ECU code 21 on my s13 sr

[silverarrow27]

I've been having this dreaded problem with this error code 21 which is ignition signal when cranking/starting. I've searched and found that the usual culprit was the ignitor chip; replaced it with a known working one from my brother's s13 and drives/idles the same. Other parts I've swapped in to test already are ecu and coil packs from my brother's running car. Also redid timing and have it at 15 degrees.

This is on an s13 red top sr20det in a 91 240sx coupe. I bought the harness from some guy in the north midwest that had already rewired the harness to an s13. When I received it..looks like he had done a poor job of and I had to rewire it myself in order to get my sr fire up and run. I noticed at the time he had for some reason used a ka tps plug instead of the sr tps plug and I wired in a sr tps plug. I am running the correct #62 ecu. Double checked the maf and maf wiring just in case and it works perfectly as it came off my younger brother's perfect running sohc s13.

Anyhow the problem has been present ever since I got it up and running with my seized turbo on there...wasn't as bad though. Last week since I've replaced the turbo it seems to have made the problem worst: bucking, stalling, hesitating, etc...I've been through at least six sets of spark plugs(NGK bkr6e gapped to about .28-.31) and fouling them out pretty bad in a day. All covered in black soot, every single one of them. This is my daily driver and getting kinda tired of working on it in this 100+ degree weather.

If I put in a new set of spark plugs in the car idles and drives perfectly for the first couple of minutes and then starts hesitating. If I take it up pretty hard in any gear as soon as it hits about 3500-4000 rpm the engine cuts off and bucks like I'm riding a rodeo horse(feels like fuel cut/major boost leak). Black/gray smoke starts puffing out of the tail pipe like no tomorrow similar to a boost leak even at idle it'll puff some black/grayish smoke out. I've taken off all ic pipes and smic and retightened everything back up to make sure there's no leak. Tightened up my Greddy type R bov as well. All vacuum lines are brand new.

This coming weekend when I'm off I'll be going through the wiring again testing for voltage/ohms to see if everything checks out right per fsm. Just curious...what are the pages as I can't seem to locate it on the s14 fsm that I have on my computer? Other than that, can anyone recommend what else to check on besides the wiring/connectors? Maybe it's the pink injectors on my motor that is causing this??? I know it's suppose to be purple injectors...but for some reason my injectors are pink on my motor(I was assuming it's a faded purple); perhaps been sitting out in the sun too long or refurbished/remanufactured injectors. Any help would be great guys, thanks!

[SiI40sx]

replace the injectors with ur brothers see what happens

[Pepperoni]

You could very well still have a boost leak somewhere. Same thing happened to me. If you check everything and still can't figure it out, let me know if you want a boost leak tester (no Home Depot crap) PM me. Comes with silicone coupler and T-bolt clamps.

[njd07]

had same problem today... got code 21 and was only firing 3 cylinders.

What worked for me:

1. Unplug battery
2. unplug harness from ecu and then carefully reinstall harness to ecu.

worked for me..seems kinda dumb...but always pays to check the little things first.

GL