When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
2007 RDX Tech with 158k miles. We've owned it about 6 years, but don't drive much so we have only put about 30k miles on it. My wife has driven it 99% of the time. 5 or 6 months ago one of the bearings started making a horrible noise. She was kind of over the RDX, so we went and got her a Prius. The dealership offered us $1k for the RDX, so I turned it down out of spite and drove it back home. I replaced all 4 hubs and bearings, shocks all around, springs in front, pretty much every bit and piece of the suspension. Figured I would just Craigslist it, but held on to it as I needed to do some work on my car and needed a daily. Ended up liking it, so I've continued fixing things here and there. Had an oil leak from the oil cooler, so replaced that. Then I replaced the leaking valve cover gasket and plugs and coils. At that point, it was really running well. However, I don't drive much myself, so I've only put a couple hundred miles on it in the last 6-8 weeks. About a week ago it started driving like crap... The idle would surge a bit and it was real sluggish. I hooked up a scangauge ii and the boost was reading 10.8 with a drop-off to 8 or 9 that would happen around 5k rpms. Seemed low, but I'm not entirely confident the scangauge is accurate. I parked it and started using my other car. The other day I happened to catch a view of under the RDX and I had oil drops on the ground on both sides of the motor. After I fixed the oil cool and valve cover gasket, the underside of the car had been completely dry for months. I pull it in the garage, crank up the AC, and come back in a couple days.
I pop the hood and start looking around. I think the pcv connections seem to have more oil residue than usual, but that could be in my head. As I'm looking around trying to find the source of the oil on the driver side, I find the intake hose off the air filter box is almost completely separated. This explains the increased "woosh" I've heard on gear changes on this car. It's probably been broken to degree for months or years. I pulled that hose out and ordered a new one as well as a new air filter. I get the new hose and as I'm going to install it. I notice a vacuum line under the rear side of the airbox that is completely kinked. I track it to the turbo. I can't even really see what it hooks to, but I'm guessing it's the actuator. No idea what effect the kink would have had, but I replace it and decide to just start replacing all the vacuum lines with new silicone lines. Everything goes goes fine. I then replaced the pcv valve. Removed the intercooler I had recently reinstalled after doing valve cover gasket, etc, to make sure everything was snug which it appeared to be. Buttoned everything back up.
Went for a drive and the car drives great. The idle is rock solid. The hesitation is gone. The loud "whoosh" on throttle let off is now just a faint whoosh.
However, my scangauge now shows 7.8 lbs of boost throughout the the entire range.
Is anyone familiar with that vacuum line that connects just under and behind the air box?
Does anyone have a scangauge 2 and, if so, what do you see for your boost?
I think there is a chance the ripped intake elbow was causing my oil drip on the driver side as residual oil would drip out and eventually find it's way to the ground. I haven't even gotten to the passenger side leak.
I pop the hood and start looking around. I think the pcv connections seem to have more oil residue than usual, but that could be in my head... Buttoned everything back up.
Went for a drive and the car drives great...
However, my scangauge now shows 7.8 lbs of boost throughout the the entire range.
Is anyone familiar with that vacuum line that connects just under and behind the air box?
Does anyone have a scangauge 2 and, if so, what do you see for your boost?
I think there is a chance the ripped intake elbow was causing my oil drip on the driver side as residual oil would drip out and eventually find it's way to the ground. I haven't even gotten to the passenger side leak.
Hi Matt!
base 08@280k km: Using a wifi and smartphone have seen max boost reaching close to 15psi. My boost dash gauge goes smoothly to max if/when needed.
verify vacuum tube to actuator, might explain symptoms if actuator malfunctioning with new unkinked hose. Is the actuator round or oval?
other
I did the pcv myself, there was no trace of oil.
Same about the torn intake rubber elbow boot.
Ditto on the intercooler in/out
1) pcv is cheap enough, not worth the risk to delay its replacement: when malfunctioning under boost, blows oil vapours back through intake manifold... intercooler, turbo, intake elbow... not good. *Turbo could also leak oil into the intake flow, that would not be good.
2) there should be another hookup to check for traces of oil and kinks/tears, check from the BPV to the intake
3) use a soap or degreaser and soak the inside intercooler to remove internal oil if any, dry it well if you do.
4) Verify engine mounts, could explain the torn rubber elbow, my mechanic did not see any mount being torn but the engine play was significant (hold the foot brake, blip the gas), decided to change just the engine mounts, very happy with the change...
I got under the car and traced that vacuum line that ends up under the airbox. It's actually for the transmission transfer breather box, so I can stop going down that path. That explains why I couldn't find it on parts diagrams for the turbo.
When I did the valve cover gasket, I cleaned out the intercooler, but it really wasn't bad at all. I checked the bypass valve connections and everything seems good there.
I did replace one of the motor mounts when I was doing the gasket for the oil cooler, but I'll check the other. (There is only 1 other, right?) I will say there is very little movement, so I would lean towards the mounts being okay. Definitely worth checking out though.
After a 5 mile test drive last night after buttoning everything back up, I ended up with a bit of oil on the garage floor on the driver side of the motor this morning, so the problem on that side of the motor wasn't coming from the broken elbow. I can't seem to find the source.
and your post reminded me that I have a bluetooth odb2 adapter floating around and Torque Pro on my phone, so I'll check the boost with that as well to make sure it matches with the Scanguage.
This car was babied by the previous owner and my wife probably didn't get in to boost much if at all, so it's possible I'm just discovering problems that were already there but only showing up now because I drive it differently.
I hooked up the other odb2 reader I have and used Torque to measure the boost reading and it was about the same as I was seeing with the Scanguage. Right around 8 lbs of boost. One thing that is interesting is it gets to 8 real quick and then stays there even when the car is obviously still building boost. It has me thinking the map sensor is bad. Even from Rock Auto it's still $165 for a new sensor, so it's not really something I want to just throw at the car.
Any thoughts?
When the car cools down, I'll double-check all the map sensor connections.
Would you be able to measure your MAF readings during a run through 1st and 2nd gear? Just peak values would be helpful. If I'm really down 7 psi, it should be evident in the maf readings.
Not a ton to update, but maybe someone else has some thoughts?
I checked the intercooler connections, bypass valve and replaced every vacuum hose I could get my hands on... Still getting a max of around 8 lbs of boost and just under 180 g/s reading from the maf. I don't think the maf reading is exceptionally low, but it might be down a bit from stock. Anyone else have Torque or similar and able to give a MAF reading with a run through 3rd gear? Seeing what other people are running might help point me in a new direction.
180 is a little on the low side, I think. 240 hp should be more like 190-195 g/s. But, perhaps an older, higher mileage engine has lost a couple steps. It's certainly in the realm of possibility. I haven't measured mine so unfortunately I can't give any first hand info. I really should buy a reader (or find the one I lost years ago). If I do, I'll take a reading and share here.
180 is a little on the low side, I think. 240 hp should be more like 190-195 g/s. But, perhaps an older, higher mileage engine has lost a couple steps. It's certainly in the realm of possibility. I haven't measured mine so unfortunately I can't give any first hand info. I really should buy a reader (or find the one I lost years ago). If I do, I'll take a reading and share here.
Agreed it is probably a little low but 168k (I think that's right) and near 100 temp could certainly cost me 10-15 hp. I'm leaning towards (today at least) a stuck open turbo flap, but it's strange there is no error code being triggered.
waste gate trouble, no code, not the actuator round ear, limited power, with their tests and fix
I remember seeing this thread because that Elizabeth person was talking about "dusting" the turbo to keep it running well (or something along those lines).
If I'm understanding his post correctly, the problem wasn't the wastegate, but the actuator for the variable flow door/flap inside the turbo and this does seem like it would line up with my issues. In post 65 he says there wasn't a CEL, but then in post 66 he says there was a CEL, so it's all a bit confusing. I can't seem to find anywhere were he describes his symptoms. Am I just missing that post?
I just went out and hooked up a mittyvac to that actuator and it doesn't hold vacuum nor move the rod when I apply pressure. It seems like it should do both.
I can't easily tell if that actuator is controlled by a solenoid, but I assume it would be. Not that that would matter at this point if it doesn't move when manually tested.
Thinking out loud, could it be the waste gate solenoid? Being stuck at 8 psi across the rev range almost sounds as if you have a waste gate that isn't closing. How quickly does the car build boost to 8 psi? Fairly quick or is it a slow ramp up even at mid to high rpm?
Thinking out loud, could it be the waste gate solenoid? Being stuck at 8 psi across the rev range almost sounds as if you have a waste gate that isn't closing. How quickly does the car build boost to 8 psi? Fairly quick or is it a slow ramp up even at mid to high rpm?
I could see it being the wastegate or the variable flow actuator.
Like you said, if the wastegate was stuck open, it would just bleed off boost and maybe it can't get past 8 lbs...
However, if the variable flow actuator is stuck closed, then it might be acting as a tiny turbo only capable of making 8 lbs of boost.
With that said, it does seem to build boost quickly.
I found this other video. The guys tests the actuator at about the 2:00 mark. When I pressurize mine, I get no movement.
Scratch part of those last emails... I went back out with the Mityvac to test that actuator again and found the hose I grabbed to test it the first time had a leak in it. I used a new hose and it holds a vacuum fine and moves the rod when pressure is applied. Now I'm back leaning towards a wastegate issue.
Yeah, the variable flow actuator won't limit you to 8 lb if stuck closed. You should make full boost, but it would taper off pretty quickly. On the flip side, if stuck open you don't make significant boost until well over 3000 rpm, but then it's full steam ahead.
I found my reader (in the center console, because of course that's where I'd put it) and did a quick log today. I'm at 190 g/s peak with boost peaking just under 15lb and tapering off to 12-ish by redline. That's on a 177k mile motor in 112 degree Phoenix weather. So 180 is definitely a tad low, but I'm honestly surprised it's not even lower if you can't get past 8lb. You might have a factory freak that's being held back by the boost issue. haha
I remember seeing this thread because that Elizabeth person was talking about "dusting" the turbo to keep it running well (or something along those lines).
If I'm understanding his post correctly, the problem wasn't the wastegate, but the actuator for the variable flow door/flap inside the turbo and this does seem like it would line up with my issues. In post 65 he says there wasn't a CEL, but then in post 66 he says there was a CEL, so it's all a bit confusing. I can't seem to find anywhere were he describes his symptoms. Am I just missing that post?
I just went out and hooked up a mittyvac to that actuator and it doesn't hold vacuum nor move the rod when I apply pressure. It seems like it should do both.
I can't easily tell if that actuator is controlled by a solenoid, but I assume it would be. Not that that would matter at this point if it doesn't move when manually tested.
If this video is of yours, the actuator is badly warn. I don't know if that causes low boost though.
When my intake pipe ripped I also heard a Turkey gobble like noise. Went away after replacement of the broken piping.
Currently at 299K and running strong!
I didn't hear any weird sounds, but the idle did go to crap.
I removed the intercooler again and checked every connection I could get to and nothing stands out as being cracked/broken/whatever. To really check the solenoids, I need to get that HDS diag tool I guess. I've got the Volvo equivalent for my V70R and it is pretty helpful, so I might pick it up as it seems like it's only about $100. Both those wastegate solenoids look like a real pain to swap out, but I guess that is something for future Matt to worry about.
Yeah buddy! I was racking up the miles, but since March I'm doing maybe 25% of what I used to. If the office doesn't open back up soon, it'll be another 3-4 years just to get to 200k (instead of next year). But I'm not complaining about the gas savings...
Got the Honda HDS software. Tested the bypass valve solenoid and it tested good. Need to remove the intercooler to get to the other 2 solenoids, but I hope to get those tested tonight. Really hoping one of them tests bad because it seems like the next step would be pulling the turbo.
I've been replacing vacuum lines as I get the chance. Checking for cracks, etc... Started with all the easy stuff on the front, but haven't gotten to the wastegate or turbo pressure solenoids yet. That will happen when I replace the solenoids. Hope to have every line done when all is said and done.
I hope you figure it out and it doesn’t cause too much more of a headache for you
Thanks! I hope I can get it figured out as well. I never would have even know I was missing some boost if I wouldn't have hooked up my scanguage. Either way, I need to get it figured out.
I ordered new solenoids once I saw how tight it was to get to the wastegate and boost solenoids. If I'm going to be in there, I might as well replace them.
I understand that your dash turbo shows full turbo on acceleration and holding there consistently, maybe right off the start, despite boost sensor reporting max 8psi. Please confirm what the max turbo reading on the dash.
I know it must be frustrating having found such a big symptom, and no source identified yet.
I understand that your dash turbo shows full turbo on acceleration and holding there consistently, maybe right off the start, despite boost sensor reporting max 8psi. Please confirm what the max turbo reading on the dash.
I know it must be frustrating having found such a big symptom, and no source identified yet.
hth
I don't know that I can say it hits the "max reading" because I don't even know if I know what the max reading is... It's not a very specific gauge. I can say I haven't noticed any difference the limited # of times I have driven the car and looked at the boost gauge over the 6+ years we have owned it. I think it goes to just below the + sign and that is where it has always gone. I can't drive it right now as the intercooler is removed.
I think this has been a problem for a long time, but it was just never noticed because I seldom drive the car and my wife never got in to boost. The 10.8 reading I saw before all of this started was probably an abnormality based on a specific set of conditions that maybe could be repeated if I knew what those conditions were. Like maybe full acceleration beginning in the middle of second gear would result in a quick spike to 10 or 11, but then it goes back to 8.
It does surprise me that this hasn't thrown a check engine light. I would think that if requested boost was 14 or 15 or whatever and the actual boost was 8, it would be throwing a low boost code. I don't know if the HDS software shows requested boost. I'll need to check that out....
Mid-range RPM boost on the RDX is 14 psi stock tuned from the factory. Peak-range RPM boost on the RDX is 8 psi stock tuned from the factory. This is due to the stock injector being at maximum duty cycle if boost is raised passed these factory tuned levels. It is also due to the octane limited tune from the factory being 91 octane only. This being not all state have fuel higher than 91 so they must provide a tune that will work in every state. I hope this helps!
... It's not a very specific gauge. I can say I haven't noticed any difference the limited # of times I have driven the car and looked at the boost gauge over the 6+ years we have owned it. I think it goes to just below the + sign and that is where it has always gone. ...
-Matt
We agree on dial limitations.
Reason I asked, iirc there was one thread with report of immediate maxing out the turbo dial, ie. Jumping to the +, instead of gradually getting there. Unfortunately cant find a reference to it and finding instead only reports of impaired power AND partial turbo indicator at maximum throttle with various causes which you have/may have already eliminated as remaining problem.
worth noting the clogged secondary CAT causing reduced power, tested by loosening up the connection at the bottom of the downpipe, creating an unrestricted leak... restriction would likely manifest itself more at WOT...
Solenoids arrived a day early, so I tested the old (both tested good) and replaced them with the new (also both tested good). I had already tested the bypass valve solenoid, but tested it again for good measure and it was good as well.
I stumbled upon a more generic turbo troubleshooting section in the repair manual and it says to use the Honda software to compare "Turbocharger Boost Sensor" and "Baro Sensor" with the engine off. If the amounts vary by more than 6.8 kPa, replace the boost sensor.
Turbo boost Sensor = 1.92 volts
Baro Sensor = 2.82 Volts (Software says around 2.8 is normal)
That is a difference of about 20 kPa if my math is correct, so way out of spec.
Yep... I've got one on the way. Just a good lesson to go with your gut. Here is my post from 6 weeks ago: "One thing that is interesting is it gets to 8 real quick and then stays there even when the car is obviously still building boost. It has me thinking the map sensor is bad. Even from Rock Auto it's still $165 for a new sensor, so it's not really something I want to just throw at the car."
So, instead I threw $150 worth of solenoids at it and then ended up buying the boost sensor anyways. I'll update when I get the new sensor. Should be here on Tuesday or Wednesday.
07-23-2020, 07:48 PM
