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98 2.5rs ecu
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Old 11-12-2018, 01:08 PM   #1
Car: 98 Arcadia 2.5rs
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Default 98 2.5rs ecu

I have a 98 2.5rs that I manual swapped. Car is running fine but idle is rough and will die when I come out of gear (coming to a stop sign, red light, etc). It seems like its mainly struggling in closed loop as above 3000rpm it runs really well.

I have heard mixed reports on whether the 98 2.5L ECU is different between Auto and Manual. And if this can be completely remedied by grounding one of the pins. According to North Ursalia, I should have to ground pin 81, from the ecu for it to think its a manual. Or do you simply leave this an open circuit? Is there a way to identify if it is a Manual ECU or not if I buy one off ebay? I am assuming that once you ground/open circuit this wire the TCU will need to be removed as well. The car will start and drive fine, so Neutral Safety Switch is working appropriately, but the idle is and low rpm driving is struggling.

I do not believe I am having any vacuum leaks, or o2 sensor issue as it has not thrown a code for it, and I have brand new oem o2 and MAF sensor. I also put a new IACV on it.

Thanks for the help, I have read through the Auto to Manual swap but some areas seem grey as whether or not they help.
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Old 04-12-2019, 12:30 AM   #2
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really auto and manual ECUs are different, but don't know exactly which one will work.
I suppose that ECU thinks that car is on parking now?
in this case you need to ground pin 81 so it will be on Neutral, but not Drive
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Old 04-13-2019, 04:05 PM   #3
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If you converted to a manual you need a manual ecu
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Old 04-14-2019, 02:09 AM   #4
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Originally Posted by jeff6666p View Post
If you converted to a manual you need a manual ecu
Nah, just ground that pin.
2001 SRP Coupe 8300RPM SOHC 257, 71 HTA, DCCD RA Drivetrain and ms3-Pro
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Old 04-14-2019, 05:46 PM   #5
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Paging #bansheeboy12, he loves idle issues on auto to manual swaps
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Old 04-15-2019, 12:47 AM   #6
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I was trying to solve the stalling issue today. Until now, I had a jumper to feign neutral and allow the car to start since my actual NPS is backwards (open in neutral, closed in gear). Well I fitted a relay with a normally closed config to reverse the NPS and wired it in so the car only starts in neutral, when I'm in gear the ecu knows it.

100000% smoother take offs and low rpm operation. I figured the slight bogging was either me or the clutch or a tired engine, but no. I can now be crawling along in first gear at like 1000 rpms, and applying the gas no longer makes the car buck and jerk.

Still occasionally stalls at stops tho.
97 LGT / 92 SVX / 95 GM∆
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