EKBOOSTDREAMS

Hey everyone I have a 99 accord v6 that is having a surging problem and a bad idle problem while in any gear. I have a code P0505 right now which says "idle control system malfunction" My question is does anyone know what exactly causes this? Maybe a bad idle air control valve or TPS? Any help is greatly appreciated.
Thanks in adavance.

h0p3l355dork

I've had this problem too, its your alternator trust me. I replaced mine myself and it came out perfectly... well sort of.. i broke my power steering pump in the process so be careful. But i am 100% sure it is your alternator. Don't think its the IACV and go spend 250+ dollars to fix it. The surging issue will still be there. Replace the alternator and go from there. Im assuming you are having electrical surging issues correct?


(I have this exact car so be careful when replacing your alternator if you're doing it yourself) I had to spend 300+ fixing my power steering pump. =( But all is well now

EKBOOSTDREAMS

Ok. No it's more of an rpm surge through the motor like the idle surging. Any help would be great.

h0p3l355dork

Hmm.. okay, when was the last time your alternator was replaced? Are you experiencing any sort of electrical problems at all? i.e pulsating lights, dashboard lights lighting up.? And have you had your alternator checked out? Worse case scenario: you would have to replace your air control valve., I thought I had to replace mine too.. but I was also having electrical problems and thus the idle surging was a in addition to the electrical problems.

I've heard stories of people simply cleaning their IACV / throttle body and have had success. If you suspect any sort of electrical issues, I would try the alternator first. If not, it's a faulty/dirty IACV.


IACV = Idle Air Control Valve



#2 on this diagram

EKBOOSTDREAMS

Ok thanks. Last week I had two codes a P1298 and the P0505. The P1298 was for the eld which I replaced. I still have the P0505 (idle control system malfunction) Should I get the alternator tested first then do the IACV? Thanks for all of your help.

h0p3l355dork

So did the P1298 code completely clear? I too had another code the last time my CEL turned on. I think it was P0141. It was something along the lines of my o2 sensor was going bad? All this alluded to the fact that I was having electrical problems and thus I concluded that the alterantor going out was throwing false positives. The weird thing is that I had the alternator checked 3+ times at different places and every where i went, they said it was fine. Most places such as AutoZone and Pep Boys check the battery/alternator for free. Try testing it out first and see what they say but take it with a grain of salt. The fact that the P1298 threw as well makes me want to believe that it may be related to the alternator as well. Clear the ECU and see if any other codes pop along with it.


Also I forgot to ask, is it ALWAYS surging? or just sometimes does it? Idle surges can ALSO be because of spark plugs misfiring. You should check those as well before buying an alternator. I replaced my sparkplugs but the problem with the electrical surge was still going on, so I just replaced the alternator.

Good luck and let us know how it goes. And remember what I said about replacing the alternator, if you're not comfrotable, try to get someone to do it for you cheap because I've read online about people who replace their alternators and the power steering pump dies (happened to me too). If you search honda-tech forums, theres been a couple incidents of this in the past as well.

Sorry for the long-winded response.

EKBOOSTDREAMS

Also the only electrical thing I was having was a slight flicker when the headlights were onand I would turn the turn signal on. Other than that nothing. And I bought the car in 2005 and have not replaced the alternator since I have owned it. It looks like a genuine Honda alternator as well so probably stock.

EKBOOSTDREAMS

The P1298 has cleared. The surging is pretty consistant. After I replaced the eld it did it after I let the car warm up and the fans kicked on twice. After the second time it immediatly started surging in park and neutral, but all other gears it idled fine. But I turned on the headlights and a/c when the surging started and as soon as I did this the surging stopped in all gears. Then after a while it started surging in all gears with the a/c and headlight on or off so it surges all of the time now and sometimes will have a very low rough idle for a moment when I first start it up.

sublime423

roflmao
don't listen to this jibba jabba.....p0505 replace the iac and be done.

The alternator is not putting out the proper voltage the car will do strange things this is true. If you think you got a bad alternator get it checked, 98-02 accord alternators are prone to fail (because they are mostly make by delphi...fcukin junk) but they are not always the cause of all the cars problems.

POS99HondaV6

First off sorry I'm adding this post but I'm new and cant create a main thread so here goes.......Automatic 99 V6 Accord around 165,000 miles ..... About a week ago the CEL came on and its throwing these Codes - P0505, P0420, and P0401. First of all I understand the mileage and that I will probably have to replace some stuff but maybe there's a connection with all the codes throwing at the same time...... About a year ago i noticed that when I let the car sit for 3 or more days, when I cranked the car the RPMs would jump from around 800 or so to 1500-2000 repeatedly, but Would go away after driving around town and the car had time to breathe for awhile, but this only happens when the cars sits for multiple days (I understand the issue behind this but need to know if all of these Codes could be tied in-together. Ive done some research on all of the codes and nothing seems to be exact when looking at other issues. I'm wondering if one main issue could be causing all of these codes to be thrown? The only other issue that is happening that I can relate to the codes is a hesitation which occurs either when driving on the highway and accelerating to get up to highway speeds (50-70) or Accelerating from a stop... When I try to accelerate to pass someone on the highway, sometimes I get a slight hesitation, 2nd hesitation is when at a stop, and I start to accelerate and the trans switches to 2nd gear I give it some gas and it hesitates, both of these seldom occur, but ever since the CEL came on I have noticed the hesitations occurring more Frequently. To my knowledge the Cat or TB has never been touched/Replaced. Again I understand what is probably causing the hesitation but would like to know if one major problem could be causing all 3 codes to be thrown. The only major item that has been Replaced/Rebuilt is the transmission. Please any help is much appreciated. I know about checking for leaks, cleaning the TB, and replacing O2 censors, but I really don't want to mess with replacing the CAT....... Thanks for any advice......

h0p3l355dork

You always gotta search man! All of these codes have been documented and written about over and over again on this forum.

but here's a quick overview:

P0505: IAC valve: that explains the jumping idle. Either clean it or get a new one.
P0420: Catalyst system below efficiency. TL:DR: your cat is gone.
P0401: EGR insufficient flow. EGR valve is stuck or clogged.


All 3 are HIGHLY typical of 6th gen accords so nothing new there. You touched upon a rebuilt tranny. these 4 things I would say are the biggest faults of 6th gens (esp v6).

For my 99 accord v6, I cleaned the IAC and it fixed the jumping a while but I know I'll need to buy one eventually. I bought a new cat + EGR valve to tackle the other two codes. I needed it to pass emissions in CA so there was no going around that. A lot of critics might say just replace the 02 valve to fix the P0420 issue or if you're not in CA, just use a trick that basically bypasses the 02 altogether.


SEARCH SEARCH SEARCH.

POS99HondaV6

Thanks man, but I have "SEARCHED SEARCHED SEARCHED" hence the fact that I’m posting to a thread that’s over 2 years old and since I'm new to this forum I can't create a new thread and since I'm battling an emissions deadline myself I figured I would stop wasting time and just find a thread that was similar and post my issues to see if someone has had all three codes pop at once like I have had. I also stated that I was wondering if someone knew if fixing one of the major issues would/could fix all three instead of replacing all three, which going into this I figured I would have to do anyways but ya never know so I thought I would ask. At least you didn’t just tell me to replace my alternator (because it’s basically new) however you did give me some credible feedback since you have dealt with these issues, but I don’t recall you mentioning that you had all three codes pop at the same time so I’m still stuck here wondering if possibly replacing the CAT could fix one of the other codes or is it best to just replace everything and not mess around with other tricks just to pass emissions. Today I did find a fairly large slit in the large Air Intake hose when I was thoroughly inspecting the throttle body, but not sure how long it’s been there or if this would cause 1 or more codes to pop. I bought an aftermarket intake to fix that.

h0p3l355dork

Short answer: no. Those 3 codes are all separate issues regarding 3 different components that do not affect one another. (i.e. fixing one would not clear the others). The large slit MIGHT cause the odd idling though. search the forums for each code specifically and tackle each of them on its own.

POS99HondaV6

Awesome thanks very much for the help. Probably going to just replace everthing since I found an old friend that will do it for dirt cheap. Thanks again.

doctorbee

is the slit after the air flow sensor or before? if it's before fixing it won't really do anything.

Lost Again

? Air flow sensor.

POS99HondaV6

the slit would have to be after the sensor otherwise it would be a crack in the TB right? It was in one of the creases of the rubber hose but I've already replaced it with an AEM Short Ram intake.

Lost Again

I'm just trying to figure out what air flow sensor on a 99 Accord V6 anyone is talking about......

POS99HondaV6

Yep not really sure. I just figured he was talking about the TPS on top of the TB where the intake connects but who knows. Either way a slit in the intake hose = NO GOOD.

Lost Again

They run fine with that hose off too

POS99HondaV6

How is that good for the engine if there's nothing to block harmful contaminants from getting in through the TB. Just doesnt seem to smart.

doctorbee

not necessary, a slit before a MAF/MAP sensor wouldn't be a problem. one after the sensor would cause inaccurate fuel metering

Lost Again

So true....my point, leaving the "clean/filtered air" out of the conversation. There is no "mass air flow" or air flow sensor on this car....

So the only "bad" to a slit in the intake tube (on this car) is un-filtered air going into the engine....period.

I wanted to hear, please go back and look, why or where it made a difference on the idle if or if not there was a slit/no tube, ect going to the tb....

Lost Again

You seem to be changing your position.....bottom line. THERE IS NOT A MAF on this car - 99 v6 Accord. And if you think a MAP would know the difference, you are wrong. Think about where it is located on this car.

Never said the "slit" was good for the engine but at the same time would not cause an idle issue.

doctorbee

right, i believe the air sensor (MAF/MAP i've lost track, i have so many cars i maintain) on my 99 accord is on the TB so a crack in the rubber intake between the filter and the sensor wouldn't affect its air metering.

by air sensor i mean MAF/MAP- a way of measuring the amount of air going into the engine.

i'm not changing my position, just elaborating.