dbjac

Hi guys!

This is my first 'technical' post, so I'm posting it here.
I'm not sure how often this section is browsed by the Rx7 guru's, but hopefully someone has some information for me!

My brother's FD Rx7 has a strange pipe with a filter attached. It's blasting soot everywhere and making a right mess.

Now, i've spent a looooong time trying to track down what this pipe even is, and I *think* I've got it identified.

The pipe is tracked back behind the intake manifold. From the various diagrams found on here and other places i believe it is the Air Control Valve, in particular, the Relief Valve dump.

So, my questions to you all;
Am I correctly identifying this? (see photos!)
Should this be coating the engine bay in soot?
Is it broken? Is it causing any issues in this state?
Is it supposed to have a filter on it, or has the previous owner done this to tame the spitting?
How would you go about resolving this problem?


Here's a couple of photos:





Also, apologies if this is a commonly brought up issue. I may not have found the other threads as I'm not even entirely sure that I know what the component is!

Thanks!

Sgtblue

iTrader: (16)

That looks to be the hose coming from the secondary air injection solenoid. In standard form, it's controlled by the ECU and allows the air pump to inject air into the cat. You no longer have an air pump and the solenoid at the end of that hose and tube should have been capped by a block-off plate. It's almost certain that filter was installed just to help with the mess. In our North American Factory Service Manual it's covered from page F-115 to about F-120...fuel and emissions section.
Charge Relief Valve (CRV) is something totally different.

dbjac

Thanks for the info Sgtblue! Though, I'm pretty sure the air pump is still in place.

You sent me down another path of research

So, I've taken a lot more photos and collected some information, I'll present that now and perhaps some one will be able to help me with a few questions.

I'll detail the first pipe that I noticed was unusual, but I have now found a second.

This is the engine bay, just in case it helps:



The pipe I initially mentioned is this:





Which seems to be this in the workshop manual (correct me if i'm wrong?);



And should have been connected to the air box through a series of pipes:



Now on to the second pipe I've found:



Which is also venting junk everywhere



Its hard to see clearly, but it seems to connect to this:





Now, I don't actually know if these two are related, or if it's coincidence, or a function of a failure somewhere else that is manifesting as this problem. However, a little bit of investigation is suggesting this may all be the result of an 'eBay special' air filter kit. I've seen some of the HKS kits that most of you guys seem to be running, and they have nozzles that I think are to attach these pipes, allowing the ACV to act either to 'water down' the cat, or to modify the O2 content of inspired air as it choses? (again, correct me if i'm wrong, I have a rudimental understanding at best).

Your lovely HKS's:




So,
Is this normal functioning components (other than the pipes not connecting to anything)?

Do I just need to get a reputable air intake kit? (I don't mind doing this, as I'd like to have quality components)

AND/OR should it not be venting dirty exhaust anyway? Part of me is thinking that if the ACV is supposed to handle clean air from the intake, it shouldn't be this dirty, which might suggest it is busted and just routing exhaust from the cat or rotor port back out into the engine bay. I can't really rationalise a reason to vent exhaust (is it exhaust?) back into the intake. Maybe it needs a new ACV or something?

AND/OR the air pump might not work? perhaps it's not feeding air into the ACV so it has nothing to pump into the cat/rotor port, allowing the exhaust to escape out instead?


Thanks guys, I do appreciate your input.

RobertC

iTrader: (1)

That second pipe under the filter is your factory Blow off Valve for the turbos. If it is leaking you will need to replace that hose and reroute it back into your intake or go with an aftermarket BOV that vents to atmosphere. But all it does is reroute the air back into the intake pre turbo after going through the factory BOV. You shouldn't see oil or anything spraying out of that, or you might have a leaky turbo at worst.

The first one you see is functioning correctly, that's why the filter on it is so dirty as well as everything around it. That needs to be re routed back into the intake. That is part of your EGR system.

dbjac

Awesome! Thanks mate, it's good to have the components identified now.

So, it's not normal behaviour for these pipes to be pumping dirty air?
I don't know if its burned oil or just exhaust muck though.

If it's not normal. Where should I be looking for causes of the messy air?

RobertC

iTrader: (1)

The EGR valve is re routing exhaust back into the intake. That is its purpose. As far as the amount of soot there should be, I don't know as I personally never had a vehicle with the EGR still functioning.

If all is plumbed correctly, you shouldn't be seeing any soot in the engine bay. If you are seeing soot at the BOV it's either a broken hide that is leaking or its venting to atmosphere. But are you sure you aren't seeing it spray oil?

dbjac

Ahhh, you guys are awesome.

Today I disassembled a lot of the air intake and FMIC piping and had a look. There's definitely oil through it.

Example of the piping:


ABV:


So a bottle of degreaser, some petrol, and a high pressure cleaner we've given the engine a clean up.

The car did have a rebuild that included fitting a 2nd hand turbo. I've asked the previous owner, and he said the FMIC was in place before the rebuild.
After cleaning it, we took it for a ride (not very long at all, so it'll need more observation). The ABV hasn't dirtied up the pipe yet, so I'm thinking the mess could have been residual oil or even have been blasted by the initial failure, or I just haven't given it time to spit enough oil to be observable.

We're planning to take off the turbo connector pipe, intake manifold, and FMIC and clean that as best as possible to try and get as much of the oil out as we can. And I'll try to see if it's still got restrictor pills in place. If the pipes are dirty again I'll have to investigate if its a busted turbo, but fingers crossed!)

I took a couple of videos to see if you think this is appropriate turbo function (i've never even owned a turbo, let alone sequential).
The owner said he got it low-tuned (8psi) so that he doesn't have to worry so much about a future rebuild, but I wouldn't mind seeing it back at 10psi (stock numbers?) since i think we can take decent care of this car.

Neutral test (a website suggested we do this):

Didn't produce boost, but I'm not sure if it's meant to in neutral.
You can see that exhaust venting to atmosphere from the EGR.

Driving test:

Sorry about the terrible video, it's pretty tough to hold steady without a mounted camera!
Seems to boost ok (to 8psi). I can't get to the 2nd turbo too well in my area since the fastest speed limit within 15-20min is 80km/h (50mph) and the police are glorified revenue raisers looking to book me.

This seems like positive news. I might just need to clean out as much oil as possible, and track down an HKS air intake system with the appropriate fittings to plumb in all the pipes correctly.

Let me know if you think anything is unusual!

RobertC

iTrader: (1)

I'm not as familiar with the inner workings of the later series rx-7s but I think you should be able to build boost even if you are free revving it. But I could very well be wrong there.

I am guessing the smoke from the first video is coming out of that filter?

Good luck with everything!

dbjac

Bit of an update just to keep active on here!

I've routed that EGR to vent under the car to prevent it dirtying up the engine bay while we work through things with the car. I should probably get the thread renamed just to "Fix my RX7 please!" haha.

We turned to sorting out the error codes to get a 'fresh slate' and fix any remaining problems after that.

We were getting 05 (knock) 17 (O2) and 71, 73 (secondary injectors front and rear).

We've replaced the O2 sensor. Now we're getting to the knock sensor. It seems fine, but at some point (probably who ever changed the plugs last) the wire has been broken from the loom. I can't see the lose end so I'll probably have to track it back from the ECU until I find it and rewire it.

The car does run amazingly rich to the point of flooding regularly. So hopefully fixing the injectors might help. We're also looking at upgrading to a Sakebomb Garage ignitor coil kit. I bought one of their Bixenon headlight kits and it's bad ***, so I don't mind sending them my money at all.

It also isn't producing much secondary boost (maybe 3-4 PSI?), perhaps this is the lack of knock sensor making the ECU retard everything and dump boost early?

I can't find much information on the injector codes. I was going to pull the injectors and get them reconditioned. Do the codes imply a mechanical issue with the injectors (need to get them reconditioned/replaced?) or simply an error with the wiring firing them causing open loop? (need rewiring?) or based on your experiences, something else?

Thanks guys,
Derek.

RobertC

iTrader: (1)

The only pieces of advice I can give right now is while I absolutely would stand behind sakebomb garage and their kit looks awesome, I would try to sort out your gremlins first before adding another potential point of user created failure.

Second, I would take a look at your secondary turbo and make sure you first have no oil seal issues (on primary and secondary for that matter) and it could be a vacuum leak causing the low boost from the secondary if the turbos are in good shape.

dbjac

Definitely good advice, I'll take that on board.
It is spraying a little oil out of the ABV, so there is probably something for me to find in the turbo.

I'll have a search about tackling the turbo trouble-shoot. But any quick words of advice?
Is it as simple as disecting it and investigating potential points of failure? Are there any gasgets I should have on hand? Or just be careful not to damage what is there and refit it?

Where would a vacuum leak be likely to effect only the secondary boost? (I at work so don't have the manual on hand)

RobertC

iTrader: (1)

With the amount of oil in the piping I would think there is somewhere introducing oil pre throttle body. Which could possibly be the turbo.

I am not 100% on the gaskets. If there are I would replace any soft gaskets. I can't remember you're exact setup off the top of my head so it could be from the relief valve that is routed into the intake.

If I were doing it, pull the intakes first to check if there is any oil there that could be recirculated back. If the intake preturbo is clean then it's probably the turbo introducing the oil.

dbjac

Thanks Hazel324,

Had the UIM and junk off yesterday to try and fault find the injectors. It actually led us to find it has an aftermarket piggyback ECU (Microtech LT10s).

This explains a few things.
a) they probably didn't bother fixing the O2 sensor as it's apparently not essential to this ECU (it's still connected to the stock box)
b) Knock sensor doesn't feed in to this ECU either, so probably weren't fussed about this. We've repaired the connection now anyway, so hopefully it works.
c) Injector open circuit might be a function of this ECU stealing the signal. I'll be contacting the shop that I think installed the unit and asking them more about it.
d) Rich running might be due to a poor map
e) Boost cut off might be set to trim at ~7psi so we might be restricted there. Or, maybe it's not and I just need to play with the pill size.

I guess we'll put the car back together and take it to them depending on what they say on the phone.

Further to the oil problem. I am relatively happy now that it was just residual oil from when the engine went bad. I investigated the hoses I cleaned out a while back, there's no more oil being deposited, so I think the thin film coming out of the ABV might be residual from the turbo air outlet and stuff that I haven't been able to clean.

I guess I'll see what the guys at Promaz say!

Thanks again for your help, you've been great this far

EDIT: one thing I did notice, the seal on the valve in the ACV unit was pretty badly deteriorated, half had broken away. With the rest of it removed, at least the valve seats better now. It's probably not ideal, but I think it should last until we find a replacement or decide to delete the EGR system. Thoughts?

dbjac

Spoke to Simon at Promaz.

As we thought, the codes aren't a problem.

But, he does want to fix the boost and then get into tuning it properly so that it's not crazy rich.

TomU

iTrader: (11)

Sounds like you have several issues at play. Looking at your engine pic, it looks like some bolt on mods have been made without fully addressing the underlying systems. My guess is the all the solenoids and vacuum hoses are original (because they are a pain to access). If they are, you may have vacuum leaks and/or bad solenoids. Unfortunately, you need to remove the UIM to access all that. Some good threads on this...

https://www.rx7club.com/3rd-generati...-stuff-802060/

http://www.rx7club.com/3rd-generatio...our-fd-904277/

https://www.rx7club.com/3rd-generati...-turbo-749702/

With the UIM and vacuum hoses off, you can then get to your injectors. Have them sent out for servicing

Next is your ECU. If it is stock, deleting your emissions can send codes. Best is to either hook back up the emissions or get a good aftermarket ECU and fully delete your emissions (to include removing the ACV and block the LIM with block off plates). You can also remove the EGR as well and block that.

Disable EGR

https://www.rx7club.com/3rd-generati...remove-255542/

Good luck

RobertC

iTrader: (1)

Hey Tom, it already has a Microtech in it.

One thing to keep in mind with the Microtech, if I remember correctly, it does not support the OMP so you need to premix your fuel so you can lubricate the internal seals.

Also, 7psi is the factory "spring" rate for the twins, if you had a electronic boost controller and turned it off (Greddy Profec B Spec II) the twins would only build 7psi.

What you could do, is just get rid of the EGR all together since it's not really doing anything now. I mean you have it exhausting through a filter into the engine bay getting it all dirty. If you are retuning anyway, might as well delete, and block it off.

dbjac

Some closure!

It turned out the cat deteriorated and back pressure destroyed the secondary turbo.

We got the car back today, hopefully it's all good now!

Thanks for everyone's help

Mrpopopo

Man... I want your cluster.