SureTrack Users General Discussion

[Tech_A]

Tech A;
I'm just pointing out that HEAT or hot air isn't enough to skew the MAF sensor.
Warmer air has less density, less mass, therefore less oxygen molecules along with the 79 or 80 percent nitrogen.

I was pointing out the actual heat emitted by the engine in proximity to the sensor may skew the sensor since some MAF/IAT sensors monitor the amperage it takes to keep the hot film element hot as air passes over it, but I realized it should not have that much bearing since the overall engine compartment temperature is the same.

But I do agree the more things change the more they stay the same. Especially if you consider the technology from diesel fuel injection systems being applied to the modern direct injection gasoline engines.

[Crusty]

I was pointing out the actual heat emitted by the engine in proximity to the sensor may skew the sensor since some MAF/IAT sensors monitor the amperage it takes to keep the hot film element hot as air passes over it, but I realized it should not have that much bearing since the overall engine compartment temperature is the same.

But I do agree the more things change the more they stay the same. Especially if you consider the technology from diesel fuel injection systems being applied to the modern direct injection gasoline engines.

Agreed. The temperature surrounding ALL the components should have been accounted for by the original engineers designing the vehicle. Stuffing some B.S. cold air box onto a street vehicle these days isn't the same as messing around with a 1967 'Vette 327 350-horse-!! LMAO
(Although that WAS a very nice setup and combination-!!!!)
Or messing around with advance curves and fuel delivery and carburetion on a big block 396 or 427.

My mentor used to say "who am I to second guess 20 million dollars of research and development". There was very little he would change from factory spec and that only a very small amount for our environmental conditions up here where we have steamy hot humid summers and freezing cold dry winters.

Without an IAT the MAF sensor can't accurately measure the grams of OXYGEN entering the engine for combustion regardless of where the inlet air originates.....from the engine compartment or from behind, perhaps a headlight or some other protected area that can pull cooler air without ingesting dirt and debris. Today's vehicles don't dirty up air cleaner elements the way they used to back in the 60's, 70's or 80's.
Like I said, you couldn't GIVE me one of those B/S add on hot rod snake oil gimmicks-!!! LMAO

Some people seem to need a prick extension, like the biggest big screen TV in the store-!! "Look at ME-!! I'm a hero because I just messed up a balanced combination of engineering-!!"
Smart like a bag of hammers.

[greasybob]

And the test results are in, After a weekend of being driven I got to take a look at the fuel trims on the F150. All looks good, the baro would be better if at 158 Hz calculated, but 155 is not bad. I think it's all about velocity with the MAF. The PCM is mapped to read the MAF where the air is calculated to moving at a specific rate. The same amount of air moves faster through a 2 inch pipe than a 3 inch. And then take into consideration cavitation and all the other swirling that goes on. The faster the air moves over the "hot wire" the more it cools it. My favorite case so far was a mosquito that killed a Ford Ranger by sacrificing it's guts all over the MAF wire.

[Crossland Auto]

I am way curious what Greasy has to say on what he did to this one.
I personally do NOT reset when I make a change. If I saw trims at max, and I made a change, I like to see the old adaption make a correction in my favor.

X

[Crossland Auto]

Guess I was already trumpt'd, I hit the refresh button before I decided to post. The last post shown was Tech A @ 6:12. Then I posted my last comment, it refreshed again, then there was Crusty and Greasy's comment.

X

[Dr.Jake]

No mess w/car's wind pipe or rectal areas. That will be ignorant..

Freezing moisture knocked out the supply of electrons in the upstate here yesserday... no spare parts, bad day. Duke Power needs to getta chain saw.

DrD and eRic#2 Guy are putting out plenty educational tv shows..Thay after the tube money.smart aye. dinaros by look see. 40,000 looks = 100 duckets.
Soon thay quit fixing, just do movies. Get a Lamborghini and a golden lab w/hero5 dog harness.

[Tech_A]

Speaking of electrons

I found this chart that converts voltage drops across a fuse in mV to amperage draw. Its method suggested to help hunt down parasitic draws on BMW's. I currently had to encounter such a situation on my friend's mother's E46; my current solution is a battery tender until I have the time to diagnose the vehicle.

See Attached

[maven]

I found this chart that converts voltage drops across a fuse in mV to amperage draw. Its method suggested to help hunt down parasitic draws on BMW's. I currently had to encounter such a situation on my friend's mother's E46; my current solution is a battery tender until I have the time to diagnose the vehicle.

See Attached

Thats a nice chart, havent seen that particular before. The one thing that none of these charts take into account though is temperature. The voltage drop across the fuse can vary .5mV or more (Ive seen as much as 1.3mV) depending on the temperature of the fuse. A fuse thats freezing cold outside ambient temperature shows a (in this situation) significantly different voltage drop than one in a warmed up engine compartment.

I also mentioned this in another thread, when you are diagnosed things at the fraction of a millivolt level there are so many tiny variables that affect the outcome. The level of cleanliness of the fuse, the condition of your probe tips, the connections between your probes and the cables, the cables and the meter, the accuracy of your meter, etc....(many meters arent even accurate at .0001 volt levels the common Fluke 116 is only accurate +/- 2 counts...other meters are even worse. )

[Robin]

In general terms, isn't somewhere around a 50 ma and under draw o.k.?
If the temperature only affects the readings by .5 to 1.3 mv, you should not have a problem finding a problem draw. I have never tried checking this way, but it sounds like something I may try.

Just trying to learn something.

[maven]

In general terms, isn't somewhere around a 50 mv and under draw o.k.?
If the temperature only affects the readings by .5 to 1.3 mv, you should not have a problem finding a problem draw. I have never tried checking this way, but it sounds like something I may try.

Just trying to learn something.

50mA is technically excessive on many modern vehicles when fully asleep, GM for example wants 35mA or less across most of its vehicles. But if youve only got 50mA its unlikely thats why your battery goes dead in 2 or 3 days, so its a solid starting point none the less.

If youre looking for a small draw, and youre using that chart on say a 5A standard fuse, a hot fuse that shows 1.1mV will equate to 73mA draw, excessive, when in reality that circuit may only be drawing a normal 13mA. ANd if you measure the fuse cold you may only see 0.2mV. So in that case 0.9mV makes a 60mA difference and a bad diagnosis. So since its a BMW did you misdiagnose a $150 HVAC output controller or was it a $1500 Enigne control module? You willing to risk that cash?

[Crusty]

In general terms, isn't somewhere around a 50 mv and under draw o.k.?
If the temperature only affects the readings by .5 to 1.3 mv, you should not have a problem finding a problem draw. I have never tried checking this way, but it sounds like something I may try.

Just trying to learn something.

It may just be a typo but there is a big difference between 50 milliVOLTS and 50 milliAMPS.

The charts can also be found in an Audi TSB issued March 2012.

The voltage drop across the fuse might be one way to isolate an area or circuit to do further confirmation testing on but ss MAVEN is pointing out there are lots of pitfalls in this test method. The quality of the meter being used is just one caveat.

[Robin]

O.K. I see where I was messing up. I was thinking the error was MA. I had not converted the MV to MA. This explains why my thinking was wrong. It still may be a good starting point????

Thanks for clarifying.

[maven]

O.K. I see where I was messing up. I was thinking the error was MA. I had not converted the MV to MA. This explains why my thinking was wrong. It still may be a good starting point????

Thanks for clarifying.

Yeah, its not a bad starting point. If youve got 1.0mV or more across a fuse on a vehicle that is supposed to be powered down and the fuseblock is cold then you can be fairly confident theres a draw on that circuit worth investigating.

Its just so tedious.

[Witsend]

Seems to me if you see any minute measure able voltage drop over a fuse you suspect but want to accurately confirm with out inductive pickup , you could fabricate something out of a current loop fuse buddy to hook an amp meter to each side of the current loop's fuse then pull the fuse from the current loop buddy after the car goes into sleep mode and all the current will flow through the amp meter for that circuit and accurately be measured without waking up any modules.
Temporarily install the lowest amperage fuse possible without it blowing on you probably give you more of a consistent measurable millivolt drop across the fuse I would imagine. Just don't forget and leave them in there!

[liljoe]

fuse buddy sells one with ammeter built in, just plug into fuse and turn it on, measures current draw on small screen.
Use it all the time for finding battery drains.....