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Voltage help!
I installed a "new" used JDM engine swap and added an Apexi Powere FC. I have been trying to do the idle relearn process but it keeps dropping voltage. When I do the initial start it reading 14.2 volts and after 5 minutes of idle it is reading 10.-11.0.
I have checked grounds I had the alternator tested at O'Reillys auto and they said it tested good. Is there anything else I can check/test? |
Check to see if the alternator is charging differently at different rpms. You may need to raise the idle a little bit to have it trigger.
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Originally Posted by FDAUTO
(Post 12622008)
Check to see if the alternator is charging differently at different rpms. You may need to raise the idle a little bit to have it trigger.
I have Set all idle settings to 900-950. It will idle good for 3-4 minutes, then the voltage drops. When the voltage drops the rpms go in the 500 range injector duty goes to 2-3% and the car dies after a couple more minutes. Could that be a bad voltage regulator? |
Probably. Check the wires on that 2 pin connector and make sure they're good. If they are, replace the alternator
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Where are you measuring voltage drop? If it's at the battery the voltage drop could be from multiple causes, even an internal battery short. If it's at the alternator output terminal, the alternator or regulator is the issue.
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Presumably reading it from the commander
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Originally Posted by Boosted843
(Post 12622020)
I have Set all idle settings to 900-950. It will idle good for 3-4 minutes, then the voltage drops. When the voltage drops the rpms go in the 500 range injector duty goes to 2-3% and the car dies after a couple more minutes.
Could that be a bad voltage regulator? |
I agree with DaveW about checking the cause vs effect. If it only takes 5 minutes to make the situation happen, I would get a multimeter and check the voltage at the battery. If the voltage at the battery drops before the idle drops, then you're chasing an electrical problem. The original alternator on my 1994 car failed a few years ago, with around 99000 miles on it. But if RPM drops first and you have an aftermarket ECU, I suspect a calibration problem like the idle settings or fuel settings in the ECU need to be adjusted.
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these chain auto shops don't know anything about alternators. Take it to a local alternator shop. If your in socal, there are plenty of them.
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Update!
I have bought a new battery. Swapped in a known good alternator. set all idles to 900 Opened the throttle body screw a little more. Nothing has changed! Car idles great and smooth for 5 minutes then voltage and injector duty drops and car shuts off after a couple minutes. As the car was starting to die I was able to rev to 5-6k with no problems other then some smoke out the back.... I have also noticed that the radiator hoses are getting hard before the car even gets to temp. hard enough to where its difficult to squeeze but cold enough to rest your nuts on if you were so inclined. Can you think of any wire connections i could have mixed up that could cause this? |
the hose stiffness is likely a thermostat issue.
post a picture of your sensor check screen with the car running and not running |
I still suspect ECU calibration problem, or possibly sensor or harness problem causing bad measurements for manifold pressure or coolant temperature. I could make my car's idle drop enough to stall the engine if I removed about 15-20% fuel from the idle section of the fuel map, or screwed with the MAP sensor scaling for similar effect. Do you have a wideband O2 sensor to measure the air/fuel ratio? I wouldn't run a standalone ECU without one.
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Originally Posted by FDAUTO
(Post 12623360)
the hose stiffness is likely a thermostat issue.
post a picture of your sensor check screen with the car running and not running https://cimg2.ibsrv.net/gimg/www.rx7...e2feddba19.jpg https://cimg4.ibsrv.net/gimg/www.rx7...7f44ecb61f.jpg https://cimg5.ibsrv.net/gimg/www.rx7...32ae8f517b.jpg https://cimg8.ibsrv.net/gimg/www.rx7...0b6c6b0eb7.jpg |
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@FDAUTO the swap came with 99 spec turbos and a oem ecu with a pan speed sticker on it. I'm guessing it was chipped or something. Could it possibly have bigger injectors? Would such a thing cause this kind of problems?
https://cimg1.ibsrv.net/gimg/www.rx7...cce0c2d889.jpg https://cimg2.ibsrv.net/gimg/www.rx7...a0f086716a.jpg |
Based on your last few photos, I think your alternator is fine. 14.0V at 630 RPM and 12.8 volts at 540 RPM both look good.
I'm surprised the engine runs at 630 RPM in the first place, I don't think the factory ECU would be trying to idle the engine so low. I would check if the idle air control solenoid valve has power, then check if the thermowax valve is still present on the throttle body, and depending what you find you might need to learn how to adjust the idle air bypass screw on the throttle to give the engine enough airflow to stay running when warm. I don't remember exactly what a stock ECU would idle at, maybe 700-900 RPM when warm. And get a wideband, a 30-year-old turbocharged car with 30-year-old fuel system is at risk of running lean and melting itself any time you're at full throttle. Your butt dyno won't feel the difference between 10.5 AFR or 13.5 AFR in boost, but the engine internals will feel it very much. |
Originally Posted by scotty305
(Post 12623416)
.... I don't remember exactly what a stock ECU would idle at, maybe 700-900 RPM when warm....
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injector size has its own set of anomalies when set improperly and you dont seem to have any that. if i am reading your images correctly then the idle dropping to ~500 is just before it dies out.
when you installed that power fc what exactly did you do? all data init? |
Originally Posted by FDAUTO
(Post 12623464)
injector size has its own set of anomalies when set improperly and you dont seem to have any that. if i am reading your images correctly then the idle dropping to ~500 is just before it dies out.
when you installed that power fc what exactly did you do? all data init? Mods are as follows. Full 3 inch exhaust Apexi intakes EBC Front mount intercooler Koyo rad Rats nest delete/ full block off kit Greddy air pump delete |
@FDAUTO
Originally Posted by boosted843
(Post 12623705)
yes i did all data int.
Mods are as follows. Full 3 inch exhaust apexi intakes ebc front mount intercooler koyo rad rats nest delete/ full block off kit greddy air pump delete |
@FDAUTO
I have been doing more searching and have another question. I tid the full emissions block of kit because I have read once you have a Power FC you can remove ot all. Now I am reading if you delete the ISC you need a datalogit (which I don't have yet) to set all the settings to 0. I have used the commander to adjust idles to 900, 950, and 1000. It has never hit these targets. Does this sound like a simple ISC problem causing the ecu to not learn the idles? |
The idle learn 30 minute thing has a lot to do with the isc yes. The strategy to set everything to 0 does work but it's just another way of going about doing something. You don't HAVE to do it that way. The short solution when not using an iac is to manually set your idel at ~1200 or so and nothing really matters at that point.
I think you need to provide some afr numbers. Im starting to think what was already mentioned and maybe youre just leaning out at operating temp after it leaves the correction tables. You can try adding fuel in the water temp correction at +80c and see if that helps. That will give you an answer to something. Buy a datalogit |
Update!
Reinstalled the ISC and the car cranked and ran like a champ. I have been driving it since it finished the relearn process with no problems. |
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