shoob

ok, where to start?

i picked up my first ls400 about a month ago, its a 93' loaded with every option available. about 173k miles. cars trac light was on when i bought the car, but the car ran and drove perfect with zero issues.

one day leaving my house i pull to a stop sign, and it starts missing, and skipping like its gonna cut out. it everytime itd miss, the CEL would illuminate. but, it straightened out after just a few seconds, and proceeded to drive normally.

fast forward a week..... it did it again, twice in the same trip, same scenario. cleared up, CEL went off, its been fine.

fast forward to this pass week. i left out of town on a business trip, and my wife was using the car to commute 7 miles to work and back. wednesday morning she goes out to start the car. it starts.....runs 5-6 seconds and dies. all while the CEL and "trac off" button illuminate, and stay on. she repeated the process 3-4 times with the same result. she calls me, i tell her to drive her car until i get back in town and can check it out.

a little background...... ive been dealing with toyotas for 15 years now, from carbbed to obd1 and all in between. forced induction, nominal aspiration, fuel injection, you name it. franken-swaps, tuning, building.......its all in the resume.

this thing has me stumped.

i get home go out, start the car and it hesitated for a few seconds, and self sustained its idle. mind you the trac off light and cel are still on at this point. i press the accelerator...holy *****, no responce, slow revving with slight popping out the exhaust. its richening up to the point you can smell the gas fumes permiate from around the vehicle. so i sit there puzzled and let it run for a few. it dropped idle from 1k to 800, and both lights went off. drove the car, it was fine.

we go out to dinner, get 27 miles from home and it starts again. mind you again, the car cruises 90mph at highway speeds with no ill manner. we eat get back in the car.......starts again.

at this point im irritated. so i grab a paper clip and do the neccesary procedures to pull obd1 codes.....nothing. rapid solid flash, no codes. wtf. it clears up, and we drive home. at this point, ive disconnected the trac unit plug, and turned trac off, ect sport mode......no issues.

we get home and decide to go out and hit the redbox. this time im driving, and the issue happens, starts missing hard, looses all power and i limp into the quick trip. as im turning into a parking spot, the car dies.

okay, so sitting in the parking lot. i check everything, maf hose, maf connection, coil connection, all throttle body components, tap on the IAC......nothing. start it up, same thing.

so i start it a few times......suddenly, it races to 2k, stays there and every now and then drops intermitantly to 1k, only to race back up. i shut it down, check coolant,and allow the car to cool, again checking codes, nothing.

after 30 minutes car starts up, no miss, no lights, and runs fine.

on the way home, starts again.

i get home, final attempt to pull codes, this time pulling abs trans and trac codes.......

nothing on the cel, still.

trac is throwing a 43

abs is throwing an 18

any light to shed here?

PureDrifter

iTrader: (10)

first place to look for any 1LS electrical issue: http://www.lexls.com/tutorials/lighting/bulbout.html


after that it' s time to troubleshoot major sensors/harnesses (CPS/TPS/AFM) and the ECU itself.

billydpowe

iTrader: (1)

yep, sure sounds like the trunk hinge wiring to me.

shoob

ok....after about an hour of troubleshooting, a few choice words and being violated in my ear by the parts store........i found a few things.

the passenger bank main coil wire, feeding the cap, was laying on the timing belt. no damage done, but it did skin back a little rubber.

i got the car to sustain idle long enough to start pullin plugs. my brother swung by to help diagnose..... we pull every plug reachable while the engines running, trying to narrow down the issue.

again at this time, still not throwing codes.

we pull the idle air control valve.......CEL goes out as well as the trac off light, then it starts rapidly idle surging. call the parts store for a price....this is when i got ear raped when i heard $595.99 for the idle air control valve....

plugged it back in, no issues. no trac light, no CEL. headed to the parts store to grab a can of intake cleaner.

report back later,

shoob

that wasnt it......ran fine in the driveway, the minute i started to drive, the problem came back.

its wierd. 1 minute it will idle fine and have a severe acceleration stumble. the next minute it will idle at 2k simultaneously dropping for milliseconds intermitantly, then shoot back to 2k.
now unplugging the IACV does nothing...

still will not flash a code to me with te1 and e1 jumpered. but will show me trac and abs codes when jumping their pins.......

WTF?

shoob

finally got the cel to throw codes at me.......i used this that i found, and it seemed to work, by using the 'troubleshooting method".

http://www.justanswer.com/lexus/2kmv...ing-began.html

24- AITS signal (air intake temp sensor)
31- AFM SIGNAL
71-EGR system malfunction

i unplug the MAF while the cars running, and it runs the same as before. shut the car off, plug it in, its fine. looks like im on the hunt for a MAF.

PureDrifter

iTrader: (10)

an AFM. you need an AFM.

and you should look at the trunk hinge since it's a common issue on the 1LS.

Cmann

I've had the same problems with my 93 ls400 and I've checked the wires in the trunk over and over again, got nothing. I've also replaced tps's (both),the maf sensor, iacv, rebuilt ecu,cleaned throttle body, even the efi fuse and Pcv valve. Oh and the ect now. What's next, the scrap yard? Cuz this is crazy!

SC400slide

iTrader: (11)

Try O2 Sensors after that.

shoob

yeah ive ran down the trunk harness already, found one green wire broken, mended it, but found nothing seem to "come back online". so im unsure as to which its importance was.

oh, and now my speedo quit working.......

and now im only getting:

CEL- 31
TRAC- 43
ABS- 18

im guessing the previous code 71 came from me having the egr valve unplugged simultaneously right before performing the troubleshooting diagnostics (TE2 and E1 jumpered while running, driving)

i cleaned the AFM sensor, and that seemed to get rid of code 24 (AIT sensor)

still cant find what trac code 43 is, or abs code 18. i know my pad wear indicator is showing, so im guessing abs 18 is related to that, because i cant find any other info.

shoob

my next insight is probably coils and 02 sensors......

shoob

wouldnt that throw a code? 21 and/or 27, 28, 29?

PureDrifter

iTrader: (10)

congrats you BROKE your AFM. it's a karmann vortex air flow meter which uses an optical sensor and is VERY sensitive to cleaning agents and contamination. the internal seals probably werent in perfect shape and some of the solvent got inside and screwed up the IAT sensor.

you need a new AFM, and for the love of all that is holy don't try to clean that one...

SC400slide

iTrader: (11)

AFM is also MAF, right? Couse if so, then you probably did break your MAF. Those are pretty pricey...

PureDrifter

iTrader: (10)

an AFM is analogous to a MAF, but very different in the way it works.