i would go with the TII harness because its meant for the engine. it'll be less headache in the long run. it is kinda pricey but i guess we sometimes pay for convenience. this way you know its done right and won't question your own work.

have you tested each wire in the harness for continuity? a daunting task but you'd know if there was a break at least. i dont know, i think i'd just replace the harness. i'm just not sold on trying to make jdm stuff work on u.s. spec cars. there's a few differences between the two parts wise and i'd hate to know if there was any difference wiring wise.

 

It's been a while since I updated this, so I completed the modified NA harness a few weeks ago, installation looks much cleaner than the JDM harness, but still the same symptoms, which indicates the wiring is not the issue. After doing a lot of reading in the 2nd gen section I came across something I'd forgotton about, seems a lot of the FC guys have issues with that JDM N374 ECU flooding, not running correctly etc, similar to my problems. Not sure why the ECU would just "go bad" (or 3 of them for that matter) but figured the next logical step was to find a US T2 ECU and try that.
Posted a WTB thread a few weeks ago and finally someone came up with one, just paypal'd him the money so it should be here next week, we'll see how that goes.
I've also been doing a lot of research on Megasquirt (promted by my recent trip to Ohio and talking to Dave's friend Eric) and have decided that if this new T2 ECU doesn't work I'll be getting a megasquirt for this car. Anyway thats all for now, I'll post again once the US ecu arrives.
-Sean

 

keep us posted on how the new ecu turns out

 

Yea will do, since fedex fails at life I won't have it until Tuesday, but I'm keeping my fingers crossed, getting into my favorite timeof year and I'll be damned if I can drive this car for at least part of it.

 

Fed EX is slow i guess. can;t wait to hear what good news you'll bring when the new ecu arrives!

 

Well, other than being able to safely rule out the ECU as the problem there is no good news lol. Got the US T2 ecu on Tuesday and it exhibits the same problems as the JDM ECU. Very hard to start when the engine is cold, runs real rough and backfires like its running way too rich. Similar to the JDM ecu, with the US one I can ground pin 2b and it smooths right out, and the US NA ecu still runs just fine. I again tried my spare NA AFM and no change, although there could be something different in the T2 AFM, maybe I'll pick up one of them and see what happens.
I'm tempted to just run a jumper to pin 2b and ground it and just run it lol, but something tells me I'll regret it later... Anymore ideas anyone?

 

what kind of injectors are you running? have you tested the fuel pressure regulator? have you inspected teh crank angle sensor?

 

Really weird. I would try taking a piece of wire and sticking it in 3A, 3B, 3C, and 3D (one by one) with the other end grounded. It might be a bad ground somewhere. Not sure why the NA ECU would work okay, but perhaps the NA is different on what parts of the internal circuitry are tied to what ground.

When you say ground 2b, you mean with the meter (+ at pin, - at ground) or directy grounding it?

 

Right by ground I mean through the meter, I've been meaning to try grounding it just with a piece of wire to see if that does it. I'll try the other pins of the afm, but I've tested them all with the meter and don't recall anything changing.
Stupid question does the afm itself need to be grounded? The way mine is setup the bracket itself is not bolted to anything....

 

Stock T2 550 cc injectors all around, fuel pressure is good as is fuel volume. Haven't looked too closely at the cas as the timing is right on and steady.

 

Nope. AFM gets everything it needs through the wiring to the AFM. This is why I am thinking you should try touching a ground wire to each of the 4 grounding points I listed earlier. Two are listed as a power ground (probably injectors and ECU power), one listed as a system ground, the other listed as analog ground. What I am thinking is one of these grounding points may not be so hot. Perhaps internally to the ECU, the NA uses a different ground for the AFM (or whatever is causing the problem) compared to the TII ECU.

For 2b, don't ground it directly. It is not a ground.

 

Ok Will do, I have Tuesday off next week, was planning to use some time for this car so I'll see what I can find out. The confusing part about this is that currently the car has the NA harness I converted a few weeks ago and its exhibiting the exact same issues and I made sure while I had the harness apart to check the grounds, or at least the obvious ones I could see. You wouldn't think that both my old JDM harness and now this modified NA harness would have the exact same thing wrong with it.
I'll poke around to see what I can find, at the same time I might spend a few more dollars to get a spare T2 afm, knock sensor, and pressure sensor just to rule those out. I'll let you guys know what I find on Tuesday.

 

A quick update, i've finished all my rewiring and its still doing the same thing (I figured it would) and also got a N370 ECU with no luck. The only real development is that if its running (with either of the T2 ecu's) and i just slightly push the plunger of the AFM in the idle will smooth out.
This made me think maybe the AFM is bad after all so I bought a spare, and nope no difference. I've got another pressure sensor and knock sensor (along with a third AFM) coming from Japan2la which should be here this week i'm hoping, so maybe one of those will do it, beyond that though I'm really not sure what else it could be.

 

Got a N390 AFM (13b-Re cosmo) and another pressure sensor and knock sensor. The knock and pressure sensors made no difference and that AFM (which is supposed to be compatible) actually made it worse.... Everything seems to be pointing to the AFM or something in its circuit, but I've replaced nearly everything, what could it be....

 

Guess its time to start a new thread lol, this one has died. I posted in the FC section and they all (the 2 that replied that is lol) seem stumped. Since I've changed basically every sensor, several computers and re-did the entire wiring harness I'm thinking it has to be something mechanical, but all that comes to mind would be the injectors or fuel rail/pressure regulator. I'm wondering if I should invest in another set of these parts and try.... ugh this is getting expensive!

 

next time something like this happens, go haltech and 13bre.. would it be about the same cost?

 

Maybe I need to come to Jersey?

I don't know what else to check. I'll see if I can think of something.

 

thunkrd: not sure about the 13b-re since its twin turbo and you'd have to switch all that over, but yes had I know I'd have so many issues trying to run the stock FC ECU system I probably would have gone with a standalone of some kind, and still might. But I'd like to get this going first, so if I do go standalone at least I can sell this stuff knowing it runs lol

Kurt, Its a nice area, and I'll put you up somewhere if you do come fix this damn thing!

 

Strange deal. Have you checked fuel pressure? It is a long shot, but I have seen cases where the regulator sticks and the fuel pressure goes to 65-70 psi...or maybe fuel pressure or fuel flow is too low??

My thinking is this:

The NA ECU works okay because it thinks smaller injectors are connected, so it may be opening the injectors more for the amount of air being measured.

With the T2 ECU, it smooths out when you push the AFM a bit making it think more air is coming in and it increases fuel to compensate.

Although, this wouldn't explain it smoothing out when you touch that pin with the meter...

It seems like ECU/harness/AFM, but you have replaced those things and the problem remains. Other thing I can think of is the coolant temp sensor (back of water pump). I have lost track if you replaced that or not. If the connector is loose or the sensor is bad, it will normally make the car run really rich.

I just don't know. If you don't have a fuel pressure tester, I'll ship mine up to you to use. I guess if the fuel pressure is good and all the sensors/wiring/ECU looks good, I suppose the next thing would be to pull the injectors and have them sent out for cleaning/testing. Perhaps one is sticking or partially clogged?

Kent

 

First off I must have been in a rush before, I know full well your name is Kent, why I typed Kurt I have no idea, sorry lol

I have checked pressure and its around 38psi, but I will recheck, and maybe borrow a friends pressure gauge to double check (mine is a crapp harbor freight one) but I'm thinking you might be onto something with a stuck fpr or clogged injector. Since the NA ecu will be telling to use less fuel etc its possible this is the problem.
I'll pull them out and send them off for cleaning.
If that does end up being the problem Dave will come kick my *** since he's be saying it might be injector/fpr for a while lol
Thanks again for the input Kent, and i'm serious if you have the time to come up I can try to get a meet together and I'll make it worth your while

 

Sean, keep us updated. .i'd still try the fpr first while sending out the injectors to www.witchhunter.com and have them cleaned and flow tested.

 

Checked the water temp sensor and it seems to be alright, although i only checked resistance at the amibient temp since the intake was off etc. I put in the set of NA injectors I have and same deal, idles nice with the na ecu, and barely runs with the T2 ecu, in fact it runs even worse than before, which makes me think the whole problem is that is isn't getting enough fuel for some reason.
Pushing in the maf slightly would tell the computer to give it more fuel (right?) and it runs worse, wants to stall out, with the smaller injectors of the NA. I guess I'll find another secondary rail/fpr and give it a shot....

 

This is nuts, Sean. I know you checked fuel pressure before. If you have a tester handy, just check it again. You should be 37ish psi with the car not running and 28ish at idle. It would have to be way off as changing pressure doesn't change flow much (2x pressure gives about 1.4x flow). While you are at it, you could do a volume test (I think you already did this, though). Should be able to put out around 1/2 gallon per minute.

It seems most like a sensor/wiring/ECU issue, but you have changed all of those things multiple times. It also doesn't make sense why the T2 ECUs have issues, but the NA one works great.

I'd love to come up to help you, but I honestly don't know what else to check. Maybe your car doesn't feel like being boosted anymore?

I know it is going to be some stupid thing that we all are just overlooking. Like:

"I forgot that I put a switch in that lets me flip between turbo mode and NA mode and it has been in the NA mode this whole time!"

 

Yea its a bit crazy/annoying to say the least haha. I'll double check fuel pressure again, I can't remember if I tested it with the engine running or not, but it was right about 38 with it off. The volume was about 3/4 gal/minute but I can always recheck that too I guess.
Agreed it seems most like a electrical issue, but I can't think of anything else i haven't looked at, unless I didn't do something right...
Also agreed that it might be a sign, the car doesn't like its new heart lol

 

Well, I have some great news! The problem started getting worse! It started running crappy even on that NA ECU so I started retracing all my steps and double checking things, figuring that since it was getting worse, the cause of the problem might be easier to spot, and sure enough it was!

Anyway, to make a long story (basically the last few weeks worth of work) short, it turned out after all (Kent your gonna kill me lol) to be the damn fuel pump!! When I checked it the last few times it was always in the 30's psi range, but when I double checked it this time it was only at 15psi.

I wasn't happy with how the modified S5 pump hanger fit in there so I got a S4 pump hanger (the correct height for the FB tank, thanks again Dave) and a Walbro 255 while I was at it. Finally got it all back together and swapped the T2 injectors back in and took it for a test drive yesterday and its running great!
Lots of little things to still clean up since I had so many panels apart to check this connection and that etc but man it feels good to have this car back.

I really appreciate all the help I got on here!