91 LS400 Fuel/Air Issues

sisterpete · Lexus Owner Joined: Jun 05, 2007 Posts: 2

hi,

i'm new here. my 1991 ls400 will run just fine, and then other times, it will barely run at all. when it is acting up, this is the symptoms. it will be idling fine, then it will act as if it is going to die, then race up to about 2000 rpm's and then do it all over again.... over and over, sometimes actually dying.

acts like it's not getting enough fuel, or maybe too much and choking out????? we changed the fuel filter, and also checked the fuel pressure according to info we found in a lexus book at the library. the fuel pressure was up around 50-60 and following the directions, found out the fuel pressure regulator was bad. change that out and the fuel pressure is now down about 30-35, can't remember for sure, but where it's suppose to be.

still the problem persists! after jumping pins Te1 and E1, watching the check engine light, we are getting two engine codes.

24 - intake air temp sensor signal

31 - air flow meter signal

we also checked the impedence of the air flow meter. it was 1495k ohms at an outside tempature of 78F. we checked it a few times, and at one point it was at 2200k ohms.....

any ideas would be great. is the air flow meter bad? and where is the intake air temp sensor, and is it bad?

one other thing as a side note... when we also noticed the o/d off light flashing with this code...

63 - open or short circuit in no. 2 solenoid valve.

any idea what this is about?

thanks for your time.... i am not much of a mechanic, but have a buddy that is so i figure if we know what to fix, we can do it. just don't have a bunch of money to spend taking this to a shop right now.

one other thing, my buddy notices a lot of what looks like steam coming from the exhaust... like i said, it was 78F out, but it was exceptionally moist tonight, sooooooo.......... and it's about 4am....

the car smells like is is running very rich.

once again, thanks for any help you may give

deller · Lexus Owner Joined: Aug 01, 2008 Posts: 1

we just bought this car last night... i am having the same problem today.. wasnt acting up yesterday. and no faults stored... did you fix yours? if so what was it i had my friend who is a porsche mecanic look at it and he was stumped along with 3 other porsche techs. i dont have the money to take it to the dealer to look at the actual values of sensors...like they suggested... PLEASE HELP!!!!

sisterpete · Lexus Owner Joined: Jun 05, 2007 Posts: 2

had to change the mass air flow valve... the intake air temp sensor is inside of it also. the best price i found was at autozone.... been running great ever since.

also, on the tranny sensor... it check out good according to how lexus said to test it.... but it wasnt. i took it to a tranny shop... the guy told me it was that sensor even though it checked ok for him also. he said he has ran across several of these that check good but theyre bad... so i change it BAM!!!! fixed the problem. actually it came in a kit with the 1 and 2 both... found it at a local distributor for the tranny shops but they sold it to me anyway....

good luck on your lexus.... you will absolutely love your car. it IS worth putting some money in to.

imagus31

My car is doing the same thing. Will be driving along and rpms drop to almost nothing then kicks in suddenly. In park it alsmost chokes itself out then revs up like a mad man. Replace Mass Airflow with no resolution to the problem. Replaced Throttle positioning sensors (2) and it seems to be ok now but have only had it out for short drives. NOW the check engine light, trac light and trac off lights are all on? Any ideas? I love the car and dont want to part with it.