g16a running poorly, erratic idle, conversion issues

Sausager
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g16a running poorly, erratic idle, conversion issues

Postby Sausager » Fri Feb 24, 2017 12:55 pm

Hey guys. I've recently put a 16v mpi g16a into my SJ413. Did everything myself, incl all wiring. I drove the car the motor came out of before pulling the motor out and the motor was fine.

She started the first time I tried it after the conversion, no dramas there. On the first start, it idled high, around 2000rpm. I wasn't too fussed - it had no exhaust, intake wasn't set up properly, etc. I ran it like this a few times and always the same - 2000rpm constant idle

Then I fnished everything - exhaust, mounted the ecu properly, sorted out the intake, etc etc. Now it idles erratically. Starting from cold, it will immediately idle at 2000rpm for a few seconds then drop down to nearly stalling, then bounce back up to 1500rpm ish for a few seconds, then die down, bounce back to 1500, etc etc. It will keep bouncing like this and sometimes die when it drops down so low. While it does this I can smell a fair amount of fuel in the exhaust which I presume means it's running rich. It idles better when warm, but still erratically. The motor also doesn't run smoothly like it should. The car is driveable as it is but I don't know how sustainable it is.

The temperature gauge doesn't show warm. I was expecting maybe 1/3 or 1/2 way up the gauge, but the needle barely gets off the cold end of the line. I suspect the temp sender here, but I don't know for sure. I tested it's resistance and I get 53 ohms, cold.

This first video is of starting it stone cold. I am not touching anything else besides the key the whole time. You can see my battery light when the key is "on" and the bright red light you can see reflecting on the steering wheel is from my (super bright haha) CEL.
https://www.flickr.com/gp/125196140@N05/e2t561

This second video is of it idling a little later that same day, warm. You can see here that it doesn't run smooth - the motor shakes. It's not missing or anything like that, but it's just running rough. Revving hard (6-7k rpm) it runs smooth, but then back at low revs or idle, it's rough.
https://www.flickr.com/gp/125196140@N05/WoU69b

I have done the VSS swap. I have a 3 wire MAF.

Any ideas here people? I just can't seem to figure it out. Cheers!

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Crawlerer79
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Re: g16a running poorly, erratic idle, conversion issues

Postby Crawlerer79 » Fri Feb 24, 2017 3:01 pm

I have a similar problem with mine where the engine will drop to about 200rpm when the engine is warm and I let it back to idle. It then comes back up to a more regular 800 odd rpm. I have no clue if the temperature sender does communicate with the ECU but I found mine loose and once in properly the issue went away.... however I don't know if that had anything to do with the sender, or if the sender feeds info to the ECU but its just a (vague) idea.... my problem comes and goes so dunno if I'm right but if I am then its probably come loose again. At the time I had issues with the temp gauge dropping to cold when under heavy acceleration as well and giving a sooty exhaust smoke.... I dunno, just throwing out ideas haha :lol:
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derk
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Re: g16a running poorly, erratic idle, conversion issues

Postby derk » Fri Feb 24, 2017 4:58 pm

an erratic high idle the first thing you want to check is vacuum leaks make sure there are aren't any ports that haven't been caped off or hoses going nowhere or something you've missed, have you got an engine light or obd port you can check for codes to see if you have a sensor that isn't working you need IAC (controls idle), TPS, MAF, Intake Air Temp, Coolant temp all working to get a good fuel mixture to make it idle and run properly. Did you use the donor fuel tank and pump has it got the correct fuel pressure at the rail?

Sausager
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Location: Silverstream, Wellington

Re: g16a running poorly, erratic idle, conversion issues

Postby Sausager » Fri Feb 24, 2017 7:39 pm

Cheers for the replies guys.

I have checked the connection to the coolant temp ECU sender and that seems ok. No idea how to actually test it though?

I have a CEL, and I get a code 12 which means no faults. I don't think I have an intake air temp sensor. Normally its on the airbox, but I didn't have one. No hole in the original airbox either. I have used donor fuel tank, and fuel lines so I'm guessing fuel pressure will be ok. I don't think it's fuel related anyway, because at high revs it goes like a cut cat and has plenty of power. Coolant temp could be it. How do I properly diagnose and check it? Same with the IAC, TPS and MAF - is there a procedure for checking these?

Thanks again

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