauge appears to be fine...it definitely doesn't appear
    to be running hot or anything. I'll check the radiator but I'm fairly
    certain radiator levels are fine. The car doesn't leave any leak
    spots at all on the driveway.

    Thanks for the response.
    zardozrocks, Dec 11, 2007
  6. zardozrocks

    Tony Hwang Guest

    Intake. You can hook up vacuum gauge.
    Tony Hwang, Dec 11, 2007
  7. zardozrocks

    zardozrocks Guest

    Thanks for the response!

    Wouldn't that problem be evident even when the car is cold? Any links
    or advice on how to test or where to buy a vacuum gauge?
    zardozrocks, Dec 11, 2007
  8. zardozrocks

    Tony Hwang Guest

    Heat/cold expand/shrink things. You already done quite a few rmedial
    tries. Checking vacuum for proper level won't hurt.
    Also checking all the ground point like fuel pump ground joint is good idea.
    Tony Hwang, Dec 11, 2007
  9. zardozrocks

    zardozrocks Guest

    OK I'll buy the heat expansion/contraction, but I'm also wondering if
    that will solve the car complaining about the EGR problem (code 12 on
    the ECU).

    Most importantly, HOW do I check for a vacuum level on the intake
    manifold? Got any links or suggestions?
    zardozrocks, Dec 11, 2007
  10. zardozrocks

    Tony Hwang Guest

    Take a minute and think about how EGR valve operates. Manifold vacuum
    does many things. One example is helping brake master cylinder. Usually
    there is a test port for vacuum connection with little rubber nipple cap
    on it, or you have to find where you can tap into vacuum line using a T
    fitting. Vacuum level is highest when idling. If it fluctuates wild or
    unsteady moving up and down, etc. Bad sign.
    I am not pretending an expert but this is very basic stuff.
    DTC code is a starting point for trouble-shooting a problem. It does not
    mean pointed part is bad. Old cars often have cracked vacuum hose
    causing leak as well.
    Tony Hwang, Dec 11, 2007
  11. zardozrocks

    al Guest

    It looks more like a clogging fuel filter...
    al, Dec 11, 2007
  12. zardozrocks

    Jim Yanik Guest

    Harbor Freight has vac gauges at "low cost".

    How many miles on the car? O2 sensors last about 60-100K miles.
    OEM are the best.
    Jim Yanik, Dec 11, 2007
  13. zardozrocks

    Elle Guest

    Admittedly one does not want to replace things willy-nilly
    at this point. And you say the Code 12 continues. (I also
    confirmed Code 12 is symptomatic of a "problem" with the EGR
    system.) Using the manuals at the sites below, I would be
    checking the EGR's electrical connections first. Yes, it's
    new, so this suggests that, if it's not working, it's more
    likely that the connections were not made correctly.

    For troubleshooting codes yada for your Prelude:

    Your Prelude's factory service manual:

    Next I would do what Motsco said. One must take seriously
    purging air from the coolant system. If any repairs you had
    done recently involved the coolant system in any way, I'd do
    a purge, per the manual. It may take 50 minutes or so for
    your car to warm up during the purge, so be patient. The
    level appearing to be fine is not enough to indicate air is
    fully purged.

    If this Prelude is on its original, OEM oxygen sensor,
    nonetheless I would consider replacing it. Your symptoms do
    suggest a failing O2 sensor. Particularly the symptom that
    it starts going amiss after warmup. If it is the original O2
    sensor, then it is in fact quite old. A code will not
    necessarily be thrown for its malfunction. You can get an
    OEM O2 sensor from www.automedicsupply.com for under $40
    total (= about $32 + shipping). In 2004, I used this online
    store for a new O2 sensor for my 91 Civic (the Denso one).
    Great service. No problems with the new O2 sensor.

    Based only on reading here and a bit of googling, I'd also
    investigate whether the catalytic converter was partly
    plugged. Google on same for more info. Of course, then the
    big question is how it got plugged. Related to the EGR

    Keep checking back. Others with more expertise will post.

    Original owner and now sole mantainer, 1991 Civic
    Elle, Dec 11, 2007
  14. zardozrocks

    Elle Guest

    P.S. for the record, when were ignition wires and plugs last
    replaced and timing checked? Distributor cap and rotor? Were
    OEM parts used?

    It's amazing sometimes how often it's just old ignition
    Elle, Dec 11, 2007
  15. zardozrocks

    Jim Yanik Guest

    If the cat was restricting,it would affect running ALL the time,not just
    after warmup.
    Jim Yanik, Dec 11, 2007
  16. zardozrocks

    Elle Guest

    I think I understand what you're saying, ("If it's plugged,
    it's plugged! Even partly plugged... ), but from my reading,
    the symptoms of a partly plugged cat converter become more
    manifest with, say, acceleration and warmup.

    http://www.aa1car.com/library/converter.htm, among other
    sites, has some stuff on how temperatures yada affect cat
    converter operation.
    Elle, Dec 11, 2007

  17. You left out the mileage on this vehicle. How many miles on it?

    Grumpy AuContraire, Dec 11, 2007
  18. zardozrocks

    Matt Ion Guest

    I'm wondering, does it also operate the EGR valve, like it does in my
    carb'd '87 Accord, via a vacuum diaphragm? There could be a leak in
    that vacuum line or even the diaphragm itself, and the leak is only
    presenting itself once the car warms up enough to activate the EGR.
    Matt Ion, Dec 12, 2007
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