Here goes my first post......

1992 SC400 1UZFE
186k Miles

I've owned the car for about 3 years and love it. I've had a lot of work done to it at the Dealership within the last year i.e. Timing Belt, Fuel Injection Cleaning, Fuel Filter Replaced, Water Pump replacement etc.

Recently it was idling rough so I decided on a Tune-Up:

Japan Caps & Rotors - http://rep.racepages.com/parts/racep...howdc=true#top

Denso Double Plantinum Plugs - http://www.sparkplugs.com/results_ap...1&AAIA=1187614

Denso Wireset: http://www.sparkplugs.com/results_app.asp

Prior to the Tune-up I did a an Engine Cleaning using the procedures I found on PlanetSoarer - http://www.planetsoarer.com/engine/clean.htm

After a few of the normal headaches and a whole lot of wrenching I got the job finished. Upon the first start I had two plug leads reversed (5,3) but once I corrected the issue it purred like a kitty cat!

Now the problems: Took it around the block for a quick test drive and noticed the CheckEngine/TRACOFF lights were both on. Second test drive revealed a misfire during acceleration only after the car is completley warmed up. As long as I'm running flat or idling the car is perfect and smooth but as soon as I put my foot in the gas it starts jerking/misfiring.

A had a couple of hoses mis-routed and after correcting them the Trac/Check lights went off and it ran great for one day. But today the light came back on and the misfire came back. Double checked to make sure my hoses had not come loose and everthing is fine. The car now idles so smooth I can't even feel it running at stop light and the throttle response it great. The Trac/Check lights will go out and come on and the problem is random not consistent. I would think maybe water in the Cylinders or on the plugs from the cleaning but wouldn't it misfire during idle too if this was the problem?? Maybe I can get some pics uploaded of my hose connections and someone could steer me in the right direction....

What you do think?? Please NOT the dealership!

 

I would wonder if maybe you got any water into some of your electrical connections.

 

I'm not sure it's really weird. I guess I should probably grab the code first then go from there.

Like your SC......

 

Any O'Reillys/Advance should be able to run your codes for free.

(and thanks!)

 

Hey man, I'm going through the very same thing. A friend of mine replaced my spark plugs, wires, and distributors last week. Well, actually he only changed 1 of the distributors which led to crazy misfiring and a very unhappy car... then changed the other one when it arrived. The car ran great for maybe 20 miles, then started misfiring, running rough (even at idle, though). I finally just took it to a mechanic I trust, but was hoping to avoid simply because of the amazing amount of money it takes to have anything done on these cars. I will let you know what he tells me as soon as I hear from him...

Never know, maybe it could help.

 

Thanks Apod....

I'm thinking Gunnar may be correct about the water in the electrical connections and I'm not sure I can really classify this as a "misfire". After driving it some more yesterday it feels more like it's choking for air or something is shorting out and not really a traditional misfire.

Anyway here's an update.....

I fired it up this morning and let it warm up for about 10 minutes; NO Trac/Check light, smooth as silk. I dropped the kiddies off at DayCare and came to work which is about a 10 mile trip and the light never came on and no problems whatsoever. In fact it ran so smooth I couldn't feel it idling at a stop light. I jumped on the pedal hard a couple of times to see it would recreate the issue (plus that goofy dude in his V6 Accord next to me who thought he was fast...haha) but nothing. I'm getting ready to head off for a meeting so I'll see if it keeps running good. I suspect whatever was wet may have just finally dried off; it was really hot here in Bakersfield yesterday.

 

Update:

Drove the car to a meeting + errands during lunch. No light, no problems....assuming it must have been water in the electrical connections from the Engine Cleaning.

 

hope that was it, and glad to hear the car's running right for you again.

 

spoke too soon...

The problem came back on the way home from work yesterday. I have Code 13, 24 & 71 so I'm trying to search for the info.

 

http://www.troublecodes.net/Lexus/


13 - RPM Signal
24 - IAT Sensor Signal (Well that blows my post in the other thread! )
71 - EGR System Malfunction

 

Not sure how some codes translate to what needs to be replaced. I'm starting with Code 24 searching on IAT as part of MAF.

 

ok, so this will probably help you none, but mine was messed up due to my friend accidentally cutting into one of the wires while he was installing the cover. that's the last I heard... they still have my car so if something else pops up that sounds like it may help i'll let you know.

i know nothing about codes but maybe it wouldn't hurt to go over the wires to see if there's a slight nick... ??? good luck!!

 

Update on this? I am having the same problem....

 

Checked out all my lines after reading what you suggested.... Realized that all of them were safely attached, but my buddy caught that one of them were torn. Trimmed the ripped section and reattached. No misfire anymore.