This is hogwash posted by someone who has little clue about electronics or automotive control systems.

First of all, the sensor wires in a car are not that sensitive. A car is an extremely "noisy" electrical environment and the electronics systems in cars are designed to withstand the "noise" from these environments. If sensors were truly *that* sensitive to noise, you would see the wires shielded, but the wires are just exposed to the environment and noise can easily couple into them from all kinds of local sources.

Second, lengthening or shortening the wires of a sensor ARE NOT going to cause any frequency or resistance issues. If there were tuned RF transmission lines operating in the GHz, then yes, changing line length could effect electrical performance, but these sensors are very low frequency and not prone to this at all. Also, the change in resistance due to thermal effects is going to be much, much greater than the change in resistance in making the wire shorter or longer. In otherwords, the total impedance (i hate using the term resistance as its only half the story) of the wire is going to change drastically when going from 20degF (cold winter day) to over 100degF (when the engine warms up) - much more than cutting the wire by 1 or 2 feet.

Finally, I'm not sure about exactly what circuitry is in the MAF sensor, but it could be prone to ESD (electrostatic discharge), so when its disconnected, any static charge on your body can damage the sensor if its wires are terminated. And as the other poster stated, cutting wires with the battery still connected could be an issue as well.

Or even more plausible, the disconnection of the MAF sensor (with power applied or the engine restarted with the MAF sensor discconected), will detect a missing MAF sensor and fault the ECU etc....

But as long as you work with the battery disconnected, discharge yourself prior to cutting or touching bare MAF wires (easily done by wearing a grounded wrist strap or simply touching the metal chassis nearby), there shouldn't be any problem. Shortening or lengthening wires will have NO EFFECT on the performance of the sensor.

Yeah, some report. Just someone, who happens to be named BikiniLust, posting some rehashed opinion he read on another website.
The only good advice in that report is the advice regarding protecting the wires against thermal damage.

Of course, this all coming from someone who refers to themself as Ham Salad!!!

 

Dude, I've done MORE than enough wiring DIRECTLY to the ECU. Lengthening the wire/shortening the wire isn't going to change anything. The only problem that arises is from the ECU not getting its signal from the MAF, TB, etc while the battery is plugged in.

I would correlate the problem to people that disconnect their TB without disconnecting the battery. They ruin the TB sometimes because of this.

 

Oh yeah. I've done this hundreds of times - everytime i work my car and need to remove the intake tube or what have you. This is no different from disconnecting your MAF sensor connector and plugging it back in. Disconnecting the connector, or cutting the wires has the exact same effect - breaking the electrical circuit.

 

^^^ LOTS of us have disconnected the MAF sensor boatloads of times... that is absolutely not the same as cutting the wires - you are delusional to think so.

For all the posts that comment on the "one" quote I posted, I already told you there are countless of reports of issues... I'm not going to name names, but a couple of people have had problems from cutting the wires during wire tuck.

Again, I suggest - to prove your points, simply make a short vid showing you cutting your MAF sensor wires, then reconnecting (however you determine works) and fire up your car.

Its real simple - you can either keep typing here that it wont cause problems or you can show that you know the secret that others apparently didn't.

Believe me - if you have some way to cut the MAF wires and not create problems, it will make wire tucks even more stealth! Loads of people would love to do trick things with that loom.

 

Oh really? I'm not sure what kind of background you have, but its obviously not in any type of electronics or electrical field. I can guarantee 100% that disconnecting the MAF sensor connector is EXACTLY the same as if you cut all the wires on the MAF sensor. Perhaps I'm missing something, but the electrical connection is broken in both instances, unless of course you have some sort of magical connector, which is sounds like you do.

I don't doubt you, but it has nothing to do with wire length or the "cutting" of the wires. What is most likely happening here is that when those people are reconnecting the wires, they are not reconnecting them properly. Bad crimps, bad (cold) solder joints, are not uncommon, especially when people don't have experience doing them.

I have nothing to prove. Your the one making the claim, therefore, the burden of proof lies completely on you.

The secret is simple:

1. Good solder joints
2. Proper signal routing - Don't route sensor wiring next to wires such as ignition wires which can couple noise into the sensor wiring.

Again, I don't know what *your* background is, but I'm an electrical engineer with many years of experience in both the military and commercial fields and also own my own engineering consulting firm which has done lots of control systems work for various automotive and industrial manufacturers. I also have specialized training and experience in the field of EMI/EMC (electro-magnetic interference / electromagetic compatibility), and work with many companies in solving their particular EMI/EMC problems they have with their electrical designs.

 

^^^ with your background it would be really great for you to do a DIY video showing (rather than typing) your claims.

I'm sure you've noticed the current trend of wire tucks in the G community (since this is your thing, surly you noticed)... lots of people would benefit greatly from a DIY.

I know several people that have steered clear of messing with the MAF sensor wires (for all the reasons I have mentioned). But apparently it’s all just paranoia and those that have had problems have unnecessarily caused others to steer clear.

I can assure you there are many people that would love to know its okay to cut MAF sensor wires. However, none of the people I know are willing to do so based on one or 2 guys saying its okay (no matter what field you're in).

Let's face it - when more than one person encounters a problem with the same issue (no matter what the subject is) - it’s going to take a lot more than "I'm an expert I say it works" to correct the "wrong" that has been done.

You really would be doing the forum a huge favor by posting a DIY (preferably with vid) so that people know it in fact can be done. Because as of now, there are more than one reports of problems -and people aren’t cutting MAF sensor wires because of it.

 

Sounds like an excellent idea, however, i'm going to need the following background information to proceed forward:

1. The people who had problems, what exactly was the problem, and what was their corrective action to solve the problem?

2. For a cable tuck, where exactly are the wires being re-routed? Pictures would be helpful here as well as what other car components the wires are passing by

3. How are the wires being dressed for the wire tuck? For example, if the wire bundle originally had twisted wires, is the bundle being prepared the same way?

4. Are the sensor wires being bundled with any wires that weren't bundled with it before?

Number 1,3,4 are very important. For example, you say cutting the wires alone is enough to screw it up. But if thats the case, than what is the solution those guys had when they had their MAF screwed up? Did they scrap the car after that? Where the bundle is being re-routed is very important as if it passes by either ignition circuits or the alternator (or any areas where their are high currents), this can induce noise on the sensor lines which cause problems. And also bundling sensor wires with "other" wires can cause a problem again due to cross-coupling between wires.

Also, its important to realize that the places where the manufacturer "puts" wire bundles is NOT arbitrary. Sensitive wiring is routed away from sources of high EM/H fields, and by doing a wire tuck and moving that wiring to a less than optimum location can be detrimental.

But, if you get me the above information, i'll be glad to volunteer my car and do a DYI.

 

Again with the cutting of the wires. Its completely beyond me to why people thinking disconnecting the maf by cutting the wires is somehow magically different than disconnecting the maf by removing the connector. This is ridiculous now. Im done with this ****.

If you guys want to keep believing shoryening or lengthening the sensor wires has some kind of evil magical effect im completely ok with that.


This is my last post on the subject.

 

Liche - Along these lines above ^^^ (And I've done plenty of wiring to understand exactly what you are saying) I agree with OCG35...if you could do a DIY wire tuck it would be MORE THAN stellar. You could help people by not only proving that its ok to cut/lengthen the MAF wires, but also show where to route the wires.

 

If you guys could tell me exactly where wire tucks typically re-route these MAF wires, then i'd be happy to look at it and see if the re-routed wires pass by anything putting out lots of noise.

Remember, current through a wire causes a electromagnetic field to be induced around the wire. If you have wires with very high currents (such as those near the alternator), these fields can easily couple into sensitive wires nearby inducing voltages on them which can corrupt the sensor voltage.

Also, the MAF sensor has three wires (power wire, signal wire, and return). When redressing these wires, all three should be tightly twisted together all the way back to the ECU. This ensures tight coupling between the wires (low inductance) and less susceptible to noise in the environment. Also, keep in mind any time you have a signal and return with a large "loop" area between them, this "loop" acts as an antenna to pick up stray noise. By twisting the wires together, you minimize the loop to almost nothing.

 

by "return" are you reffering to a ground wire?

I have no idea where people route the MAF wires, i know that typically they route the passenger wire loom under the fender. The drivers side people normally route through the drivers side fender just like on the passenger side. The ignition coils/grounds/MAF wires seem to get route behind the plenum.

 

Yes, return wire would be the ground. Now that you mention it, i'm wondering if people are cutting the ground wire and attaching it to the engine chassis in order to "neaten" up the wire bundle and reduce wire count. That of course would be a very bad thing for the sensor wires as the return wire needs to go back with its signal wire directly to the ECU.

Anyways, this is a very interesting topic and i'm looking forward to investigate the wire tuck further . . .

 

Anyone know what type of MAF sensor the G35 uses? I believe its a hot wire type sensor (as opposed to vortex type, or vane type) -

In that case, its just basically two heated wires with thermistors (in wein-bridge configuration) which output a DC voltage depending on amount of air flow. Nothing magic there.

 

Yes hot wire type. Usually sends a voltage of 0-5(or similar) to the ecu.