Hi all, my S5 has a strange boost problem. The car starts fine and idles nice but and the fuel/air ratio goes nuts when I try to boost it. You can read here the whole story...
(https://www.rx7club.com/2nd-generati...nside-1142527/)

So...I bought a brand new TPS and tried to adjust it by using the LED tester. One light is on and I also fine-tuned it to have a solid 1Kohm as a narrow range value (closed throttle).
But when I rechecked the TPS with a multimeter, I found out that the full range value (full throttle) is a little lower than the recommended 3.4 in the FSM. My value is around 3.24.
Can this be adjusted somehow?
Can this lower value cause running/boost problems?
Any info would be appreciated.
Thanks in advance.

 

you can try adjusting the TPS a little, 1.2v should get you to 3.4, although i would be surprised if that made a difference.

 

I just read in another thread that the full range value cannot be adjusted, so now I am wondering why this value is lower than normal. Anyway, thanks for your reply.

 

@erevos , Its not the TPS my man. Everything you need to fix your problem is in the previous thread.

Make this and use it. Confirm you dont have any boost leaks. I know you already used the smoke machine but this works better. Clamp it to your turbo inlet.


And again you need to get some OEM injectors.

 

Thanks for the tag mate, I appreciate it. I have been checking for vacuum leaks again and again and again. I have bought a vaccuum check kit like this one : https://lincos.tools/4773-large_defa...e-test-kit.jpg
but I think that it can only suck in order to create pressure. I bought it to ckeck the boost sensor. So let's suppose that I make the device that you show in the photo and I attach it to the turbo inlet. Then I just have to apply air and it must create pressure, right? How much and for how long?
Also I read in another thread that there is the double throttle diaphragm (#4) that probably redirects intake air (?). I cant find how to check this in the FSM. The word diaphragm is greek and it means "a thin layer between something or a valve". Can this thing be torn or break? Is there anyway to check this?



As for the injectors. As I told I you before I would have suspicious about them too, but there were 2 months that I drove the car with no problem at all while these injector were on (the period that I thought that I had fix the problem...)

 

You could explain the issue in more detail. You say your AFR goes crazy. Does it seem to lean out? Does is get rich? Explain.

How is the car acting when this happens?

 

Did you mess with the throttle body?

 

I just realized who I was telling this to. Dude, you yourself said that this problem started when you put those nasty grey bullets in for injectors. We told you numerous times to burn those things. The injectors that you said were garbage are STILL GOOD. Put them back in.

I seen a photo of a new ACV. This... is really not a good sign.

 

The AFR seems to lean out. My gauge is not that accurate (led type with rich, stoich and lean zones) but the leds dive to the lean side and then go off. This happens when I try to boost and the pressure on the stock gauge rises from minus pressure to 0.

 

Yes the guy who replaced the injectors tried to adjust it. I also tried to do that by following the instructions of the FSM and also some forum members.
I have adjusted the TPS with the multimeter (1Kohm) and the 2 LEDs method (one lamp is lit at 1Kohm also). I have removed the AWS and the BAC valve and plugged the holes.

 

The problem started to be really bad after the injectors replacement but now I believe that a certain strange startup procedure that occurred before the replacement could be an early sign of the same problem.
So, in the past the car could not cold start without some throttle pressure right after the turning of the key. BUT...it could cold start just fine every time that I pressed the clutch and had engaged a gear in the gearbox, lets say 1st gear.
So...I used to start it with a gear and the clutch pressed and then drove it with no boost until the engine was warmed up. If I tried to boost it while it was cold, the car behaved like it does now. Also during warm up my idle was a little high, 1500 rpm just after start and then slowly settled to 900 rpm. Back then I had the AWS and the BAC valve on the engine but the BAC was unplugged.

So after the injector replacement the start up procedure changed and the car started fine without the clutch and gear trick. My hypothesis is that something is wrong with the throttle body screws adjustment.
Another fact also supports this hypothesis. One year ago I replaced the AFM, adjusted the TPS and the thermowax idle screw. After that the car was fine for 2 months or so and that's why I think that the problem is probably not related with the injectors.

Indeed my ACV looks bad. But how can I check if it is stuck?

 

You mentioned that your car ran fine for 2 months -are you saying you were boosting without issues and healthy AFR? Could you floor it and sweep through to 7-8000 rpm? The TPS will not cause the boost issue.

Don't worry about the ACV. You had it blocked off and judging by the silicone pattern it was blocked off well. You're wasting your money on the wrong parts man. In fact to fix this problem you probably didn't have to buy anything.
Your idle sounds fine in the video.

This is my hypothesis:

You are running crap injectors. These injectors are supplying enough fuel below boost however, when you reach boost they simply cannot keep up.

If you have a vac leak you would notice in your idle... your idle to me from here sounds fine.

The real question I think is, and don't take this the wrong way -Do you want your car to run properly?

If the answer is yes you will stop ignoring the elephant in the room which is .... drum roll please .. drdrdrdrdrdrdrdrdrdrr INJECTORS!!!!!

If the answer is no then keep ignoring the advice being given to you.

Think of all the time and money you've wasted trying to hunt this problem down. I can't remember if you through those OEMs out(if so that was a huge blunder). They're still good and DISCONTINUED.

If you still have your injectors this is what you need to do and please for the love of god do it. There are a couple of us in here that want your car running just as bad as you man lol! Oh the pain... kk... DO THIS:

Take an OEM injector.
Attach two wires via alligator clips or an extra connector and connect them/it to the injector.
Connect ONE wire to a 9v battery.
Now tap the other wire on the other battery terminal and confirm that the injector clicks.
Do that with all four.
DO NOT hold the wire on too long or your risk frying it. Just tap for a split second.

If they all click they are GOOD. If they don't click then they are ready for the pit.

Now this is probably like the 10th time this has been mentioned. You need to do this.

 

Post your results.

 

Thanks for your interest.
You mention in your post that I should not worry about the ACV because its block off well but my ACV is in on the car! I said that I removed and blocked off the BAC valve! The ACV was leaking air with engine off when I tested it with the smoke vacuum check device. That's why I wonder if it is stack open.

Now...I am not ignoring the elephant on the room. The injectors were the first thing that came in mind... BUT how can you explain the fact that after the minor advancements that I did to the throttle body screws and TPS the problem was gone (or was not obvious...I don't know...) and the car was fine for 2 months or so? Also the car boosts fine for a minute or so after I turn off the engine and then on again. If the injectors were the problem shouldn't the car behave the same all the time? To summarize my argument...the problem was minor before the injector replacement, It became obvious after the UIM removal and the injector replacement, then the problem was gone for two months (AFM replacement, TPS and throttle body adjustments ) and then reappeared again.

I found some videos from the period that the aftermarket injectors were on and the car was boosting fine. You can see a friend's RX8 (streetported) in the video. I could be next to him when we were racing for fan. The boost level with almost WOT was not that high as you can see in the gauge. My boost level was kinda low even before the injector replacement but apart from that I never had any serious boost problems like now.
In the following video the car has the aftermarket injectors on. At the "night" part of the video is when the car had was boosting fine and at the "day" part the problem appears when I try to boost above zero pressure. You can see the AFR gauge going mad and dive to the lean zone.

I also noticed that the problem occurs more when the road is bumpy...this also can been seen in the video (1:57). Can this be a clue?
The problem is also obvious at 2:20 before I turn off the engine. Finally you can see that the problems disappears for like a minute or so, when I turn off the engine. Then the car behaves ok for one or two hits (2:57-3:10) and then the problem appears again at 3:13
Here is the video:

So...right now I am going to my garage and see if I can find the parts that I need in order to check the OEM injectors. I will post the results. Thanks again for your help.

 

This is a photo of my injectors from the other thread...they obviously need refurbishing...

 

I just measured the resistance of the injectors with a multi meter. It shows 16,2 ohms which is a little higher than the FSM value (12-16ohms). I could not find a 9 volt to battery to check if they click. I guess that if I replace the rubber rings they could be used again. But if an injector needs only cleaning, then why is there the leaking injector problem that many rotaries have on hot starts?

 

That's why you need to make that boost leak tester. Put it on your turbo inlet, pressurize the system, 15-20 psi should suffice for your application. You will need to clock the engine to the correct position that it holds air, and will have to hold it in place, otherwise it will turn and let the air out. Ideally the pressure shouldnt drop at all, but a slow drop in pressure over a 20-30 second period should be fine. Mainly what you are doing is listening for hisses (leaks) in the system.

Simple. It's evident that you dont know much about car engines, let alone these rotary engines, considering the fact that you have to send the car to a mechanic for simple maintenance work. Therefore, nobody can trust your judgement on what you think is "running better" or is "fixed". Also, throttle body screws aren't going to make or break your engine at WOT. Maybe the TPS might cause some issues, but you've already adjusted the brand new TPS in your previous thread with no success. So there's another reason for some skepticism. And if i recall correctly, you had a vacuum hose broken off on the UIM before, and it was fixed after you reinstalled the UIM. I don't know why you think you have a leg to stand on arguing with anyone on this forum.

Hard to say considering the amount of variables you have that may affect that engine. SOunds like youre leaning out to me. One thing I do know is that this problem didnt exist until you worked on your car, as you stated in your first thread, and the only variable left that you had "fixed" was the injectors. I'll post it again, see below.

So what you need to do is put everything back the way is was before you did that, and start from square one.

If by refurbishing you mean a simple oring, grommet, and filter kit then yes.

You think yours are bad? Here are some I pulled off of a NA FC. Wire wheel and rebuild kit and they were good to go.





Those injectors are fine. You probably don't need an injector cleaning considering that your car wasn't having hot start trouble before, and if you weren't having that problem before, you probably aren't going to now. Get a rebuild kit and run them. And your mechanic is a moron for saying that they're garbage. You should get rid of that guy and start learning and working on your car yourself.

And make the boost leak tester.

 

You said you have a wideband O2 sensor. I'm assuming that since you installed it yourself that you didn't weld a new bung and have installed in in the OEM location. What did you do with your OEM O2 sensor and wire?

 

Bro, FuhrerTuner and I and many others on here have been dinking around with these things like... forever man. I get that we want to be right about stuff. And it feels good to figure something out by yourself. But, this one is over your head. Just listen to us and you will thank yourself for being humble. That's how you learn man. If you are interested in learning the car then expect a bit of humility. 'Plenty of great minds on this thread that are more than willing to help people who want to be helped.

Ugh, in all honesty, I just rewrote this post like three times. I'm staring at a wall of text, text explaining someone how to do something that's been explained to death in this very thread. For this reason, I can't do it man lol. Kenny Rogers is singin'. He's telling me to fold.

The information you need to conquer all is contained within this thread. Now it's up to you or a mechanic to do the work properly: no stripped bolts, no cracks or bad gasket jobs, no shitty wiring, no shitty injectors, no pinched fuel orings, etc..

 

Guys I really appreciate all the help and I assure you that I am not considering myself a rotary expert. I just have read again and again the FSMs and I have spent many hours during the last 19 years in this forum reading about various things.
Also I have been visiting many mechanics in my area and none of them can figure out what is going on with the car but as I said previously they are not rotary experts. They are charging 50-60 euros for an hour of work and most of them do not even want to take a look at an old rotary engine. The worst thing is that some of them are clueless about RX7s and just want to take your money. That's why I try to find out what is going on by asking people. I do not want to bother anyone, disrespect any opinion or spend other people's time.

I do not have installed a wide band, just a LED halmeter gauge that is plugged to the O2 sensor.
I do not know if this helps but the problem appears exactly at the point where the throttle pedal is getting harder to press, just before the turbo starts to spin. At that point the leaning starts and If I keep pressing the throttle pedal the LED lights turn off completely and the car feels like it is out of fuel, bulks and jerks. This whole situation happens really quick, like some valve is not working or not opening properly. You can see this in the videos.

Right now I have send the OEM injectors to a specialist in order to check them for leaking and measure them properly. If they are ok, I will reinstall them and post the results.
A friend told me to also check the fuel pressure regulator, the fuel pump wiring and the pump relay. Should I do that or is it irrelevant to my problem?
I will also make the vacuum tester and search for leaks like FurerTuner describes.

Thanks again for all your help. I will update in the other thread as soon as possible.