Weird Fueling Issues

Discussion about ECU Tuning Products and Theories
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dj_smooth
240sx Wannabe
Posts: 196
Joined: Sun Aug 10, 2008 12:35 pm
Location: Guam-- Moore, Oklahoma

Weird Fueling Issues

Post by dj_smooth » Thu May 05, 2016 7:21 pm

Can someone take a look at my log and give me an idea of what might be the issue? I'm not sure if my fuel pressure regulator is relieving on and off intermitenly, or my wideband o2 sensor needs to be replaced. The gauge dips widely while boosting. It's an MTX-L gauge. It has been recently free air cal'd and the sensor has been covered with a rag and brake cleaner to visually watch the gauge get rich and slowly lean out. The wideband is cal'd with megasquirt. I used the voltage reading for the o2 sensor to match the high and low values vs voltage. Another thing to note, if at idle I increase the VE value to rich as in 11.5, the afr doesn't change but a few points. I'm really thinking it's the fuel pressure regulator, but just looking for a second opinion. It's an aeromotive fpr. On a side note, feel free to give me some pointers about things that stand out to you guys in the log.

Megasquirt PNP2
TD06 20G
550cc injectors
Stock cams
91 Octane

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dj_smooth
240sx Wannabe
Posts: 196
Joined: Sun Aug 10, 2008 12:35 pm
Location: Guam-- Moore, Oklahoma

Re: Weird Fueling Issues

Post by dj_smooth » Thu May 05, 2016 8:25 pm

Maybe it's all my fault. I changed the MAT temprature curve to help combat heat soak. IAT 88* to 97*

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Matt Cramer
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Re: Weird Fueling Issues

Post by Matt Cramer » Fri May 06, 2016 11:23 am

The O2 readings look rather spikey. How exactly is the wideband wired up, and what sort is it?
Matt at DIYAutoTune.com - Megasquirt ECUs, fuel injectors, wideband O2 sensor systems, and more
Nissan plug and play engine management now in stock!

dj_smooth
240sx Wannabe
Posts: 196
Joined: Sun Aug 10, 2008 12:35 pm
Location: Guam-- Moore, Oklahoma

Re: Weird Fueling Issues

Post by dj_smooth » Fri May 06, 2016 12:12 pm

It's an MTX-L wideband. Ground is on the same ground as chassis ecu. Analog output of 0 volts to 5 volts. I ran the car rich to about 10.5 at idle and shut the car off. Then looked at tuner studio 0-5 volt o2 gauge and put that voltage value in plus what the mtxl wideband was saying for the custom calibration. I watched the mtxl lean out and then inputted the mtxl afr at 16.5 and tuner studio o2 voltage for the high end of the custom linear wideband reading.

dj_smooth
240sx Wannabe
Posts: 196
Joined: Sun Aug 10, 2008 12:35 pm
Location: Guam-- Moore, Oklahoma

Re: Weird Fueling Issues

Post by dj_smooth » Sat May 07, 2016 9:13 am

Update. The LSU 4.2 sensor was bad. Also changed MAT curve back to ka24de base map value.

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BigLoukaT
Dont Question My Nissan Knowledge
Posts: 879
Joined: Sun Jul 23, 2006 11:03 am
Location: MA

Re: Weird Fueling Issues

Post by BigLoukaT » Sat May 07, 2016 6:34 pm

So all's good now?
1990 S13
Boosted single slammer
MS DIYPNP
npx from 240sxforums wrote:i figure from my very limited knowledge about the 240 and under the hood about cars in general i would follow the sr20det trend.

dj_smooth
240sx Wannabe
Posts: 196
Joined: Sun Aug 10, 2008 12:35 pm
Location: Guam-- Moore, Oklahoma

Re: Weird Fueling Issues

Post by dj_smooth » Fri May 13, 2016 6:23 am

Yup, o2 sensor was just worn out. Biglouka-t, have you tried the headphone output on the megasquirt pnp2? I gave it a listen yesterday and it's pretty cool, but it sounds like I have alternator whine as well.

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BigLoukaT
Dont Question My Nissan Knowledge
Posts: 879
Joined: Sun Jul 23, 2006 11:03 am
Location: MA

Re: Weird Fueling Issues

Post by BigLoukaT » Sun May 15, 2016 6:05 am

Nice! negative, I am on a DIYPNP so I don't have the head phone jack output. Actually, I don't have a knock sensor for that matter lol. I need to make some knock muffs this year and start playing with timing.
1990 S13
Boosted single slammer
MS DIYPNP
npx from 240sxforums wrote:i figure from my very limited knowledge about the 240 and under the hood about cars in general i would follow the sr20det trend.

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