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Help with idle tuning

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88BB8B

Proven Member
179
18
Oct 14, 2016
Coldstream, BC_Canada
Hey guys. I've ran into a problem. I just replaced my stockers with my FIC 850cc injectors. Before the install the car was running fairly iffy, but idled smooth and was even able to pull a bit. Since installing the FICs the car has become more difficult to start, especially when warm, and it idles like crap, even runs like crao when I'm holding at about 3000 rpm.

My AFRs are all over the place, dancing around as low as 11:1 and as high as 16:1 or 17:1 both at idle and when revved up.
I definitely am nervious to try to drive it with AFRs jumping around like that so I can't go ahead with tuning until I get the sorted out.

I've got the AEM infinity 506 and have tried smoothing out my target AFRs, ignition timing, and VE in the idle part of the maps.

I'm pretty sure I have my injectors setup properly, I put in the deadtimes and flow numbers that were provided with them and they averaging AFRs right where my target is, its just bouncing up and drown from target all the time. Help me out please.
 
Can you post a log?
Maf or Speed Density?
BLT done?
Any exhaust leaks?
All of that is valuable to us if we want to try and figure it out with you.
 
I didn't do the sensor setup on the car, it was all done by a local shop when the previous owner had it. I'm pretty sure its running a speed density setup because the MAF sensor has been unplugged since I've owned it, and before I swapped the stock injectors it ran just fine. I didn't do a boost leak test, but again, this issue didn't start until I swapped the injectors the other day, it was keeping stable AFRs and running well before that so I dont think its a boost or vacuum leak. There is probably a very small exhaust leak just before the wideband sensor because I dont have a gasket on the downpipe, but it was running fine with the old injectors so I don't see how that could be the culprit either, although it may help a little to fix it.

the log I have posted is zipped but in the infinity tuner format, it is also not just for VE despite the title. I think the best way to view it would be to download the infinity tuner software here: https://www.aemelectronics.com/prod...cu/infinity-engine-management-system-software
 

Attachments

  • VE log.zip
    414.3 KB · Views: 27
I am sure it is SD, It requires a lot of work to run with MAF on AEM, so..
The file you uploaded is not visible inside, couldn't open it. Log and calibration is separated. if you want to upload a log file you go PC log, take a log, save it and upload the file. If you want to upload a calibration file, connect the ECU, go save session, save it and upload the file.
 
Last edited:
Maybe the afr swing is telling the ecu to add fuel then dump then add then dump like a DSM ecu works. I am not familiar with AEM units tho.
 
Thank you guy. This helps a little. I wasnt able to upload a log in the format the ecu spits it out, I'll try to figure it out though.
 
I’m not familiar with the AEM but does it show what the fuel trims are doing at idle? I was able to get 1250cc low impedance to idle almost like stock after some tweaking.
 
There are several things cause the AFR swing at idle. Could be tuning issue but still could be mechanical issue. If it is a tuning issue, my first guesses are, the O2 feedback is not matching to the fuel trim or incorrect injector battery offset. In case if the O2 feedback is activated, I recommend @88BB8B to disable the O2 feedback first and see how the AFR would react.
 
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