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P0446 after installing 98 ecu in 97 gsx

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98spyderboost

15+ Year Contributor
265
0
Aug 2, 2004
Mount Juliet, Tennessee
Hello everyone. I have just installed a 98 ECU in a 97 GSX. The car is now throwing a P0446 code and dying at idle after 20 minutes or so of running. All the my research is coming up with very limited info. The only applicable post I have found is posted below.

http://www.dsmtuners.com/forums/newbie-forum/380404-99-gsx-ecu-97-gst.html

Now on to the details; Both cars are completely stock. It's a simple ecu swap in preparation for upgrades and tuning etc. I have no experience with a 97, only 98-99. I realize there is a difference in the evap sensors. Is there a straight forward fix for this? IE - Can I simply replace the 97 purge solenoid and pigtail with the one from the 98 and fix the issue or does it actually need a differential pressure switch added to pin 61 of the ECU? I can find no info beyond this point on the issue... I am continuing research but it is very slow and frustrating at this point. Any help would be massively appreciated...
 
Why not just keep the stock ecu in the car until you have the money/time to flash the 98-99 ecu? Why change solenoids and wire up things, if when you have the ecu flashed you can just ignore the codes? Erase them etc.?

I get your thought process on the preparation side, but if preparing is going to cause headaches and CEL's why not just wait until the ecu is flashed for your setup etc?

If you have to have to run the 98-99 I would start with wiring it up to the ecu first as that is free and see if it changes anything, then move on to buying pigtails or another sensor etc.

If you need a 97 ecu I have a oem 97 gst.

Again if it were me I would put the stock one back in until I had the 98-99 flashed etc.
 
I am not TOO familiar with the 2g electrical stuff, but is the new ECU a CA spec? That could be an issue for you if it is...
 
I had the same exact problem installing my 98 ecu in my fiance's 97. The problem is because the 98+ has a slightly different evap system. Different solenoids and an additional pressure sensor at the fuel tank. Just disable the codes using a tactrix cable.
 
I had the same exact problem installing my 98 ecu in my fiance's 97. The problem is because the 98+ has a slightly different evap system. Different solenoids and an additional pressure sensor at the fuel tank. Just disable the codes using a tactrix cable.

^ x2
 
Thanks, I did disable it. Worked just fine for getting rid of the code. But the car is still dying at idle. Where this issue started being intermittent, it seems to be getting worse. It now will not start without holding the gas pedal down. I have determined that it must be unrelated to the P0446 code. I did this by reinstalling the 97 ECU and the same problem occurs. Installed a different 97 ECU just to be sure, no change. Here are some other things I have done that were easy and part of just visually examining. Found fuel filter was leaking, so I replaced it. It ran fine for about 20 minutes and the problem came back. Confirmed that it is still no longer leaking. I had an extra mass air flow that was newer so I threw that on. No change. Had an extra gas cap that was newer, threw it on. No change, though not likely to begin with. I checked all the vacuum lines for wear and proper routing and replaced most of them. No change. Changed the MAP to a known good one. No change. I know I'm stabbing in the dark but these are free 1 minute changes so I just did them. It has had a full NGK tuneup, oil change, air filter cleaning, filled with good 93 octane and a little seafoam. My next thought is to clean the throttle body, and then replace the fuel pump. And yep, this car's name is Nightmare :mad: Any thoughts/suggestions?
 
I would replace the fuel filter again. Your tank might be that dirty.

If that doesn't help check fuel pressure.

Install the 98 ecu and use evoscan to log while starting so we can see what inputs the ecu sees.
 
ed1380.

which is better for clearing this code? evoscan openport 1.3u cable or tractrix cable.

I have a 99 flashed ecu in my 97 gsx. The same code is keeping me from getting my emissions done.

I dont have anything to log with now and am trying ot figure out which one to get.

I had a tuner shop out here tell me that clearing codes with evoscan is intermittent and wont stay cleared. but I'm not sure if they were just trying to sell me on dsmlink.
 
any cable can clear codes. Even the $15 volkwagon cable or the $15 bluetooth dongle. But clearing the codes won't make you pass emissions, it'll fail for not being ready. They'll tell you to drive for a week and bring it back.

Evoscan can only clear the check engine light. it can't stock it from coming up again. To stop this code from coming up you need to reflash the ecu and to do that you need the 2.0 (aka tactrix cable)
 
Sorry it took so long. It's been a long week at work :( Here is the datalog I took today. It started after some coaxing of the pedal, and stayed running for a minute or so. The download may take a sec to show up but it's there... I hope you can get something out of it. I'm still learning this stuff. Not even sure I have the right parameters logged. Thanks again for the help...

http://www.tourismoworks.com/evoscanlogs/EvoScanDataLog_2012.10.02_15.40.07.csv
 
good news. you logged it well. bad news. i don't know exactly what to make of it. Do you have a wideband?


Here's what I can make of it. After 20 seconds the o2 (yellow) starts reporting to the ecu and it drops for 800 to 450rpm. 5 seconds later the ISC goes full open(top line). Another 5 seconds later the fuel trims start getting lower and lower and the o2 keeps reporting richer and richer until it died. The injector pulse width(green) didn't really change with the fuel trims, hence me asking if you have a wideband. It's the best way to tell what's happening in the cylinders.

I can't guarantee that the o2 is bad because it still cycles, but it reporting richer and richer conditions with no change in injectors cycle duty makes me believe it might be bad( a vacuum leak will show up lean). Can you get a log with the o2 unplugged?

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Finally had a chance to work on Nightmare today for a bit. First log was done with the O2 unplugged. Second log was done after switching to a known good TPS and O2 plugged back in. I'm still baffled... Gunna pull apart throttle body to clean it out. That's something I've been wanting to do anyway. Hopefully there will be a mouse nest or something crazy like that in it :) As far as the wideband goes, this car is completely stock. No wideband or gauges or anything. I know that's not helpful but it is what it is cus I'm broke :p Thanks again for your help!

http://www.tourismoworks.com/evoscanlogs/EvoScanDataLog_2012.10.09_13.20.46.csv
http://www.tourismoworks.com/evoscanlogs/EvoScanDataLog_2012.10.09_13.53.33.csv
 
It's only throwing the code with the 98 ECU in it. At first I thought it was related to the idle issue. But when I switched to the 97 ECU the P0446 went away and still have idle issue. So the code isn't the issue anymore. It not idling and leaning out is the issue. I'm going to do a spray test of the manifold area today and see if I might have developed a leak I haven't found yet... Thanks for the info!
 
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