Tuning my RB20?

[craz4240]

Sorry a bit long winded....

Well it's been about 4 pain staking months with my rb20 powered s14.

Anyone who hasn't followed along basically I had a real botched wiring job...which I had fixed in July. Long story acoided found out the ecu was bad,bought a new one,had it shipped to someone to be tuned,bought a wideband,Z32 MAFS,threw on a custom turbo,and Installled the 6 195500-2020 Series 5 RX-7 injectors.

Now were all down to a properly enriched idle and how to achieve it.The K constant and fuel tables on the tune seem almost perfectly spot on under load and boost,however I have an incredibly lean idle 22.4:1 to be exact and the car seems to have a miss in this range.Also idle was way high like 1500-2000 rpms when cold and about 1.2k-1.4 when warm.

I have,cleaned the mafs,TB,IAC valve and adjusted my idle switch as per Carl H's advice.Idle is now down however i am still very lean and when i let off throttle the motor decels fine but right before idle it cuts out and then goes into the loppy idle as well as lean.

Now I am no tuning genius but i have been trying to learn what I can,that being said the settings within my ecu program seem to be right......lag time is 60 hex and k constant is EC hex.The only time I could get the idle close to being stoich is when the lagtime was set at 163 decimal.....when doing this it still doesn't 100% remedy my low throttle issue......does anyone have any ideas??

[craz4240]

Wow trials and tribulations...what a pain I have had with this car.Tune after tune thanks Carl!!boost run one after another,set of plugs after plugs.....all to no avail.

Made no sense theoretical AFR's were set perfect.....k constant was set right and lag time was as it should be, but idled 22.4:1 AFR SUPER LEAN!! And was going somewhat rich under load as well.Haven't driven the car since July and it's almost time for her to go to rest for the year.

After tune after tune I came to the conclusion that my issue may be resorted to mechanical....and god knows my wiring was perfect...:P.Previously I had used brake clean to search for vacum leaks with no luck hoping it was something that simple.Those who don't know how to do this well you simply let the car idle while doing so spray areas that may leak air creating a loss in vacum ie:around intake runners,intake plenum,iac valve,throttle body and all vacum lines: when you find a leak the idle will rise momentarily it's that simple.I sprayed everything and had no change in idle at all so oh well no vacum leak.

I got thinking "Ok I cleaned my IAC valve out (absolutley a good idea even if you don't have an issue) cleaned the throttle body,check CAS position,sprayed everything,maybe the MAF is dirty or I have a stuck injector". I took the MAFS to work and cleaned it with a good air intake cleaner DO NOT USE CARB CLEANER!! carb cleaner will leave a residue on the sensor wire making it malfunction and spray gently. Also whilst doing this I had great advice from Carl H on setting the idle switch also the tps (they are all in the same unit),basically pull the plug off the TPS body,on the body will be the terminals in which the plug,plugs onto set your multimeter to OHMS put one lead on each of the terminals which the wires of the plug go to you should have continuity with the throttle plate closed if not loosen the screws on the tps and adjust it till you do,now with the leads still on, open the throttle plate....you should have no reading at all in a manual car.So I reinstall the mafs,had the idle switch set and was hoping the car would run good....now if it didn't plan B was to tap on the injectors to see if I could loosen a stuck one.....this stuff helped some issues however did not solve my lean running issue...DAMN.So I conversed with a few ppl and while doin this we came to the conclusion that yes I indeed have a vacum leak somewheres(basically Carl just plain out told me heheh)....BUT where?? I already did what I thought was a thorough test for vacum and came up short.

Got the idea that it couldn't hurt taking the car to work and running a smoke test on the vacum and intake system.....I must say this unit could have saved me soo much time in the beginning I found a suitable sized vacum line for the smoke fitting and stuck it in,turned it on and commenced test.Turns out the brake clean test alone wasn't sufficient enough I had 2 small leaks comming from the T between my AAC valve and IAC valve and a very large leak coming from the inlet area of the AAC valve...trick on this was that the leak is on the bottom hence not getting hit with brake clean spray.So I fixed the leaks on the T cause they were easy to get at,however I have to wait till tomorrow to fix the main leak as I have to remove the upper plenum once again.

I was curious though if this was indeed my issue so I started the car up and let it idle,sprayed a good amount of brake clean where the leak was found and the idle went up.Well I was satisfied but i wanted to see what affect this had on my AFRS down low.Had someone watch the wideband while I sprayed the leak....AFR's went to perfect 13.5:1 just what the ecu is set for.So looks like we have found the problem.

Tomorrow I will fix this and update...as well we are getting down to the dyno before the car goes away for the winter now....after all this hell i need some numbers.

[turbocrisper]

is your pcv valve still hooked up and drawing air through the engine. if so and the other end is not hooked up after the maf than that could be un metered air going in at idle.

[craz4240]

PCV is hooked up and running fine...check above problem solved... Thanks for the input.

[craz4240]

Guess I got ahead of myself replaced AAC hose with a generic one I had here now my problem is the same....Idle is great idle screw works...however if the aac valve is restricted from air what can this cause?? the new hose wasn't exactly a proper shape so there is a small kink in it,will this have the same effect as a leaking AAC??Also still running 22.4:1 AFR under idle...:S
Modified by craz4240 at 1:21 PM 10/28/2007

[craz4240]

Anyone have any input....I have replaced a broken hose on the aac valve and it doen't seem to be leaking now...however I seem to have a leak underneath the aac......how often does an intake manifold crack???Not gonna get the car running this season properly but I'd ike to pick at it over some time.

Also anyone know where I can buy good or factory replacement hoses for an rb20?

[Vkoslak]

I have a rb20det with the same injectors. However mine is doing something different than yours and our tunes are quite a bit different as well. What mine will do is run rich most of the time(especially under load) but ever so often while sitting at a stop light it will lean out to the point of stalling.

As far as your leak goes, could it be possible that your gasket for your aac valve is the source?

[craz4240]

We actually have the exact same problem it seems as after the car warms up it no longer just runs lean but it also wants to stall under idle.

I dunno I have to get time to build a leak tester I guess as the smoke tests haven't pinpointed the issue.

[Yellow4g63]

Did you try and install a new fuel filter? Well you should have anyway since you swaped in the motor.

[jdmser]

Can you guys list you're setups and what you've changed lately. We all have the same problem and there has to be a common denominator. Mine never did it until after my last round of mods. Over the summer I did tomie cams and springs, q45 maf, emanage blue, chip from Carl, port and polish head, and 720cc injectors with dropping resistors. I also have the lm-1 feeding the o2 analog signal.

[craz4240]

Well my mods are as follows, Custom Built and bored rb25 turbo,Denso Series 5 RX-7 550cc injectors,Z32 MAFS,GTR FMIC, Innovate Wideband, New ECU tuned by Carl H (multiple times I might add lol sorry bro!!),3" turbo back exhaust,and I think thats it.

I am pretty certain all of us have an air leak pre-throttle body.I have to get time to build a leak tester and check mine,I have used smoke but it's not accurate enough for me.

Check for leaks boys and post up what you find.

Yellow I have indeed changed my fuel filter but it may be due for one again soon,I forget the milage they are good for.

jdmser have you recieved your new tune yet?? I know our common denominator is the tune but it's not that theres something else......I am almost leaning towards the extra boost blowing a hole somewheres and causing us both air leaks.

[jdmser]

I haven't got the new tune yet but, it should be here soon. I have checked for leaks and found a ton of them in the intercooler and piping. I had a kid that works for me tig the piping up and his Dad did the intercooler and that fixed almost all of the leaks. There was a small leak in the intercooler and I was getting the same results. Once it got warn in would lean out and stall. It did however fix the surging at idle. I just finished mocking up a new fmic and will let you know what happen this time around.

[craz4240]

I am thinking that possibly my GTR cooler might be doing the same...I am gonna pressure test it asap.Let me know what you come up with.

[Vkoslak]

I would have to buy or borrow a decent air compressor before I could seriously test for leaks.

Anyhow, my mods since you asked, (engine related) z32maf, rx7 injectors, nismo fpr, j30 igniter, koyo racing radiator, hks gt2530 turbo, blitz electronic boost controller, apexi bar and plate fmic, custom ic pipes, chipped ecu using a tune that I got with the z32 maf and injectors and then customized myself using some advice from Carl H.

I have a wideband o2 in the car.

I tweaked on the tuning a little bit this weekend, and I have it running better. Tonight I drove the the grocery store, did my shopping, and when I got back in the car (maybe 30 min), it wanted to stall.

I was thinking it was something related to the idle air control.

I have heard that the spray pattern on these injectors can cause it to do weird things at idle.

[craz4240]

I have the same injectors as you and same issues....the rx-7 injectors are sparatic at idle but should be much more driviable then what they are for us.I'm calling huge air leak or tuning issue with our problem.

[Vkoslak]

If I hadn't modified my wiring harness to fit these injectors, I would try some different ones.

I have a rb25det fuel rail with 370cc injectors. But they no longer fit my harness and I don't feel like hacking it up a second time on a hunch. Plus it would be smaller injectors.

BTW, my current K value is DA. I am using 60 for the latency setting.

[craz4240]

K value is EC and 60 lag here as well.

[jdmser]

Are you guys using the analog signal from your wideband also?

[Vkoslak]

My wideband doesn't have a narrow band out. I'm just using a normal o2 sensor for the ecu.

Someone mentioned fuel filter. I put in a z32 fuel filter when I put in the rb20det.

[craz4240]

O2 feedback is turned off on mine...i run strictly wideband.

[jdmser]

I finished up putting on the new intercooler. I let it idle till it got hot and the afrs stayed in the low 12s. I had the idle turned up to keep it from stalling before so I started to turn it back down. While I was doing that the afrs went way lean again but, this time right before it stalled out it caught it self and went back to the 12s and continued to idle fairly well. Only thing I don't like is that the vaccum goes real low when it gets hot.

[Carl H]

cams will drop vaccum to nothing, its normal.i'll have your chip out tommorow with anyluck.

[craz4240]

I finished up putting on the new intercooler. I let it idle till it got hot and the afrs stayed in the low 12s. I had the idle turned up to keep it from stalling before so I started to turn it back down. While I was doing that the afrs went way lean again but, this time right before it stalled out it caught it self and went back to the 12s and continued to idle fairly well. Only thing I don't like is that the vaccum goes real low when it gets hot.

Keep us posted to how things go man.

[jdmser]

Well, the fmic didn't fix the idle but, I can blow the tires off at 5500-6000 in 2nd at 15psi. I can't wait for 20.

[craz4240]

Same here lol My 2nd gear response is out of this world at the same rpms and same boost

I wouldn't drive it with the lean idle though mine was going so lean the plugs were starting to mushroom.

I had no time or cash to get a leak tester made this week gonna have to be next weekend,my cars about 2 weeks away from going away for the winter so hopefully this gets resolved b4 then...:s