NEED a quick ECU code help plz!!

**ICEMAN707** · 04-16-2005, 04:29 PM

Hey guys, I've been having code problems lately. (Seems to be the sickness with these 3geez). Anyways, I've been having problems with my idle being too high around 1500 rpm. (That's with the idle screw on the throttle body all the way down closed). Also when it warms up after startup, it pulsates up and down between 1000-2000 rpm. I can hear the IAC solenoid valve clicking and sounds to be doing it. (I have an 87 which has that external mounted IAC valve next to the wiper motor). But I changed that to one I got from the junkyard and still the same thing. I even tried to change ECM units. Could it be the damn EGR again? When the PGM-fi ECU light comes on, it runs better and the idle holds steady at 1500 rpm again. The light is a steady 1 pulse when I looked at the ECU under the seat. So help me out and tell me what code that is fellas!

**mouchyn** · 04-16-2005, 04:51 PM

vacuum leak on the intake manifold. if your idle screw is all the way closed, the car shouldn't idle at all. with the throttle palte closed and the idle screw all the way in, no air is bypassing the throttle plate which should be the only way for air to get into the engine.

here's a quick test. take the intake pipe off the throttle body and start the engine. put a piece of thick cardboard over the TB opening. the engine should die immediately with no sputter. if the engine sputters or you hear sucking still, then you have a gasket or seal leak on the IM.

you can also take starter fluid and spray all around the intake. make sure you really coat all the gasket areas well. if there is a BIG leak, the engine will suck in the starter fluid and you should hear a change in the engine's sound.

if you have a vacuum pump and gauge, you can test that way, too. with all the intake valves closed and the TB sealed off, you should be able to pressurize or draw a stedy vacuum on the intake manifold.

remove all vacuum lines and plug the ports. seal off the TB and make sure all the intake valves are closed. then attach your vacuum pump or air compressor to one open vacuum port. you should be able to pressurize the intake manifold and see that reading on the gauge. If the needle moves at all, you have a leak!

**YK86** · 04-16-2005, 04:54 PM

Code 1 would be the primary O2 sensor (86/87's only have one anyways). Here's a link for future reference:
https://www.3geez.com/showthread.php?...ight=ecu+codes

There's a good chance the fast idle valve (on the back side of the intake manifold beside the TB, 2 coolant hoses going to it) isn't working. Take it out, take the cap off the top, and clean it out with carb cleaner. The plunger is probably gummed up with carbon. If it still does it, take the cap off again and turn the big nut thing inside clockwise until it stops pulsating. This should also help to drop the idle speed.

**ICEMAN707** · 04-16-2005, 05:00 PM

yeah i suspected a vacuum leak for weeks. all the hoses are connected. so i dunno what else could be wrong. i'm gonna try what's up with the IM gasket. it's just a bitch to remove the intake manifold with the hidden bolts underneath the runners. i had the block replaced years ago when i overheated the engine. the IM flange could be warped somehow cus they used my old IM. the 89 IM the block came with is different and the mechs couldn't figure out how to make it work. i wanna use it, but i don't exactly know what there is to do to make it work. might as well swap a b16 IM.

**ICEMAN707** · 04-16-2005, 05:10 PM

Originally Posted by YK86

Code 1 would be the primary O2 sensor (86/87's only have one anyways). Here's a link for future reference:
https://www.3geez.com/showthread.php?...ight=ecu+codes

There's a good chance the fast idle valve (on the back side of the intake manifold beside the TB, 2 coolant hoses going to it) isn't working. Take it out, take the cap off the top, and clean it out with carb cleaner. The plunger is probably gummed up with carbon. If it still does it, take the cap off again and turn the big nut thing inside clockwise until it stops pulsating. This should also help to drop the idle speed.

that would suck if it's the o2 sensor. that thing is new when i put in my dc header. my throttle body was new about 7 months ago. so that can't be it either.

maybe this:

my dc header has two o2 holes. i plugged the other one up with a dummy o2 sensor and put the other o2 sensor in the other hole. could that be causing it? does the o2 sensor really need to read o2 on all exhaust ports instead of just two? if so, that would require me to move the o2 sensor to the downpipe instead and plug both holes on the header.

**YK86** · 04-16-2005, 05:22 PM

Have you tried plugging the O2 plug into the other O2 sensor? Also, the fast idle valve is on the intake manifold so it wouldn't have been changed when you got a new TB.

**ICEMAN707** · 04-16-2005, 05:32 PM

Originally Posted by YK86

Have you tried plugging the O2 plug into the other O2 sensor? Also, the fast idle valve is on the intake manifold so it wouldn't have been changed when you got a new TB.

no the other o2 sensor is just a dummy sensor, it's been cut off of all the wires so it looks cleaner and it doesnt dangle and get burnt up by the header. but i'll check the 02 sensor for gum buildup and try switching the sensor position and see if that helps.

it sux that not only do i have the idle problem, but i haven't been getting steady power like i used to. i get shitty throttle response like the car doesn't wanna go when i run it from cold start. sometimes i get pissed and i just mash on the accelerator then it hesistates for a bit then it catches on and goes. sorta like having turbo lag without the turbo

**mouchyn** · 04-16-2005, 05:35 PM

the vacuum leak could also be caused by another gasket on the intake manifold. the vacuum test still applies, whether it's the FIV or a gasket causing the problem. Once you determine that there is, in fact, a vacuum leak, you should be able to track it down pretty easily.

opening up the FIV will reveal a lot and it only takes a few minutes. spraying the manifold down with starter fluid is also cheap and quick.

as for the O2 sensor... If the manifold has two O2 sensor holes, there needs to be two O2 sensors in it. Unless you have done the 4-wire heated O2 sensor conversion, which requires the O2 sensor to be on the downpipe just before the flex pipe. If you haven't done this conversion, then you NEED to have two working O2 sensors in the manifold.

The ECU reads both sensors for their associated cylinders. If you're only using one, then the ECU thinks two of your cylinders aren't firing at all and is trying to calculate accordingly. This shouldn't really affect idle speed and stability. That's purely controlled by vacuum.

While you're tracking down your idle problems, disconenct the IAC (EACV). It just makes fine adjustments in idle speed, anyway. The shop manual procedure for adjusting idle speed says to disconnect the IAC.

**YK86** · 04-17-2005, 01:58 AM

I think this problem is happening on an 87 LX-i so they would only use 1 O2 sensor. I have 2 sensors as well on my 86. One is for the ECU and the other I'm using for my air/fuel gauge. I can't remeber which one is which though so I'll have to check tommorrow.

**ICEMAN707** · 04-17-2005, 10:29 AM

yasu you might be right about the fast idle valve. i took the cap off today and found carbon buildup. the plunger might not be working like you said. i'm gonna unbolt the fast idle valve and wash it out with carb cleaner. if that doesn't work, i'm gonna try and look for a good FIV from the junkyard. hopefully that works. if not, any other ideas what it could be?

anyways, i'll try that out. i'll get back to ya guys. thanks once again!

**mouchyn** · 04-17-2005, 10:33 AM

remember that the plunger stop on the FIV is adjustable. if it wiggled its way loose, you can just screw it back down.

**ICEMAN707** · 04-17-2005, 10:40 AM

Originally Posted by mouchyn

remember that the plunger stop on the FIV is adjustable. if it wiggled its way loose, you can just screw it back down.

it's pretty tight on there. looks like i need a wide flathead screwdriver to turn it loose cus an ordinary flathead can't reach the ends.

i should give the whole intake system a thorough washdown with some carb cleaner. i think all that carbon buildup is from the previous cone filter i used to use. it had the regular cotton filter cone but at the end of it is nothing more than fine mesh grill. when i noticed how that filter doesn't really filter anything if the end is just a mesh grill like that, i changed it for a standard k&n cone filter with a closed end. but i guess at that point it was too late. that's why i'm having intake idle problems.

**shepherd79** · 04-17-2005, 12:14 PM

1. if your fast ile screw is all the way down and your idle is up, you need to get a new fast Idle valve because the spring is gone.

2. since you have code 1, why don't you fix one problem at a time. put two sensors and connect them together. that solved my problem on my header.

3. Remember to reset ECU after you connect the O2 sensors. fuses #10 and 11. or just pull the ground wire for 30 seconds.

**ICEMAN707** · 04-17-2005, 06:27 PM

yeah i was thinking of using two sensors and splicing them together with a quick splice connector that way i dont have to cut off the plug on one of them. but i was afraid it might not work and would screw up the computer reading. now that you've said it, i'll try it. i'll also try to find another fast idle valve from the junkyard. or a new one from autozone if the price is ok. thanks everybody. anybody else have more input, please post so i can check it out. thanks again.

**mouchyn** · 04-17-2005, 07:59 PM

i doubt you'll be able to get the fast idle valve from autozone or any parts store. Every honda i've worked on, that was a dealer item only and about $40.

**ICEMAN707** · 04-20-2005, 12:16 PM

I just wanted to say, THANKS to you guys. Without your help I would have never known it was the fast idle valve all along. The ECU keeps saying it's the O2 sensor even though it's not. Now I got a new FIV and gave it a 3-stage candy blue pearl paintjob with my little airbrush:

Funny how such a little thing affects the overall performance of the car. The car is way more responsive now and power is as it should be. Thanks!!!

I tend to have this habit of painting parts that I install or replace in the engine of my car and cars I've owned in the past. I just like that clean and custom look.

**YK86** · 04-20-2005, 12:20 PM

Hey glad it worked out for you!! I guess you're getting no more codes? And that is one of the nicest FIV's I've ever seen LOL.

**ICEMAN707** · 04-20-2005, 12:23 PM

Hey Yasu what should the idle RPM be at? Mine seems to be happy at around 900-1000 RPM, no lower or it shakes.

On another note. I'm glad my idle screw works again! LOL

Here's a pic of my dirty engine bay:

I can't wait to do a b-series swap and clean up that engine bay soon.

**shepherd79** · 04-20-2005, 02:40 PM

the idle should be set at 750 or 850.
the fast idle should be set to 1400-1600 rpm on cold days.

**ICEMAN707** · 04-20-2005, 02:53 PM

Thanks Alex!

**ICEMAN707** · 04-22-2005, 07:50 PM

Originally Posted by YK86

Hey glad it worked out for you!! I guess you're getting no more codes? And that is one of the nicest FIV's I've ever seen LOL.

nope my idle is perfect now but i still have that code. 1 steady flash every 3 seconds. is that code 1 for O2 sensor? i guess it's logical my O2 sensor crapped out too if my old fast idle valve got gummed up with carbon. i'm sure the same thing happened to my O2 sensor. i'll check that out next. can it be cleaned with carb cleaner and it would work again? or do i have to get a new O2 sensor?

**mouchyn** · 04-22-2005, 08:03 PM

how old are yours? if they're more than a couple years old, might as well replace them. They aren't expensive.

**ICEMAN707** · 04-24-2005, 12:50 AM

my O2 sensor still looks brand new. no more than a year old since i got my dc header. but i still have yet to take it out and see its condition. if i buy a new one, should i stick with Ngk's and Denso's for O2 sensors too?

it seems im having one problem after another. now my auto tranny is starting to slip RIGHT AFTER i changed the fast idle valve and fixed my idle. weird how that happens. maybe it was that lucas synthetic oil stabilizer i put in there. i need to do a 5 spd swap soon anyways. auto sux!!

**YK86** · 04-24-2005, 02:25 AM

Is there a possibility you touched the throttle cable for the tranny (since it is connected to the TB)? That might mess with the shifting points. The AT's are pretty picky with what ATF you use so it is possible the Lucas has something to do with it. The only stuff I put in is Honda ATF and if it's still shifting weird, I add Lubegard ATF additive.

**ICEMAN707** · 04-24-2005, 06:58 AM

Well the auto tranny has always been acting weird like hard engagement when put into drive. Might be something with the differential or synchro. But it never slipped before. I doubt I touched the TV cable by accident when I changed the fast idle valve. It's too tight in there as it is and the fast idle valve is very easy to remove without touching anything else. I can't even turn the bolt to adjust the throttle cable. I think it's seized up. I never looked into fixing the auto tranny cus it's not what I want anyways. I need to do a 5 spd swap soon once I get the time to do it. But I've also been procrastinating on doing that too cus I'm waiting to see if Ray Fong will be able to sell his custom B-series swap kits. I'd rather put money into a B-series than the A20. So in the meantime, I'm saving money and running on the shitty old auto tranny. Kinda embarassing cus the engine's got power but barely any of it goes to the ground and I can't accelerate as fast as the car sounds and looks.

Yasu, Alex, or anybody, can you tell me the proper way to wire the reverse lights to work when I do the manual swap? The FAQ doesn't really cover much about it. Also, what do you guys recommend for a daily driven 5 spd setup? Mine is a lighweight flywheel, Exedy stage 1 clutch kit, Civic Pacesetter short throw shifter, and a good 2nd gen prelude tranny. Sounds good?