CRuby

iTrader: (1)

Hey CL gang. Haven't been on here much since I had gotten my son's SC400 working back in Sept. '10. Been keeping busy getting my '89 Ranger in shape to hand down to son #2. Now the Lexus is acting up again. Similar to last time...very hard starting... rough idle & poor throttle response. Guessed ECU since it fixed problem before. This time I sent ECU out for repair, reinstalled but no change. Hmmm...so is it something else or is ECU not fixed? It only throws code 71 for EGR, but it did that for a long time and ran just fine. Starting at the beginning again, checking fuel, checking spark, etc. Stay tuned.

Ali SC3

iTrader: (10)

could be ignition related but you said you changed all the components last year. Give it a one over just cause of the symptoms.
how many miles since you changed the 02 sensor? could be time for new ones, especially since your engine was running so bad before it could have given out from too rich mixtures or too lean mixtures. you can reset the ecu one more time and this time unplug the O2's before you do it (just the connectors). if you see an improvement its either the sensors or a closed loop issue.

CRuby

iTrader: (1)

Hey Ali, Well yesterday I checked fuel sytems & I think that's OK. Went to check spark on LH coil but battery near dead, so I recharged the battery overnight. Today I pulled coil wire from LH distributor & held near grounded bolt to test for spark. Had wife crank engine AND IT STARTED! Even with me holding the coil wire, so no spark getting to 1/2 the engine. That surprised me! But I couldn't see that there was any spark coming from the coil wire when held near ground. I plugged it back into distributor while engine was running, but didn't notice any difference in how engine ran.
I recall coming across some CL posts mentioning that this engine would run on 4 cyl, but now I'm a believer...although I prefer all 8.
Anyway, so far I've only checked resistance on the coil. Primary = .8 ohm (.4-.5 spec) & Secondary = 5.3K ohm (10-14K spec). Both are out of spec limits, but is it enough to cause no spark?? I'll check the RH side to see how much different it is before I replace coils. Last year I replaced distributor, rotors, caps, & plugs. Not coils. So at least for now I have some clue to follow to get to the source. Hope it doesn't lead me to the ECU. Although I now have 3, but I am not yet 100% confident they are working.
Tommorow I'll dig a little deeper.

CRuby

iTrader: (1)

Oh, I forgot to mention the O2. Never changed O2 sensors...but I did hollow out the CATs. They were half gone when we got the car. FL doesn't have emmision testing, so I'm cutting corners where I can. Never had any O2 codes on check engine, just EGR.

Ali SC3

iTrader: (10)

well thats good you narrowed it down, coilpacks on these cars is a very common repair. alot of people experience one going bad sooner or later, but yes the 1UZ is a great engine it can get you home on 4 cylinders if it has to. if its running right when its on all 8 cylinders again I wouldn't bother with the O2 sensors unless you still get bad gas mileage. you can also put in a resistor in to prevent the egr code.

CRuby

iTrader: (1)

Update: No spark on LH coil wire @ distributor. Coil wire resistance checked OK @ < 25K. Switched igniter L-R to R-L just because they are easily accessable & to rule out igniters. Still no spark on LH side, so igniters not the problem. Rechecked LH coil Primary & Secondary resistance & it measured .8 / 12.6K ohms. Hmmm... the other day the Sec. was 5.3K, one day it's out of spec & the next day it's in spec. ???? So I then checked RH coil and it measures about the same .8 / 12.4K ohms. RH is getting good spark, LH nil. So I swapped coils L-R to R-L & now L has good spark & R dead.
Therefore...LH coil (after switching back) is bad!!! I check it again after the switcheroo & it again reads .8/5.6K which is out-of-spec.

Getting new coil tonight & I expect that will fix my problem. But my advise to anyone going thru similar issue is to not necessarily conclude the coil is OK based on Pri/Sec. resistance check. Mine measured bad/good/bad. When it measured good it got me questioning whether the problem was not the coil, but elsewhere. Probably should have stopped after the 1st bad reading but sometmes I tend to want to be sure I'm not fixing the wrong part.

FYI, after looking at both coils it appears the bad LH coil may be original (toyota sticker intact) while the good RH coil may be after market, so the RH coil was possibly replaced before my time, & newer than LH. I'm not replacing both, since RH OK. (Knock on wood).

Ali SC3

iTrader: (10)

glad you found it, those coils seem to eventually go out, more common on the 400 for some reason than the 300. the last person should have just changed both, but since you have one semi new one just go ahead and replace the bad one.

CRuby

iTrader: (1)

Brief Update: New coil fixed the problem. Car running good for now. Ali, thanks for the insightful feedback. It sure helps having knowledgeable folks offer advise on what things to check. Although I'm a rocket engineer (really), it doesn't necessarily mean I can immediately figure out what's wrong with this car when it doesn't start. Experience matters! Anyway, if you haven't gathered from my posts, this is my son's car & I'm the mechanic...because I like to tinker. He seems to like to drive it rather than mess with the mechanics but I continue to try to get him to understand how to fix things for that time when I'm not around. Maybe I'll buy it from him when he's ready to flip it & soup it up some more. Beware, it's probably the booze talking. Hic!