whattheF

I recently performed the 60k service, changing plugs and air filter with OEM replacements.

The battery was disconnected so ecu was reset.

The car now feels like it doesn't have the pep it used to. Can't narrow it down to engine or tranny behavior though. From a non full throttle start, it likes to start from 2-3 in normal mode. It used to hold 1-2 much longer. Full throttle acceleration in 3-4 is not as fierce on highway.

Could it be plugs aren't tightened enough? Wouldn't it throw a CEL light if something was wrong? Is the ecu still relearning? I've only driven about 300 miles since I did the service.

Thanks.

ihadboost

If the ECU was reset, the car could still be in a "learning" mode. Maybe drive it a few hundred miles and see if the behavior changes.

lorenr

iTrader: (1)

Go back and recheck your work. The PCM or ECU would have learned everything within the first day of driving.

I would check:

1. the seating of the air filter. Was it installed correctly? Same dimensions? Same quality. Which side up?
2. re move a spark plug, compare it to the ones you removed. Are they exactly the same? Compare part numbers. Remove more of them checking the condition of each. Check for cracks in the porcelain, plug gap and sealing surface.
3. Look for something that was disconnected during the install. This is usually where we goof up.
4. I always use a LITTLE never seize when installing plugs, especially in an aluminum cylinder head.
5. If all else fails re install the old plugs. You saved them didn't you? The plugs in this motor will last a long time. Save the old ones.
6. Read the codes. If it is doing what you say, it probably threw a code. If we are going to work on these cars get a code reader. For sure, you'll need it.

This is a real pain in the rear and the very reason when working on these high tech cars to, "take your time".

whattheF

When you say read the codes, do you mean if the car throws a code? Because right now there are no warning lights or CEL.

lorenr

iTrader: (1)

If a code is set it does not always do CEL.

Code readers are cheap. Check this forum under "search" for what appears to be a pretty good one. I bought it but so far haven't needed it. I'm also a bit lazy about reading the directions, but that might just be because I'm male and can't read anyway.

whattheF

So I'm guessing a free check at auto zone is not going to reveal anything useful?

kauaian

iTrader: (18)

Double check your vacuum lines attached to the intake box and make sure your plug wires are seated correctly. If both check out and are good to go reinstall your old plugs and see if the problem still persists.

whattheF

So I checked vacuum lines and wire connectors. Everything looks fine. Next step is tearing down the engine again to check plugs. Sigh.

MisterSkiz

iTrader: (2)

have you checked to codes to see if you have any stored? Codes csn be stored.without a chrck engine light....do that first before wasting your.time with.the.plugs....

lobuxracer

iTrader: (2)

Did you install the plugs with a torque wrench? Did you use OEM plugs or something else? The plugs in late model Lexus engines are unique with a triple ground strap.

A code reader will let you know if there is a code pending.

The ECM learns very quickly - once you get up to operating temperature and closed loop, it's very busy tweaking short term and long term fuel corrections to get you into the ballpark from the initial calibration (which it recognizes) after removing power to the unit.

When I did the valve lash inspection, I did not notice any difference in performance after also changing the plugs.

FWIW, we do not have plug wires on this engine. We have COP, so the wires are to the coils and there are eight coils, so the likelihood of a high voltage issue is pretty near zero.

whattheF

I used OEM plugs purchased from Sewell.

Did not use a torque wrench but knew the spec to be 21 ft/lbs so I think I tightened them enough.

whattheF

To give more color, the car behaves fine. To anyone else, there wouldn't seem to be a problem. The difference is so slight, but I think it's there.

I'm going to run the codes, then...

I'm going to race against my buddies stock Isf to find out the truth.

ISFPOWER

iTrader: (20)

i made sure to torque my spark plugs to specs with a wrench, i think it was lobuxracer who said if a spark plug that comes a bit loose will mess up the engine pretty bad.

only thing i can think of is that you left some vacuum line unplugged. i had the opposite effect, car felt a lot better after my spark plug change.

lobuxracer

iTrader: (2)

The worst thing you can do is over-torque a plug. It changes the heat range because the shell distorts and it can cause detonation. This is why I always use a torque wrench to install plugs.