1. Home
  2. Honda Cars and Trucks
  3. the old PGM-FI thing - i have 87 honda prelude

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.

Reply to
zardozrocks
Loading thread data ...

  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.

Reply to
jim beam

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?

Reply to
zardozrocks

How about

formatting link
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

Reply to
Michael Pardee

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.

Reply to
zardozrocks

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

Reply to
nm5k

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.

Reply to
zardozrocks

"zardozrocks" wrote in news: snipped-for-privacy@n67g2000cwd.googlegroups.com:

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

See here:

formatting link
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...

Reply to
Tegger

"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'

Reply to
zardozrocks

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

Reply to
Gordon McGrew

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

Reply to
Art_Vandolay

Art_Vandolay wrote in news:XHyeh.102$U6.58@bigfe9:

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.

Reply to
Jim Yanik

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?

Reply to
zardozrocks

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.

Reply to
William Burke

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.

Reply to
zardozrocks

Ah - EGR system fault. Page 24 of the PDF

formatting link
Mike

Reply to
Michael Pardee

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.

Reply to
zardozrocks

"zardozrocks" wrote in news: snipped-for-privacy@80g2000cwy.googlegroups.com:

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).

Reply to
Tegger

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?

innews: snipped-for-privacy@80g2000cwy.googlegroups.com:

turned quoting on.

Reply to
zardozrocks

"zardozrocks" wrote in news: snipped-for-privacy@79g2000cws.googlegroups.com:

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?

Reply to
Tegger

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.