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ECMlink Log Showing Bad Map Sensor???

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JCL84

10+ Year Contributor
110
4
Jun 13, 2012
McHenry, Illinois
Im trying to diagnose a issue and im thinking its a bad map sensor which is a AEM 5 bar. My AFRatioEST and LC1WB are way off at idle. It sputters and dies when trying to drive. I have a key on log and a idle log below. The key on log shows the map sensor at -1.1 and in the idle log you can see things are way off. I was also thinking my fuel pressure regulator may be bad but the gauge on the FPR is fine. In my log at idle fuel pressure is reading funny but I think thats just my cheap fuel pressure sensor taking a dump. Just wanted some opinions here before I go out and buy another AEM map sensor.
 

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To me it looks that the MAP sensor is working correctly. It's hard to tell by seeing only those two logs but at least the MAP sensor is sending 1.25v when the engine is not running which means around -0.5 psi (approximately -1.1 in hg) and 0.95v ~ 0.98v at idle which is around -5.5 ~ -6.5 psi (approximately -11.5 in hg ~ -12.5 in hg), so it seems correct. If I were you I would doubt something else and not to buy another MAP sensor yet.
Before buying another one, you should test the MAP sensor by applying some air pressure and see if the sensor’s voltage output is following the table below.
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I think your right. I was letting it idle again and now my fuel pressure is in the mid 50's so maybe the fuel pressure sensor is showing a correct reading. I can adjust the fuel pressure all the way out but it doesnt help much. Diaphragms are cheap enough so ill give that a try. Thank you.
 
ISC is very far off, Air flow per rev is to high, Fuel trims show car is very rich at idle. In SD table you are set to 2.7L of displacement as well. The timing and fuel maps look very familiar to me.
 
I should have stated that this is a tuned car and all was fine. Well the tune wasn’t finished but it was close. After a pull things became all out of wack.
 
I know who tuned it just by looking at the tables :p. But lower ur fuel press to stock and the displacement is set wrong in SD table unless you are running a 2.7L LOL.
 
You need to adjust ur Biss to get ISC to 30. Then adjust the SD table to get air flow per rev down. Then play with dead time to get fuel trims to zero. You may have to adjust global fuel after changing the displacement back to 2.0.
 
Everything is lined up again! Lol thanks for spotting that error, after I put it back to 2.0l I’m back in business. My finger must have slipped and changed it without me knowing. But yes I will adjust the biss screw. Thank you!
 
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