suprasoup

New Update: Sad to say but have to bring this thread back to life.
So things I have done: I replaced all capacitors with the appropriate one mentioned in a thread here on clublexus, replaced cap and rotor, put new throttle body gasket on and new iacv o-ring, new spark plugs, cleaned throttle body, cleaned iacv, fixed all vacuum leaks.
For the most part this fixed practically all my problems however I am still experiencing some sort of symptom.

So when the car is started on the new day completely cold engine it starts and idles fine and drives great, however once it gets warmed up if I sit at a light or a stop the idle will slowly drop to about 400rpm but it will not idle rough and I don't feel any misses and it will stay steady at the 400rpm the entire time. Once I hit the gas there is no hesitation. Only other thing I have noticed is later in the day if I start the car after I have drove it already for that day it starts fine but rpm will fall and then the system notices it and kicks it back up and it begins to idle fine. Something I'm thinking it may be is I did have a leaking water pump a little bit ago that was dripping on the alternator could that be part of the problem I'm experiencing. Any suggestions would help.

thanks in advance.


Need help.

The reason this all started is I noticed my car was having inconsistent idle sometimes at a light it would be around 1k and other times 600rpm also when backing out of my driveway when I would turn the wheel it would bog down a little then catch itself and send the rpm's back up.

So I did a tune up last weekend. I changed spark plugs, air filter, cleaned the throttle body, cleaned IACV, and MAF.
For the IACV and the MAF I just wiped them off with a microfiber cloth nothing more, they weren't dirty hardly at all.

Put everything back together and the car started fine then it started to idle low it would drop down to about 300 then bounce back up to about 600rpm and just bounce back n forth and the car would shake as if it is about to stall, sometimes it does stall. Now when I actually drive the car it seems to drive fine except there may be a slight misfire hard for me to tell. I thought it was strange that it got worse after I made these changes so I figured it has to do with something I touched or changed.

The problem seems to happen regardless of the gear I'm in
I have ruled out the MAF by testing with multi-meter and even put a different one on that I had laying around.
I have ruled out IACV by testing with multi-meter and trying a different one that I had laying around.
I did bypass the fuel pump ecu as I have read that can cause issues however still had same problem, so put it back to stock.
I have looked for vacuum leaks everywhere I found one hoping it would solve my problem, it helped but not solved.
I did delete my EGR a while ago so I do have less vacuum lines to worry about.
I did change PCV a little bit ago.
No engine codes unfortunately even though it will pop up for like a sec then disappear and it doesn't save it.

I did not change the gasket on the throttle body due to it being metal and did not look bad and I did not change the O-ring on the IACV.
Maybe its leaking at one of these points or maybe TPS.
Is it possible that after cleaning throttle body that it threw the TPS off or maybe that throttle plate is not closing enough?

any ideas would be helpful.

Thanks

Update: I did found a cracked vacuum that was creating a leak seems to have fixed my rough idle.
However I noticed either in park or driving the car if I let off the gas the rpms drop low and then bounce back up. Seems like there is a delay with the computer noticing the throttle has closed. Maybe TPS?
(Fixed had to adjust transmission cable) Also something just started noticing is it seems like the shift points of the transmission has changed (earlier).

Update: After driving the car for about a day it seemed ok rpm around the 700-800 mark at idle and now today I noticed when I'm sitting at a red light the rpm will slowly start dropping down to about 400-500rpm the car has not died yet however the rpm does not go back up until I give it gas. I'm really stumped. I may try bypassing the fuel pump ecu again and actually drive around. The last time I tried it was before I found the vacuum leak and did not drive around.

scsexy

iTrader: (1)

400 is alittle low. I'd start with replacing all your vacumm lines. If ones was cracked chances are they may be more. After that i'd think MAF or Capacitors in your ecu.

gerrb

iTrader: (34)

how old are your fuel filters ?

suprasoup

Thanks for the help, I did read about the Capacitors leaking but just thought nah ha-ha. So I did remove it and open it up and sure enough blown leaking caps everywhere and it smelled burnt. So it is defiantly ECU/Capacitor related. Funny thing is lately I have been smelling an electrical burn smell and this was exactly where it was coming from.

So if anyone ever has the symptoms mentioned above then check ECU seems to be pretty common.

suprasoup

I replaced the fuel filter underneath the car about a year ago.

babycrab

hey suprasoup, did you ever find out what was wrong with the low rpm when turning steering wheel? i'm having that problem