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Engine light code, high idle, and then erratic idle (revs up and down without acceleration). Replaced idle air valve. DID NOTHING. Still does the same thing as previously mentioned. No vacuum leaks. Burped the radiator (read somewhere to try this). Everything is plugged in correctly...same code....same high idle followed by erratic idle.
Something to note: This situation did NOT happen until my mechanic replaced my valve cover gasket. He also had to pull the plenum up (because the bolt on the valve cover was too tight and his could not remove the bolt until he pulled the plenum up). He also took off the throttle body. He moved alot of stuff around in order to make room. The plastic clip on the side of the throttle body that holds the throttle cables is broken. He is saying this is the problem. However, the clip has been broken for a few years (I cannot use my cruise control) so I do not believe that is the issue. So either this is all coincidental or something isnt right (even though I checked every line, power line, and everywhere for vacuum leak). What could he have done to cause this issue? What are your thoughts?
I am going to return the idle valve since it was $90 and obviously not the problem.
Acura did a free diagnostic. Said to replace throttle body and idle air control valve. They said when they disconnected the throttle body hose (from mouth of throttle body), they "plugged" the little slit/opening" at the bottom of the throttle body circle, and the car ran perfect (the revving idle stopped). So...that is why they are saying it is the throttle body itself and I need to buy a used one. If it is the throttle body, maybe it isnt the idle air valve. Idk....I will probably replace the throttle body and see if it fixes the problem and if not, I will also replace the valve.
The whole point of an idle air control valve is to regulate the air coming through that bypass channel. If they are plugging it and it is going away, then the IAC valve is stuck open when it should be closed (or not closing to the point of properly sealing that channel).
I wouldn’t buy a new throttle body unless there was physical damage and definitely wouldn’t buy one if they fix it with their finger??? lol.
Something electromechanical (a valve or its control circuit) is not working there.
I doubt it it is the seal on the IAC if they remedied it with their finger; so they helped you there at least.
I would consult the manual about IAC circuit troubleshooting.
is the IAC valve you installed a genuine Honda part?
I replaced the IACV with a Dayco brand but the problem didnt go away. It did the exact same thing. So I took that part back and got my money back (since I didnt think it was the valve and it was $100).
If I go replace the IACV again and it still does it, now what? I guess I should have an electrical guy look at it. But I assume Acura did that today (I am sure they tested to make sure the IACV is getting power). I mean, they worked on it for a while.
The throttle body has no damage, and I find it weird that it was fine and all of a sudden they are saying to replace? Again, all of this started after a mechanic replaced the valve cover gasket (he also pulled up the plenum). But I told Acura that today and they checked to make sure everything was proper and no air leaks were found.
They said it could also be low coolant but it was full. And they burped the system (whatever that is).
This is all the information I have. Not sure what to do. I dont want to buy a junkyard or ebay throttle body (especially since mine looks 100x better cosmetically than what I am seeing online).
Appreciate your time very much! Many thanks to you!
Another thing: Why the hell would my Throttle Body itself go bad? It isnt damaged. It isnt messed up. The gasket is brand new. None of that makes sense. One day it was fine and they next day it wasnt. There is something weird or dumb and I cant figure it out.
The ONLY thing that you may consider as damaged on the Throttle Body is the black plastic clip holder that holds the throttle body cables. The secondary throttle cable (which also controls my cruise control, I think), isnt "right". However.....the clip has been damaged since I bought the car years ago. Acura thought this was the problem, and they messed around with it, but still wasnt the case. But I wanted to tell you about it since you have been kind enough to try and help me. Thanks.
Hey Domenic, no problem. I looked at the service manual, and it shows a troubleshooting process for IAC on page 11-148. It's basically the same workflow that the technician at the dealer did. The next steps after that though explain how to go through it deeper and possibly adjust the idle speed (11-157) BUT the more important bit of info here is that before you adjust idle speed, they explain to check these subsystems:
the MIL light has not been reported on
Ignition timing
spark plugs
air cleaner
PCV system
Because these components can impact your idle, they want you to make sure they are all in working order. Those in bold stick out to me, because I can't recall if you mentioned they were checked?
Hey Domenic, no problem. I looked at the service manual, and it shows a troubleshooting process for IAC on page 11-148. It's basically the same workflow that the technician at the dealer did. The next steps after that though explain how to go through it deeper and possibly adjust the idle speed (11-157) BUT the more important bit of info here is that before you adjust idle speed, they explain to check these subsystems:
the MIL light has not been reported on
Ignition timing
spark plugs
air cleaner
PCV system
Because these components can impact your idle, they want you to make sure they are all in working order. Those in bold stick out to me, because I can't recall if you mentioned they were checked?
Thanks for replying.
I have not checked spark plugs or PCV system. Although when you mention spark plugs, I wonder if when mechanic replaced valve cover gasket (pulled up ignition coils) if something became off with spark plugs/coils. Remember....ALL of this Idle situation started immediately AFTER mechanic replaced valve cover gasket.
As far as PCV system...I do not know much about this system. I dont even know if the car has a PCV valve.
Are you still of the mindset that the Throttle Body does NOT need to be replaced??? This is my thought right now. And we must remember the diagnosis that the dealer performed, where they placed their finger/towel over the hole in bottom of throttle body opening...which made the car run PERFECT (no RPM problem). Maybe the NEW IACV I purchased and installed was "dead on arrival". I am getting another new one tomorrow, will install, and see.
Also........ if spark plugs (or coils) were suspect.....I imagine I would get a specific misfire code, which I am not getting. I am still getting the IACV code (P0505), and the car runs crappy/weird.
The one I purchased last week was new Denso from Auto Zone. When replaced, it didnt fix the problem at all.
Acura told me to puchase a Throttle Body with attached sensors. I did not do that. Instead last night I purchased a IACV from Amazon.
I CANNOT tell a lie....it was CHEAP. It was not the one recommended, but I am trying to see if it will at least fix the problem...need a fast fix. I can buy the recommended IACV later perhaps? Money is tricky right now since Acura cost me over $500 yesterday, and $160 last week (Harmonic balancer install) and I also replaced a valve cover gasket and accessory belt tensioner. Been a rough month!!
Zeta - are you thinking the problem is a crappy IACV? What do you feel about what Acura said (needing Throttle Body)?
^
Do you know if either your mechanic or Acura (you would think Acura would have unless they are trying to pull a fast one) performed the ECM/PCM idle learn procedure after working on the car?
The easiest way to do this, especially if power was disconnected at the battery or pull the No13 clock back up fuse in passenger side fuse box to keep from reprogramming radio/navi, is to turn off all electrical devices in the car (fan; radio; lights et al). Then start the car without touching the throttle and just let it idle for three fan cycles (this may take tens of minutes). Maybe it's as simple as that?
Acura said they were going to do a ECM reset but not sure if they did.
My problem is......I can try that.....but the RPMs are so crazy that it just revs up and down up and down, and I am not sure if its good to leave the car do that for 3-5 minutes until the fan comes on.
Speaking of the fan, they also told me the fan ran for about 15 minutes after the car was turned off. They said that could be a block somewhere in the coolant line. It does that to me once in a while....I generally just ignore it because I never have other symptoms.
Did you try the troubleshooting sequence on page 11-148 in the manual? the left hand side contains a lot of very specific information/decisions that can't be made by anyone not in front of the car.
wish I could comment further, but I am pretty sure it's either a bad IAC valve, idle speed that needs adjustment or some vacuum leak somewhere (possibly from a bad IAC valve). What happened when they blocked the hole? We know that the RPM's stabilized, but did they go above the correct idle speed or below?
I mean, the video you sent was a wide swing in engine speed...that has to be a significant leak (or open port) for that to happen.
latest update - over the weekend I installed a new IAC valve, which did NOT resolve the issue. This would be 3 IACVs that are not fixing the issue (1 new from Ebay, 1 new from Autozone, and one that was replaced).
The other day I went to a junkyard and bought a throttle body (it came with the IACV). Cleaned it up. Looks nice.
I attempted to install it last night, but the damn screws on the throttle cable plate assembly stripped. FML. Very annoying.
So my latest update is....I have to install the throttle body and go from there. If that does NOT fix the issue, it is going back to Acura as they told me to replace IACV and Throttle Body and if that doesnt fix it they would diagnose further for free.
Installed Throttle Body (junkyard part, included affixed IAC Valve). Problem still occurring. Same old sh*t. Acura cannot get me in until Monday.
Some research is showing there is a leak at the plenum. I pulled plenum up and the gasket looks good. However....there is old permatex on there.
I am thinking I need to clean that up and put a new layer down. Remember...ALL OF THIS STARTED immediately AFTER my mechanic replaced my
valve cover gaskets. He was also concerned it was leaking air at the plenum but the gasket looked OK. He tried scraping the old permatex off but we
didnt have any new permatex to put down. I have new permatex now and will try to see if that fixes it.
As far as I know, none of the baskets associated with the intake manifold require permatex. They either use a soft metal or paper type that (I would guess) should be replaced with the same type. I could be wrong, but I’ve never taken that chance simply due to the amount of work involved in taking that apart.
It is not the intake manifold gasket, its the upper plenum gasket. When the plenum was pulled up during the valve cover gasket job, there was permatex there prior. So the plenum is not perfectly smooth. i think it may be getting air at the upper plenum gasket.
No sealant is specified for that metal gasket, It's installed dry. I wonder if the permatex was causing leaks. If yours is goobered up with sealant I'd get a new one.
I've had the plenum cover off several J series engines and always reused that gasket dry with no problem.
The issue is - the mechanic from earlier in the year used permatex. I did not want him to use permatex. so when the mechanic from a few weeks ago did the valve covers, he pulled up the plenum. I think this broke the permatex seal, that the mechanic from months prior set on. Because this problem ONLY STARTED after the plenum was pulled up a few weeks ago. Right now the gasket is affixed to the plate (normally it sits on the plenum and you can pick it up and set it down). There is permatex residue on the plenum. I dont want to use permatex but i am thinking the vacuum leak is because the months ago mechanic used permatex, and the weeks ago mechanic pulled it up.
It is not the intake manifold gasket, its the upper plenum gasket. When the plenum was pulled up during the valve cover gasket job, there was permatex there prior. So the plenum is not perfectly smooth. i think it may be getting air at the upper plenum gasket.
Also be sure to position the 'tab' toward the firewall for proper gasket placement:
The issue is - the mechanic from earlier in the year used permatex. I did not want him to use permatex. so when the mechanic from a few weeks ago did the valve covers, he pulled up the plenum. I think this broke the permatex seal, that the mechanic from months prior set on. Because this problem ONLY STARTED after the plenum was pulled up a few weeks ago. Right now the gasket is affixed to the plate (normally it sits on the plenum and you can pick it up and set it down). There is permatex residue on the plenum. I dont want to use permatex but i am thinking the vacuum leak is because the months ago mechanic used permatex, and the weeks ago mechanic pulled it up.
Makes sense. Get all that goo outta there(especially around the EGR passage holes) and throw in a new gasket for good measure. Also double check nothing is warped with a straight edge.
Also like Zeta said, make sure the gasket is oriented correctly. If it's backwards(which will still fit), it will block the EGR passages.
Cleaned plenum body as best as I could and put down a new smooth layer of permatex. I feel I did a good job with this - it was smooth and went around all the areas necessary.....
YET....the problem did not go away. Still high idle, followed by fluctuating/revving idle, and driving like crap with P0505 code and TCS light. Still the same issue.
I guess today I can try cleaning the EGR ports and EGR valve....I believe its best to remove EGR valve when cleaning ports? I have a new EGR valve gasket, so that is good.
I could not remove the plenum gasket as it was affixed to the plenum plate. It is literally stuck (I guess permatex by previous mechanic). In a perfect world I would have removed that gasket and replaced it with the one I got at the junkyard yesterday (it had no permatex residue on it). I know that would have been the fix but like I said, I could only do so much last night. I even thought about going to junkyard today to get a plenum (not because I need a plenum, but because I need a clean plenum and plenum plate that never had permatex!). But I dont know if I feel like dealing with it.
Still cannot understand what the hell happened when the mechanic from weeks ago pulled up the plenum and replaced the valve cover gaskets (he also did a belt tensioner). I mean....what could he have done to cause this? I did NOT have this problem before he touched it. I did not have a P0505 code. Since...I have replaced the IAC valve multiple times, and now it has a different throttle body on it (junkyard part - cleaned it up too) which it probably did not need. I do not see anything disconnected and I do not see any cracked hoses.....anywhere! I replaced the PCV valve yesterday. I it would fit more snug down into the engine compartment but I guess it is me. But again, what could the mechanic have done to cause this? I mean....even if my EGR ports are gunked up, they were not gunked up prior to him working on the car. Although when I went to an Acura mechanic yesterday (he had no time to get me in but was nice enough to look at car real fast), he told me it could be my EGR valve or ports. BUT....I think there would be a seperate check engine code for this.
I dont know. The mechanic thing.......he literally changed the valve cover gaskets, put everything back to together, and once the car fired up..it went to CRAP. Is there anything under the plenum that would cause this?
I will keep everyone posted. I greatly appreciate the replies and feedback. You guys are the best! Thank you so much!!!!!!!!!!!!!!!
I assume when Acura looked at the car last week, they would have checked for sufficient power/ground to the IAC valve.
I tested it by....starting car and problem occurs. I pulled power from IAC valve and the car noticeably "changed" (didnt get better or worse, just saying it was "different"). So that tells me their is power
to the IAC valve because if I pulled the power cord, nothing would have happened.
No - doenst feel like a misfire. No other engine light codes expect P0505 Idle Air Control. Actually runs pretty good when its cold or when you are on the gas.
Car is currently at Acura right now for full diagnosis. Wish me luck!!!!!!!!!!
There's another gasket between the intake manifold and the heads. Wondering if the previous mechanics goobered that up too. I took my intake manifold OFF to replace valve cover gaskets, perhaps your mechanics did too.
I have never had the intake manifold gasket replaced. The previous mechanics stated they didnt pull up the entire manifold, but just the top plenum.
I am thinking if there was a leak at the intake manifold gasket, I would get other symptoms or other engine light codes.
But at this point....I do not know what to think!
Still havent heard back from Acura. Stay tuned!
Mechanic said he didnt take the entire intake manifold up. He ONLY replaced the one valve cover gasket, the one closest to the radiator. The other gasket was fine and wasnt leaking so I tried to save on labor.
But to your point, both valve covers were replaced earlier in the year (yes, I was mad to have to do the one again). So maybe that mechanic gunked things up. But why would it have been fine all this time?
The intake manifold has a specific torquing sequence, perhaps over time it has become loosened from not being tightened down properly? I mean, unlikely: but so is putting permatex on a gasket that didn't have any type of silicone on it prior to.
Does the dealer know that work was done to the valve cover gaskets? maybe tell them about that so they have a more targeted approach to what problems they are looking for.
Bottom line: I would never take my car back to the guy who did the permatex; and possibly leave a bad yelp or google review for that. AND....check the work that the dealer does you can't trust anyone's (but your own) work unfortunately. I had my transmission replaced by the dealer years ago and they replaced the breather tube (from the valve cover to the air intake) with a rubber hose. Yes,that's still functional for that purpose, but the breather tube is bonded with a coolant line that was also replaced with some other sub par hosing that would break often and create an extreme coolant leak that left me broke down once.
I'll try my best to put down these chain of events.
1. Acura said the problem was severe vacuum leak at the plenum due to previous mechanic (we'll call him Mechanic V from now on).
2. They ordered the plenum / fuel injection gasket set and replaced all gaskets that are part of that set. They also removed all remnants of permatex (or as they call it "hondabond").
3. They said the issue was resolved and told me to pick the car up - which cost me $540.
I picked the car up and it drove fine. Seemed like the issue was gone! Pulled into my driveway and BAMMMMMMMMMMM it did it again. Revving idle!!!
I drove the car back to Acura immediately.
Acura pulled it right it.
Disgruntled tech rechecked his work and found no vacuum leaks.
They burped the coolant system.
They installed a different IAC valve (the one that I bought new from ebay last week).
They said they literally have no idea why it keeps having problems, but now the problem is intermittent, when it never was before.
They told me they are not sure what to do next, other than replace the ECU. I do not think it is the ECU. Why would the ECU be bad? And why are there no other codes? And why would the ECU go bad after Mechanic V did what he did? That doesnt make sense to me.
So now we have to examine the clues - or things Acura said.
1. When the car was idling and revving up and down and having problems at Acura, it all of a sudden stopped. And it stopped since I drove it home. It was like the problem went away again. Even putting the car in neutral, the RPMS didnt rev/fluctuate.
2. I noticed that when I put the defroster on while in drive, the RPMs do not change. When I put the defroster on while in park, the RPMs jump and hold at 1.5K.
3. It ran fine and I could not get the problem to duplicate no matter what I did (revved engine in park, turned defroster on and off, in and out of neutral).
4. Problem came back when I finally arrived home and placed car in Park. When I then put car in drive and then back in Park, it stopped and was normal.
5. I rev engine in Park and it starts acting up again. I go back into Drive then back into Park, it stopped and was normal. That is very weird!
Other clues:
The coolant fan came on after I turned car off. Literally AFTER the car was OFF.
A few weeks ago I replaced the engine coolant temp sensor. (Acura asked me why........duh because I kept getting a code and temperate was very high)
Acura said the top hose and bottom hose were 50 degrees apart in temperature (no idea what that means...but that is what they said).
So I do not believe this is related to the ECU (which is my 2nd ECU because I had to replace when I replaced the fuel pressure regulator).
I think this is something to do with the coolant system. Like if I was not broke (did I mention Acura charged me $540 today) I would get the coolant system power flushed and fluid replaced.
There are too many little "coolant" related things that are happening. Acura mentioned they burped the system 3 times. While the problem isnt fixed, it is better. And apparently when it acts up in Park, all I have to do is going into Drive and then back into Park for the revving idle to normalize.
I'm thinking there is still air in the coolant system. Acura burped it so the issue got better. But there still remains air, so the issue comes back as I described above. Until all air is out, I think I am going to have the same problem.
It was weird that I drove the car home from Acura without any issue, but as soon as I pulled into my driveway it started revving. My driveway has a medium size incline. So when the radiator was at the high point.....that air in system made the car screw up even though Acura thought it was fixed (as did I since it drove home perfectly).
Domenic,
Maybe I missed it but you never mentioned anything about coolant/temp issues in this thread which is a huge clue. Yes, these engines can be finicky when it comes to air in the coolant system. Sounds like 2 issues at play here, intake vacuum leak and coolant air.
If it were mine I'd completely drain the system(reuse the old coolant) including loosening the block drain plug and do a refill and air purge(burp). A coolant funnel is a must in my opinion when doing this
I have not been having coolant/temp issues other than what was described above. Other than a few weeks ago, I got a code for engine coolant temp, so I replaced the sensor and the code never came back and never had any problems. I think what is going on here is - Acura fixed the plenum vacuum leaks but the problem is that all of the air is not out of the system.
If I can talk Acura into doing a power purge/flush, would that get all air out of system? I think for the price I paid ($540) to still be having the issue, they can afford to flush/refill my system.
Also...I drove the car early this morning without issue. So now the problem is more intermittent.....but still there.
Problem is now intermittent, but much better overall. It still drives a bit "different" as if the idle situation is not 100% settled but overall, it is able to be driven. When I say "different", I mean when I slow down and am off the gas, the RPM will slightly surge or rev up prior to car almost stopping. Or it sometimes feels like the RPMs are "stuck" when I am coasting...like it just hangs or something. This is not transmission related or anything like that. The "feeling" I get is all related to the weird idle.
Usually the problem only surfaces when in Park and at idle. If in Park and at idle, IF I rev the engine, the idle will then rev, up and down, up and down to/from 2.5k RPMs. However, if I then go into Drive and then back into Park, the revving stops, usually. Does this make any sense? Why would changing gears make the crazy idle get better?
Luckily I was able to find a reputable mechanic yesterday. I took my RSX for an oil change and was able to talk to the shop owner, who is a very nice guy and he was once the chief tech at Honda Las Vegas. The shop is named H-Tech Auto on Rainbow Blvd in Las Vegas - good guys! Besides changing my oil, they gave the car a FULL look over and spent time working on some odds and ends regarding a motor mount situation that I am going through. They inspected the entire vehicle (brakes, tires, hoses, leaks, suspension, you name it) for no extra charge. They only charged me $20 to change the oil (I brought my own oil, they provided the filter). Mechanic (Pete) mentioned he would need the TL for several hours so he can get to the root cause of the problem. He said it sounds like the car had a vacuum leak which Acura fixed, but there is still something else going on. He said the throttle body/idle may need to be reprogramming/relearned, but he needs to spent time on the car to know for sure. He said these things take time and he will figure it out for sure (unlike Acura). And...his labor charge is HALF of what Acura charges! I feel really good about meeting him and I am glad that I found someone out here (I moved here in March) who can take over the car of my Acuras. Once this idle thing gets fixed, the TL needs front end work (ball joints) and new tranny mounts.
So for now, I am going to drive the car and get through Christmas. Need to save a few bucks and I cannot keep working on the TL right now. Not saying I am neglecting the car, but I need a little break. It runs OK and I have a mechanic that will look into it further after the holidays.
Thank you everyone. I appreciate any further comments and I will keep you posted. Many thanks!
11-29-2019, 12:50 PM
) performed the ECM/PCM idle learn procedure after working on the car?
