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Discussion Starter · #1 ·
I have another quick question. Does anyone know what the idleing voltage is? I am wondering if this is part of my problem. At idle (lights radio ac on) it is reading 13 and dips everyso often. driving it gets to a max of 13.5 . shouldn't it be higher than that? Thanks in advance, Bryan
 

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Mine idle's at about 13.5 VDC or lower as stated. I idle at around 950 RPM's and I have the U/D pulley installed.

D.J.
 

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I see about 14.2 volts on the DIC when the engine is cold, and it goes down to about 13.8 volts after full warm-up.

I've also measured directly across the battery, and the DIC usually reads about 0.3~0.5 volts lower.

I'd suggest checking across the battery to verify if your gage is accurate. If it's 0.3~0.5 volts lower than the battery, and the battery voltage is low then maybe your battery is going bad or the charging system is a little weak.
 

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14.2 cold or hot hot idle 750 rpm
 

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14.2 to 13.8 :z:
 

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You didn't indicate whether this happens right after starting it or later when the engine reaches normal temp.

If you are refering to normal temp range, it probably has to do with the fans turning on or off, as well as, the ac compressor.

Keep in mind that the voltage is relative to the pulley speed, battery condition, and most importantly the LOAD on it. Of course, the voltage regulator attempts to compensate for these factors, but there is only so much it can do when the pulley speed is low during idle.

Hope this helps.
 

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Get a decent DVM (digital voltmeter). Sears has one on sale for about $19 during the Craftsmen tool sale. You may want to spend a few more dollars and get one with a MIN and MAX hold. Nice feature to keep you from guessing about fluctuations or trying to read an analog meter.

Are you reading 13 at the DIC or are you looking at the analog display?

When you say it dips are you looking at the DIC or at the analog display? And how much and for how long does it dip?

Does it dip at idle if you rev it? If you crank on the stereo, AC and play with the windows how much does it dip at idle and if you rev it a bit?

Measure the battery with the car off. Should be around 12.5 or so.

Measure with the car on. As others have stated you should see 13.8 to 14.2 or so.

If voltage is low, you logic systems are going to do "funny" things. Need to determine first if the battery is just weak, or if there is a regulator issue. Then we can move on! :D
 

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Discussion Starter · #11 ·
Hey everyone thank you for all the replies. I will check the battery in a little while, I have a Craftsman Professional Multimeter. I got it for work so i will bring it home and check it out. It does have the min/max feature. when the dic is showing 13.9 + volts my car runs great. When it starts bucking and missing the volts come down to 12.8-13.5. and they stay the same whether at idle around 950 or at 3500rpm. I shut the a/c off and radio and it may only increase by 1-2 volts. yesterday my current codes were p0112 and p1112 saying my air temp sensor voltage was low. It wouldnt even get out of its own way. I am also having several of the right/left hand door U1016 Loss of Communication with PCM
U1064 Loss of Communication with BCM
U1096 Loss of Communication with IPC
U1255 Serial Data Line Malfunction. That is what is making me wonder about voltage. So now i run with the Dic showing the volts and i can usually tell when i am getting ready to have problems. when i check the voltage across the battery i will post it. Thanks again Bryan
 

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You better start looking for a new battery!! TODAY!!
You have a cell going bad and the alternator is being over worked trying to make up! The stock batteries are crap, don't put that strain on the alternator which is marginal too!!
Time for an Optima Redtop!! $90 battery-$450 alternator!!

Ken
 

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Discussion Starter · #13 ·
Update

Ok, sorry it took so long to test it out. My dad had knee surgery and was having to help out. It isn't a battery issue. I just put a brand new battery in yesterday. I charged it fully with a battery charger overnight 12v/2a. Drove it this morning around a total of 50 miles. Check engine light back on. I was riding a bucking bronco.
Error Codes
P0102 H C Mass Air Flow (MAF) Sensor Circuit Low Frequency
P0112 H C Intake Air Temp (IAT) Sensor Circuit Low Voltage
P1112 H C Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage

These were not on all at the same time 102 and 112 on at the same time (current) then went to history and 1112 became current.
I read the codes off of the DIC and went to Autozone just to get a print out. He suggested buying a new MAF and IAT.
Well he didn't really suggest it, he just read it out of a little book.

I drove it home and let it set to cool off. I went out this afternoon and checked it, here are the results.

Battery sitting 2 hours
Meter- 12.65
Dic reading 12.1-12.0

idle 800-820 rpm cold engine
meter-14.18
dic-13.7v

Idle warm engine fans on
meter 14.06-14.11
dic-13.6

a/c max on, radio on
meter-13.82-13.89
dic-13.4

increase rpm to 2000
meter-13.73-13.79
dic-13.3
increase rpm to 3500
no change

return to idle
meter-13.81-13.88
dic-13.4

after 30 mins of running
meter-13.5-13.75
dic-12.9-13.2

I hope this is what you were asking for . If not let me know I will check again. Thanks again for all the help. Bryan
 

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Your battery looks right and the running voltage levels appear in the ballpark.

Looks like a sensor issue (duh). Only thing I can think of is the connector to the MAF OK -- may want to seat it. Have you washed the engine lately or taken anything apart?

Or look at and perhaps clean the MAF wires with a gentle solvent and a q tip.

You may want to repost under a new title, like Help Diagnose MAF / IAT codes to get input from the more knowledgeable. :D
 
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