the old PGM-FI thing - i have 87 honda prelude

My car has the good ol' PGM-FI dash light on problem. This seems to be
a common problem and I have seen a variety of explanations.

The light normally comes on when you turn the ignition key and
immediately turns off after I successfully start the car. However,
after I drive the car for 15 minutes, the light comes back on again and
doesn't turn off until I turn the car off. This is not normal. When
I start the car again, it will stay off again for a few minutes.

I have seen a number of explanations for this:
1) bad oxygen sensor (replace sensor)
2) problems with the solder connections on the main relay (replace
relay or re-solder all connections)
3) put fuel injector cleaner in the tank or get injectors cleaned

I understand the ECU might help me figure it out. But then I also
understand that the ECU is sometimes mistaken.

Any help would be much appreciated. My car stalled out today. I think
it was due to a problem with the ground wires but I'm still pretty
concerned.

 

1. go to tegger.com and get directions to the manual for your car.
2. locate ecu.
3. read error code.

the ecu's are usually pretty good for diagnostics. the only exception i
know for sure is the main relay in obd0 which often gives code 16,
failed injector circuit. but since the main relay does energize the
injectors, it's not all wrong, just misleading.

 

I checked all over tegger and looked at every online manual they had.
the only one that was remotely close to describing where the ECU is
located was on the english website and the diagram was so vague I
couldn't tell what it depicted. the *other* diagram on that page was
the driver's seat so I assume it's somewhere in the cabin.

Anyone? please?

 

How about http://tinyurl.com/y6scej

If they talk about a "code reader" they mean a shorting jumper. (I bought
the manual with two "code readers" for $35 before I found out what it was!)

Mike

 

Aha! so the ECU appears to be in the side panel behind the driver's
seat. now I just have to figure out how to get that off. Those
service manuals looked pretty helpful but didn't contain much info on
how to disassemble body panels.

 

It's under the front seat, covered by a plastic cover. You first
need to remove the seat, "4 bolts, and plastic covers need to
be popped off to get to the back two." Then you take off the
plastic cover , and there it is..
The PGM-FI has a LED that blinks to show the trouble code.
You need to access the puter, and when you get a trouble
warning light, then count how many times the LED blinks.
There will be a 2 second pause between each series of blinks.
I have a list of the blink code if you don't have it.
MK

 

Thanks for your response, but according to that document michael pardee
posted, it's in the right side panel behind the driver's seat. I have
no idea how to get that panel off.

 

That's wrong. It's under the driver's seat. Run the seat all the way back
and you'll see it.

See here:
http://www.tegger.com/hondafaq/misc/3173_ICCR_E_14JAN03.pdf
specifically page 15.

My OBD-II pages are confusingly written and I apologize for that. A rewrite
is in the cards just as soon as work slows down a bit...

 

That document is where I was looking before (although a different
link). My car is a *1987 Honda Prelude* which is the first row of the
table on page 16. That says:

"Procedure: Access ECU (located behind
driver's seat within door pillar assembly)
(H8). Turn ignition on and
observe LED on ECU for codes.
Codes: Codes blinked out by LED are
separated by two second pause, then
repeated. For example: 2 blinks - two
second pause - 2 blinks = code 2 (H14)"

No tool necessary it says. however, i don't really know how to get in
the 'door pillar assembly'

 

Look under the drivers seat (from the rear seat side.) That's where
it was in the '86 integra.

 

Replace your oxygen sensor and see what happens. I have an 88 Prelude
and I think mine is out as well.

 

around $100 parts cost.

"replace" costs at least $50,resoldering costs only your time.

IMO,it would be wise to get the ECU **trouble codes** read before you go
replacing expensive parts.

Chances are,a trouble code would point you in the right direction.

You could also have loose or corroded grounds;the OTHER half of the wiring.
(or a loose or corroded connector)


BTW,I noticed today Harbor Freight had O2 sensor removal sockets(3/8"
drive) selling for about $5.

 

I took both seats out of the car and it's not under either seat. so
i'm guessing it's in the side panel behind the driver? how do i take
that apart?

 

The ECU is located next to the rear passenger seat behind the drivers
seat. Is there an ash tray there? If so, then pull it out and you can
see the LED. Turn on the ignition (Don't start car). Count the blinks.
You can do a search online for Honda error codes.

 

THANK YOU william burke. You are THA MAN. The LED will pause and
then blink twelve times. It repeats this over and over.

I am so very grateful for your help folks.

 

Ah - EGR system fault. Page 24 of the PDF http://tinyurl.com/y6scej

Mike

 

yeah i've been googling around for what that means exactly and haven't
had much luck yet beyond figuring out what an EGR is. i still have no
idea which part might need to be replaced.

 

It sure would be nice if you turned quoting on.

Your Code 12 means the EGR system is not responding correctly. This can be
due to quite a number of things, especially at your car's age.

Several possibilities:
1) EGR valve carboned up & EGR valve not lifting correctly;
2) Valve lift solenoid not operating correctly;
3) CVC valve not operating correctly.

You need to obtain a copy of the Helm manual, which gives detailed
troubleshooting for the EGR system. I think I have an Accord shop manual
from that era somewhere, which should be close enough. You'll need a vacuum
pump (Mity-Vac).

 

Your site has been tremendously helpful, Tegger. It led me to some
shop manuals in PDF format. i can't remember where exactly i found
them but they are quite helpful.

I don't know yet if they mention the EGR. They are scanned images
rather than text so I can't search them...just have to keep looking
through the 1200+ pages. Where would EGR be? Under exhaust? Engine?
Carb? Emission control?

Also, do you think that my stalling problem could be related to the
EGR? I am having this problem where the car loses power dramatically
when i'm accelerating with the engine around 2500 rpm. It's as though
it were running out of gas. Then as soon as I push the clutch in
and/or take it out of gear, it idles just fine. The problem also
doesn't seem to occur when the engine is not under load - I can rev the
car just fine when it's not in gear.

The PGM-FI troubleshooting table suggests any number of things could be
the problem when you have a lack of power at lo/mid/hi RPM
* faulty ecu
* fuel injector open or short circuited, stuck injector (they do seem
to be leaking)
* faulty fuel pump / fuel pump relay OR poor grounding
* improper fuel line pressure OR clogged fuel filter
* manifold absolute pressure sensor - open or short circuited, broken
or disconnected hose, faulty sensor

and none of those seem related to EGR, do they?

 

Usually under Fuel System (PGM-FI or PGM-CARB).

Classic sign of an EGR valve that's carboned up and sticking open. Your
Code 12 is telling you the ECU is seeing incorrect lift heights from the
EGR valve.

It is possible to disassemble the EGR valve and clean out the carbon by
using a drill bit (held in your fingers) to gently clean out the holes in
the valve diaphragm.

It's likely your whole damned EGR system is choked with carbon, including
the passages in the head.

Somewhere there's a TSB that shows how to unclog the EGR valve, but I can't
find it just now. Help anybody?