What did Dyno Tom think the 'bumps' in the TQ dyno were about?

 

Bit - I didn't think to ask Tommy the first time I called so when I called him back ( after seeing your post ) he pulled the sheets & said that he'd seen similar "spikes" before. Thunder Racing USED to handle mostly imports but now have gone over to the F-bodied GM rydes. He told me that they sold ( & tuned ) alot of APEXi controllers for Hondas & other imports running intakes, exhausts or NOS ( or all 3!!:eek: ) & that occasionally they found a leanout condition in the upper rpm ranges similar to what Loyd's car showed with the TM's. He was in agreement with RA - just let the ECU finish "learning" the better combustion of the TM & they should go away. He also said that those weren't the worst "spikes" he'd seen - some took some serious tuning with the APEXi to remedy. His educated guess is that the stock plugs weren't fully burning the air/fuel mixture so there was no leaning out. The TM's were so effective the they could stand a richer mixture & this is in line with TM's advice on their website & on the instruction sheet ( they mentioned advancing the initial timing on the older cars where that wasn't computer controlled ). If the stock Lexus fuel system can indeed handle 400 flywheel HP then the factory ECU SHOULD have enough extra fuel headroom to adapt to the more efficient ignition by richening the mixture. The only way I'll know for sure is to install them in my GS & put some miles on them & the ECU before dynoing. That's my next plan but don't know when I'll get around to it as the car hasn't returned from Tennessee yet!! :eek:

 

On my way to SRTnow, so that Mo & I can take a look at the charts & give an opinion, per Mean gene's request.

Later.

 

Well, im sold. Now the only question that I have is the change of the plugs on my 98 GS400 a DIY project??? Looks to me like if I take the engine cover off, it should be pretty easy access to the coil packs and then plugs. Could anyone let me know on the plug change??? Thankx!

 

very straight forward process. the only hard part may be the 2 spark plugs closest to the firewall on the left (battery side) it is a little tighter to get into the space, but it isn't too hard overall. Just take it easy when you pull on the coilpacks, don't just yank at em.

hope this helps

 

MRGS - Percy ( & others ) posted this somewhere but:

1) Remove V-bank ( engine ) cover - 10 mm socket for the stock
fasteners or T-25 Torx driver if U have the RMM cover.
2) Remove the intake pipe ( might need to remove the air filter
housing as well ). I have the SRT intake but I think the stock
intake requires a 10 or 12 mm socket.
3) Disconnect the coil pack electric connection ( push the upper
tab inward & it will snap free then slide it upward ).
4) Remove the coil packs with a 10 mm socket. They R held on
by a single bolt & then just exert a decent amount of pressure
( as Ricky said, don't yank ) upward. Might have to put a bit of
twisting as U pull up to break the suction/connection. Some
WILL be hard to break free but they'll come.
5) U'll need a 16 mm deep socket & probably (2) 3" extensions &
a single 6" extension to handle all the plugs. U'll need to be
creative on some because 2 of the locations R tight for the 6"
extension but too deep for a single 3" so I had to snap the
3" xtension onto the socket & lower it partially into the hole
before adding the second 3" piece & finally the ratchet.

Reinstall in the reverse manner using 20-24 ft/lbs torque on the TorqueMaster plugs or 13 ft/lbs for the iridium plugs. To make removing them easier the next time, use a LITTLE anti-seize on the middle few threads & exercise caution when threading them as the aluminium heads will cross-thread if U're not careful. The coil pack bolt needs 66 in/lbs ( or roughly 6 ft/lbs ) & it's plastic so don't overtorque!:eek: U can figure on maybe 30 minutes if U're handy with car work or an hour at most if U're not. Have fun!!

 

Thankx guys....looking forward to changing out the plugs. One quick last question, would you guys suggest re-setting the ECU after the install of the TM plugs (ie pull fuse or disconnect the battery)??? Thankx!

 

MRGS - By all means reset the ECU!! Even the TM plug instructions recommend disconnecting the negative battery terminal for 1 hour. It's ALWAYS a good/safe idea to disconnect the power when working on any electrical component of your car ( although I personally don't see it as necessary to do so in this case but I did anyway )!! Just disconnect the terminal or pull the ECU fuse ( whichever U've done before ) & wait at least 30 minutes. Of course, if ya do this while U're doing the plug change it times out perfectly!! Word of caution - Bitkahuna's sources say it take 200 miles for the ECU to reset itself to the new data so be patient.

 

Does that mean that whenever u reset the ECU, it'll take 200 miles to get back to working with the TM plugs?

ShOwGS

 

Show - U probably won't realize the maximium gains until the 200 mile mark. I read an article in a 4-Wheeler magazine where they installed the TRD supercharger on a project Tacoma & their tech told them not to expect too much until about 200 miles. The author said that when he drove the Tacoma away from the dealership he WASN'T that inpressed. He could feel the extra power but the response wasn't there. However, he kept the tech's words in the back of his mind & ALL the staff said that the Tacoma woke up after about a week or so ( around 200 miles! ). I noticed an immediate smoothness at idle that wasn't there before the TM's & the car seems to be getting stronger! Don't currently have any more dyno plans but U never know about me!!:eek:

 

Am I missing something here? I see two dyno runs; one with a fully “learned” ECU and one with a reset ECU whose short learning experience is on a Dyno. This learning is analogous to driving short spurts on a permanent steeply graded hill, about as unrepresentative of real driving as you can get. The ECU would default to a safe baseline condition and gradually adapt to a low emission condition. A safe baseline condition avoids lean burn out i.e slighly rich. This is likely to result in more power and more emissions during the learning phase, although many other factors come into play. The change of spark plugs is just one of many factors that could influence the power in either direction.

To make ANY pronouncement, a back to back comparison under identical and "learned" conditions needs to be done, and preferable a third test with the old plugs replaced to eliminate any accumulative errors from all kinds of factors like car or dyno heat soak. I know that's a lot of work but without it everything else is guess work. Seat of the pant measurements are fine, but just remember how much better the car feels after a wash and polish.

 

Girvan,

You want to take on a retest yourself ?

Interesting thoughts however & one counterpoint... I've done dynos (as well as other folks) where we did runs both before & after an ECU reset and there was NO change in dyno performance of my car. No other changes were made. The largest change the ECU reset seems to make is unlearning the 'milder' shift points of the transmission which doesn't affect a dyno as it's kept in a single gear through redline (and rev limiter).

I'll look for MG to chip in some here too.

 

Girvan - I never said that this was an EXACT science project. I suppose U could make a case for the improved mpg on the drive home being based on wind direction/speed & road inclination? While I agree with most of your thoughts ( in theory, at least because I know that the GM ECU ( not sure about the Toyota/Lexus programming ) has a closed loop program that, while it increases the air/fuel mixture to the rich side it also reduces the spark advance as well which would yield LESS power but will still getcha home which is what it's designed for ) please see my post made a few days before the dyno runs. This was a procedure not endorsed by anyone or contributed to by anyone else other than Loyd & myself. Yes, power readings COULD have been different had I left the car on the dyno for another hour & made some more runs or "dumped" the ECU again ( back to back as U suggested ). However, at $85/hour the dyno time isn't cheap ( even with my "buddy" discount from Tommy ).:eek: I did the best I could under the circumstances & I leave the interpretation of the results up to you Members.
FWIW - the majority of the group have immediately noticed a smoother idle with the TM's plus more responsiveness ( & wheelspin!! ) even without the fully relearned ECU status.
As Dave said, I too have dyno'ed parts w/o allowing the ECU to relearn & noticed no immediate improvements. However, things tended to get better ( or worse ) after a few hundred miles. Unlike Dave, the biggest change after resetting the ECU comes ( at least in my GS4 ) not from the shift points/feel but from the throttle responsiveness. In any event, thanks for the imput!

 

Guys thanks for not flaming me. I know that getting a real scientific answer is not easy and also very expensive.

Good point on the spark advance too. It's really anybody's guess what ECU baseline strategy Lexus uses and how close it is to the optimized full throttle learned setting.

 

Has anyone tried the bosch platinum +4, they are half the price of the TM star series, and was wondering if they are equal