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Discussion Starter · #1 · (Edited)
And yes I have read a lot of other threads I've searched on and I was hoping since it's been a few years you guys could help me out.

Hey guys, I have an 01 e-shift and had my Mazzuri V1 headers/ypipe installed not too long ago and finally got around to dyno'ing it. Sadly my numbers were literally crap and I'm not sure what's wrong. I'll have my charts up in a bit but basically I ran 174.4 peak hp with an AEM short ram intake/Apex-i full cat back/HKS Exhaust cam hear at -4 (And I was on a mustang dyno not a dynojet so my numbers are a bit lower)

When I went to dyno today I had my O2 sim in and no CEL's or anything and I ran a 169 peak. It WAS a little warmer today (15degrees max?) but still I LOST hp after taking my cats out? So my dyno guy suggest I take out my O2 sim so we did and I went up to 174.8hp. Wow a gain on .4hp... I can't really imagine what's wrong? I drove the car around for about 15-20 min with no o2 sim and still no cel. I'm so confused it isn't even funny. Please chime in and help out a guy in need >.> Thanks in advance.



 

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And yes I have read a lot of other threads I've searched on and I was hoping since it's been a few years you guys could help me out.

Hey guys, I have an 01 e-shift and had my Mazzuri V1 headers/ypipe installed not too long ago and finally got around to dyno'ing it. Sadly my numbers were literally crap and I'm not sure what's wrong. I'll have my charts up in a bit but basically I ran 174.4 peak hp with an AEM short ram intake/Apex-i full cat back/HKS Exhaust cam hear at -4 (And I was on a mustang dyno not a dynojet so my numbers are a bit lower)

When I went to dyno today I had my O2 sim in and no CEL's or anything and I ran a 169 peak. It WAS a little warmer today (15degrees max?) but still I LOST hp after taking my cats out? So my dyno guy suggest I take out my O2 sim so we did and I went up to 174.8hp. Wow a gain on .4hp... I can't really imagine what's wrong? I drove the car around for about 15-20 min with no o2 sim and still no cel. I'm so confused it isn't even funny. Please chime in and help out a guy in need >.> Thanks in advance.
Your problem seems to be else where......How many miles on the car?? Maintance done??? Compression test maybe needed for safe measure...
 

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Discussion Starter · #3 ·
I've got 118k on the car but it's been kept in really good condition. And also these dyno's were like 1 month apart. Not much I can see going wrong in that time since I don't drive too much when i'm at school.
 

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I think alot of people forget that the 215 horsepower was rated when the car was new. So If you add in some wear and tear you could lose i'd say up 10 -15 hp (flywheel). Were you the original owner? MAybe previous owner was not as generous with maint as you. Lots of possibility. Plus these autos in these cars seem to sap powa!! So i think typical drivetrain loss for rwd is 11-15% plus a power robbing auto and you got those numbers sounds about right.
I was devastated when i went to my first dyno in my first car. Although, That should still be a reasonably quick car.
Your a/f's look extremely lean...14.7 is stoich under normal driving conditions. A n/a car should be in the 12.5 to 13.5 range i still think 13.5 would be lean though. Also people get so caught up with there peak output they forget what matters the most. CURVE!!! Look at your power and torque curve. Those lines are nice and linear. Your car looks like it would have a nice pull to it. Just my.02 cents
 

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you need some kind of tuning device. A SAFC, emanage, etc.. would prolly net you sum more power lookin at your graph. Tuning is so often overlooked.
 

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Discussion Starter · #7 ·
you need some kind of tuning device. A SAFC, emanage, etc.. would prolly net you sum more power lookin at your graph. Tuning is so often overlooked.
Lol, dude I know trust me. I'm saving up for a EMS or something but still I don't think you're getting it. I was running 174.4 (which I know is normal) with just a full cat back exhaust, intake, and exhaust cam gears. Then I threw on a header/ypipe with NO cats and gained .4hp. Hahaha Dude I totally think you're missing the point, and the car was "Lexus certified" when I bought it so it was kept well and I wasn't dumb when buying the car, I read the carfax... Thanks for your .02 cents though.
 

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If an exhaust gives you 3hp and the header have you 10hp. You cant add them up and think you would gain 13hp thats not how this works....You stop to think that maybe by putting your headers on threw your a/f's off?? you said unplugging the sim made a diff, Look at your afr. That is lean. Very lean. Taking out that sim made for a slightly richer mix. Thus a lil more powa. Trust me i know afr's ive owned rotarys and that car is finicky. I think with tuning you could gain 5-10 whp plus a even better curve.
 

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It WAS a little warmer today (15degrees max?) but still I LOST hp after taking my cats out? So my dyno guy suggest I take out my O2 sim so we did and I went up to 174.8hp. [/IMG]
This right here tells me that its in your tune. Look at those afr's. Thats very lean.
 

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Discussion Starter · #10 ·
the 1st dyno chart had no o2 sim and had stock headers/y-pipe.

I don't have the dyno chart of the pull with the o2 sim in which dropped me to 169 hp. I know it's running lean but I don't understand how taking out the cats could gain .4hp even if the tune is off a bit. I'm running a stock ECU so I do'nt even know how I'd tune it?
 

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Discussion Starter · #11 ·
plus from my understanding B1S1 and B2S1 is what affects the A/F and hte o2 sim affects only B1S2 and B2S2? I just don't understand why the A/F would change with an O2 sim.
 

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A piggyback fuel computer would really help. I mean sumthin as simple as a SAFC from apex'i would work. Since most of your modifications are minor and you have a cam gear to control the exhaust timing, I really see no need to have a more expensive piggyback or standalone(unless you planning on going with turbo). With a tune I'd say you would pick up (im jus guessing) 10-15 whp. That would put you close to 200whp. Sound closer?? Tuning is everything man!!!
-B
 

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the 1st dyno chart had no o2 sim and had stock headers/y-pipe.

I don't have the dyno chart of the pull with the o2 sim in which dropped me to 169 hp. I know it's running lean but I don't understand how taking out the cats could gain .4hp even if the tune is off a bit. I'm running a stock ECU so I do'nt even know how I'd tune it?
I would love to see that chart. I can't believe your tuner didnt say anything? Were you at a performance shop? I think the idea of cats really robbing power was formed back in the 80's when cat substrate was horrible and restrictive. Now in the present cats actually flow very well, The actual power to me on the is300 doesnt come from removing the cats but the design of the header. If those cats were further downstream a better header design may have been implemented. The reason the are so close to the head is for emmisions. The cat can warm up much more quickly thus cutting down on hydrocarbons at startup/warmup.
-B
 

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plus from my understanding B1S1 and B2S1 is what affects the A/F and hte o2 sim affects only B1S2 and B2S2? I just don't understand why the A/F would change with an O2 sim.
the o2 sim only supplies a steady voltage. It cannot adjust for changes in a/f. So with your free flowing mods you are introducing more air and not fuel that equals a leaner situation. Most factory cars use narrowband o2 sensors. Google wideband vs narrowband o2 sensors for a detailed difference. A widebands range is usually 0-5 volts. Thats huge for tuning!!
 

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a bone stock E shift IS puts down about 174 to the wheels... something is fishy here. The Mustang dyno is definitely not helping you. this car is rated 215 AT THE CRANK. not to the wheels. i mean, it seems like with your mods you should be in the 185 range... i would try a different dyno and then get cams!!!
 

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Discussion Starter · #16 ·
a bone stock E shift IS puts down about 174 to the wheels... something is fishy here. The Mustang dyno is definitely not helping you. this car is rated 215 AT THE CRANK. not to the wheels. i mean, it seems like with your mods you should be in the 185 range... i would try a different dyno and then get cams!!!
From my understanding a mustang dyno reads "true" number of RWHP as opposed to DynoJets that read 8-11% higher? I don't really mind that. I'm just baffled that I gained .4 hp from adding these headers? I'm not quite sure but I don't think I have a leak.

And yes, I am going to get some cams so don't worry =P I'm just deciding on which ones because I plan to boost so how I gather all my parts together is key~ (Going for a V160 swap first ;D)

And Sebastian, am I correct in that the B1S1 and B2S1 sensors are the ones that adjust the A/F? The B1S2 and B2S2 are there purely for emissions... right? So how would adding an O2 sim affect my A/F's? I still don't get it and the guy re-rex or w/e is avoiding it kind of. Thanks~
 

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A compression test will help you eliminate the worst possibility. I imagine an improperly wired O2 sim to be pretty bad for A/F reading as well. I would check the wiring of the sim and if its good, maybe you need a reflash.
A wider/taller than stock rear tire may affect readings combined with the last two problems, and maybe get a fresh synthetic oil change, synthetic diff and tranny fliud too, and maybe get more accurate baseline
 

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From my understanding a mustang dyno reads "true" number of RWHP as opposed to DynoJets that read 8-11% higher? I don't really mind that. I'm just baffled that I gained .4 hp from adding these headers? I'm not quite sure but I don't think I have a leak.

And yes, I am going to get some cams so don't worry =P I'm just deciding on which ones because I plan to boost so how I gather all my parts together is key~ (Going for a V160 swap first ;D)

And Sebastian, am I correct in that the B1S1 and B2S1 sensors are the ones that adjust the A/F? The B1S2 and B2S2 are there purely for emissions... right? So how would adding an O2 sim affect my A/F's? I still don't get it and the guy re-rex or w/e is avoiding it kind of. Thanks~
I explained it earlier.....the o2 sim maintains a steady output voltage. Your AFR is essentially a voltage put into a number for a reading. The problem is it can not compensate for modifications since that o2 sensor is not there to take a reading. Example: if your o2 sensor had voltage range of 1-3 volts that o2 sim is set up to run right in between that to keep cel lights from illuminating. It(the sim) doesnt know anything about how the rest of the car is running because it is not tied into the ecu in any way. The maf and o2 and other sensors work together to keep a optimum voltage(AFR) for the the load the car is under. You took out a important sensor with the sim. Great for small mods not so for bigger mods. So the car thinks that the fuel trim is fine and does not try to adjust.
 

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A compression test will help you eliminate the worst possibility. I imagine an improperly wired O2 sim to be pretty bad for A/F reading as well. I would check the wiring of the sim and if its good, maybe you need a reflash.
A wider/taller than stock rear tire may affect readings combined with the last two problems, and maybe get a fresh synthetic oil change, synthetic diff and tranny fliud too, and maybe get more accurate baseline
A compression test never hurts. Also who installed the cam gear. IS your timing spot on??
 

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Discussion Starter · #20 ·
But the O2 sim only affects POST-cat sensors... the AFR is adjusted from the PRE-cat sensors from all the reading I've done. This is why I'm confused about why it would make a difference. My Cam gear was installed by the same guy who did my Headers and my dyno pull. It should be spot on, I can check tomorrow morning when it's lighter outside.
 
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