s5 13b n/a, s4 electronics, all in an AE86 and terrible sputter
 

Hokay so. I have an ae86 with a s5 in it with all s4 electronics. It came out of a fc with this same set up and ran perfect. I put it in, wired up all the shit, it starts and idles, but as soon as I give some throttle it falls on it's face. Sometimes while it idles it just dies, like out of no where. WTF is up with that? I timed it, but I didn't set the check connector to ground.

Also, I have a fuel cell with a walboro 255 and -8 line running to a gauge, then injectors, through the stock regulator, then a -6 return. Before start pressure is 54psi, cranking it's ~45 psi, and idle it's back up to 54 or 55. Will this affect my injectors negatively?

I have a stock bosch o2 and an AEM wideband. The wideband is at about 14.5 at idle, but then gets erratic and jumps from 12.5 to 17+.

Please halp!

Sounds like an AFM issue...either a dead AFM or you have not got it plugged in well. The AFM is needed anytime you apply throttle for fuel correction.

hmmmm its it turbo? have you checked vacuum leaks? check cold start system. was the TPS tampered with? if so adjust it according to FSM spec. check and or clean MAF sensor.

Non turbo. All stock s5 with s4 electronics. Tested maf as per fsm and it's in spec. It's dirty as shit though and has been in the rain. There was a vacuum leak, but it's plugged now. The tps was never messed with, but I'm testing that tomorrow.

All grounds checked and I have power to all the pins that need 12v. The coils have power, but the trailing isn't firing, so it's running on just the leading for now. Timed at 10* and holds it perfectly at idle.

Side note, the 5th and 6th ports are tied open with atkins sleeves.

Trailing plugs need to be firing to operate correctly IMO. If someone thinks otherwise please chime in.

Nope. Trailings aren't needed. They will cause problems if they are crossed, though.

Walbro 255 and 54 psi is too much fuel for an NA. But won't cause your issue here.

What do you mean by "timed at 10 degrees"? What gun, settings, marks, pulley are you using? Stock leading timing is 5 degrees ATDC, so put it back to there. Also, there is no mark for TDC on the pulley, unless it's an aftermarket pulley.

Absolutely check the TPS even though it hasn't been messed with and you need to check for vac leaks by spraying something like carb cleaner. Visual inspection isn't good enough a lot of the time.

Update:
Base timing is now set to 5* atdc. It is an aftermarket pulley btw.

It is now running 45 psi at idle.

Wideband is reading between 12.5 and 14 but it fluctuates between these quite speraticly.

Tps and afm are in spec, bac has been removed and blocked off. This didn't change a thing really.

Could the high fuel pressure and non working trailings cause this to run shitty? As soon as I give it a little bit of throttle it backfireslike a son of a bitch.

higher fuel pressure will make it run rich. thats obvious.

At this point, I suggest looking at the FSM (available at Foxed.ca - Mazda RX-7 Manuals) and all the ecu inputs in the "Fuel and Emissions Control Section" Page 4A-30.

What rpm was it at when you set the idle? Hopefully down around 750.

It was under 1k, but I don't have a working tach atm because my trailing coil won't fire, so I'm guestimating.
I have 12v at the coil and a solid ground, but still no spark.

As far as power and grounds, I checked and have 12v at pins 3j and 3i. I have grounds at 2c, 2r, 3g and 3a. Pins x, u, m, and v are to the coils and quadupled check several times by two people.

I'm going to guess that Your injectors are wired up backwards???.
I did a swap..the same Damn thing happened on me.
It Stumped me for weeks!

I never touched the injector wiring. Engine harness was on the engine when taken out of the rx7 (running perfect) and stayed on till I put the engine in my car. Putting a regulator on today and replacing the trailing coil. If this doesnt work, the only thing I can think of is either bad afm (even though it tests in spec as per fsm), tps (also in spec), or a bad cas (even though the car runs).

Unless theres something I'm missing...?

food for thought. stock AFR at idle is usually 13.5 ish or richer. Those who try to adjust it leaner, learn that it simply won't. as 13.5 is the actual afr, but the effctive afr around the spark actually is stratified( rather then homogeneous.) This is a phenomena of the 13b.

Also, have you done the simpler things, like ohm out, or check the tps for 1v on the green wire. either method gets you close enough.( said the AFM and tps is in spec, but are the signals reaching the ecu,-test at ecu connector)
or sprayed starter fluid everywhere while at idle, to double check for leaks?
does it high idle when cold, and slowly drop?- see therowax system on the throttle body

did you remove the injectors at all? maybe they're not seated fully?

A friend and I took the upper off to plug the oil injectors. The gasket looked great with no tears or what have you, so we kept it there. Gasket had about 20k miles on it. I thought it might have been leaking so I sprayed the piss outof it with some brake clean, but with no effect.

I will have the upper fuel rail off later today to take the regulator off and have a nipple welded on, I'll double check when seating the injectors.

Haven't thought to check the afm and tps at the ecu. Will do that tomorrow.

The thermowax has no vacuume running to either nipple, is this an issue? It has also been replaced with another one. The idle did not change between cold start and when warm, but it is florida lol.

As far as the afr goes, I'd be happy if it was even constant. But the only time it shows any stability is at 12 to 12.5. The rest of the numbers are when you rev it up a tad. Sputtering, afr all over the place, and occasional backfire. Basically runing like shit. At idle it runs almost smooth. Rich, but fairly smooth. Still feels sick though...

Injectors checked, seated correctly. Checked lim to uim gasket and it's fine, double checked all vacuum nipples were capped. Also capped the brake booster nipple. Added an areomotive fpr and the fuel pressure is steady at 36-38 idle.

Still stumbles. Heres the current symptoms:

>wideband all over the place including off the charts lean to 11.8

>idles kind of rough

>trailing spark doesnt work

>timing mark is speratic when timing at idle both with the base timing connector grounded and not

>when given any throttle it runs extremely rough and sometimes stalls.

trailings are not Needed? I would have to not agree. i tried it. Runs like garbage. Pig rich hard to start

Not quite a stock s5 13B....but something to keep your eyes on the prize nonetheless!! ENJOY!