jdm ecu on a non jdm motor
- Thread starter VooDoo
- Start date
Is there anyway to "fix" the speed cut and retain proper function of the automatic transmission and TEMS?
First time I used the JDM ECU I was trying to overtake some 18 year old young man in a Fiat Uno doing 80 km/h. He used the opportunity to start racing me (that idiot). I barely made it past him before we started to drive up a hill with no forward visibility. When I looked down at my speedometer after passing him it was stuck at 180 km/h. The car felt like a snail from 140 to 180 km/h. I slowed down again. Then I after 20 seconds I was passed by the guy flipping the bird at me while doing at least 230 km/h (in an 80 km/h zone). It turned out to be a Fiat Uno Turbo (with a couple of mods....)
Yanked out the JDM ECU when I came home since I still have EGR......
First time I used the JDM ECU I was trying to overtake some 18 year old young man in a Fiat Uno doing 80 km/h. He used the opportunity to start racing me (that idiot). I barely made it past him before we started to drive up a hill with no forward visibility. When I looked down at my speedometer after passing him it was stuck at 180 km/h. The car felt like a snail from 140 to 180 km/h. I slowed down again. Then I after 20 seconds I was passed by the guy flipping the bird at me while doing at least 230 km/h (in an 80 km/h zone). It turned out to be a Fiat Uno Turbo (with a couple of mods....)
Yanked out the JDM ECU when I came home since I still have EGR......
Can anyone verify that this is an authentic JDM ECU?
7MGT A/T
89661-24112
I would assume that if you don't have you speed sensor connected the speed cut would not be an issue? My cars is a 86.5 that started life as an na, have had the turbo swap for many years with no issues. The car does not have ABS, is that why not having the speed sensor hooked up is not an issue?
Thanks
7MGT A/T
89661-24112
I would assume that if you don't have you speed sensor connected the speed cut would not be an issue? My cars is a 86.5 that started life as an na, have had the turbo swap for many years with no issues. The car does not have ABS, is that why not having the speed sensor hooked up is not an issue?
Thanks
A clarification: If you have the EGR installed with the correct vac set-up, exhaust gas will flow above idle...the VSV is not active. The EGR is controlled by vac port positioning inside the TB at lower RPM ops. The USDM ECU cuts EGR flow above ~4000 RPM using the VSV...with a JDM ECU this will not happen, flow will continue in the higher RPM range because the VSV is not activated by a JDM ECU. Kristian - this is probably what you felt from 140-180 km/h before speed cut kicked in.
HKS made a Speed Cut Defender to get rid of the issue. On a manual tranny you could disconnect the SPD wire at the ECU, but may experience low idle/stall when coming to a stop. There are some fuel trim issues...you probably won't even tell the difference with these. However, you may . An auto tranny is a different story, the ECT uses the SPD input to control shifts....not a good idea in this case.
I'll have to look closer, but I'm pretty sure ABS uses wheel sensors vs ECU SPD for ABS input.
HKS made a Speed Cut Defender to get rid of the issue. On a manual tranny you could disconnect the SPD wire at the ECU, but may experience low idle/stall when coming to a stop. There are some fuel trim issues...you probably won't even tell the difference with these. However, you may . An auto tranny is a different story, the ECT uses the SPD input to control shifts....not a good idea in this case.
I'll have to look closer, but I'm pretty sure ABS uses wheel sensors vs ECU SPD for ABS input.
But isn't EGR off by default and then actively enabled by the ECU?
The reason I ask is that I once had an EGR valve stuck open and the car couldn't idle at all. Actually I couldn't even start it at first. So if the EGR is actively closed by the USDM ECU shouldn't it be on at idle when using a JDM ECU and making idle very rough and give the same sort of problems as a stuck EGR?
The reason I ask is that I once had an EGR valve stuck open and the car couldn't idle at all. Actually I couldn't even start it at first. So if the EGR is actively closed by the USDM ECU shouldn't it be on at idle when using a JDM ECU and making idle very rough and give the same sort of problems as a stuck EGR?
Kristian_Wraae;1276555 said:
Nope...at idle the TB plate is positioned behind the vac port that supplies the EGR. Above idle the plate moves, allowing vac to the port. It's mechanical.
Kristian_Wraae said:
The USDM doesn't use the EGR VSV at at idle...it's a mechanical vac cut per above. The JDM EDU doesn't have the EGR programming, so the effect is the same. If the EGR is present with the correct vac routing, the EGR will function above idle with both a USDM & JDM ECU. The VSV is used by the ECU to cut EGR flow in the lower RPM range when the coolant temp is low (< 57 deg C) to improve drivability until the car warms up.
In any case, the EGR is never flowing at idle (unless the EGR valve is stuck open) regardless of VSV position due to the location of the TB vac port.
Take a look at this:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EC&P=16
Ok. I see. So that is why the car felt slow.
So to test the JDM ECU out I could just unplug the vacuum line from the EGR valve (and plug it) ?
So to test the JDM ECU out I could just unplug the vacuum line from the EGR valve (and plug it) ?
Kristian_Wraae;1274757 said:
Yes, late '89 ECU's have gray plugs.Kristian_Wraae;1274760 said:
There is also a company called GANG that made a speed cut remover. I have one of those, and it's the only one I've ever seen.HKS speed cut defencer, or the GANG unit I mentioned above.VooDoo;1275613 said:
SupraDrew;1276328 said:
I don't have that P/N in my list. This is the closest I have to yours:
89661-24111 - MA70 (Oct 1987 - Oct 1988), Automatic Transmission
Maybe Jeff or JJ can check for you.
Kristian_Wraae;1276587 said:
Yep...the fictional HP gain you hear guys talk about when removing the EGR is BS. On a USDM, the EGR does not function in the high RPM area. In your case (with a JDM ECU) and EGR flow at higher RPM, it is a true statement.
I would plug the vac line to the modulator on one side and the VSV on the other to prevent a vac leak back to the TB.
You will still have to deal with speed cut on the JDM ECU. On an auto tranny, you will need a HKS SCD.
jdub, a few guys have said they dont have an issue with speed cut. Is there something that is different from car to car that would allow this? Is the speed input used on abs cars vs non abs car?
No it won't. Its running closed loop and the A/F will be fine.
The issue is, with no EGR and a USDM ECU the base timing will be too advanced.
The issue is, with no EGR and a USDM ECU the base timing will be too advanced.
SupraMan1987;1274069 said:
Can anyone explain how the SLD works? and if there are any down sides to it's use with automatic gear and TEMS.
I have a PCS transmission controller waiting to go in so its a minor problem with the automatic gearbox. But how about TEMS?
I have a PCS transmission controller waiting to go in so its a minor problem with the automatic gearbox. But how about TEMS?