DJGeQue

Setup:
88 10th AE
Rtek 1.7
720 secondaries
New FPR
Streetport
Less than 100 mile on rebuild
Spark plugs are new (but I have already had to burn them off twice from being so rich)


Ok.. So the problem is as stated in the title, the car runs between 10.9-11.3 AFR (.75-.77 Lambda). This is at 1900 rpm idle (i think this is due to the tps). The car also seems to be missing a lot.

What is a general check list of things to go through if you car is running rich?

*Also I was told that if the car is running rich it means that you most likely don't have a vacuum leak, is this correct?

88t2romad

for the 1900 rpm idle, check your throttle cable, and throttle body. That rpm on idle tells me your throttle plates are not closing all the way.

well uhhh

you need to set your idle before attempting a tune. you also need to set your tps. so do everything you need to do to set a solid idle and try again. it is running rich because you have too much fuel (obviously). once you have a good idle, then you can lean out with the rtek. as far as not having a vac leak, running rich is not a dead give away but it is an indication.

For the record a REX is a microcar produced by subaru. Not an rx7.

Aaron Cake

iTrader: (1)

That idle RPM is way high. High enough that the ECU is ignoring the idle mixture screw.

Is your new FPR an OEM part? If it's an aftermarket adjustable FPR, then adjust it to lower pressure to factory specs.

Aside from that and obvious mechanical problems (vacuum leak, bad ECT, etc.) it may be the RTek. I don't know enough about the RTek to comment on that as I prefer real standalones.

I Hate Ricers

Hi, I'm the OP's friend and we've been working on this car for a while now.

Some updates:
The idle speed is always around 1800 RPM with the idle air speed screw all the way, and with the mixture set at full lean, we're still way too rich.

The coolant temperature was tested and is working well.

The car hovers around 10.8-11.5 to one AFR almost all of the time. We see high 12's under boost. Car has flooding/spark plug fouling issues.
We adjsuted what seems like a fully functioning TPS to the FSM specs, yet when installed in the car, the idle bounces. Only way to get the bouncing to stop is to fiddle with the throttle plate screw.

The o2 sensor has been disconnected ever since we put the rebuilt engine into the car, so we found the wire that goes to pin 2D and hooked up the o2 sensor directly to a cut wire (brown shielding, black color inner wire, o2 sensor right?) that ends near the BACV plug. This certainly did not effect mixture at 1800 rpm, but we haven't gone for a drive yet. Maybe the o2 sensor needs to be replaced still.

The timing was set a few months back when the car would idle at 900 rpm.

What else should we check to get the car to run leaner/avoid flooding?

Aaron Cake

iTrader: (1)

Find out why the car is idling at 1800 RPM. That's 75% of your problem.

High 12s under boost is way too lean.

The O2 sensor is not used to adjust idle ratios. It's only used for steady state cruise.

Sounds like you have a massive vacuum leak somewhere. How much vacuum does the car pull?

arghx

iTrader: (3)

fabricate (or purchase) a pressure tester like the universal tester sold at www.boostpro.net/prodtester.html to locate boost/vacuum leaks. Make sure your throttle and cruise control cables are within the specified level of freeplay (1-3mm per the FSM). What idle control equipment is still on there? BAC? thermowax/fast idle cam?

And the car will probably not idle much leaner than 12.5-13:1 on the Rtek. Mine idled at 12.5:1 with a big streetport when I had the Rtek 1.7. Rotaries idle richer than a piston engine, that is why they have a smog pump to inject air into the exhaust ports for emissions purposes.

Also have you rewired the fuel pump? You need to verify fuel pump voltage or it will lean out under boost no matter what.

I Hate Ricers

Hi,

Sorry, I forgot to mention, at 1800 rpm, there is 15 lbs of vacuum. Max boost seems to be about 11 psi - this is with stock turbo and not cat or cat-back. Eventually that will go on, should bring the boost creep down, no?

Why were you guys assuming vacuum leak? If the car is as rich as it is now, it wouldn't run if it became richer from fixing a vacuum leak.

What else should I do to try and fix the idle? Does the ECU have a fail-safe mode from too many sensors being faulty? I think the next thing we'll do is make the checker and check for error codes, but that probably won't be for the next few days.

The fuel pump is an FD unit. I believe we just plugged it in and no wiring was done, could be wrong. This car is an ongoing project..

Thanks so far, and keep the input coming please!

SaabGuy

You sure you didnt swap the primary and secondary injectors on install?

wrankin

Read the other posts. You have an air leak somewhere. As far as I know, there is no way you are 1800 RPM at idle with the throttle plates fully closed unless you are getting air from somewhere else (eg. a vac hose, a bad intake gasket, etc).

Have you checked the throttle linkage? Are the plates closing completely?

It is likely you have multiple issues. Find and fix the idle issue first, you can't do anything about tuning the AFR until this is settled.

Btw, 15-in of vacuum at 1800RPM is meaningless. if you didn't have a vacuum leak and the throttle plates were closed, you would make 20+ in (like when you are at speed and lift).

Actually, so it isn't meaningless. Find the leak.

-b

arghx

iTrader: (3)

15 lbs of vacuum at 1800 rpm doesn't mean anything really. I make 15-16 lbs of vacuum at a 900rpm idle, and that's with a big street port. A stock motor with no porting will make 16-18 lbs at a 750ish idle.

You need to verify that there are ZERO vacuum/boost leaks anywhere. It's just part of a logical troubleshooting sequence. It has nothing to do with whether the car is rich or lean or whatever. If it's not causing an idle problem, it's causing a loss of power. This has to be verified. Do not assume and do not skip this step. After fixing misc boost leaks I can test mine to 15psi before the tester flies out of the intake from the built-up pressure. This is a high priority diagnostic test and it doesn't cost much money or time.

You also did not answer the question: what idle control systems are on the vehicle? BAC? Thermowax etc? We can't help you if you don't give explicit information. Also, Boost creep is a function of exhaust restriction and the size of your wastegate. You MUST port it, you can't skip this step if you have a full exhaust system. Aaron Cake's site has a writeup.

You need to rewire the fuel pump. I just cut out my stock resistor relay and ran straight juice to the pump through a new relay, others relocate the resistor relay to retain its low and high voltage arrangement. There are writeups about this wiring stuff. Once again, it HAS to be done or you are risking a dangerously lean condition. Skip this step, your motor eventually blows in a lot of cases, no matter how big your injectors or high-flowing your fuel pump. This is a HIGH PRIORITY MODIFICATION.

You also have not said what you are doing for your FPR. If it is an aftermarket unit, jumper the yellow fuel pump check connector with the key in the on position (engine off). Set the base fuel pressure to 36psi. Did you set the throttle and cruise cable freeplay? If you really want to be sure about it (and given your idle troubles, your cables should be set very precisely), put a piece of masking tape on the cable and use a dial caliper to just eyeball how much play is in it. Should be 1-3 mm freeplay.

HAILERS

I think you need to put about a 1000 miles on the engine. Hundred miles isn't much of anything. Well, at least five hundred miles.

AreExSevenProject

iTrader: (1)

check to make sure your MAFS is level. One way or another can make it rich or lean.

I Hate Ricers

He has an S4, so it has an AFM. Is that what you mean?

DJGeQue

I am back with more info...

To answer your questions...
-The FPR is OEM so i can't adjust it.
-With the throttle plates fully closed it doesn't idle at 1800 it will go lower but 1800 is as low as I can go without having a bouncing idle. I understand that the TPS is the leading cause of a bouncing idle but mine met the specs of the FSM. It is not a new TPS (would you opt for a new $190 one, if it meets the specs?).
-As far as the rewiring of the fuel pump. Is this still necessary with the built-in fuel cut defensor the rtek has? I am just not sure if it serves the same purpose.
-The idle control systems I still have in place are... Thermowax, BAC... I actually don't know what other ones fit in that category so if you could let me know..

I think that answered about everyone's questions. I believe it all still points to like you guys are say that i need to lower my idle. Which I am guessing means buying $190 tps even though my tps meets the fsm specs? Let me know what you guys think.

Thanks for all the help

Turbo II Rotor

iTrader: (2)

Did you test for vacuum/boost leaks yet?

HAILERS2

You need to find the LARGE air leak on the other side of the throttle plates. Eighteen hundred is not a idle. Playing with idle screws/bac screws, TPS screws etc do nothing at all. Can't do anything with the engine speed of eighteen hundred.

Injector lower grommets hard as a rock, hose off the rear of the thottle body, hose off the front of the throttle body, something b/t the upper and lower intake manifold, small line off the intercooler itself. Stuff like that. Or the throttle plates are NOT fully closed.

Plus timing cannot be set with a timing light with the rpms over 1100 rpm.

If you disconnect the TPS will the idle go lower and stay lower with no bouncing or not.

http://www.teamfc3s.org/info/articles/idle.html

2-N-D-pink

iTrader: (27)

Ok, so once you get below 1800 rpms the idle just bounces?!

What are you using to calibrate your TPS? How do you know its to the FSM specs?

DJGeQue

Yes once I turn the screw on the throttle body to lower the rpm past 1800 the idle just bounces. I tested it with the Om/volt meter like it says in the FSM.

I will try playing around with the hoses. The injector grommets are new. The timing was set when the car was idling properly. I don't know what happened but the car was idling and running just find and well now it doesn't. Would the car really be this rich if I am looking at a massive vacuum leak

arghx

iTrader: (3)

I'm going to ask one more time.

DID YOU PRESSURE TEST FOR VACUUM LEAKS???

HAILERS2

If I went out to my car, and sat in the driveway and rev'd the engine to eighteen hundred, I wouldn't be surprised to see eleven afr. I might do that later today.

Why not just disconnect the TPS and then lower the rpms below eighteen hundred to see how things are? Takes but a minute or so. TPS isn't required for starting or driving. I'd do that. Then find the large air leak. Use starter fluid to spray connections etc and listen for a change in rpms as you do that.

DJGeQue

How does one pressure test for a vacuum leak?.. I am going to try the spray method today. my car reads 15 lbs of vacuum at 1800rpm but i think we already established that does not mean anything. If disconnecting the tps stops the idle from bouncing i will post the updated vacuum reading at idle.

arghx

iTrader: (3)

I mentioned this almost two months ago... you could have determined whether you have leaks a long time ago

DJGeQue

You know I passed over that idea, but your right that what i need to do and will do. Will that Single Pop (Gauged) with Tire Valve Adapter work on the RX-7 or is that strictly for the Z32? If it doesn't do you know of one I can buy that fits the rx7?


Something else I noticed since last time I posted is that when the TPS is disconnected I am unable to lower the idle with the idle screw (the screw on the throttle body assembly, close to the tps).

arghx

iTrader: (3)

get the one that says universal tester at the bottom. then depending on your air compressor etc choose which one you want. I got the one with the male compressor fitting and no gauge.

you can also make this out of home depot stuff, I just didn't bother though