1993Ls400s

OK, if any of you have read any of my other posts about the problems i have been having, you will know what i am talking about... I am going to try to explain this the best i can... The car has a bad vibration/shaking at idle that started getting worse about a week ago. I still have the EGR valve's power connector disconnected because of severe bucking around 45 to 55.. Car has been doing fairly well since i unplugged it.. Now here comes the weird part yet again related to me unplugging the maf sensor.. I can unplug the maf sensor the vibration and shake disappear, the car runs really well.. I have talked to so many people on here about unplugging the maf , they tell me that when the maf sensor is unplugged it throws the computer into default mode ignoring some sensors.. This has started to make me think. When i unplug the maf the car runs good, and the EGR valve can be plugged in and there is no bucking, That there must be a sensor on the car that is reading wrong and not telling the egr valve to open and close when its needed and is giving the car like a lean mixture.. Sensors that come to mind are, Oxygen sensors, Coolant temp sensor for computer, and last but not least, The egr temp sensor.. What do you guys think? I have already replaced literally over half the car, i haven't changed those things up there that were mentioned. SO, will anyone of those cause this idle problem/egr problem? Any help would be greatly appreciated..

Car is a 1993 Lexus Ls400 with 116,xxx miles..

atoyot

have you replaced the coolant temp sensor?

Rocan

do any codes show up?

if a sensor is bad, a code will show up

1993Ls400s

NO codes, and i haven't changed the coolant temp sensor yet, do you all think it would make any diff to change it since it is fairly old?? Thanks...

python

iTrader: (4)

no codes with the maf unplugged? ecm maybe bad, u must be getting horrible gas milage

Och

iTrader: (3)

Did you clean the throttle body and idle air control valve, and did u replace the power steering air valve?

atoyot

no codes is really strange. Usually when you are bucking it's because one of the cylinders is not firing. This can be from many issues, spark plug may have moisture on it (at the connection to the wire), plug wire may have a crack in it, distributor may be bad..... ect. But the fact you get no codes even with the MAF unplugged, something is not right.

Starting to lean towards a bad ECU.

Och

iTrader: (3)

Wait, do you not get a CEL when you unplug your MAF? I remember you said you didn't get a CEL when you unplugged your EGR valve.... If you're not getting a CEL when you unplug your MAF, then it's either your ECU is shot, or the bulb in your cluster behind the CEL is burned out.

I remember when my car was stolen, they stole my gauge cluster together with the harnesses by cutting the wires. When I purchased new cluster and harnesses, I had one hell of a time splicing at least a 100 tiny wires! To make it worse, once I finished, I had an oil light that was permanently on, and ECT PWR light would not light up. Turned out that I spliced two pairs of wires incorrectly, which caused the oil light to be on... And ECT PWR light didnt light up because the bulb was burned out.

1993Ls400s

NOOO guys, I have a check engine light on when the maf is unplugged. I have already replaced distributor cap/rotors, fuel pump, Both coil packs, wires, plugs,cam position sensors,Maf, Egr valve,Fuel filter. and maybe something else i missed but i have replaced allot. so i am thinking the o2 sensors are bad i have noticed now when i floor the car exhaust comes in the car and smells bad like stinky smell. cant the o2 sensors be out of range and cause this with no check engine light?

atoyot

yea, if you are getting a code, what is it?

If you get a bad smell then the cats could be gone, i would add that probably the o2 sensors are gone as well. Just a hunch.

Pull the code and let us know what it is.

1993Ls400s

WTF?? You dont have to get a attitude dude... I DONT have a check engine light until the MAF is UNplugged like i said in the post earlier....

McSwine

You mean that thing were you said people who disagree with you should be shot? I can't imagine those pesky admins calling you on it.

python

iTrader: (4)

taking a comment like that litterally is a little moronic, and i never said i would shoot them did i? and it wasnt for disagreeing with me either.....u said "NO codes, and i haven't changed the coolant temp sensor yet, do you all think it would make any diff to change it since it is fairly old?? Thanks..." that to me says no codes,does it not?also disconnecting the egr should have thrown a code also,i would clear all codes and restart the car, make sure everything is hooked up as it should be...if the car is "bucking" and u have no codes,it could be a bad coil, tuneup parts, but it could be fuel delivery.....i would take it to a shop and let them figure it out

LexFather

python, please exit the thread. If you already have a problem with this situation on one forum, why drag it to this one?