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GGSX/4G63 NT Help.

92_talon_awd

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Feb 11, 2014
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456
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Knoxville, TN
So I have my Galant running and driving, does pretty good. Replaced the fuel pump, plugs, wires, fuel filter, and thermostat. Also replaced the turbo MAF with a NT MAF. Still idles kind of goofy at times, like 2500 steady at times and other times at 400-500. Also still running big pig rich. The weirdest thing is that the car won't go over 4k. Pulls nice and strong until 4k, then it bucks like a bronco. I'm thinking ECU, anybody have another idea that I may have overlooked? /ubbthreads/images/graemlins/dunno.gif
 

AllanL

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Aug 4, 2008
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294
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NV
ecu caps OK?

ecu driver for the ISC may also be shot?

i've had an ecu trace to the ISC driver open before as well...

by the way what pump as you using?
 

92_talon_awd

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Feb 11, 2014
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456
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Knoxville, TN
I haven't opened the ECU yet, I'm leaning towards that being the problem so I'll probably just rip it out and send it off if nobody has any other suggestions. I was using the stock pump but it was on its way out so I put a Denso 195130-2020 in there. Supposed to be 100lph just like the stocker.
 

tektic

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Dec 19, 2012
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ronkonkoma, ny
You can't run a turbo maf with an nt ecu. It's not the same it wont work right.
Edit: you swapped the other way. never mind

sounds to me like your isc is bad. You said nothing about checking that. Also try swapping in a new transistor.
 
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transparentdsm

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Jul 27, 2011
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Cherry Hill, NJ
^ man owning/building that VR4 has really put you on top of your sh*t.. hahah these would be the same areas i would start in for those issues.
 

92_talon_awd

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Messages
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Knoxville, TN
Quoting tektic:
You can't run a turbo maf with an nt ecu. It's not the same it wont work right.
Edit: you swapped the other way. never mind

sounds to me like your isc is bad. You said nothing about checking that. Also try swapping in a new transistor.



Thanks man, I'll try the ISC and transistor, see what happens. When I bought it there was a turbo MAF in it but it made it buck like crazy when you tried to cruise, accelerating was fine. NT MAF fixed most of it, there is still a tiny area in the throttle where it will buck but nothing like before.
 

92_talon_awd

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Feb 11, 2014
Messages
456
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Knoxville, TN
Tested the ISC, 34 ohms all around so I'm gonna say good. Would the transistor make it run super rich or just stutter at higher RPM's?
 

MellowVR4

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Jul 25, 2009
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Location
Milwaukee, Wi
My guess its the ecu.
 

92_talon_awd

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Feb 11, 2014
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456
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Knoxville, TN
So I opened up the ECU, I think it is probably the problem child.


 

prove_it

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Jul 3, 2008
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Sioux Falls, SD
Meh, just get a syringe and inject some smoke back into it. /ubbthreads/images/graemlins/grin.gif
 

92_talon_awd

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456
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Knoxville, TN
I wish /ubbthreads/images/graemlins/rofl.gif
 

tektic

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ronkonkoma, ny
I'm on my phone and can't see the pic too clearly, but i'm asuming by the comments that the caps smoked? Since it was still working some what you can try to solder in new ones or just get a DSM unit and sawp the case. All 94 nt DSM units have eproms but also California emission. You should solder in new caps for what ever ecu you use if it was not already done.

My isc tested fine for restance, but did not funcion properly if at all. My car devoid of its fast idle air valve did not start without my foot on the gas while isc was bad. It did not follow the idle map values based on ect either.
 
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92_talon_awd

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Feb 11, 2014
Messages
456
Location
Knoxville, TN
Yeah, bro. A lot of smokage goin on in this ECU. I sent the pics to Thomas and he is gonna hook it up for me. The car ran, just drank gas like crazy. I want to DD it while I build the turbo motor for it so it was annoying
 
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AllanL

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Aug 4, 2008
Messages
294
Location
NV
ouch!

that big capacitor by the green transistor is dead.

happened to an ecu i was socketing...

cleaned it with carb cleaner sprayed on q-tips to clean u the area at first...
 

AllanL

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Joined
Aug 4, 2008
Messages
294
Location
NV
Quoting tektic:
I'm on my phone and can't see the pic too clearly, but i'm asuming by the comments that the caps smoked? Since it was still working some what you can try to solder in new ones or just get a DSM unit and sawp the case. All 94 nt DSM units have eproms but also California emission. You should solder in new caps for what ever ecu you use if it was not already done.

My isc tested fine for restance, but did not funcion properly if at all. My car devoid of its fast idle air valve did not start without my foot on the gas while isc was bad. It did not follow the idle map values based on ect either.



if it isn't fixed yet, this may help...

click

especially post 12 in the link above...
 

strokin4dr

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Aug 30, 2005
Messages
2,770
Location
Savannah, GA
I'd try to locate an EPROM ecu instead of repairing that one.
 

tektic

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Joined
Dec 19, 2012
Messages
1,497
Location
ronkonkoma, ny
Check out this item I found on eBay: click

Non eprom listing for $15. Just swap out the caps when you get it. It looks like its from a Galant too. Check the part numbers.

Here's an nt eprom ecu on eBay: click

It's a little pricey at $95 a turbo version could be had for little more. Md304481 has the eprom with out the knock board. This ecu will throw check engine light with the eb20 chip because its will be looking for an egrt sensor. If you connect a wideband input to this wire it will pass the sensor test and not throw the code.

 
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