I cleaned tons of carbon from the EGR passages(removed fuel rail/injectors & cleaned plate underneath)
Got everything back together, and P0401 code(EGR) is gone
But, check engine light, no code, and it's surging synchronously up & down, roughly 1000-1500 ish
Looked for missing vacuum line connection.. can;t find anything..
It was fine before I did any work: doing this because of the EGR codes so it'll pass inspection

Thoughts?

Thanks,
Rich

 

I think I'm gonna go back out, remove the ril & see if I can clean the injectors a bit: I do recall they bumped the valve cover, and might have picked up
crap....

 

Year, sub model, engine?

 

1997
Accord EX 2.2
Found that I had shredded the o-ring on injector closest to the battery: replaced it.
Just took it for a drive, and even though it's surging at idle, it drove fine.
I get no OBD codes, since cleaning out carbon, BUT the check engine light IS on..??

Video link to see what it's doing..

Thanks,
R

 

You should backtrack your work to make sure you sealed everything up right again on the EGR rail, and that the EGR valve itself is good and functional, but your trouble looks like the classic symptoms of the Idle Air Control Valve (IACV) malfunctioning. It might be clogged, or bad. You can unplug that valve and let the car idle, which will be a low idle due to the valve not regulating the idle, but if it is not surging with the IACV unplugged, you've narrowed it down to the IACV.

Easy to unplug the valve take it off and clean the screen and gasket on it.

On some Hondas you can unbolt the valve and pull it away from the throttle body enough to get to the screen and clean the valve a little, and also the ports on the throttle body, but I recommend removing the valve completely to give it a good cleaning. I have done it many times on my 93, and never had any significant coolant loss requiring any refilling or air removal from the cooling system. I always work with the ending dead cold through. A warm or hot engine is going to spew coolant if the IACV is removed.

If you take that valve off, avoid getting any chemicals into the electrical parts of it. Don't soak the valve in fuel injection cleaner or the like.

If you isolate the IACV as the trouble, but cleaning and working with it still leaves the same surging idle problem, replacing the valve is recommended.

 

thank much brakedrum..
I made one of those DIY injector spray testers & all 4 are squirting a nice looking stream(from what I can see anyway)
I ordered o-ring sets for all 4 injectors, as 1 injector is spraying all over the place, so I'll be replacing those Tue night.
And if that doesn't make it idle nicely, I'll definitely do the steps you outlined.
It would be a crazy coincidence that the IACV all of a sudden went bad too...but hey, it's a mechanical device...anythings
possible so I wouldn't rule it out.

Appreciate the tips very much: I'll report back with what happens Tue after the o-ring replacements.

Rich

 

Coincidence, but not a crazy one. Cars with a lot of miles get used to "sameness." Changing one thing, changes other things. You might find that the small screen on your IACV is "sooted" up because of disturbing soot in the EGR rail.

Sometimes the IACV malfunction will place a code in the computer, but not always. But it will always place a code when you unplug it, so watch for that. After you check or install your other stuff, consider unplugging the IACV wire while idle is surging idle. If the system settles down to a very low RPM, almost stumbling, idle, or stalls out, but no surging, then your IACV isn't working right.

 

ahh ok, that makes sense: the whole disturbing the system theory...
Thanks for the reply!
I should have my o-ring kits in the post today, so should be back on it tonight to install, & retest.
(if I don't keel over from exhaustion... IT Manager & it's end of month...)

:O

 

ok, well:
1) installed all new o-rings, reinstalled all injectors
2) started... ran ok until warmed up... them surging again
3) unplugged IACV... rpm's went low: re-plugged & it stayed low & sounded great.

After dinner I'll go out & see if it drives ok etc
I do believe the check engine light was on, sadly... I'll read for a code(I only have a cheap ODB reader)

Rich

 

I take it back: I disconnected the elec connector off....something (top of throttle body)
oh, ok just looked closer at pic: "SENSOR ASSY, , MAP"

 

MAP sensor on order...

 

I would set your base idle, its a procedure that re-establishes function of the IACV and its control by the ECU.

I Lifted this off another forum:

Procedure:
- Warm the engine up completely.
- Turn off all loads (AC, blowers, defoggers, stereo, EVERYTHING)
- Unplug wire harness from IACV (engine will almost stall)
- Adjust the idle-air bypass valve for 550 RPM (See Below)



- Turn the engine off & plug everything back in

Now you should force the system to re-learn the idle behavior:
- Allow the engine to cool down completely
- Reset your ECU (Disconnect Battery Positive Terminal for 12 Seconds or so)
- Start the engine without touching the gas pedal
- Allow it to run & warm up completely without touching the gas pedal

That should set your base idle. It's the first thing to do when you have idle problems. Then cleaning the IACV, then bleeding the coolant system.

 

great post Accordian guy...
that's one to file away fer sure..

 

put on a new MAP sensor... that of course, did nothing
Question: in this pic, is the circled device, the IACV?

 

If you've never turned that idle screw under the seal, I recommend NOT turning it. Fix the other thing(s) that have the idle out of whack.

I can hardly tell from the photo, but it looks like you are looking at the Throttle Position Sensor (TPS)

Your IACV should look like this, and poke out from the front (or possibly back) of the throttle body. The way it attaches to the throttle body, you will not see the gasket view. Those will be flush with the throttle body. But should should see the hoses. Very distinctive looking valve, with an elctrical wire plugged into it.

Don't forget that coolant will release when you take out the hoses, but if the engine is hot, the coolant will shoot out. Work on cool engine, and if possible, clean the gasket and IACV ports without taking the coolant hoses off. That valve does not need to be soaked in anything. A clean, flush fitting gasket, clean screen, clean ports, and clean mating surfaces on the gasket, and the throttle body are what you want to aim for.

 

ok, I'll look for that thing...

Also, I have to remember that nothing was wrong with the idle until I cleaned out the EGR passages, which were completely blocked
with carbon..
Is this just a matter of doing a 'reset' for the computer to recognize new input from EGR system or something?
Or is it really just a seriously coincidental failure of another part?

 

You could try pulling off the negative battery cable to clear the computer. Or locate the right fuse for your generation and pull it out for minute or so. Also, unplug the IACV to see if it resets.

But your idle rising and falling repeatedly like that means there is something else wrong.

You are just two bolts away from having that IACV loose enough to inspect it and clean it. A tooth brush and some carb cleaner and you're good. If the gasket is very old and badly squashed, you should be a new one. Same thing with the little screen.
But mainly, inspect that valve to make sure it is getting good flow. It is the heart and soul of the idling process, and responds to power demands by pumping in more air to increase rpms when you turn on something that draws a lot of power. It's job is to keep the RPM's right around 550, no matter what you turn on.
Even if you leave the hoses connected, you should disconnect the plug on the iacv while working. I also work with my negative battery cable off when I'm working on electrical stuff. If you have a factory radio with security feature, be sure you have the code to get it going again.

This guy is cleaning IACV on on a 5th Generation Accord:


Good luck on your decisions.

Here's another video where the guy works on the IACV without removing the hoses. He also makes a good point that you should make sure the holes in the throttle body the match to the ports on the IACV are unobstructed.

 

Great post thank you!
I'll have my hands in this either tonight, or tomorrow morning..

 

ok..so disconnected negative battery terminal
removed the IACV, sprayed the crap out of it, with carb cleaner.
Let it sit for 20 minutes or so..
Reinstalled, noticed check engine light was on solid..
Took it for a drive, and it drove fine.
Stopped for gas, and when I put it in park, it did the same freakin thing...revving engine up & down.
Brought it back home, put on the diag tool, and read a P0141, which I believe was the original code that it failed
inspection for: which is typically the O2 sensor(rear one) if I'm not mistaken..
So, the big question is: could that component cause any engine flakiness, like revving?
I thought the rear O2 sensor was just for monitoring the CAT?

Am I looking at some other faulty component...?
IS the next logical thing, to replace the IACV? Which sucks, being a non-cheap part...
Again, this stupid revving thing did NOT occur before all of this work I've done..
So frustrated..

 

I feel your pain. I spent almost two years chasing down an idle problem on my 1996 Accord LX Wagon. And still have a surging idle problem, just when warm, and only in park. I can tell you I tried switching throttle bodies, 20 different IACVs from the junkyard, purge valves and every other vacuum valve in that food chain to no avail.What ive learned it cleaning an IACV with carb cleaner does about as much good as trying to cut your throat with a feather. And that you never ever, unless you have to, want to swap throttle bodies and NEVER mess with that idle screw ith the yellow dab of factory paint. All useless drivel and old wives tales. Have you got a bad rear O2 sensor? because I dont have one either. I have a test pipe and didnt feel like welding a bung to it. Try spraying carb cleaner around the manifold gasket. Listen for any sounds like the engine RPM going up. My issue might be my throttle body, TPS adjustment, manifold gasket leak or on wagons there are some weird vacuum solenoids on the auto tranny I think. I also cleaned all my egr ports out. Good luck,keep us posted!

 

wow, interesting bit of info there johnny.. thanks for all that
it definitely feels like I'm chasing my tail here..
Is it true that the 97' doesn't have a FITV?

R

 

BTW, it is currently doing the following:
1) still surging as per the video posted above
2) idle now stays high even warmed up
3) P0401 code, as it originally had

~sigh

 

You most likely have a vacuum leak somewhere. In the process of removing the EGR and cleaning it, you may have damaged a hose or gasket. The IACV works to control idle but will "hunt" or surge when it is unable to, for example, when there is too much "un-regulated" air reaching the MAP sensor or intake manifold due to a vacuum leak. It makes most sense, since you just took apart the intake manifold to clean the EGR, air is getting in somehow and your IACV can't compensate.

 

ok, as good a theory as anything else...
I think I'll try the old spraying of carb cleaner on the lines etc with it running & see if I can sniff it out..

Thanks again, it's so easy to neglect to try simpler t-shooting items when you've been at it for so long...
Tunnel vision / fatigue sets in!

 

What does the idle do when the IACV is disconnected (unplugged) while the engine is running?