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2009 Avalon XL
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231 Posts
Discussion Starter #1
For those that don't want to crunch paragraphs worth of data, here's the short story...
Why is my car faster with the check engine light on? I have a 2009 Toyota Avalon XL.

Now, for those hardcore data lovers like myself, here's the gory details...

In September 2012 I ran a 15.108 @ 92.82 mph. It was 90 degrees out. I had a K&N cai, deleted 3rd cat and resonator and Dynomax mufflers. I was on the stock 16 inch alloy wheels and 215-60-R16 tires. Also, My CEL was on at the time.

Since then, I've installed the MKC y-pipe, replace all of the exhaust after that with 2.5 inch piping, switched to Borla Pro XS mufflers, got a throttle body spacer and a Jet performance maf sensor. I "upgraded" the wheels and tires to 18 inch Enkei J10's and 225-40-R18 Continental Extreme Contact DW and lowered the car with "Ebay" springs. Also I added the rear wing from a dodge charger(looks amazing!).

After all of that, on May 22nd this year I ran a 15.050 @ 93 mph. It was 78 degrees out and my CEL was on.

Of course, I was expecting a faster time after adding so many "mods", so I scoured the internet looking for validations for my mods, or the reason why my time was virtually unchanged. Well, hard evidence supporting or dismissing throttle body spacers and the Jet maf sensor proved to be super elusive, so I just decided to take a page out of Myxalplyx's book and answer my questions on the track with a good ol' fashioned test n' tune. The wing was the first thing to go... :wink:

Here's the times I ran today. The temp outside was 89 degrees.

No Jet maf, no spacer, CEL ON...
14.604 secs @ 96.04 mph
14.725 secs @ 95.91 mph
14.770 secs @95.64 mph

No Jet maf, no spacer, CEL OFF...
14.984 secs @ 94.80 mph
15.021 secs @ 94.14 mph
15.111 secs @ 94.87 mph

Installed Jet Maf, no spacer , CEL ON...
14.808 secs @ 95.61 mph
15.035 secs @ 95.10 mph
15.039 secs @ 94.52 mph

No Jet Maf, installed Spacer, CEL ON...
14.784 secs @ 95.84 mph
14.826 secs @ 94.86 mph
14.886 secs @ 95.17 mph

Great day at the track today! Looks like I gained half a sec with lighter wheels and tires and the performance y-pipe. As you can see, the Jet Maf not only didn't make me faster, it appears that it was slowing me down. I was honestly surprised, because my "butt dyno" was telling me the complete opposite. The throttle body spacer was also a slight bottleneck. I imaging its because its slowing air down at higher RPMs. the most baffling thing is the check engine light. Why is the car so much slower when everything is supposed to be working correctly?
 

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Registered
2009 Avalon XL
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231 Posts
Discussion Starter #3 (Edited)
I used the "pedal dance" to disengage the tractin control when the cel was off. The vsc was still active, though. The vsc is off when the cel is on.

The stock y-pipe is pretty restrictive and is a major bottleneck in the exhaust system. There is definitely performance to be gained by replacing the stock part. With the y-pipe and the intake, can relly feal the dual vvt-i kick in now.
 

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2014 HL XLE AWD
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2,170 Posts
The stock y-pipe is pretty restrictive and is a major bottleneck in the exhaust system. There is definitely performance to be gained by replacing the stock part. With the y-pipe and the intake, can relly feal the dual vvt-i kick in now.
I no longer mod, but have done similiar mods on a ford engine.. I ended up having superchips write new running program (for pcm/ecm) to change air/fuel/timing etc. which was needed cause my DIY bolt on's confused stock pcm program, again trial, error, test & retune. Anyhow, just brings back ole mems. Do agree..what goes in, gotta get out..air intake, exhaust.. Good luck & have fun. :smile:
 

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2009 Avalon XL
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231 Posts
Discussion Starter #7
No problemo... and thank you for being one of the guinea pigs for the ovtining reflash! I can't wait to see how well that works.

I'm going back to the track again on Friday to test my DIY port and polished throttle body, not that I've been driving with it for 3 weeks and the ecu is done making its adjustments... hopefully.
 

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Slow 2010 RAV4 Sport
2010 Toyota RAV4
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279 Posts
No problemo... and thank you for being one of the guinea pigs for the ovtining reflash! I can't wait to see how well that works.

I'm going back to the track again on Friday to test my DIY port and polished throttle body, not that I've been driving with it for 3 weeks and the ecu is done making its adjustments... hopefully.
I wouldn't expect too much to be honest with you. My air/fuel ratios could be a little better but as lean as it is, it didn't seem to affect my horsepower/torque on the dyno in any negative way.

A little extra if any hp from more aggressive timing advance and better air/fuel ratio. Maybe! However, Monkey Wrench Racing do have aftermarket cams (CAMS), that requires your car to be able to rev to 7500rpm and for the ECU to be modified to take advantage of it. This would be interesting. I'm not quite as gung-ho as I usually am about getting this stuff done at the moment.

There are options on here though. :wink:

Also, good luck on testing your throttle body. I did not see any measurable improvement when I had my throttle body bored out by Maxbore. The pics are gone but the thread is still there ~~~>RAV4 Maxbore Throttle Body
 

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Honda-Tech White Ops
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1,581 Posts
Wow.. 11.67 of lift... that equals to 0.459" which is a hellava lot of lift.


Id like to see dyno sheets of these cams in action! I wonder what the Lobe Separation Angle (LSA) is on these. I would hope they would promote some sort of scavenging while keeping a nice idle.


So OEM springs and retainers are fine with these cams?


Also, Going to this flash on the ECU-

Do you have a wideband hooked up? Whats your AFR's at WOT?


Im curious as to what they actually lean it to as they are working on a flash for the camry 2AR-FE. They are taking deposits before any tests have been done or dyno sheets posted to prove their gains and claims..

Shady if you ask me, which is why Im curious as to your specs.

Also, This NST pulley you have is going to cause you issues down the road.

Since DC sports started making pulleys back in the F&Furious days, kids were buying them up. Underdrive this and that. Throttle response.. a light weight flywheel will yield alot more throttle response as your shaving off 15-20lbs on the rotating assembly. a few ounces..? Not so much.
You dont see too many of them anymore.. What they didnt understand is the OEM was light as well AND it has another important thing where most everyone doesnt realize.

It dampens Engine Harmonics. These waves of vibrations will cause oil pump issues, bearing issues, and possibly more depending on the engine.

OEM have a rubber cushion near the crank bolt to alleiviate the harmonics. Now ATR makes a competition dampener which works wonders as the OEM can only do so much with the thin rubber.
 

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Slow 2010 RAV4 Sport
2010 Toyota RAV4
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279 Posts
Also, This NST pulley you have is going to cause you issues down the road.

Since DC sports started making pulleys back in the F&Furious days, kids were buying them up. Underdrive this and that. Throttle response.. a light weight flywheel will yield alot more throttle response as your shaving off 15-20lbs on the rotating assembly. a few ounces..? Not so much.
You dont see too many of them anymore.. What they didnt understand is the OEM was light as well AND it has another important thing where most everyone doesnt realize.

It dampens Engine Harmonics. These waves of vibrations will cause oil pump issues, bearing issues, and possibly more depending on the engine.

OEM have a rubber cushion near the crank bolt to alleiviate the harmonics. Now ATR makes a competition dampener which works wonders as the OEM can only do so much with the thin rubber.
This makes a lot of sense. However, I've have an Unorthodox Racing pulley on my 1996 Subaru Outback Sport Wagon. Purchased the pulley in 1997-1998. Car was turbocharged 3yrs later and nitrous added (to the stock engine). I still have this car 22yrs later. It still runs and the pulley has given no issues. Unorthodox Racing used to have me and my car listed under their testimonials sections back in the day. Guess they've since removed that page.


I have a ProECM lightweight pulley on my 1989 Subaru XT6. Purchased it in 2005. Car still runs fine with no issues. This is 12yrs later after the install, on a 28yr old car.

Had a custom NST pulley made for my Honda Fit at the same time as my RAV4. Both are running. Both have no issues.

So when you say 'Down the Road', what do you mean. 5yrs, 10yrs, 20yrs. 40yrs? People usually don't own their car for as long as I have owned my Subarus and if they did, they usually have other problems than from the pulley. This is my experience I'm talking about. At the present, no hearsay. I've read many of the information and articles you speak of. I just haven't experienced issues with any of the vehicles I've owned or currently own. So....
 

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Honda-Tech White Ops
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1,581 Posts
ost of the time this is for racing purposes where the engine spends most of its life in the upper RPM bands (where more harmonics occur)


Your usual jaunt up and on ramp on the hwy or from a red light wont have much effect as the engine is stays in the lower rpm area.
 

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Senior TN Member
Porsche
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7,508 Posts
Too many mods to pinpoint anything, except for...

In September 2012 I ran a 15.108 @ 92.82 mph. It was 90 degrees out. I had a K&N cai, deleted 3rd cat and resonator and Dynomax mufflers. I was on the stock 16 inch alloy wheels and 215-60-R16 tires. Also, My CEL was on at the time.

Since then, I've installed the MKC y-pipe, replace all of the exhaust after that with 2.5 inch piping, switched to Borla Pro XS mufflers, got a throttle body spacer and a Jet performance maf sensor. I "upgraded" the wheels and tires to 18 inch Enkei J10's and 225-40-R18 Continental Extreme Contact DW and lowered the car with "Ebay" springs. Also I added the rear wing from a dodge charger(looks amazing!).

After all of that, on May 22nd this year I ran a 15.050 @ 93 mph. It was 78 degrees out and my CEL was on.
What is the weight of the stock wheels+tyres versus the upgraded ones? This makes a HUGE difference in ET. HUGE!!! More than anything else combined!!!
 

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Honda-Tech White Ops
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Im sure the enkei versions are lighter then OEM

and your right, unsprung weight has alot of dis-advantages
 

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Registered
2009 Avalon XL
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231 Posts
Discussion Starter #14
Stock was a 22 pound wheel + 24 pound tire = 46 pounds

Enkeis are 20 pound wheels + 21 pound tire = 41 pounds
 

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Senior TN Member
Porsche
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7,508 Posts
Im sure the enkei versions are lighter then OEM

and your right, unsprung weight has alot of dis-advantages
Not just unsprung weight, which makes a difference in handling. But rotational weight as well. Which is typically counted at 2x as weight of non-rotating parts when it comes to accelerating.

A long time ago (10+yrs), I switched to carbon-fibre wheels on my CBR600RR and did back-to-back comparisons at Willow Springs raceway with the exact same tyres on the same day. Just that switch alone was worth about 1.25 sec/lap on that track. That's a HUGE difference. If I was racing myself with stock wheels, I would be pulling away about 100 ft/lap!


Ok, back to analyzing this difference. Note that the CEL is the result or effect of a change in the system. It's not the cause of these differences. Simply, the ECU was flagging something non-stock with parameters that's outside its approved ranges. We just need to datalog all the sensors in these 4 scenarios and compare the differences. It is most likely multiple variables that changed between runs to create those differences.
 

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Honda-Tech White Ops
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Uhhmm.. uhh..


Unsprung weight is more towards acceleration.. not handling.


In all my years, I have never heard of rotational weight.. That might be be important for bikes as that whole gyroscope thing to keep the bike up, but you swapping out steel to CF just proves my point as well.



Theres many threads already of lighter wheels while racing to which unsprung weight has a drastic effect on acceleration.. Not sure your angle on handling, a wheel is a wheel when turning.


But whatever..
 

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Senior TN Member
Porsche
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7,508 Posts
Most people have never heard of Kobe Lobster either, doesn't mean it doesn't exist.

Unsprung weight is more towards acceleration.. not handling. ..
Google "unsprung weight", which is components that are below the springs: wheels, control-arms, bottom of strut-housing, ball-joints, 1/2 axles, brake-rotors. All these follow the contours of the road and are not controlled by the springs & dampers. Racers try as much to lessen weight of unsprung components because they force the body up & down too much if the ratio of unsprung-to-sprung weight is too high. That's why heavier cars tend to have smoother rides, because the sprung-weight above the springs aren't tossed around as easily by the wheels & unsprung weight. Wikipedia - automobile handling.




However, rotating-parts have to deal with polar moment of inertia which is different than the upward linear push from unsprung weight. For every foot of forward movement, you have to rotate a piece of wheel & tyre through twice that distance. Rotational inertia

where:
meq = equivalent mass of rotating parts [kg]
= [ Iw (1/rw)^2 + Ip hf (if /rw)^2 + Ie ht (if ig / rw)^2]

where:

Iw = polar moment of inertia of wheels and axles ≈ 2.7 [kg m^2]

It's the square-root function of mass that causes rotating parts to have more inertia (harder to accelerate for given weight), than parts that are moving only in a straight line.


You've got your concepts correct, the terms aren't matching up.
 

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Slow 2010 RAV4 Sport
2010 Toyota RAV4
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279 Posts
I'll leave the math to you guys. But my personal experience is that by installing lightweight wheels and tires on my RAV4 (Including my Subarus as well), I dropped 3/10th's of a second in the 1/4 mile. See my thread here ~~> Post #35-43
My wheel weight loss may be a little.......more than usual though. Hehe! My wheel diameter is also smaller than stock. So the wheel response is way more exaggerated. I will say it is not to most people's liking. Bothers me some as every bump has the whole RAV4 moving. The acceleration from idle and throttle response is amazing though.


I measured no extra power to the wheels though (Of course) when testing this on the dyno. However, I measured much better acceleration numbers on the dyno. My dyno plots are gone (Thanks to Imageshack). Rav4 Wheel Weight Dyno Test


So....if you want something you can feel everyday with better acceleration, better throttle response and better breaking, get yourself lighter wheels and tires. Don't compromise on your tires either. Get one of the best performing lightweight tires you can purchase. On smaller diameter wheels (to get the weight closer to the center of the wheel). And if you are nuts, get a smaller diameter tire than stock on your smaller wheels for even more amusement. Do so at your own risk and be safe. Trust me! I have a 2015 Honda Fit with a dirt slow automatic CVT Transmission. All I've added was my homemade intake, exhaust and lightweight wheels and tires (with slightly smaller diameter than stock). Took me from [email protected] to a best of [email protected] It has no business being as quick as some sportier cars. Here I am having fun with some Mustangs.
 

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Slow 2010 RAV4 Sport
2010 Toyota RAV4
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279 Posts
Here's the times I ran today. The temp outside was 89 degrees.

No Jet maf, no spacer, CEL ON...
14.604 secs @ 96.04 mph
14.725 secs @ 95.91 mph
14.770 secs @95.64 mph

No Jet maf, no spacer, CEL OFF...
14.984 secs @ 94.80 mph
15.021 secs @ 94.14 mph
15.111 secs @ 94.87 mph

Installed Jet Maf, no spacer , CEL ON...
14.808 secs @ 95.61 mph
15.035 secs @ 95.10 mph
15.039 secs @ 94.52 mph

No Jet Maf, installed Spacer, CEL ON...
14.784 secs @ 95.84 mph
14.826 secs @ 94.86 mph
14.886 secs @ 95.17 mph

Great day at the track today! Looks like I gained half a sec with lighter wheels and tires and the performance y-pipe. As you can see, the Jet Maf not only didn't make me faster, it appears that it was slowing me down. I was honestly surprised, because my "butt dyno" was telling me the complete opposite. The throttle body spacer was also a slight bottleneck. I imaging its because its slowing air down at higher RPMs. the most baffling thing is the check engine light. Why is the car so much slower when everything is supposed to be working correctly?
Never did ask Moondogg but what got you from the 14.7-14.8 range down to the ...what....14.3's your at now?
 
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