Can someone enlighten me about exhausts systems?

Huh, believe that my injectors are turning off as I notice more decelleration without braking than can be accounted for. Also, my Scanguage goes to 9999 mpg for decel, up until about the time that it downshifts to 1st, then it gives a reading.

 

I believe if you put it in neutral the Transmission will not be pumping fluid as it would be if you were in gear. However unlikely this could cause overheating of fluid. (please correct me if I am wrong i don't want to spread false information )

My scan gauge also says 999 when i let of the gas (not all the time, more often at higher speeds and with a sudden release of the pedal) and it only stays like that until around 20 mph where it seems like the injector cutoff system lets the injectors turn back on ( you can feel this happen if you really think about it next time your coasting to a stop ). So I'm pretty sure there is an injector cutoff system in these trucks.

 

Thanks for the info

Thanks, but can you explain how it could overheat?

 

Oh, by the way... Went with my dad to the local muffler shop, the guy refuses to just install an exhaust system that I bought myself, he wants to do everything himself. we agreed on running dual side exit flowmasters w/chrome tips for 450 plus tax, for those of you who were wondering.

 

You continue to pump fluid just fine, it is only if you shut off the motor and coast that you can and likely will cause damage.

Transmission on vehicles that can be "dinghy" towed will not be damaged even if the engine is off.

Tacomas can not be dinghy towed.

 

I know they lose a couple of horses, but it's not like I'll feel it. And they don't sound that bad. How'd you get your Banks Monster exhausts? Did you just order them and install yourself?

 

Must have read it wrong when i saw that. Thanks for the clarification

 

Regarding the injectors shutting off during engine braking it is only above 1500rpm or so that this works.

For me on a mild hill if I coast i am slowing down in gear but in neutral I can pick up speed and coast a lot further.

Short distance with no fuel, plus long distance using fuel requires more overall fuel than coasting a long way while idling - most of the time for me.

And my scangauge isn't smart enough to know the injectors are off, scangauge needs to upgrade the program to reflect this!

 

So what is something you recommend I can get that will sound good, and can easily install with my father? Preferably duals.

 

Did you know exhaust will help in the prevention of knock? Just FYI

 

That stuffs like 800 Bucks...Aint got that.

...What is knock

 

Actually you are burning more gas while in neutral than when you are in gear.... SG/UG all that crap is wrong..... Your best bet is using a standalone AFR Gauge..... I can take a vid in a bit and show you. AFR Gauge plummits to about 50s sometimes because the injectors do shut off while in gear compared to neutral where the afr stays at stoich so about 14.7 compared to 50s

 

Ah. Anyway, I guess I'll stick with 450 for some flowmasters.Thanks though.

Alright now everyone's saying different stuff. Whats the actual facts?

 

?... I said it will help in the prevention of knock... you are less likely to have knock due to the better exhaust flow although you are losing low end and mid rang power you will gain in the top end but also help in reducing your chance of knock.

 

Exactly.... it can only read what an ECU can produce.... A standalone gauge reads air to fuel ratio directly.

 

Lol.... really?? Do you know what a knock sensor is?... Did you know that sensor makes your truck knock on purpose?

 

With the scangauge all I can see during fuel shutoff is the system goes into open loop. Scangauge needs to make some additional assumption like maybe open loop + thottle position closed = fuel cutoff, to decide zero fuel.

Fuel does shut off.

Easy test, coast from 2500rpm to around 1500 where you will feel a surge as the injectors start firing again.

 

http://www.youtube.com/user/xrunnin20?feature=mhee#p/a/u/0/gm8TuartrNQ

first part is coasting in gear... as you can see the gauge fluctuates between 20 - spiking around 80s or so at one point

second part is it stays at stoich in neutral meaning 14.7

So since AFR means a ratio of air to fuel. 14.7 to 1 compared to 20-80 to 1 is a big difference in fuel consumption.

 

Is that with an automatic xroller? I can tell what rpm my manual kicks from cutoff back to fuel on, if you would can check what rpm automatics no longer cutoff? I've always guessed that an automatic would cu=toff only at a higher rpm than a stick.

Your video nicely answers the question about whether there is cutoff or not.

Since neutral does not slow the vehicle down the the same as in gear, that doesn't answer the OP question which is.

My answer is under most situations neutral is better. If the downgrade is steep enough to require braking keep it in gear and downshift, same with slowing down toward a stop. If you will slow down too much because of engine braking neutral probably wins.

 

Thanks!