86 RX7 TII conversion wont start.
 

Hello everyone,

I have tried to search for answers but I have not found anything that helped.

I have a 86 n/a that i recently put a 87 tII motor in. converted the NA harness to work with the N332 ecu(cut PIN 1R, 2K, 3D) TII AFM, TII Boost sensor N370. Emissions removed, still have the BAC. I have spark, and fuel but i cant get it to stay on. so here is what happens. I time the motor (yellow mark on crank, notches on CAS), go to start it and it will start for like 2 seconds and get to like 3k rpm and just die. it doesn't matter if i hit the gas. Then if i try to start it again it will crank and sound like it wants to start but it just wont. If i take the CAS out and spin it by hand it sparks and burns what ever fuel is in the the motor and it does about a full rotation. then when i re time it it will do the exact same thing. im stuck in a constant loop right now. Im sure im missing info that will help you guys understand so just let me know what else you guys need. Thanks

Hard to say what's wrong with your setup. Why didn't you use the harness designed for the TII engine?

FYI -- Atkins Rotary still sells these harnesses (https://www.atkinsrotary.com/store/8...2-18-051K.html)

I heard its easier to use the NA harness because you have to adapt the TII harness to the harness in the front of the car

Converting the NA harness is indeed easier than switching over to a TII harness. Some pins don't match and others don't exist on the other harness.
My setup in terms of wiring is exactly the same as yours.

Have you checked if the flap in the AFM moves freely?

It shouldn't be able to enrich to the point where the car floods, but turn the idle mixture screw all the way to lean and see what happens.

Adjust TPS/BAC.

Gonna be a fun one to diagnose, lol

haha yeah i know thanks for the advice. i messed with the idle mixture scew but still nothing. afm moves freely its brand new/reman. TPS is set to 1ohm and i will try the BAC. im going to upload a video if it lets me.

Sorry about the camera angles lol. Every time i get it to where it wants to start its right after i deflood and re time it.

update. 3k if im lucky. mostly its under 2k

Switch the primary injectors with the secondaries.

I have a feeling one of your injectors is leaking/stuck open.

Ill Check them out tomorrow. thanks. do you also think maybe i could have put the injector connector on the wrong injector? i cant seem to find a write up on which connector goes where but as far as i could tell they can only go one way because of the length of the wire.

sweet. thanks a lot ill let you guys know how it turns out

The S4 tii ECU like all the S5 cars has a fuel pump resistor relay. Your chassis being a S4 N/A never had that, did you add one or are you bypassing it(switched relayed battery voltage to pump)? It seems like the car is only starting on whatever fuel is in the system from the pump priming.

Also your car being an '86 model would have the low ohm injectors along with the resistor box, '87(the engine your using) is a mid model year change where it could have either low or high ohm injectors. You should have around 11-14ohm of resistance per injector, that either the injector on its own, or a low ohn injector + the resistance of the injector box. If you have the high ohm injectors and still have the resistor box from your '86 N/A harness you need to bypass it, if you have low ohm Tii injectors in it ignore that part.

^^^That's an excellent theory. It would make a lot of sense that the injectors would not work properly or at all if the resistor box was still being used.

I would have just swapped in an entire TII harness and ecu. For me this would have been much easier as all of the wiring would have matched and be plug and play. No de-pinning and or shortening or extending any wiring. It takes maybe an hour to pull the dash..you could have just laid the entire TII harness in half a day and have no guess work in diagnosing issues. That's just me though.

I have the low imp. Injectors. I'll have to look into adding the resistor relay or just hard wire the pump for testing.

RotaryRocket88 said in his s4 TII swap guide that

"Pin 3D is for the fuel pump resistor/relay on turbos, but is unused on manual NAs. However, on Automatic NAs, it runs to the inhibitor switch. But lets face it, no ones converting to turbo and using an AT transmission https://www.rx7club.com/images/smilies/smile.gif. So the wire at this pin can really be ignored in most cases."

so i dont think it would be a resistor/relay problem. but i also cut that wire so maybe ill try re attaching it. if that also does not work ill try to just wire the pump to a 12v and see it i can get it to run.

Are they not compatible with each other? Ive never messed with a S4 Tii so i really dont know.

Not interchangeable, they are not even wired the same way. That is why the FCDs for the S4 and S5 are different.


https://cimg0.ibsrv.net/gimg/www.rx7...44fa6816b3.jpg
https://cimg4.ibsrv.net/gimg/www.rx7...b6d53a6005.jpg
https://cimg5.ibsrv.net/gimg/www.rx7...080a1e9a8c.jpg
https://cimg6.ibsrv.net/gimg/www.rx7...1b1887ad83.jpg

So you think this is why I cant get it started?

It is not helping your issue to have the wrong parts on your car

Thanks to all that have posted. I will try these this Wednesday or Thursday when I have the time and let you know if anything comes of it. Unfortunately my boost sensor wont be in for a while so I'm at least hoping to get it started with this one. I will see how it goes.

Hey everyone

so i switched my primary injectors with my secondary injectors and made sure all the wiring looked good. had to strip them pretty far back to actually see some wire colors. After i did that i re timed it and attempted to start it. it turned on and ran for about 35 seconds. longest i ever got it to stay on. after it died to tried to crank it over again and it wouldn't start but it sounded like it wanted to more then before i switched injectors. i did not play with the idle resister switch or the BAC because it started raining. do you think my next step is throwing a timing light on it? do i have a vac leak? I cant really do the brake cleaner or whatever check because i cant keep it running long enough and Iv been over the motor so many times and cant see any loose wires.

Unplug the boost sensor or temporarily install the S4 NA one. See if it helps.

DO NOT DRIVE THE CAR WITHOUT THE N318 SENSOR.

I'd figure out the resistor situation for the injectors as well.
Note: If your NA injectors are low impedance and your TII injectors are low impedance, there's no changes to be made.
When I did my swap, my NA injectors were low impedance and my TII injectors were high impedance, so I had to delete the resistor pack.

ill see if the s4 na boost sensor does anything. my NA motor had Low IMP. injectors and i replaced them with higher CC low imp injectors.

I've tried 2 remanufactured AFM's from A1 cardone before and both were bad. I've also heard from others that the remans for s4 TII's have been bad and I'm currently using the 30+ year old one. If you have the original AFM or know someone that has one switch them out and try.

yeah i also thought about that. maybe its a bad reman. ill try putting my stock s4 NA boost sensor in with the stock AFM just to see if i can get it to start. Dont worry im not gonna drive on it. haha

Hi everyone,

So i put my NA AFM and Boost sensor back on, re timed it and turned the idle resister thing to all the way lean. After holding the throttle down about half way it started. With the pedal halfway down it was about 2.6k rpm and wanted to die if i completely let off the pedal so i had to slowly easy off of it. after it started warming up it idled at about 1.2k. While i let it warm up i made sure the coolant was full and did a few little other things. gave it a few little revs (under 3k) because i dont wanna push it not running the correct sensors. turned it off then had the same problem again where it sounds like it wants to start but wont. ill post a vid of it running a little later so you can hear it and tell me if she sounds okay.

yes i know i have an exhaust leak right off of the turbo.

Yeah I need to check compression. But I'm having issues with hot and cold start.

I figured it had to do with the over boost fuel cut differences between S4 and S5. Well good to know.

so today it started no problem. me and my brother timed it to the yellow mark. i think i just need to wait for my new afm and my boost sensor now. If i shut it off i need to clear all the fuel out of it by pulling the egi fuse and cranking it then it will start right back up.

So i got the n318 boost sensor and AFM and it starts up a lot better. still have to hold the gas down for a min until it can idle on its own. i dont think my BAC is adjusted correctly. was gonna take it for a slow drive around the block but forgot i need to do my brake booster line first. good thing i remembered hahaha

Did you ever add resistors? Or do you have oem resistor packs?

my car came with the low IMP injectors originally and since i used the factory harness i kept low IMP injectors with the new motor.

I had a pretty rad hot start issue when I first did my swap. Early model 87 TII engine into an 88 convertible, modified the stock N/A harness and wired in resistors for the injectors. Also rewired the alternator so the cluster lights wouldn't stay on.

My hot start issue was solved using this thread:
https://www.rx7club.com/2nd-generati...oblems-499744/

I put a switch on this wire in the glove box, so I could toggle it. Cold starts no problem (as long as the damn battery isn't dead) and then after driving around for a while I can flip the switch and crank it. Haven't gotten stranded anywhere yet. This was after I had determined that the compression was fine and I had sufficient fuel and spark. This one wire thing did the trick for me.

Just a quick question: Did you remove the blind cap from the CAS when you timed your engine?

if u mean the cover on the CAS with the 2 screws. then yes. i also marked it when it was timed. after the correct boost sensor and AFM was installed the car runs pretty much as expected now except that its burning some oil.. I didn't rebuild the turbo so im just gonna start with that before i end up tearing the motor back down to check the Oil control rings..