Silvertear

iTrader: (3)

I recently swapped a J-spec engine and drive train into an American n/a car. Both s4.

With the Turbo II ECU, it was a struggle to get the car started. Once started, it ran extremely rich and was sluggish. After taking it for a drive, it stopped starting back up.

We were suspicious of the ECU so I bought another ECU.
With this ECU, the car still would not start.

Both of the Turbo ECU's were J-Spec.

I swapped an American n/a ECU back into the car. The car starts fine, but idles at 1,300-1,500 RPM back and forth as though it's revving. The car runs fine as long as I keep it out of positive pressure.

I pulled parts from both turbo ECU's and replaced some transistors, and got the car to start a lot easier than before, but was very rough and shaky. It sounded like it was missing. I tried starting the car again for a sound file, and was unable to get it started again.

The engine seems to be getting fuel. Every time it fails to start, there is a strong smell of gas.

So for a recap, the car (s4 US model, Japanese engine) runs and drives fine with a non-turbo American ECU. Will not start with JDM TII ECU.

FirstRotaryExp

iTrader: (3)

Did you remember to swap the NA AFM for the Turbo AFM? Did you also remember to swap the NA pressure sensore for the Turbo Pressure sensor? Did you also replace the NA fuel pump with the Turbo pump (or equivalent aftermarket unit)? Did you also remember the resistor pack for the injectors (moot point if you swapped into an 87 or older chassis)? Check to make sure the injectors are 'stock' and non leaking?

I listed the more likely suspects of your swap issues first with what may also cause issue's later. Good luck with it, though have you also checked for vac/intake leaks and compression #'s? Also pick up a good working US-spec ECU if you suspect the jdm ecu's being a problem.

Silvertear

iTrader: (3)

I do have a TII AFM and Boost sensor. The resistor pack though, what do you mean by that?

I have yet to pull the injectors, but if the injectors were larger than stock, wouldn't I have problems with the n/a ECU as well?

2slow4stock

iTrader: (18)

are you sure you don't have vacuum leaks?

Silvertear

iTrader: (3)

I checked for them earlier and couldn't find any. Although the car runs at about -15psi. Not sure what it's supposed to be at.

turbo_dave

iTrader: (50)

You need a American turbo ecu.

turbo_dave

iTrader: (50)

What engine harness are you using,I know that the jdm ecu has some pins in different location than the US version.

Silvertear

iTrader: (3)

The harness was a JDM harness, but it has since then been re-pinned.

RotaryRocket88

iTrader: (7)

Ditch the J-spec (N340?) ECU, and get an N332 or N333. There's little info on that ECU, but if it's anything like the S5 N374, it's more trouble than it's worth.

If you use a J-spec turbo EM harness, and swapped pins around for the FEM connectors, make sure you got the right order. Using a turbo harness just makes the conversion more complicated than it has to be.

Silvertear

iTrader: (3)

I received in the mail, an N333 USDM ECU. I plugged it in and the car fires up with ease, and revs much more smoothly. However, when I start it, it revs to about 1800 rpm, then dies out. If I keep on the throttle it's fine, but the second I let off the gas, it dies out.

I have it set to full rich atm so I could tune it down after I got it running.

On the old n/a ECU it ran fine and idled (just idled a bit rough)

Any ideas?

RotaryRocket88

iTrader: (7)

What's set to full rich? The variable resistor on the strut tower? That only affects idle mixture, and it should be somewhere in the middle. All the way rich or lean will generally make the engine stall. If that isn't the issue, the most likely case is a vacuum leak or intake leak before the TB.

Silvertear

iTrader: (3)

I had it all the way rich on the VR, but it's set about mid-ways now. I tweaked the TPS and got it running, but when I give it all the throttle, the very second it crosses 3500rpm it jerks and loses all power.

Silvertear

iTrader: (3)

I seem to be losing everyone who has tried to help me (including my mechanic) so I'm going to recap what I've done to try again for some assistance in the matter.

Car: '86 n/a chassis; full TII Conversion (Engine and drive train)

I ran the car on the n/a ECU just fine for about a month. The car ran smoothly, had some pep, and all was well.

I finally bought a N333 TII ECU (USDM) and plugged it in. When accelerating in first gear, it occasionally accelerates smoothly and the turbo spools up just fine. However, when I shift into second, third, fourth, or fifth, the very second my RPMs reach 3600, it begins to act up.

The car will bog way down, then the turbo spools up and it accelerates for a second, then it stops, so on and so forth. When it does this, there is the very strong odor of gasoline. It's hard to describe what happens, and you can't really hear it in a recording. The car just accelerates for a split second at a time repeatedly.

When I try to simulate the car being under load (unplugging the TPS & plugging up the vacuum hose connected to the boost sensor) the car accelerates fine with very little hesitation at 3600 RPMs before it powers through it.

All this is with the VR <--L R--> adjustment at full rich. I've also tried leaning it out a bit. Nothing has helped yet.

I have set my TPS dead on. I have cleaned off the grounds in the engine bay and coated them with dielectric grease. I even added a ground to the boost sensor.

What am I missing here? The car runs perfect on the n/a ECU (staying out of boost of course) but when I plug the TII ECU in it acts up no matter how slowly and gently I try to rev it past 3500 RPMs.

RotaryRocket88

iTrader: (7)

Are you able to free-rev the engine past 3600 RPM, and can you get past that point with partial throttle/low load? Are you making boost when it does this, if so, how much?

For your conversion you said you used a J-spec EM harness and re-pinned; did you get both connectors FEM-01 and FEM-02 (as in Front harness to Emissions harness)?

Have you tested the voltage output of the boost sensor? FSM fuel and emissions section will have the voltage at the ECU pin or at the corresponding wire on the sensor plug.

Silvertear

iTrader: (3)

The boost sensor was showing 2.4 DCV. I believe it's supposed to be 2.5-2.7 range. The car free revs fine, but when driving down the road, I absolutely cannot rev smoothly past 3500. Boost reaches 6-8 PSI if I push it. It's still very jumpy accelerating when I do so though.


As for the connectors, I have no idea. I paid someone to put it all together, and he has quite a good reputation. I just had the wrong ECU when it came time to drive it home, so I ran the n/a ECU while I waited on my N333 to come in the mail.

RotaryRocket88

iTrader: (7)

The FSM says Pin 2B (Pressure sensor) should show 2.3-2.7v with the vac line removed (atmospheric pressure), so you're in that range. Did you test at the ECU pin or at the sensor?

It sounds like your issue is related to the secondary injector staging. Disconnecting the TPS and allowing the boost sensor to see atmospheric pressure will force them to come online immediately. Normally they won't stage until the ECU sees ~3800 RPM, 0 manifold pressure/1 ATM, and the throttle is open a certain amount.

Now why the NA ECU would work, I don't know. The common 3800 RPM hesitation is generally resolved by cleaning existing grounds, or adding new ones directly at the ECU. I used to have a little hesitation when my car was NA, but it disappeared after converting to a turbo engine/electronics. My grounds did not change, but maybe the solder joints in the current ECU are better than my old one.

Silvertear

iTrader: (3)

I have yet to pull my UIM off for the ECU ground, however I'm leaning more and more towards it being a grounding issue. This morning it ran perfect for a few miles, then after work, it ran perfect for about 10 miles. What has me troubled is why the grounds wouldn't be an issue for the n/a.

I saw a quote a while back... 'An RX-7 in it's natural habitat... On jack stands.' It's all becoming oh so clear to me now.

blackrotary23

water thermo sensor on the back of the water pump...

Silvertear

iTrader: (3)

What should it read? Know off the top of your head? If not I can go through the FSM.

HAILERS2

WAter thermo sensors read a half volt dc when the engine is fully HOT. It will read b/t 2-3vdc when cold. Voltage checked with all plugs connected and the sensor wire backprobed at the ECU plug.

If the sensor is disconnecte the ECU defaults the signal to 178* F so nothing should be out of whack if the engine is fully hot. Will start funny when the engine is actually cold, but never if the engine is fully warmed up.

Silvertear

iTrader: (3)

I pulled the UIM off last night to reground the ECU ground. Fixed a clip on one of my secondary injectors. Got it done, re-set my TPS to 1.00....

When I started the car, it ran extremely rough and missing really bad. I killed it, then it wouldn't start back up. I pulled the UIM back off and noticed 2 things right off the bat.

1.) The coolant line under the UIM was kinked.
2.) The wires leading to my Air Supply Valve had cracked and showed bare wire at the base where they enter the valve.

Would the Air Supply Valve have anything to do with the problems I was seeing beforehand when the car was running somewhat?

blackrotary23

air supply valve should have nothing to do with the car running the way you described unless you have a vacuum leak in that area. check the wire harness. i checked mine yesterday. i thought it was in really good condition, but i found at least 3 wires that were corroded within the harness wrapping. one of which was the o2 sensor wire. the other 2 were grounds.

recap: check your wires thoroughly

RotaryRocket88

iTrader: (7)

Did you replace the UIM/LIM gasket after taking the UIM off the first time? A vacuum leak will cause it to run very rough. I'd also double check that everything was plugged back in again.

The ASV is only used to boost idle speed when the P/S is in use.

HAILERS2

Sounds like a air leak. like rock hard lower grommets on the injector and or a manifold gasket or vacuum line left off or???? too many things to go wrong to list.

Silvertear

iTrader: (3)

I guess I'm going to have to swap in the n/a harness.

Will have to quadruple check vacuum hoses and that the UIM gasket.