plain ole wanker

My story today goes stopped at a light and noticed a little rough idling didn't think much of it took off revved between 4-7 through gears. Went and filled up at my usual shell gas station started car noticed the CEL on. Thought it might be the old gas cap trick, nope it was on tight. Went to Advanced Auto get OBD CEL check and this what he showed me on the read out 'stuck intake manifold valve' I can't recall the code but I think may have been p 2060.


The car runs fine just as smooth as usual haven't noticed the rough idle other than that one time. Is this something to be concerned about? Anything I can do to prevent or help this problem?

jasonrxeight

take your MAF out see if you have oil inside your intake.
oil inside your intake tube is usually due to overfilled engine oil.

DarkBrew

Jon316G has a nice video for troubleshooting stuck intake valves.

plain ole wanker

Yep found the diy thanks for the help all.

ASH8

Hey mate...How did you get on?..

Funny you should put this up, Only Yesterday I had a 'similar' thing happen to me.

Idle was/is fine, but, 25 minutes into a trip at stop light, wanted to open her up, and got this hesitation around 5000 RPM up ish, almost like rear Wheels were slipping which they weren't, but it appeared the intake shutters were either sticking or fluttering or whatever you call it, car kind of bogged down for some seconds until it OKed itself...definately coming from the intake side.

Yesterday was a really humid and hot day, used to cool weather, rotaries like Cool Weather.

Has not done it since, but perhaps one of those weather related things or??, got no code or CEL.

A bit strange.

plain ole wanker

Hey Ash, it only had rough idle at the light. A few minutes later stopped for fill-up that’s when I noticed the CEL. It is cool here in 40’s when my problem hit not much humidity. Haven’t added oil in couple weeks so can’t be over filled and I always keep level about ½ cm below full on cold check.


Hasn’t happen again I was just looking on S1 about similar findings. Saw there is a diy about the maf and intake valve so was just wondering if this is common with the 8 in general?

ASH8

Mate..good to hear from you..

The S2's have a slightly different intake Accordion Tube (one less Vac feed line) and some 'plumbing' changes to prevent any Oil being sucked into intake, I have not heard this to be an issue on ANY series 2's, obviously if anyone overfills Oil Pan then excess oil has to go somewhere, but that is not an issue with you.

There are other changes to the S2 Inlet manifold, less Vacuum Lines but the principals are the same re SSV etc...time will tell.

The problems is a far less number of S2's on the road world-wide, so issues will not be as common.

jasonrxeight

it happened to mine when dealer overfilled my oil.
I found there are two breather tubes on the filler neck that goes to the intake tube, which means if its over filled it will be sucked into the intake tube.

Mazurfer

And....continued sucking into the intake tube leads to gumming up in the throttle body and all valves downstream.

ASH8

I guess it has to go somewhere when Too much Oil is put into Oil Pan then the OEM Plastic Filler Neck/Tank or Overfilled by some dumb *** dealer who should KNOW Better!

My reference was what Mazda did to stop engine oil being vacuumed back into intake on S1 set ups, even when Oil Sump Level was where it should be.

I am not aware of any S2's that have this as an issue (provided Oil Pan in not overfilled with too much engine oil by someone).

I checked mine recently after 38,000 KMS and it was bone dry.

T-von

I already know what going to eventually happen based on my knowledge of these engines. Here's something you guys need to understand. The lower intake on the S1 and S2 will still be subjected to carbon intake runner build-up over time. VDI sticking open and AUX 5th and 6th port actuators sticking open WILL be a problem with S2 engines also regardless of it's slightly different design. The old S4 and S5 Rx7's had problems all the time with sticking aux 5th and 6th port actuators. For those of you that have never pulled these engines apart, carbon will work it's way far up the intake runners causing those components to stick/freeze open. Revving your engine on a regular bases helps since it keeps these components in operation on a regular bases, however revving still wont prevent the carbon from still building up the runners. This is where I found that premixing was very helpful. Not only is it the absolute best way to lube the rotary combustion chamber and fight carbon, but when the injectors spray the fuel/2 cyl oil mixture, you get an oil film that evenly distributed all over. This film will also work it's way up the intake runners. As long as you have an oil film, carbon can't stick to it.


I personally have a 91 Rx7 NA convertible that I rebuilt 5 years ago that gets granny driven all the time. When I say granny driven, I need shifting at 3k all the time with NO hi rpm revving. The engine have 45k on it. Based on my driving habits, my engine should be carbon infested but it's not. My OMP doesn't work so I've premixed that entire time. My aux actuators still move freely and I haven't driven my car in a year and a half.


Now my advice to all you S2 owners is to premix. Yes I understand Mazda improved the S2 OMP set-up but even that system will never lube the combustion chamber was fell as premixing will. I can assure you that is fact based on how Mazda designed the OMP delivery system.

T-von

True to a point but oil itself wont gum any of the Aux valves or VDI in the lower intake. If anything that oil is helping to lube things up. Gumming in this engine is a direct result of carbon that has worked it's way up the intake runners over time. That's why doing what I suggest in my above post will prevent all these potential future problems.

T-von

See my above post. It's not oil pan related and there's nothing Mazda can do about it. You could engineer a 5 gallon oil sump if you wanted and add oil directly to it and it wont make a difference. The turbulance that happens during the intake stroke causes reversion with-in the intake runners. Now this is more especific to the 5th and 6th ports with there late closing timming. These ports have such late closing timming that as the rotor sweeps across that port, the rotor is actually beginning it's compression stroke. Since you have compression on an open port, some of the air will reverse back up the runner. Mazda knew this and designed the VDI to take advantage of it to make more power. Anytime you have reversion in the intake runner, your bringing some of the fuel/air mixture up with it. This is why you have the gumming problems. It's the nature of all NA rotary engines. Renesis is no different!

ASH8

Could not agree with you more...

I have been pre-mixing my S2 since day 1..

1. Because I do not trust Mazda's conservative injection oil levels (remember S1 was not enough oil originally).
2. My own insurance policy, plus some peace of mind.
3. For all the other "lube" reasons you suggest, including Fuel Pump..I use Synth 2 Stroke meant for pre-mixing.

And YES, I also agree the CARBON is the enemy/killer of ALL/Any rotaries, it was the same back in 1974 when my Dealership would overhaul RX-2, 3, R100's for coolant entry, Carbon and Marbles in a Can was an issue all those years ago, even on those lower compression Carburettor Rotaries with thick Apex Seals and Double Side Seals using Standard Gas with low lead levels...back then it was a NO NO to use Super Gas /Petrol with high octane/lead composition.

The main reason Mazda is excited about Hydrogen Rotaries as a possible future...Zero or little Carbon because of the fuel used.

But after ALL that, I will always love Mazda's Rotary Engine...it IS Special

Mazurfer

^.............true and I agree of course, but dirty oil from the pan is not the same as a good 2 cycle pre-mix!

BTW.........excellent post above. I've been super busy at work and am catching up on all my subcribed threads!

TeamRX8

iTrader: (25)

well I accidently overfilled my engine oil recently. It is so full I cant even tell how much over because it completely covers the dip stick. Yet I ran the last four or five races of the season like this without so much as a single drop of oil getting in my intake

so please keep on with the forum wives tale ....

Mazurfer

Hmmmmmmmmmm......I myself have never had the issue TEAM.
Nor have I ever overfilled my oil, so maybe I need to re-evaluate how oil gets into the intake for some folks. Especially since it seems to occur usually after a dealer or someone else had indeed overfilled?
Have an ideas?
You think it's just some sort of blow back that can happen under certain conditions?
You're by far more of a car guy than me, so..................take the bag off for once "M", I have seen you do it in other threads(momentarily) from time to time.




p.s., I'm not about spreading false info, but only compiling data(over time) as it comes in to hopefully identify trends or commonalities.
This is usually for my own benefit since I am not a mechanic but also to hopefully ease other owners potential issues along the way.

TeamRX8

iTrader: (25)

IMO the likely causes are excessive blowby from poor rotor sealing or the pressurized pump dispensers either positioned so that oil is being pushed into vent hose on the side of the filler neck or filling too quickly and it backing up into the neck and into the vent hose opening. The internal valves on several LIMs I've pulled were all remarkably clean, but none of them were high mileage use either.

Ive never said it doesn't happen, just that people were coming to erroneous conclusions on what the cause is. When I first got my RX-8 in 2005 I was running 1 qt over on purpose because I knew there was no crankshaft to whip the oil to death and I didnt want the pickup to pull air in high G load situations. I learned later that this was unnecessary in the Renesis, but that experience proved to me that excess oil level does not cause this issue. Thats why I wasnt overly concerned about having overfilled the sump recently.

Mazurfer

Good food for thought.
Thanks!

plain ole wanker

Damn CEL went back on last night and this time no real change in drive feel or idle at anytime. Now the CEL turned off this afternoon is this something that the dealer should check out or just intake valve again it has been freezing *** here wonder if that has any effect on it?

templar99

I had the same problem. Car was running great, turned it off, went in the grocery store and back out and I got the CEL. Code reader says, "stuck intake manifold valve". The car is still running good so I'm hoping the problem is weather related and goes away when the temps get warmer, but probably not. What I'm not understanding about what I've read here is, can this not be pinpointed to one area? From what I'm reading in the forums it's sort of like you have to keep taking the engine apart and cleaning parts until something works. I'm lazy guys, and it's cold outside so I don't really want to be doing a lot of dis-assembly/assembly work that ain't necessary . In a perfect world you would just find where the intake manifold valve is, tap on the housing with a hammer and then, wow, no CEL. Also, since I don't see any performance problem, what's the downside to driving the car with a stuck intake valve?

Mazurfer

Won't answer all your questions(Templar99), but I believe this is by far the best thread on the SSV.

https://www.rx8club.com/showthread.p...&highlight=ssv

plain ole wanker

templar99 this more likely coincidental but just added premix in my last tank fill up and after about 1/2 way through the tank the CEL has gone off. I haven't premixed in a number of months just being lazy. Give the premix a try it's a lot easier then trying take things apart and clean them in this nut freezing weather.

Just noticed you said after coming out of the grocery store that's when your CEL came on mine was after going into the grocery store as well.

templar99

Hi ******!
i used the code reader to re-set the CEL last night. Drove all the way to work this morning without the CEL returning so I'm hoping it was just a weather related fluke. I thought about adding some Lucas Gas Treatment on my next fill up but may try the pre mix instead. What did you use?

Jon316G

iTrader: (1)

We do see more "stuck valve" related issues when the outside temps drop.

No.
The link Mazurfer directed you to was created to help pin-point your particular issue because we've seen SSV related codes caused by almost every component of that valve.
You didn't mention the code, so we are assuming its SSV (P2070) because that is the most common, but we've seen "stuck valve" codes for all of them (APV, SSV, VDI).

Most of the "advise" on this forum is randomly throwing ideas at you until you solve it and not much true troubleshooting, which does get frustrating to watch.
But to some degree, you have to test various components so you know what needs to be taken apart to clean/fix/replace.


And as I pointed out before... its not always a stuck valve causing these codes, but another component such as the actuator or solenoid.
In which case "tapping with a hammer" will not help.

If you don't notice issues driving or idling, you'll probably fine to wait until the weather gets warmer.
But keep an eye out for the code to return and if it comes back more frequent, you may need to tackle this sooner.

Did I miss something?
What does pre-mixing have anything to do with "stuck valves"?