Hope you guys can help, vh45 running rich

[gs14racer]

Hey im posting this over here since theres more traffic on this forum, I have a vh45 swapped in a 240sx with a z32 transmission, i have a problem with this motor running rich.

I used to have another vh45 with 227k miles from a 1990 swapped in this car with pretty much the same setup that spun a rod bearing so bassicly i swapped a lower mileage 90k 1995 motor into the car.

The car drives great with no hesitation or stumbling and even makes great power too, just it goes through gas like water. Basiclly 3 gallons in about 30 miles, (granted thats punching it pretty much the whole time but its seriously drinking this stuff).

Now onto what ive done. I put new spark plugs in the car (ngk irridium series), Ive checked all the coils and i have ohmed all the injectors directly on the injector. They all ohmed between 11.2 and 11.9 ohms. Also i pressure checked the rail up to 70 psi of fuel pressure and no leaks.

Ive checked for codes on the ecu but have gotten nothing. Im gonna try and pull the spark plugs tommorow to see if i can visually see one thats running richer than the others.

I found this out when i went to dyno the car, up to 4000k rpms it runs clean but after 4k rpms as you see on the dyno it goes completly rich, i have over layed the new one ( blue line) with my old motor (red line) so you can see the difference, funny things is this motor runs rich and still makes more power than my old one go figure.



I had gone to the dyno with the purpose of testion a rom tune a friend sent me, so we stuck it in there to see if it would make a difference and it did big time but still ran rich after 4500 rpm now and power suffered. here it is blue line is base line vs red line with the rom tune



What gets me is it runs fine and has good power thru the power band even up until red line. I know theres more power to be had up top but i dont want to push it with as rich as its running. There are two possibilities im thinking of at this point, either the wideband at the dyno is messed up or possibly a bad/dirty maf?

What do you guys think?

[maxnix]

Ever bench test your injectors like Deatschwerks does for NICO members when they are serviced?

Any chance of pinched injector O rings? Very dangerous for hydraulic locking, so do a leak down test.

First, check your MAF connection. Even if that is the problem, doesn't mean the other problems I mentioned don't exist or will not soon exist if ignored.

The VH45DE requires the PFRG plugs, not the iridium ones. There is no reason to change type as the PFRG are specific to the VH45DE.

[gs14racer]

Ive never taken the injectors out of the rails but i did pressure test them with an external regulator adjusted up to 70psi and no leaks.

As for the spark plugs the irridium ones where an upgrade from the stock but i guess we will see how they look tommorow when i pull them out. Im also gonna check the maf and connector tommorow.

The only think i can think of thats different between these two motors that would somehow matter is the fuel pressure dampner was damgaged on my new one so i removed it but that shouldnt cause it to go rich.

[maxnix]

As for the spark plugs the irridium ones where an upgrade from the stock

What makes you think that? Revue the NGK specification sheet. There is a reason they are cheaper.

Regardless, the PFRG is the plug around which the VH45DE combustion chamber was designed. Nothing works better and many others do actual fatal damage.

[Unnatural1]

Not again. Do we really have to listen to this again? If he really must spend more money to make you happy then NGK makes a Laser Iridium plug (used as an OE plug in many current engines) that is just as expensive as the OE Laser Platinum the engine came with. I'm POSITIVE using iridium spark plugs is NOT the problem.

There is always the possibility of the MAF reading incorrectly. If you're sure the o-rings on the injectors aren't leaking are you sure you are getting a good spray pattern from all the injectors. It's possible the wideband O2 the dyno facility used could be contaminated with leaded race fuel or something like that causing an incorrect reading. Are you sure that compression and leak down test are okay on this new engine?

[maxnix]

I'm POSITIVE using iridium spark plugs is NOT the problem.

Since I am not able to observe the internal combustion process as those rpms increase, and I am sure the flame fronts differ, I am not so certain.

Might be worth the $65 to see if everything else checks out. OEM is best unless one has evidence to the contrary, and here we don't.

Kind of like if it works perfectly, why use something else? I certainly don't have a guinea pig complex, not do I wish it on anyone else for my amusement.

[subtle_driver]

dirty maf makes a car run lean. it covers the wire and insulates it, so when more air goes by, it doesn't get noticed as much, thus the lean condition.So this dyno is at WOT? if so i would say your fuel map is too rich. and if you had a missfire, i would imagine you would get a lean condition on the air/fuel. the sensor only picks up oxygen right?/ not fuel... there are alot of possible things that can cause a rich condition.... but i would check the open loop status, if your not going into closed loop something wrong with the coolant temp sensor or wiring/connection, or a stuck open t-stat.

btw, your a/f comparison map looks pretty close to the old engine. but you should be tuned for 11.5 to 1 ish*ish* a/f at wot. am i right? that is a educated guess... i think you should be richer at the peak torque and after that you lean it out and advance timing. peak torque is when you can detonate more easily.

doesn't the 1990 engine minus the vvt? does it have secondary butterfly valves?

btw, 10 miles to gallon... hmmm, im not sure what is normal for constantly being on the gas pedal for a v8q45 engine. i know if i'm heavy on the throttle i get 12/16 mpg on my 320hp, rom tuned, ka24de turbo powered 240sx and if im driving normal, i get 22/26 mpg. my q45 gets 12 to 18ish mpg.
Modified by subtle_driver at 11:46 PM 11/9/2008

[gs14racer]

i will check the plugs tommorow to see how they look. As for misfires i have not gotten any misfires that i could notice. How do i check to see if it is in closed loop.

The dyno pulls are at wot, and as the wideband sensor reads oxygen and is possible that it has been contaminated. But i doubt it as it would read rich all the time and not just at high rpm.

Im not sure where to go here , the only thing i can think of at this point is coolant temp sensor.

As for the a/f the other motor ran an average of 1.2 points leaner than this one after 4k rpm, it should be around 12.5 -13 to 1. The way it is now is like a boost map, crazy amount of fuel for n/a.

[Q45tech]

To protect and cool cats and oem cast pistons and increase durability [low stress], Nissan runs all their engines extremely rich at WOT and above 60% load factor.

If you calculate what 11 millisecs of fuel creates at 4000>6,000 rpm you will see AF of ~ 10-11.

Proves how little effect a rich mixture has, whereas too lean is like falling of a cliff powerwise. when viewed with exhaust temp going straight up.

http://www.daytona-sensors.com...e.gif

Unfortunately both the AF and the ignition advance are related in determining the peak torque, so seeing AF with advance is pretty useless.

A rich mixture speeds the flame speed up so less advance is required as you lean you need to add more advance probably 1 degree for every 1.0 point of AF.

[gs14racer]

Tech i get what your saying, peak torque is made between 12.5 and 13.5 to 1. In the first graph i posted its two stock motors, the red line is the first one and its right where it should be but the blue line (my new one) runs pig rich, after 4krpms for some reason. I did have to remove the cas at some point, but i put it back on in the same position and checked it with a timing light and verified 15 degrees at idle.

I dont want to lean out or add ignition advance if something is wrong, is there anything you can think of that would cause it to run rich in high rpms?

[Q45tech]

The AF ratios only apply if the ignition advance is OPTIMUM. Such that the flame speed creates the peak pressure at 16 degrees after TDC.

All ecu can do is juggle AF [injector open time] and ign advance..........as the air part of WOT equation is mechanically FIXED by Barometric pressure and temperature.

I always data log MAF, Inj open time and ignition advance vs RPM.

History has show 22 degrees at 4,000 rpm slowly increasing to 28 degrees above 6200 rpm on a optimum reprogrammed ecu. The injection time of 11.0 at 4,000 slowly decreases to 9.0 above 6500 rpm as the VE declines due to flow restrictions cased by filling time and intake valve restrictions.

The point is you must try different AF and different ign advance to zero in on which works the best at a particular rpm range say every 200 rpm across 4,000-7,000......................those test are best done on an engine dyno not a chassis dyno.

Whether you run AF of 11.0, 11.5, 12.0, 12.5 is not significant if ignition is correct and you don't mind the changes in exhaust valve, cats, or piston temperature.

Nissan had to be concerned with the possibility of more than a quarter mile test such as 10-15 minutes at WOT on a racetrack in testing at 150 mph +.

That is the rub with tuning on a chassis dyno with very low load and a 10 second or less run. You will [might] melt things on the highway in taking 50 seconds to reach 150 mph.

Engine optimized for chassis dyno should have a dash sticker warning against long acceleration runs in summer

It is easy to calculate the gasoline consumption in creating 300 HP plus the extra wasted gasoline to cool down the systems [multiply by excess above 14.7A/F]...................11A/F consumes 33% more than 150 pounds per hour or roughly 200 pounds per hour or 32 gallons per hour or 0.53 gallons per minute of 300 HP or WOT acceleration above 4,000 rpm.

That averages 6 mpg.

[gs14racer]

um i feel kind of dumb but i think i may have possibly figured out the problem.

When i put the motor in timing, i did it to the same specs as an sr20det or ka24, however after looking at the service manual for the vh45de, it looks like the timing marks are in an different orientation.



on all the other nissans i have ever owned the timing 15 degree mark was 2nd from the right, and apparently the vh45de is 3rd from the right, so basiclly i was at 20 degrees of base timing.

Is it possible that 5 degrees of base timing on a stock ecu would push it into knock and as a result the ecu would compensate by adding fuel?

[gs14racer]

looks like the plugs confirmed to much advance, i guess the computer was picking up some knock, and was spraying fuel. My bad for 20 degrees base timing lol.

Heres pics of the plugs, they where all in the same condition as this one.

[Unnatural1]

Opps. That may be it. Timing makes a massive difference in how these engines run. Just ask anyone that has had a bad knock sensor on one of these engines. How far off do you think you have it?

Those plugs don't look to bad. You can definitely see the carbon build up starting. I'm guessing you don't have too many miles on them with it running rich like it is. I would reuse them as the electrodes look relatively good. Just hit them with some carb/brake cleaner. Or you can spend another $65 for OE NGK Platinum (old technology) plugs to make Maxnix happy. NGK Iridiums (new technology) will apparently blow up your engine, steal you credit cards, kidnap your dog and so on.

[gs14racer]

it was advanced 5 degrees, so 20 base.

[Unnatural1]

Okay...well reset timing and clean off the plugs. Then put some miles on them, pull them out and check them again. Are you going back to the dyno soon? Or do you have your own wideband sensor for tuning? You may need to put some fuel back in that you removed with that last ROM tune. Then again, it may be good as is.

[Infinitiguy19]

Maxnix is right, OEM from a Nissan or Infinit dealer is what is good for the car.

Plus Autozone sells NGK Iridium and call them OEM, Being that Autozone, Pep boys and NAPA all suck for the Q45 I would go with OEM.

Only thing the above are good for are cleaning supplies for the car.

Joe at IOS is the man.

[Unnatural1]

A made in China light bulb from a parts store and NGK spark plugs are two completely different things. If you want to use OE spark plugs purchased from Infiniti that's fine. It's just ridiculous to tell people they are going to DAMAGE there engines, etc... because they use the NGK Iridium spark plug specified for the VH by NGK (or Denso for that matter)!

When I change my spark plugs I'm going to go with a set of iridiums from NGK or Denso. I'm also not going to experience any issue with them what so ever. Iridium plugs are superior to platinums. This is like saying that using synthetic oil in a VH is bad and will cause damage because Nissan originally filled it will conventional from the factory. We all know synthetic oil is better but it's not OE...oh no!

There are certain parts that it's best to buy OE but spark plugs are not one of them. As long as you have the correct heat range plug specified for the VH you will be golden. I can't believe this is even an argument. If you don't want to believe this then don't. But there is NO reason to beat people up about using the "wrong" spark plug. It's not like he said "I'm using Bosch Platinums," or something like that. Then I'd yell at him too.

[Infinitiguy19]

I am just a OEM man my self but if you can provide me proof I will believe you, I will look this up as well.

But after all this is the internet not face to face or written in stone type things.

[Unnatural1]

I am just a OEM man my self but if you can provide me proof I will believe you, I will look this up as well.

But after all this is the internet not face to face or written in stone type things.

http://www.ngksparkplugs.com/p...e=nml

There's NGK's product overview. They have 2 levels of Iridium plugs.

[gs14racer]

Im running the laser iridiums oe plugs, they're just as expensive as the platinum plugs at 9.00 a peice lol.

This is a good lesson for all to make sure your knock sensors are working, they probably saved my motor.

[maxnix]

Im running the laser iridiums oe plugs, they're just as expensive as the platinum plugs at 9.00 a peice lol.

This is a good lesson for all to make sure your knock sensors are working, they probably saved my motor.

The OEM specified Laser Platinums are only $6 from Joe when on special.

Actually, it is really a good lesson to RTFSM. Knock Sensors are also mentioned therein.

[Q45tech]

Over the years I've mentioned that engineers look to MBT [maximum brake torque] and how in a performance gasoline engine this occurs a 15-16 degrees after top dead center. The ignition advance 15> 40 BTDC is necessary to create the time for optimal burn time so this [15-16] occurs correctly.

In a 4V penta roof engine the distance from spark plug electrode to cylinder wall is equidistant and shorter than older wedge [2V] types so less advance is needed. Why big 2V may use 34-36 while 4V only need 28 at same 7,000 rpm.

Anyway some might find this interesting:http://ocw.mit.edu/NR/rdonlyre...k.pdf

Why too much ignition advance is worthless and just creates knock and less than optimum ignition advance is not as significant as one would think.

The only usefulness of ragged edge advance is to make a dyno graph to try to beat your friends or publish on inet.

In the real world +-10 HP or torque is insignificant and often the less ragged edge engine out performs the stressed one.

For those with time:http://ocw.mit.edu/NR/rdonlyre...ering/

[Unnatural1]

Any updates? Your engine running any better after resetting timing? Get any miles on it yet?

[maxnix]

Anyway some might find this interesting:http://ocw.mit.edu/NR/rdonlyre...k.pdf

For those with time:http://ocw.mit.edu/NR/rdonlyre...ering/

Thank you for the great links and the simple explanation of flame fronts in different combustion chamber designs.

Makes one wonder why ordinary owners think they can improve on a perfectly operating plug. It is a shame OEM engineers are so dumb.

[Unnatural1]

Iridium has a higher melting point than platinum which makes them better suited to operate in modified engines (such as gs14racer's). Iridium plugs also use a smaller center electrode. Platinum will not last as long under the higher temps and pressures of an engine used for racing, especially one that is using forced induction. They are very durable spark plugs. Again the biggest thing to be concerned with is not platinum or iridium, but heat range.

~Brendan
Modified by Unnatural1 at 10:55 AM 11/13/2008

[Q45tech]

In an Aluminum head that melts at 660C, even copper which melts at 1084C is good enough:Platinum ~ 1172CIridium ~ 2443CCommon lamp bulbs use inexpensive Tungsten which melts at 3407C.

The point is melting point of electrode is not an advantage.

Coil on plug ignitions create so high a voltage that in NA situations it doesn't matter as long as the electrodes are kept clean.

Research the electrode rounding situation and see why tiny electrodes must be replaced just as frequently as Platinum IF you demand as new performance..............luckily the extra voltage from coil on plugs allow this to be ignored somewhat on the street by typical owners.

[maxnix]

Again the biggest thing to be concerned with is not platinum or iridium, but heat range.

And actual plug construction and design. Periodic charts are helpful, but not sufficient in the case of purposefully designed device.

[Unnatural1]

In an Aluminum head that melts at 660C, even copper which melts at 1084C is good enough:Platinum ~ 1172CIridium ~ 2443CCommon lamp bulbs use inexpensive Tungsten which melts at 3407C.

The point is melting point of electrode is not an advantage.

Coil on plug ignitions create so high a voltage that in NA situations it doesn't matter as long as the electrodes are kept clean.

Research the electrode rounding situation and see why tiny electrodes must be replaced just as frequently as Platinum IF you demand as new performance..............luckily the extra voltage from coil on plugs allow this to be ignored somewhat on the street by typical owners.

In that case, lets just all use standard copper plugs since it doesn't matter.

Iridium alloy is a tougher material than Platinum. The melting point just proves this out. Also, combustion temps can far exceed 660*C. In fact, according the Denso spark plugs operate best between 500*C and 950*C (the point passed which pre-ignition can occur). Also, NOx is a combustion byproduct typically produced by an engine at temps above 1600*C. Obviously, that is an extreme situation and regulated by EGR operation but my point is combustion temps are usually higher than the melting point you posted for aluminum.

The OE style Laser Iridium plugs gs14racer is using are designed for long life (as are the Laser Platinums). The Iridium IX plugs are gear more toward maximum plug performance albeit for a much shorter life span.

[Infinitiguy19]

Well, I think then that plug goes to the few who have turbo'ed or supercharged the VH45DE.

Plus the plug its self doesn't give you much or any performance its only made for performance engines right?

I think I will stick with standard as my Q is stock, For now