thelastaspec

Hi all,

A problem has come up with my TL...

Car background:
-55,000 miles, 2003 TL Type S A-Spec
-7 year service done
-have not changed spark plugs, no EGR cleaning done

-94 octane fuel, no ethanol (problem persists with 91 octane)
-Don't drive often - drive 1-2 times per week
-Live in mild climate, no snow/salt, temperatures never very low, never very hot
-Temperature about 24C or 75F right now/past month, not humid

-I usually drive in sport shift mode as my city has many hills, slowdowns etc. that would cause D5 or D4 to constantly go up and down gears
-I have not pulled the clock fuse or disconnected the battery in a long time
-The car has a AFC controller, exhaust, CAI, headers, downpipe etc (see sig.)

Problem:
-When driving at ~30mph (50km/h) and coasting, light throttle will cause the car to bog and have the RPM to fluctuate more and more like a pendulum.
-D5/D4 drives stays in 4th gear 99% of the time when driving in the city at ~30 mph - I try to match that with my manual driving style

-RPM at "~30mph and coasting" is ~1000-1200 RPM in D5 or D4 - the car in the past has always driven fine like this - it is a nice way to drive without the exhaust getting loud

-if you continue to stay at light throttle, the RPM will start to fluctuate more and more (like an undamped spring or pendulum) - eventually leading to the RPM fluctuating up by 1000.

-While the RPM fluctuates the exhaust sounds "burbley" (similar to a muscle car letting off of throttle) except this is happening while under light throttle

-The problem is most noticeable when driving on a slight downward grade and lightly pressing the throttle. Driving uphill in 4th/low throttle there is no problem (that I have experienced).


An example scenario experienced today:
-Driving ~30mph, downward grade, tiptronic mode 4th gear, rpm ~1200
-very light throttle car rpm starts to fluctuate like pendulum, fluctuations getting worse to the point where it goes up from 1200 to 2000 and then downshifts by itself.
-after the downshift into 3rd and now that the car is at a higher RPM, light throttle is fine with no ill effects
-the downward grade is steep enough for the car to speed itself easily up to 40mph from 30 in a short period of time just via gravity


Other information:
-Idles fine with no fluctuation in RPM (I have seen videos where the RPM will bounce at idle, nothing like that)
-Temperature normal
-A/C works fine
-Revs / drives fine under hard acceleration or higher RPM
-Highway fuel consumption/highway driving seems fine
-No lights or anything else on, local autoparts stores charge to read codes



Sorry for writing so much,
Thank you for all your suggestions - Cheers

thelastaspec

In addition, a known problem with my car is the motor mounts are all most likely broken. They have been this way for at least a year or two. I have not zip tied the motor mount vac lines off. There is no oil residue from them visible however.

I keep the engine bay clean with no visible dirt/oil.

Running Mobile 1 full synthetic. Getting close to change interval however oil is very clean.
oil level has gone down from full to half of the dipstick indicator over the past 9,000 + miles.

3.2TLc

Some basic items that tend to cause similar issues are the following, in no particuliar order. Probably a simple fix.

~Try a quality fuel system cleaner product.
~ Replace the original plugs with new "NGK's".
~Check for a dirty air cleaner and any vacuum leaks.
~Plug the motor mount v-lines at their solenoid source.
~Replace the PCV valve, clean the EGR passageways and TB intake.
~Check the rad's coolant level and fan's operation.
~Have the electrical charging system load tested.
~Have the fuel system pressure checked.

thelastaspec

Thank you!

I hope this does not become one of those wild goose chases.


I don't care about the vibrations, I more so care about the vaccuum leak.
Should I zip tie before the solenoid? disconnect it? plug the line going to it? will the car notice if I disconnect it/if its disconnected will it stay shut? - one less thing to make a clicking nose...


I guess I'll start with the low cost things (which are good basic maintenance items) and work up...

tlmane03

I know of a tl that at idle the rmps would rev up to around 3000 then drop and repeat. Egr was then cleaned and it eventually stopped. If that helps you at all. GL.

thelastaspec

Thats a great idea just as a general maintenance item.
I'll do that next free weekend I have and clean the throttle parts.

I also read that this person has the identical problem with the EGR being the solution: http://www.mdxers.org/forums/14-prob...s-low-rpm.html



Also, I possibly found the problem:
I disconnected the solenoid power clip (2 pins) on # 11 and the problem went away when I was driving today...


Time will tell if it actually has gone away or if there is more to this than a vacuum leak.

Thanks everyone!

3.2TLc

Then if that's the case....ya may seriously want to consider replacing your motor mounts !!!

tlmane03

Its seems especially with what your saying that cleaning the egr intake would repay you well bc of the suspicious reving, plus the fact that these cars egr gets dirty, messes with emissions and poor gas mileage. There is a diy sticky on this site for the diy.