emissions???

[sleepersinc.]

anyone here remove the emissions on the vh engine?? or if anyone knows which vacum lines i need to keep i would really appreicate it or if it was even possible to get the diagram for the emissions on the vh engine

[Q45tech]

The emissions are primarily the cats and internal design since EGR only fuctions at middle rpm and low load [[ shuts down at WOT in any rpm]]............PCV valve is necessary to control oil pooling so nothing left.

The VH is not a low emission vehicle especially the 90-93.

The FSM shows all as little as it is.

[sleepersinc.]

well is this similar layout to the vg engine??? really havent look at the engine yet cause i work so much ??

[RichZilla]

I've removed the EGR off mine - purely to make fabricating the LHS exhaust manifold a bit easier.

[T45]

You can remove all of the emissions but not without sacrificing something else.

EGR-get rid of it. lose highway mpg. gain cleaner intake and no egr piping, hoses, issues.

IAC-get rid of it. lose proper idle speed in all conditions. gain loss of weight, hoses, issues. just crank up the idle screw to desired rpm's.

PCV- get rid of it lose a few hoses and a cleaner intake. not really worth it due to the fact that you will have to add some kind of filter to the atmosphere and will most likely have oil film all over engine. this is one system I kept. some experience higher hp numbers with scavenging pumps on crankcase so it will only hurt to remove it.

Also deletable is the coolant hoses that go to the throttle body. They are to keep it from freezing up but also do nothing to help performance in hot conditions. For this I am keeping it but adding in a valve so I can close it in above freezing weather.

I also deleted the TCS butterfly and gianormous motor off my engine. If I had a choice I would choose the non-tcs engine but I got what I got. No biggie but does lose some good weight.

The only hoses and systems on my engine are coolant, PCV and fuel.

[sleepersinc.]

how does removing the egr lower your mpg??? i thought it would raise it cause you no longer have ****ty exhaust air recirculating back through your engine ???

[Q45tech]

When at cruise the throttle plate is 95% closed causing a 20/29.92 or 1/3 drop in plenum pressure [so called cruise vacuum reading]. This restriction requires work to overcome. The EGR being at above atmospheric pressure supplies 10% of cruise air flow into cylinder without adding work [IMEP].

The effect is to reduce the O2 content in plenum air from natural 22% to 20% or less thus 10% less fuel is required to achieve 14.7 AF ratio.

The higher the EGR reinjection the better the fuel mileage, unfortunately there are limits and of course EGR is immediately shut off when the throttle is opened even half way to accelerate.

Removing EGR will immediately require more fuel at cruise to balance the mixture equation.

[moss13]

I'm trying to get my engine together. Please excuse my noobness, but is everyone keeping or getting rid of there o2 sensors on the headers?

[SSDwellah]

Keeping: that's how your ECU does closed loop fuel control. Now if you had an OBDII motor, like the US VH41DE, then I might recommend throwing away the second O2 sensor if it doesn't fit your application. All that the secondary O2 sensors are used for is to determine Cat converter health - there might only be one secondary O2 on the VH41, I am not so familiar with the exhaust plumbing on those cars but I'm guessing it goes into one pipe which then goes to the back. Anyway the second O2 is obviously useless if your swap is not going to have cats.

Removing either front sensor (primary) or rear sensor (secondary) on an OBDII motor is almost certainly going to set off the CEL/MIL and throw a code. Removing the primaries on the older motors usually does NOT throw a code or set off the CEL but it could cause your engine to run crappy if your mixture is way off (in which case the sensor is probably fouled already anyway).

Toyota has a very brief introductory piece on this that I see people refer to a lot. Check it out here http://www.autoshop101.com/forms/h58.pdf

[moss13]

Yep, very informative. Thanks ssdwellah for the link. I've got a lot to learn on this swap:)

[SSDwellah]

What I said applies for most of the late 80's to present nissans, and a lot of other Japanese imports with EFI in general (as you can see from the toyota paper). You're welcome. Remember if you are running your own standalone EFI you can choose to run in open loop, but I don't recommend it for any modern fuel injected car whether street or track driven. If you want to run open loop, get a carburator

[Hogg]

I currently have a 1991 Q45 that I have plans for major horsepower gains and a good drift build.

However I am very curious as to the emissions in the FSM, section EF and EC. All those labelled - can they not be removed for less strain on the motor and computer?

My Check engine light came on for a few hours, and then shut off - I figured well I am in Alberta and we have no restirctions on emissions here, why not remove all of them? I noticed that when my Check Engine light was on I had serious power loss - and when it was flicked off later on in the evening, my car was very strong and pulled great.

Still the main question is all the little things that are listed on the motor as Emissions, may they all be removed?

Thanks,Spence

[Raxephon]

When at cruise the throttle plate is 95% closed causing a 20/29.92 or 1/3 drop in plenum pressure [so called cruise vacuum reading]. This restriction requires work to overcome. The EGR being at above atmospheric pressure supplies 10% of cruise air flow into cylinder without adding work [IMEP].

The effect is to reduce the O2 content in plenum air from natural 22% to 20% or less thus 10% less fuel is required to achieve 14.7 AF ratio.

The higher the EGR reinjection the better the fuel mileage, unfortunately there are limits and of course EGR is immediately shut off when the throttle is opened even half way to accelerate.

Removing EGR will immediately require more fuel at cruise to balance the mixture equation.

This should be copied and pasted into an article of nothing but technical posts from Dennis regarding the Q45.

[Q45tech]

As you can see EGR is only used over a very very narrow range!

Here are some typical requirements for EGR to flow:Engine temperature more than 170 F. Ambient air temperature more than 20 F. Engine run time more than three minutes since 170 F. Engine speed 1700-2500 rpm. [45-75 mph]Manifold absolute pressure from 5-20 hg. Short Term Adaptive Fuel Trim is adjusting pulse width by less than +7 percent and more than -8 percent. TP sensor from 0.6 to 1.8 volts. [none at idle]Vehicle speed sensor more than 45 mph.

Then ecu opens vacuum solenoid allowing EGR to flow.

[T45]

Spence, your problem sounds more knock sensor like than an emissions issue.

[Hogg]

Hm, yeah T Im hoping - I have 2 spares from that S13 build :P I guess I have to give in and send my car to a dealership I like doing things myself but this is out of my budget and league it seems!

[tmorgan4]

Vehicle speed sensor more than 45 mph.

Then ecu opens vacuum solenoid allowing EGR to flow.

Does this mean that all the guys running VH45 swaps that didn't hook up the speed sensor wire into the ECU don't have functional EGR systems?

[darinz]

I have removed all the emission control piping. The coolant hoses to the TB, Idle control, PCV, O2 and everything else that isn't either oil, water or fuel. The down side is having to use an expensive standalone. The plus side is simplicity and mine gets covered in mud so this was a factor. It colds starts and idles from cold everytime without and issue. It is quite astounding how well it starts and idles without idle control!

[Hogg]

So wait, and possibly T45 has more info on this.

In Alberta we have no emissions regulations and I want to take advantage of this in hopes to reduce problems with my car.

When removing emissions systems, most likely all of them - should I plug or block off all the vacuum hoses and piping? (eg. the IAC on the back of the plenum, I would remove it and put a metal plate where it used to be?)

Also would I need to run a different ECU or make changes to my stock one in order to compensate?

-Spence

[Q45tech]

IAC is very necessary not just to maintain idle but to act as a dash pot when you suddenly want to decelerate so it drops progressively and doesn't stall.

Removing any emissions [except cats] will not help you gain one single HP !!!!! It will just make the engine almost undriveable.

[craigztoyz]

Still looking

Does this mean that all the guys running VH45 swaps that didn't hook up the speed sensor wire into the ECU don't have functional EGR systems?

for clarification on this one

For those of us that will not have a speed sensor hooked to ecm, do we not have an egr at all? or since it is unhooked, is it going to try to work all the time? Went through fsm, had no luck, its all in the comp. i thnk. WES

[T45]

On most cars the EGR is controlled by vacuum but on the VH it is computer controlled IIRC. As for the speed sensor it's quite possible that it uses it along with TPS and a signal from the trans to activate the EGR.

Spence, you'll need to make a plate to delete the EGR port on the intake. It's a diamond shape about 1.5 inches long. Although the IAC appears to have a passage into the intake it doesn't. It's just mounted on the back of the intake but totally separate from the intake "bread box" chamber. There are a lot of vacuum lines from iac and egr that will need to be blocked off but that's just a matter of some vacuum caps. You'll need to plug the exhaust manifold where the egr pipe used to go.

Although I haven't ran my engine more than 3 minutes alltogether, every time I fire it up it doesn't hesitate at all and starts up like I just turned it off 5 minutes ago. No bog, no sputter, idles perfectly and there is no sign of stalling. I don't think GSracer had issues with stalling either after removing his iac. Granted with a colder climate you'll probably have to warm it up a little longer but it should be good once warm.

[Hogg]

Sweet well maybe when my car gets back from Infiniti, hoping that I have some money left over - Ill dig into removing the emissions to clean up the engine bay and reduce problem possibilities!

Thanks Mr.T heheh-Spence

[darinz]

So wait, and possibly T45 has more info on this.

In Alberta we have no emissions regulations and I want to take advantage of this in hopes to reduce problems with my car.

When removing emissions systems, most likely all of them - should I plug or block off all the vacuum hoses and piping? (eg. the IAC on the back of the plenum, I would remove it and put a metal plate where it used to be?)

Also would I need to run a different ECU or make changes to my stock one in order to compensate?

-Spence

I actually cut the IAC solenoid of the manifold and had mounted on the fire wall as it made the plumbing easier. We then moved the manifold inlet to by the TB instead of underneath te manifold. But then we found the motor runs so well it isn't even needed except for really cold start ups. Even with cold starts after sitting for a wcouple of weeks it fires first time and just needs a minute or so and then it will idle of it's own accord. I think people seriously underestimate how smooth this motor really runs. Mine idles at about 600rpm without any of the crap and it has yet to stall etc in offroad competition use even when going from full boost, full throttle to no throttle.

I should add that my ecu uses MAP, air temp and barometric pressure so I don't have airflow meter etc so this may make a difference.

[Hogg]

Hm well so should I go through the FSM and basically follow all the lines from each emissions piece and either plug, remove, or disconnect them? Im hoping its that easy!

-Spence

[Hogg]

My engine wont run like crap without these emissions if theyre blocked and removed properly? I was told not to remove the Charcoal Cannister as well.

Just reading in the FSM about the EGR Control Solenoid, wondering how you guys got around that

As well as the EGR Temperature Sensor

Input?
Modified by Hogg at 11:10 PM 3/19/2008

[tmorgan4]

I've found that there are a lot of people on this forum (diehard Q owners) that like to tell you anything other than the way it came or factory Nissan parts won't work. You just have to take this with a grain of salt.

That said, I do have an EGR temperature sensor code on mine now. I haven't had it running well enough due to a vaccum leak to assure you it won't run like crap, but enough guys take out the EGR systems that it should be just fine. I had read that I wouldn't get an EGR code as long as I left the solenoid hooked up, but thats obviously not the case. Maybe when I get a reflashed ECU I can have them take the EGR functions off.

[Q45tech]

When EGR is commanded open during highway steady cruise rpm the ecu monitors the egr temp sensor to make sure hot egr gas [Nitrogen primarily] is flowing past egr temp sensor so that it increases a few hundred degrees.

Most people will miss the 5-8% increase in highway MPG EGR creates especially with $4 gasoline.....................saving up to $200 per year with zero downside [other than ocassional cleaning].Impossible to pass Nitric Oxide portion of an emission dyno test without a functioning EGR system.