JDM TII Swap car goes into limp mode
 

Just recently put a JDM S5 TII motor into a 1989 Convertible. I used a LHD N370 harness with the computer, MAF and Map sensors. The car idles perfect, but when you go to drive the car it will not accelerate normal. It will only drive normal when you give it very little gas. I checked all vacuum lines and electrical connections. I am at a loss. Can any of you guys suggest anything? Thanks in advance.

Did you pull the code?

I can't seem to get the car to give me the code. It blinks once and then twice but nothing steady.

Are you grounding the Orange wire near the lead coil and turning the key to on to pull codes?

Yes, but it doesn't seem to work.

You could unplug the TPS and force the ECU to throw a code so as to see if it is working in that manner.

Is it a JDM or USDM computer you are using? JDM computers don't always work in cars that were originally non-turbo. From what I have gathered on here most of the time they don't.

"I used a LHD N370 harness with the computer, MAF and Map sensors"

I assume that to mean N370. If the CEL lights up at all I figured that meant USDM.

It wasn't clear to me whether he's using a LHD Harness for a N370 ecu connected to a JDM or USDM ecu. You may be right though. Just tring to get clarification to rule that out. Since the CEL lights up that may also verify a USDM ecu like you suspect. We'll find out when he replies back.

To be honest I thought an N370 computer was the USDM computer.

it is. N374 is the JDM

Is your computer a N370? Your first post didn't make that clear to me in the way it was worded. The statement "I used a LHD N370 harness with the computer" made me question which computer? N370(USDM) or N374(JDM)? The LHD harness plugs into either one. Just wanted to rule that out. Sorry if I've derailed the thread.

^ Good point.

Although I know almost nothing on the topic, I'm wondering this, so I'll throw it in: Would the pins on the harness go to the same functions/components/circuits? As in, you plug in a USDM ECU into a JDM harness - would the pins at the check connector go to the right place on the ECU?

there are a couple of differences, but the check connector is the same

Would you happen to know the differences in the actual pins? I want to use a USDM ecu

S4 or S5? i have the diagram in japanese?

I remember correctly, someone in the past had the wrong plug connected to the OMP and it was a plug from the TPS. If this were the case make sure this is not the problem. And did you try pulling a plug off of a sensor to see if the error code aspect of the ECU was working approriately as it takes but a minute to do.

I finally figured out that I have a bad OMP. Thanks for the help.

what test did you use to determine bad OMP. As I'm having the same issue going to limp mode with no error codes

It turned changing the OMP didn't solve the problem. The shop I brought it to said that's what it was, but when I went to pick it up the car, it did the same thing. So I am still stuck.

Does the car free rev when in neutral?

Are you using the NA fuel pump or did you upgrade to the turbo pump?

The JDM fuel supply and fuel return hose are connected differently (opposite) than the USDM engine. Did you account for this?

The car free revs in neutral and I upgraded to a walbro GSS341 fuel pump. The shop now says he pulled a code 9 from the computer and says that the idle control valve should be the problem. Does this sound right to anyone? Would the car run if they are backwards?

Old electronics fry one another in the case of the series 5 OMP and ECU. If you change a bad OMP to a good one, the ECU is probably bad. Because you now have a bad ECU and put in a new OMP, it kills the OMP. Vicious cycle!

Or it could be something else...

No it doesn't sound right because a code 9 for an S5 is the water thermosensor.

http://www.banzai-racing.com/FD_S5_error_codes.htm

s4