Voltage to Mass Air Flow sensor on 99 V70XC

warcraftjunkie · Post by **warcraftjunkie** » 22 Sep 2012, 07:06

I've run with the MAF unplugged, but only for short distances. The performance was the same. I'll try again this morning to see if it runs better over a longer period of time and greater range of throttle.

I'm not 100% certain what you mean by "Adaptives". If you mean disconnecting the negative battery terminal for 30 minutes, and then also clearing all codes with an OBDII reader...yes. If there's another procedure that should be done, let me know. I've wondered if my ECU needs to readapt to the new Throttle Body, but from what I've read about Xemodex TB's, is that it is simply plug in and go.

warcraftjunkie · Post by **warcraftjunkie** » 22 Sep 2012, 10:57

Just so everyone knows, the current codes I got yesterday are...
P0030
P0650
P0453
P0102
P0236
P0121

Post by **BEJinFbk** » 22 Sep 2012, 11:56

Have you taken a look at your battery and B+ voltages?
B+ is the line that moves power from the battery to the main fuse box.
They have a reputation for failing on your model year.

Search "voltage drop" and check it out.

warcraftjunkie · Post by **warcraftjunkie** » 23 Sep 2012, 09:33

I tested the power last night on the B+ line by touching the +end of my voltmeter to the nut in the main fuse box and the -end of the meter to the negative post on the battery while the car was running. I was getting a fluctuating reading of 13.20 to 13.8 on that line. Those measurements seemed to be fluctuating in conjunction with the rough idle as it was hunting between 800, and 1200 RPM.

Post by **Pauloil** » 23 Sep 2012, 20:43

test this cable under load and measure the voltage drop. under load is at 2000rpm with lights on, rear defrost, and fan on high.

http://www.aa1car.com/library/voltage_drop_testing.htm

warcraftjunkie · Post by **warcraftjunkie** » 25 Sep 2012, 00:59

Ok, alternator and battery tests as follows.

Car off and measure between posts of battery = 12.16v
car running at 2000RPM measure between posts of battery = 13.2v
alternator charging cable to ground = 13.84v
alternator charging cable to positive post of battery while car running at 2000RPM = .64 voltage drop
battery positive post to end of B+ cable in fuse box while car running at 2000RPM = .12 voltage drop

While car was at 2000 RPM, seat heaters were engaged, rear and mirror defrosts, and cabin fan blowing on High.

Thoughts? seems the voltage drop from alternator to battery is a problem.

Post by **Pauloil** » 25 Sep 2012, 06:28

yep, anything over 0.2 volts drop is bad the B+ cable is going bad also

Post by **regent** » 25 Sep 2012, 08:25

I would inspect the contact surfaces and crimps for oxidation, signs of overheating (discoloration) before condemning the whole thing.

warcraftjunkie · Post by **warcraftjunkie** » 25 Sep 2012, 08:34

I was just about to say that I should probably do that. The measurements were done from the posts to points of contact. I should probably also do mesurements from wire harness contact at post to wire temination on B+ wire... and the same thing for alternator.

Post by **Pauloil** » 25 Sep 2012, 11:08

i agree: good to look for the oxidation. i saw some at the end of my B+ cable and the voltage drop was 0.15. changing the cable out inc batt. voltage form 12.3 to 12.6!!!