L giving up part 2

[XsivPwr]

going from my previous post

http://www.svtperformance.com/forums/showthread.php?t=287332


I replaced the fuel filter and that had no effect. Although it was pretty restricted flow, it needed to be replaced anyways.


After a little more tinkering, i found out that if i unplug the MAF, the truck will idle.... rough idle.. but it stays running and i can rev it a little bit. Is there a way to test the MAF to see if it is metering correctly? I dont want to plunk down 75-100 bucks on a new sensor that wont get me running.

Thanks for the help guys..

 

[AZ ERIK]

Clean it, it's probably coated in oil and misreading.

http://www.partsamerica.com/ProductDetail.aspx?categorycode=3225&mfrcode=CRC&mfrpartnumber=05110
pull it off to clean it and spray from a distance, don't stick the hose on the sensor, spray from like 9 inches away.

 

[Derek@Amazon]

Clean it, it's probably coated in oil and misreading.

http://www.partsamerica.com/ProductDetail.aspx?categorycode=3225&mfrcode=CRC&mfrpartnumber=05110
pull it off to clean it and spray from a distance, don't stick the hose on the sensor, spray from like 9 inches away.

the or rubbing alc. with a q-tip with light pressure on the lamp coils on the sensor

 

[AZ ERIK]

lightly clean. You can see one of the sensors, I can't remember if there are 2 or not, which is why I used the spray cleaner.

 

[boca ron]

do you have hand held programmar?

 

[XsivPwr]

already cleaned it with a q tip and rubbing alcohol

Yes, i have a predator programmer, it did throw a code when i had it unplugged saying low voltage reading.

 

[boca ron]

there you go

 

[AZ ERIK]

That was only while unplugged. Find out what the MAF voltage is at idle, It might be reading bad still.

 

[Screaming01L]

so, your fuel pressure is ok, you checked your plugs too, do an ohm check on the coils. Datalog the maf, check voltage and MAF counts, check O2 readings. You could even have a bad injector. When you unplug the maf, the truck goes into limp mode, so it will run, which kinda makes you want to look at the tune. IAc can do it, egr. Theres alot of places to look.

 

[vwjunkie53]

I have the 80mm maf out of my truck. You can HAVE it if you want to try it out. Let me know. It worked fine on my truck when I took it off. Just a thought

Jason

 

[boca ron]

how is your battery is it the stocker?

 

[XsivPwr]

VWJunkie, that would be awsome, even just to borrow to test.

Ill have to work on it tonight to get those readings for you guys, i was out camping all weekend, and then yesterday it was storming all day.

Battery is an Optima, Never a lick of trouble, always turned it over real nice.

 

[XsivPwr]

Ok guys, I went and hooked the predator up and tried to start the L up a few times and heres the numbers that came up.

IAT seemed normal at 76 degrees F
MAFV also seemed to be alright, it ranged from .23 when the engine was off, to about 1.32 when the idle got up to about 1200rpms
Now what looked funny to me was the o2s22 and o2s21 readings. o2s22 never changed from .01v the entire time, wether the engine was running or stalled, it never changed. o2s21 was pretty much always .00 volts except for a couple moments when it did go to .01


Hope this helps out

Thanks again for everyones help.

 

[XsivPwr]

bump

 

[Fade 2 Black]

The first thing you need to do is check fuel pressure when you turn the key on and see what happens to it when you start the truck. Also jump the relay under the hood and see what it reads. Did you check the resitor behind the front bumper? Is it in tact and if so did you jumper the wires at the connector and see if the truck runs? The resistor should read ~620 ohms. Once you check and verify this then:

Turn the EGR and rear O2 sensors off and see what happens. This will eliminate some stuff for you. If you can aslo check the voltage of the battery static and then the output of the alternator when running.

 

[boca ron]

are the rear o2s turned off in the predator? 021s are not switching? is this what your saying? 021 are not switching?

 

[XsivPwr]

Just a reminder that im new to the Lightning.

How can i check the pressure without a gauge?

I just had the predator log real time data on those sensors.

How would you go about turning the o2 sensors off?

Fade, do you have a picture of this resistor?

 

[Fade 2 Black]

Here's a pic of a bad one:

It should just look white and is mounted at the top right (passenger) side of the heat exchanger behind the bumper cover.

You have to have a gauge to check fuel pressure.

I don't know if you can modify the canned pred tunes or not but with a custom tune go into modify parameters and you'll see it in there if you have a custom tune.

 

[XsivPwr]

I was running the canned performance tune on the predator, but i have since changed it back to the factory tune to troubleshoot this.

Ill try to check that resistor, but didnt you say if it was bad, there would be no fuel pump power at all? I can get the engine to run if i unplug the MAF, its just a rough idle, and cant power itself to move, but it does have a rough idle that doesnt die out.

 

[XsivPwr]

This is driving me nuts...

Bump