I do know veequee I think is running a walbro fuel pump and an aftermarket FPR I think...which may account for his timing up top...

aftermarket B-pipes are considerably lighter than stock one's so that might be a reason to run them...the udp sheds some weight too...all the weight eventually adds up...plus you are getting rid of the crush in the b-pipe right by the rear beam axle...which would be good for a few hp...!

also, Dave B, when I dynoed with my mevi switchover @5200, I got a large dip in power as seen on my dyno graphs that you can see in the dyno forums or the first page of the link eng92 cited on the first page of this thread...nealoc suggested I raise it to more like 5400 which looks like 5500 on the tach and 5400 as set on the summit rpm switch...according to him the dip on power should go away by doing such...I have to re-dyno to see if he was right...but the powerband does feel more continous and smooth!

 

My mods

1. JWT 7200 RPM ECU
2. eBay CAI w/K&N + stock resonator
3. MEVI w/5150 RPM activation (I used to have it set @ 5400RPM but my dyno run yesterday shows a dip beginning @ 5250 RPM - yes at the tq and hp crossover - and picks back up @ 5500 RPM - so now I have the switch set @ 5150, 100 rpms before the dip begins. Is that ok??!?!)
4. Cattman headers
5. WSP metallic cat + Budget B-pipe + Superturbo muffler

I had my engine swapped out and I used all the parts off the new motor. I had fuel issues, and bought a couple of Adjustable FPRs, fuel pumps etc to isolate the culprit- the stock '99 FPR diaphragm would not fluctuate because I was getting idle PSI @ WOT. My motor mustve been sitting in the donor car for a long time or something. I am now using a Nismo adjustable FPR (WOT psi is a "stock" 43- confirmed by my in-line fuel pressure gauge in the feed line), stock fuel pump, 99 injectors and 99 coilpacks ( ). I had my car dyno'ed yesterday on a dynojet with the stock ECU for my baseline for all the bolt-ons and the dyno operator told me I had a 12.8:1- 13:1 AFR across the RPM band through redline.

I will not dyno again until there is another affordable group dyno @ the same dyno facility, so I cant confirm the AFR for the JWT on my car at this time.

When I ordered my ECU, JW told me they have only one program for NA and they didn't care if I have a MEVI. They only cared about trying to sell me the MEVI activation through the ECU itself for $260. I asked about the 14:1 ratio and requested for a lower AFR even if it cost me more $$$ and he went about how theyve been working on this program for more than X-yrs to get the best AFR and that's their "golden AFR" and they don't WANT to change it . Since most of the dynos I've seen on NA cars using stock ECUs are 12.5:1 or lower and I'm roughly .5 pt higher is it same to assume that I will probably be near stoich/stoich w/ the JWT ECU, considering that there is only one NA program??

The auterra only logs airflow rate from the MAF not the voltage. Will airflow rate data help????

 

Walbro is now sitting back in its box because my stock fuel pump works fine. I bought an AEM FPR and a Nismo FPR and I decided to keep the Nismo. Its set at the stock WOT psi (43).


Also you have an auterra too so adjust your Summit switch using the RPM on the PDA not the tachometer. Much more accurate.

 

veequeue...according to nealoc my dip in power on my dyno graph was b/c I had it set too low @ 5200...he told me to raise it to 5400 to get rid of the dip...but I didn't know you got a dip @ 5250...this is strange....as I don't know what to set it at now...according to most of the mevi guys on here...have it set to low hurts the ET's...by as much as a tenth! I will have to play around with it....I was taking nealoc's word for it, as he does have quite the reputation for running great ET's with his car....

wow...that AFR is actually pretty good...power-wise...that would get the most for your money...!!! I hit like a high 13's almost 14 for the AFR up top...coming from about a 13 or so in the midrange...

what did you hit on the dyno if you don't mind me asking?

I do use my auterra to set the rpm on it...

I would think setting your mevi lower would accentuate the dip in power...as many members on the org here have discovered at the dyno...the trick would be to find a dyno graph on here of a member that has no apparent dip and then ask him what his switchover is...

 

The beginning of the dip is when the switchover should occur. I just need clarification whether you set it at the indicated rpm when the dip begins or 100 rpms prior for the smoothest curve. Supposedly takes 100 rpms for the butterflies to fully open which would explain why my power went back up @ 5500pm.

I would imagine the HP would be slightly higher if it weren't for the dip, because I lost momentum and had to regain it.

I went to the R and D group dyno yesterday and used my stock ecu because I want baselines. Looking at it right I got 182.9 hp @5800 and 186.6lb-ft of torque @4800.

I just uploaded it:




I was making more peak torque and more torque throughout the entire powerband from 2500rpm + (may even be from 2000rpm, Im not sure) than some guys there who dyno'ed with the USIM and y-pipe, so I think the headers are to be credited to regaining the torque one usually loses with the MEVI. This is also assuming that their motors are in good condition w/ good compression #s across the board, etc.

I wonder if wet dyno rollers would reduce the output somewhat because the entrance to the dyno had several puddles so basically everyone drove over them when backing their cars into the garage. Though I was making more hp and torque than guys with the USIM and y-pipe I am still pretty disappointed in the numbers.

 

Playing with the MAF voltage using an SAFC will change the ignition timing on any ecu: stock, TS and JWT. The ecu uses the MAF voltage and the programmed AFR to determine injector pulse width for a given RPM. Ignition timing values come from a preset map of RPM and injector pulse widths. So if you play with the MAF voltage you are indirectly playing with timing regardless of which ecu you have.

I find it interesting that JWT only has one NA program. That JWT ecu with the USIM must make some good torque in the midrange. I think I know what timing data I will be sending to TS to load into in my ecu.

 

The conversion is done by the ecu. The airflow rate and rpm data are what I am looking for.

 

eng92....could you by any chance send me the timing data that you are giving to TS....to me? I would like to have Brian try that timing on mine as well....I would like to recoupe the midrange loss I see with the mevi...and the JWT has a good deal more advance in the midrange...


veequeue, now I am very confused as to what to set the mevi switchover too...I always use my auterra to set the rpm...but looking at my previous dyno graph, I get a dip with it set to 5200 rpms which looks like 5300 on the tach...I now have it set @ 5400 (5500 on the tach) and it feels smoother....but that was on nealoc's advise...I originally set my switchover @ 5200 on the auterra from advise of other members and from reading some threads...it looks as if the switchover isn't happening fast enough...so the dip in power happens...I don't know...some have entirely smooth power graphs with their mevi set at 5200 and some at 5400...I've seen the graphs on here...I will have to play with it some more...maybe you need to set it at 5300 so the switchover completes at 5400...is what nealoc was suggesting...?? I don't know...

check this thread out:
http://forums.maxima.org/showthread....=1#post3452450

also this thread:
http://forums.maxima.org/showthread....evi+switchover



also, eng92, check out this thread by requin6 when he was N/A...it includes a link in his post with a table chart of b4 and after comparison of power with the JWT ecu vs. stock...the JWT starts making more power than the stock ecu at as low as 2300rpm!!!
http://forums.maxima.org/showthread....evi+switchover

and the pic is:
http://memimage.cardomain.net/member...48_82_full.jpg

 

To be most certain dyno w/ the MEVI activated late like 6000 RPM (MEVI butterflies will stay closed till 6K) and one real early (any rpm before say 4800RPM ) and you should be able to see the power curve of the early activiation run continue to climb right when the late activiation run begins to fall. Where the curve picks up is where you should set it. If you look at the torque curve of my dyno it begins to fall @ 5250. If that line were to continue it is obviously falling at a sharper rate because the butterflies haven't opened until after 5400RPM. For my setup mine should open somewhere @ 5250. I just need to know which will make a smoother curve. Activate right on it or before, because either way opening up the butterflies will affect the power curve.

 

well the goal should be no change in the power curve...or a very miniscule one...I think the goal should be to switchover at 5250...so I guess setting it 5150 is smart...I was looking at a graph of a guy who dynoed back to back with his mevi zip tied open and closed all the way...hp curves crossed at 5250....spooky if you ask me how the USIM and mevi trade volumetric efficiencies at the magic # of 5250 which we all know the importance of! the only problem being that a switchover set at 5150 to actual occur at 5250 would only be seen on the dyno....on the streets or in our garages, it's really hard to see the differences made my tiny changes...!!

also, if you read the threads I cited above, the data is all over the place with half the guys consenting on a later activation (5300 or 5400) according the dyno and the other half to the guys saying a 5K activation or 5200 activation is ideal...iansw says he has had 20 some dynoes saying 5K is optimal...and then you got guys like mardigras and nealoc that are saying according to the dyno and track 5300 or 5400 is ideal...my head is spinning...

 

looking more in depth at my dyno graph when it was set @5200, it looks like the switchover begins to occur immediately after 5200 and the dip of power continues and is not evened out till 5400, then power starts increasing above what it was after that...leads me to believe that the dip in power is not just a resonance occuring at such rpm, but also that the primaries do indeed breath okay after 5200 and I am cutting their life short....and I am switching over prematurely...so maybe mardi and neal are right, 5300 is ideal so the switchover ends at about 5400 rpms...which is where my graph evened out and started being positive



looking at another members graph that shows mevi zip tied open and mevi closed...we see the graphs swap at exactly 5250 which leads me to believe you are on the right track:



of course looking at my graph, the actual switchover happened at 5200 or 5250 which would make me think 5250/5200 is not optimal for the beginning of the switchover...but I don't seem to see when it ended? 5400??


next time I dyno...I will try to end all the debate on the forums here by trying back to back 5000, 5200, and finally 5400 as set on my summit switch...which has to be done that way b/c everyone else on here according to them quote their switchover as what they set on their switch...so it's basically the ruler on the forums here...

on another note, veequeue, you wanted me to let you know when the next maxima meet was...check the west coast forum or the calendar on december 18th...there is going to be a small gathering of us and we are going to JGTC in fontana (california speedway)...but you have to buy tickets for it either online at www.jgtcusa.net or at the door for $10 more...should be a great event though and a fun race! we are only meeting up for the saturday race...I can't go on sunday...
much more info here:
http://forums.maxima.org/showthread.php?t=359036

 

so eng92, it looks like the JWT starts adding timing very early in the power band...even at 2500 as seen on your graph where you compiled them all 2gether...that is the kind of timing we need from TS...

this all sounds really weird as we are basically asking another company to make us an ecu just like some other companies!!!LOL

are you just gonna ask for the timing as seen on dave b's and veequeue's graphs?

there is only one JWT na program that I know of...and when I asked them back in the day if they program differently for the mevi...they said no...it's the same program for anyone...so all that extra midrange/low-end timing is just how it's programmed...b/c the mevi breathes less around there, wouldn't the maf be reading lower than the USIM, so the timing would be less than what it is? I would guess the USIM would have even more timing during that range (from 3.5K to 4.5K)...with the JWT chip, wouldn't it? but you have the USIM and the timing programmed by TS is still much lower in that range then the JWT guys with MEVI's...I would think I just should send Brian Dave B's timing curve and raw #'s he provided...

 

I haven't dynoed with my JWT ECU, but here is my dyno with just the MEVI. The red line shows what happens when you engage the switchover too early (4600rpms). Take note of the huge dip in power and then it finally recovers at around 5100-5200rpms. On the next run I set it at 5200rpms and the curve flattened out perfectly. I think setting the switchover anywhere from 5200-5400rpms will be fine. The motor spends so little time in the range and the switchover occurs so fast that it's not going to make much difference. Take a look at car's with VIs and variable cams and you'll see they have huge power drops on their switchovers. In the end, it doesn't make a huge difference as long as your close.

 

oddly, with my rpm switch set at 5200, my dip is really large on my dyno...are you using the summit switch?

 

I hope it as simple as that. But I have my doubts.

What we have been looking at so far is ignition timing as a function of 1 variable, namely rpm. The part throttle maps for ignition timing are a function of two variables ( rpm, injector pulse width). I see no reason why the WOT map wouldn't be a 2 variable function as well.

Timing can actually be retarded for an increase in MAF at a given rpm. This is why all the timing curves drop between 3-3.5K even though rpm is increasing. If you go back to page 1 of this thread, you will see the VE plot I overlaid on the stock timing curve.

This is why I want to see the MAF data for the MEVI and the ignition timing for a JWT with USIM.

If the timing advance is lower in the midrange with the JWT-USIM combo, then I know the WOT map is 2 variables and that is what TS would require.

Without that information, all I can really do is give TS the degree offsets between stock and JWT at regular intervals through the rpm range and have them apply that to the entire table. This assumes linearity between ignition timing and MAF but I do not have any better information available.

I will discuss with Brian tomorrow what data they need.

 

Nope, it's the Harlan switch. I had the Summit switch for about a month and got rid of it because it was more inconsistent than the Harlan. I think the Summit switch has some sort of problem engaging at the specified RPM because when my Harlan rpm switch engages, I can hear my VI's induction noise change, much like a Honda "hitting VTEC". With the Summit switch I heard no such noise. I've also got my VI wired up with a toggle switch just in case the rpm switch flakes out while I'm at the track. When I manually open the VI, the induction noise change it just like that of the Harlan's which leads me to believe the Summit is possibly fluttering the butterflys and may be the reason you're seeing the power drop. The Summit switch didn't allow me to use my manual toggle switch because it wouldn't work with the switch wired in. This ticked me off because when I ran at the track, it flaked out on every pass.

 

People with the auterra, how do you export the rec. data to the computer? I have recorded several runs and would like to graph them. Also at 7k which is my rev limiter, my advance is at 30 degrees.

Mods are

MEVI, rpm switch set at 5200
JWT ECU W/ 7K rev limiter
WS Ypipe
Place Racing HAI
Greddy SP1

 

I hear a huge difference in induction noise with my summit everytime it switches over...
looking at the valve in the engine bay when someone revs it, it slaps open as fast as I would think possible..., so it doesn't flutter...

 

1.hotsync the .pdb files to your computer.
2.Use the PDB converter from this link:
http://lib1.store.vip.sc5.yahoo.com/.../PDBExport.zip
to convert them into comma separated values .csv files
3. Open in excel or whatever spreadsheet/graphing program you use.

email me the .pdb files and I can add them to the graph. Address is in post #31.

 

VeeQueue,

You can lower your afr at WOT by increasing your base fuel pressure. The change in afr will be proportional to the square root of the pressure difference. So if you bump up fuel pressure to 50 psi at WOT (41 psi at idle), then your afr should go down by a factor of sqrt(50/43) = 1.08. This will lower your afr from 14.1 to 13.1.

Doing this will not affect closed loop operation of your engine, since it is within the capability limits of the ecu to control afr based on O2 sensor info. It will make your cold start afr richer, though.

 

I have a summit fuel pressure gauge installed on the feed line right after the fuel filter . fuel filter > fuel pressure gauge > fuel rail > adjustable FPR > return line. The max psi I can get out of my stock fuel pump and nismo adjustable FPR (supposedly good from 20-80psi) is 46 psi @ WOT. With WOT set at 43psi my base pressure fluctuates between 28-30 and sometimes falls back to 20-25 however whenever I go WOT whether I'm checking it under the hood or driving with the fuel gauge taped to my windshield it always hit 43PSI and maintains it. This also happened when I first used an AEM adjustable FPR (however with the fuel guage installed directly onto the AEM so the pressure readout is on the return line). There are no kinks in the feed line and return line @ the fuel pump itself. The pump secured in the cage and the siphon back is fit below it. I used a new pump cover gasket too. I had a bad oem FPR so I do not know if my base fuel pressure was acting like this prior to all the aftermarket **** I bought to rule out my fuel problem (I originally thought my fuel pump was crapping out). Fuel filter replaced 6k miles ago. The inside of the tank looked spotless when I was fiddling with the pumps.

Should I install the Walbro back in there or is there something I'm missing?? Driveability is not affected. After trial and error with adjusting the FPR I have no hesitation whatsover during part to WOT throttle acceleration. The OBD scanner doesn't indicate fuel starvation whatsoever. Based on o2 voltage data from my scanner I'm actually it looks like my car runs rich. Ever seen or heard of someone having similar problems with fuel pressure like mine???

 

How are you setting the summit switch? Do you fiddle with the dip switches or are you turning the potentiometer screw? I do it with the screw and I can pretty much get it within 10-15 rpms using the auterra and finessing the gas pedal while I lean over to adjust the screw. Basically if I want it set @ 5150 the green light will flicker around 5150rpms and 5160 it will stay solid. I will open up the throttle till 5000 and very slowly craw up to the desired RPM. If i slowly let go of the gas pedal the green light will turn off when it fall below 5150. Takes a long time (15 min sometimes) and may sound lame but its pretty accurate in my case. When

 

OK I will try to get you some data sometime during the end of the week. Its suppose to rain a couple of days in Socal and traffic is much lighter during the weekend.

 

Sounds good.

It is wet snow mixed with freezing rain outside my window right now. The four snow tires and steel rims went on last night. My WOT pulls are done till March/April.

 

Your oem fuel pump should be good up to 60-65 psi, but that is for the static case when it is not delivering any fuel (deadheaded). I would have thought it would be able to pump more than 46 psi when delivering fuel, though. It does sound like you have a weak pump.

If you have a Walbro you ought to throw it back in and see what you get.

 

i use the dip switches typically...without a dyno...apparently the best way to set it is to set it so you feel the changeover the least...(granted not the best way, but still better than nothing)

so veequeue, did you figure out whether to put it on or after the dip in the powerband (the switchover that is)--when to start the switchover...??so basically you just took down your switchover from 5400 (how it was when you dynoed) recently to 5150....how does it feel now? maybe you should set it at 5300 so that the switchover ended at 5400...I dunno...

eng92, it is wet everywhere in SOCAL right now...so testing is not ideal...plus humidity is really high (obviously) anyway, maybe the reason I felt no difference between my technosquare and stock ecu is b/c I was expecting a huge low-end/midrange difference like JWT ecu guys experience due to their significantly high advance early in the powerband...their maps seems to start at 2500 or so...whereas the TS doesn't begin till 3500...so maybe I barely feel the midrange/low-end difference....whereas the JWT guys have a significant advantage in that department...either way, I want Brian to had Tadashi program in more advance to recover some of the low end loss of the mevi...but I also do want the extra top end that still remains unexplained in veequeue's data vs. Dave B's...although Dave B's is showing more than any of us in the 4 to 5K range

maybe I should send JWT both veequeue's and Dave's B graph and ask why they think even with the same manifold and intake, with relatively similar atmospheric conditions except for elevation, they are so different...maybe they have revised the program....

dave B, when did you get your ecu modded by them?
veequeue, ""?

 

I got my ECU done back in March of 2002. I doubt they've change their program at all. I would be curious to know what Veequeue runs in the 1/4 mile or what he has put down on the dyno. With okay 60 foots, my car has seen 14.3s at close to 100mph in the 1/4 mile at 1100' above sea level which equates to over 14.1s at over 101mph on a sea level track. I wish I could have figured out my drag radials because I know the car has 13.8s@100mph in it. Too bad my car will be gone early next year.

 

Im sending my ecu back and having them put the air fuel stock and ignition timing back to stock. So i can tune these myself YUPPP To bad i paid $800+ with ecu to get a raised redline

 

My experience with the MEVI activation point is that 5.4K rpms is the best. I spent a dozens runs at the track trying different activation points and 5.4K gave me the best trap speeds. I also had no dip in power on my dyno either.

 

so 5.4K is where you set your summit switch....or where the mevi finishes it's opening?
do you use a obd scanner type thing to see what rpm the mevi really activates @?

 

5.4K indicated on the tach, can't remeber what setting it is on the summit switch. But the trap difference between lowering or raising the acivatoin point was less than a 1/2 mph.

 

How are you going to adjust timing? I'm aware of ways you can retard timing, but not of any way to advance it. Well, except indirectly with the SAFC.

 

I30mike....do you use only the dip switches in the summit or did you use the screw as well?

 

Just the dip switches. IIRC it was 3.2 or 3.3 on the dip switches to give me a 5.4K activation. I no longer have my MEVI or summit switch so I can not tell you for sure.

 

I bought my ECU in July 04. After I replace my axles and clutch and buy new tires I will probably run my car up in Sacramento raceway when I go visit my friends next month. By then the clutch should be properly broken in. Its 50' above seal level not unlike LACR which is 2700' and windy. Also LACR is slighly uphill and has a motocross dirt track right next to it w/ no barriers whatsoever so dust gets blown all over the track.

I'm basically rebuilding my car instead of selling it and put the $ towards buying a 2k2-3 6sp which will still run circles around my car.

 

If youre using the tach as a reference then its probably opening up @ 5200rpm when you see 5400rpm.

 

Maybe, maybe not.

 

Michaelnyden - I just realized I gave you some misinformation about my setting of the RPM switch. It is set to 5400 indicated on my tach. The summit switch is not set up for 6 cylinder operation, thus you have to set it to a lower rpm to get it to activate when you want. If I recall mine is set to 3400rpm, I still have the switch in the basement I will look at it for you guys later today. I don't recall ever touching the potentiometer screw on the switch, just the dip switches. I do know that the times where I experimented with lower or higher switchovers (in increments of 200rpm, which is all the summit rpm switch allows for) would show a marked decrease in my trapspeeds at the track. I am consistent enough at the track that I typically trap within .25mph on every single run, and within about .15mph on probably 80% of my runs. So a drop of .75mph in my trapspeed was immediately apparent, and was consistent each and every time I tried a different rpm setting. Even though I only tested this 5 or 6 times, there was no appreciable variation or any exception to the rule: setting the rpm switch to anything other than my preferred setting resulted in reduced trap speeds on the order of .75mph. That is how I am so convinced that there is an optimal setting (though it could be different for each car) and that deviating from that will affect your acceleration to a noticeable point during a 1/4 mile pass. For switchovers, ideally there should be zero drop whatsoever in the hp and tq curves when switching from closed to open. There is a point at which the hp of the butterflies closed and butterflies open is equal, and that is the exact point at which the switchover "should" be made. For what it's worth, I did dyno which showed I had exactly a 7200rpm rev limiter (rpm signal taken off the coil) and my rev limiter as read off the tach was about 7250-7300rpm, so my tach didn't read appreciably high, only about 50-100rpms high.

Unfortunately I never did test my timing, but was told by JWT in Feb 2002 when I ordered my ECU, that they would do nothing to compensate for the MEVI, Ben's words as always were "the normal program we use will work fine" and that was that. I did convince them to give me the 7200rpm limiter which I believe I was the first to do. I made that choice based upon the hypothetical results in Cartest.

Have any of you guys talked to TS about the "Cheston Program?" When TS was G-Force formerly UPRD, they had a program which you could request called the Cheston Program, which advanced timing a bit more and leaned it out a bit more, that was separate from their "normal" program and had to be requested. This was because it was considered borderline safe for use in california where they only have 91 octane gas as opposed to the rest of the country which gets 92, 93 and even 94 regularly.

 

I think you guys are putting way too much thought in determining switchover. If everything is hooked up right, you should only see a 2-3hp difference if the switchover is set between 5200-5400rpms. If something is wrong like a bad vacuum canister, vacuum leak, flakey rpm switch, or early switchover (below 5000rpms), then you will see a drop in power when the valves open. Every dyno I've seen shows a very smooth curve assuming the switchover rpm is good.

The performance difference between setting the switchover at 5200 to 5400rpms should result in no change in performance. The only thing I can think of that would influence performance difference between 5200 and 5400rpm switchovers is potential valve flutter for those guys using the 7200rpm limiters and 5200rpm switchovers. When I hit 3rd gear, I'm right around 5100rpms indicated and my valves open at an indicated 5300rpms (5200rpm switchover). If you've got the 7200rpm limiter, you could be hitting 3rd right around 5200rpms and almost instantly you're back into switchover if you've got the 5200rpm setting. This rapid closing and then opening could flutter the valves and cause a slight decrease in performance, I guess.

I've noticed no difference in the performance between a 5200rpm and 5400rpm switchover with my 7000rpm limiter. Think about it for a second. How long do you really spend accelerating from 5200-5400rpms in 1st, 2nd, and 3rd gear? It's just not that significant, IMO. Those of us that go to the track a lot have played with a multitude of settings and have seen the results. If you use 5200 to 5400rpms, you should be fine. You really don't need to watch your parameters to know what works when you've got that timeslip telling you the whole truth.

 

But take a look at my dyno graph

I set the summit switch @ 5400 rpm with my auterra and the opening pretty much coincides with the curve picking up after 5400 on the graph. As you can see around 5250 the hp curve begins to drop then when the switch activates @ 5400 the hp curve picks up again. From 5400rpm to 5600 rpm it climbs from about 173hp to about 180 (i'm just doing my best to eyeball the green line in the online pic because the printout is at home). In my case 5400RPM is too late.