Rundown of the car:
S4 NA
Mazdatrix Street port
K&N intake
Header, catback and cat delete.
Rtek2.0

Before I installed the RTEK 2.0 The car ran very lean, around 18:1 AFR under load. Now I have the RTEK installed and have the fueling down into the 13s. I had to add 35% fuel to get it there though. Does this seem right? Doing the math to get from 18 to 13 AFR, adding 35% fuel is plausible, but I am wondering if I have something else wrong.

Injector duty cycles are under or at 50%, so obviously I am not running out of injector.

I pulled the fuel pump thinking the sock was clogged. There was a little metallic debris on it that I cleaned off, but not enough to hamper flow. The inside of the tank looked brand new. No rust at all in there. There is 13 volts getting to the pump while the car is running.

I have not checked the fuel pressure yet, and probably will this weekend.

The fuel pump has 210 thousand miles on it. While it still works, could it be getting weak? I have a replacement that is coming in the mail, so I guess we will find out.

My next step is looking at the injectors, and the fuel pressure regulator if I am seeing low fuel pressure.

 

I'd suspect the AFM internals have been *messed* with. Pull the afm out and look at the large plastic cover. Stock cover will have a clear/yellowish RTV sealing around the outer perimeter of the plastic cover.

Most non turbo run rich, especially around 5000-6000 rpm (memory).

If someone took the plastic cover off, and tightened up the spring so to speak, then it'll run leaner. IF you take the cover off you see a wheel with teeth. There is a small lockdown screw that if loosened will allow the large gear to be tightened by moving it anti clockwise or loosened by moving it clockwise.

So they would have loosened the set screw.................made note of where anygiven tooth is relative to the non moving case (like make a mark on a gear and a mark on the case just opposite that tooth).................then, while holding the large gear in place with one hand, move the gear holding device away from the tooth it's engaged with, and then move the large gear a tooth anti clockwise to make it run richer.

One tooth makes a large diffence in mixture. You HAVE TO/MUST make a mark on a tooth and a mark opposite that tooth on the case so if you let the large gear with your hand, you'll have the ability to come back to where you started. If you DO NOT make a mark , and release the gear, you'll NEVER EVER be able to get back to where you where before you started messing around. Well, you can, but it'll take forever and ever and ever and ever and ever to get there.

Or the injectors/primary are not stock parts and don't have the -1350 embossed on their sides near the electrical jack.

Deadhead pressure should be 64-80 psi with a fully charged battery. Just remove the pressure line AT the pump and install a gauge on the pumps hard line and run the pump.

 

Did you change the high pressure fuel filter in the engine bay?

What wide band O2 meter/AFR reading setup are you using? You won't run 18:1 AFR under any kind of load. The engine would hiccup and cutout and you would have nearly zero acceleration. I can run as lean as about 17:1 AFR with my FD and still have enough power to hold speed and maybe very slowly accelerate but at 18:1 AFR all I can do is decelerate smoothly. Maybe with a little higher compression and some timing tweaks I could have some acceleration at 18:1 AFR. You aren't using your narrow band O2 sensor to try and figure out your AFR are you? I would think you would want to aim for 12.5 to 13.5 AFR at WOT for an N/A. This is generally considered best power territory. You probably shouldn't go leaner than about 15.5 AFR under light load. It's less efficient on gas and emissions get worse to go any leaner. Of course you need to get a reliable AF meter first.

 

Thanks for the responses guys.

Hailers -

I believe these are stock injectors (1350s). They are the same color as the 1350s I have seen, but I will verify their specification.

I will pop open the AFR meter and check it out. It will probably make more sence once I am in there. You could be on to something.

Matt Hey -

I have a brand new high pressure filter in the engine bay. The old one only had 15K miles on it as well.

I am using a Innovate LC1 wideband, and it is accurate. I checked it against my TurboXS wideband I use for mobile tuning and it showed identical readings.

The car WAS bucking, and hesitating between 3000 and 4000 before I started tuning it. After 4000 the car would pull to redline smoothly, between 17-18 AFR. I am new to rotaries, and the RX7, so without the wideband on the car I thought the bucking was because it was rich, and I was experiencing the problems that everyone complains about between 3500 and 4000. I really have no frame of reference as to how fast the car should be. It did feel slow though.

It burned up a fresh narrowband sensor, and was giving overheating errors on the LC1 so I know it was lean, and confirmed it with my other wideband. Oddly however, the plugs did not look bad.

Now that I have given it some fuel it has a lot more power. I also lowered the secondary staging to 3200 RPM, and wow what a difference! I still have more work to do, as the car is in the low-mid 13s now, but I am concerned I will run out of headroom with the RTEK, as it only allows for a 50% +/- adjustment.

I am going to rule out the injectors as the cause for now, because the car runs very smoothly, and after seeing how clean the tank was, I'm not too concerned with gunk in the fuel system.

Thanks again for the insight guys.

 

The LC1 should be accurate. That is what I use. It sounds like you may actually have been running 18:1 AFR. The N/A rotary is higher compression than the FD and more efficient out of boost no doubt. My FD would have fallen on it's face way before WOT. Whatever you have wrong to make you run so lean, it's pretty major. Maybe smaller injectors than what you thought were installed? If it were the fuel pump, pressure regulator or an injector (or 2) that wasn't working correctly, your AFR would probably get leaner as the RPM's rise. Weird.

 

holy sh*t you in low-mid 13s whats the specs on the car ?full interior or gutted?sorry to get off topic

 

im pretty sure he ment low-mid 13 AFR ...not low-mid 13s 1/4 mile...

 

intake air temperature sensor accurate? what is it reading according to the palm? I'm not sure how warm it is out there, but I would expect it to read anywhere between 100-120 F. If it's reading over 140 I would begin to question the accuracy of the sensor. A hot IAT reading will lean the mixture out when it's not under O2 sensor correction.

One more thing. When I had my CAS advanced too far the ECU inexplicably leaned the mixture out under WOT. Do you have a matched crank pulley and hub with accurate timing marks? Is the timing correct according to the light?

 

I meant AFR, not 1/4 mile time.

 

I just got the RTEK in a couple days ago, and haven't logged the air temp yet. I will next time I get on the road. I would expect temps in the 100-120 F range as well.

I have not checked the timing with a light, But it was checked with a light a couple months ago when it was smogged and it was correct.

The RTEK is reporting the timing as 5 leading and 20.5 trailing, which is basically spot on.

 

my bad i re-read it again,, sorry

 

No problem!

 

back on topic did you get a stock replacement or aftermarket pump?

 

I got a stock replacement because it was cheap, but still waiting on it to arrive. I am going to check my fuel pressure this week and see if it is indeed the pump.

I will be putting in a Walbro in the car anyway because I plan on an LSx swap later in the year. I may just go straight to that and sell the pump I have coming if mine is bad.

 

What exhaust system you have? Port air still feeding the exhaust air? Do you have the ACV or air pump at all?

 

There shouldn't be any Port Air when under load if the thing is working right. When you floor the pedal the Relief solenoid should de-energize and dump the airpump air out the side with no air going to the Port Air.

So maybe Spike has a good point. Fully heat the engine up. Then at idle pull both the vacuum hose off just above the ACV. One at a time. At idle both should have vacuum. If you pull the electrical plug off the Relief solenoid, one of the vacuum hose should lose vacuum AND air should dump out the large metal nipple on the side of the ACV. Engine has to be up to temperatures for this check.

I forget right this minute which of the two vaccuum hose is from the Relief solenoid. Relief solenoid is the one with the Blue connector on it.

 

I have an OBX header, no main cat, and a catback. There is no split air pipe on the car right now. The tube that would feed the split air pipe is plugged.

5th and 6th ports are wired open. The air pimp is still on the car, but currently serving no purpose.

 

Is the ACV still connected to the airpump? And does it still have the belt on the pump?

Split air pipes feed the converter and don't influence the 02 sensor in anyway. Just FYI.

Airpump air goes to the ACV and the ACV feeds that air thru the housings to the exhaust ports which are prior to the 02 sensor and therefore influence the 02 reading. But shouldn't feed air to the exhaust ports if the pedal is to the metal and the ACV is functioning right.

 

I see. I knew that about the split air pipe. I'm running my wideband off the stock location on my header.

Yes, the belt is still on the air pump. The ACV is that tube that goes between the 5th and 6th ports correct? All that stuff is still connected. Is that why I see higher than 14.7:1 AFR while cruising sometimes?

What kind of injector duty cycles do you see on your NA car?

 

No. The ACV is a block of metal that the large hose from the airpump goes to. It's held on with three nuts. If removed you'll see a round, spoked check valve about the size of a silver dollar. The air passes thru that spoked check valve and goes to the sleeves in the exhaust ports and mixes with the exhaust gases. That is prior to the 02 sensor. That causes the afr to read leaner at idle and in some conditions while driving.

IF you put your foot to the floor, the relief solenoid stops feeding vacuum to one of the areas on the ACV which in turn makes the airpump air dump out the LARGE metal nipple on the ACV that faces the feder area. On a stock car that large nipple has a hose on it and that hose goes to the right front fender to a silencer (small muffler) near the washer bottle.

Do yourself a favor. Remove the airpump belt and go for a ride and see if the afr's are richer or not. But if the ACV is plumbed right, the same effect can be done just by removing the BLUE connector off the Relief solenoid. That act on a functional car will make all the airpump air go to the fender instead of the exhaust ports.

Do this. Get the engine fully warmed up. Observe your afr's at idle. Now remove the BLUE connector off the Relief solenoid. The afr's should go richer if everything is plumbed right. You can leave the airpumps belt on when doing this. Write back what happened.

Remember though, when the engine is/was under load, the airpump air should have been dumped overboard instead of going to the exhaust ports on the engine. That's why I never mentioned the ACV and airpump before.

EDIT: The ACV on that engine is for a turbo, but the non turbo is located in the same area.

 

Yes, all of that is still on the car. I will try that today and let you know what happens.

Correct me if I am wrong, but if something is wrong with that system, I might see leaner reading on my wideband, but the car would not actually be running lean.

The car was truly running extremely lean, so I am doubtful that this is the cause.

 

IF it was hesitating a lot during load, then it was really running lean and not the ACV causing the problem under load. The air coming out the exaust port sleeves into the exhaust can't cause a true lean condition (since it's after the combustion act). It can only cause the afr meter to read lean.

But like I mentioned, it shouldn't cause the afr meter to read lean during LOAD anyway. Only at idle and under some light load conditons. And even then, it would only make the afr meter read lean, the engine itself would not be running that lean.

An example is my 86 non turbo. At idle I might very well see something close to 14.8-15-3afr idling. If I pull the BLUE elect plug off the Relief solenoid, the ACV air gets dumped overboard and now the idle afr reads in the low 13afr. The actual afr the engine has been running on has not changed a bit, it's only the afr meter that has really changed due to no more ACV air being mixed in the exhaust prior to the 02 sensor.

Anytime I drive that car with airpump/ACV functional, and I step hard on the pedal, I'm now seeing the real afr........because the relief solenoid will de-enerize when I step on the pedal and cause the ACV air to dump overboard.

Ignore the words on the attached jpg, they're there for another person. But the large round hole is where the ACV sends the airpump air. That large round hole usually has a round spoked check valve in it. The hole leads to the exhaust port sleeves eventually. Just fyi and that's all.

 

Guys,

Sorry, I have been lagging. Haven't checked the fuel pressure or the ACV yet. I do have some more observations.

I think the problem may have something to do with the primary injectors. I have the secondaries set to fire at 3200.

I will be cruising along at 2500-2700 in 4th, the AFRs will be in the 15-16 range. The car seems to randomly jump to 19-20 AFR. You can feel the car loosing power. If I got WOT as this is happening, the car will hesitate and slowly gain RPM, then at about 3000 the car picks up, the AFR comes down, then the secondaries come online at 3200 and the car takes off and goes.

It did the same thing it did before I lowered the injector crossover, just now it is happening at a lower RPM. I am wondering now if it is a primary injector problem, either electrical or if they are physically clogged.

Also when the car is cold and running just on the primaries, it goes lean at times from about 1500 to 3000 while accelerating from a stoplight at low load. This goes away when the car warms up.

I guess I need to tear into things and start checking stuff.

 

Remove the airpump belt and some of your *problems* will go away.