1987 Honda Prelude losing power once warm

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.

 

Hi,
Manifold vaqcuum leak?

 

--------------------------

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.

'Curly'

 

Hi,

Which manifold? How does one test it? Also, sounds expensive.

 

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.

 

Hi,
Intake. You can hook up vacuum gauge.

 

Hi,

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?

 

Hi,
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.

 

Hi,

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?

 

Hi,
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.

 

It looks more like a clogging fuel filter...

 

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.

 

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:
http://www.autozone.com/az/cds/en_us/0900823d/80/0c/fb/59/0900823d800cfb59/repairInfoPages.htm

Your Prelude's factory service manual:
http://www.honda.co.uk/car/owner/workshop.html

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
system?

Keep checking back. Others with more expertise will post.

Elle
Original owner and now sole mantainer, 1991 Civic

 

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
parts.

 

If the cat was restricting,it would affect running ALL the time,not just
after warmup.

 

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.

 

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

JT

 

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.