fsuguy

Daniel24,

I am also experiencing occasional missing - it is not my coils, since after replacing them both, the problem still persists. I find that while in park, if I rev the engine to about 1600 RPM and hold the pedal at that point, there is a miss about every 6-7 seconds for about 1 second; the RPMs drop and then climb back, drop and climb back - almost as if a switch is being thrown off and on. Also, after warm up, my idle is lower than specs -450 instead of 650. I still have to check the Vacuum Switching Valves to see if they are faulty. Would like to know what you find out from your efforts as well. Just hoping it is not the ECU!!

I have replaced the following, since this was part of my routine maintenance (all parts are genuine Lexus/Toyota parts):

1. TPS

2. FP resistor

3. Rotors, Caps, Wires, Coils

4. Spark plugs

5. Thermostat

6. Water pump

7. Timing belt

I still need to change the fuel filter and ECU Water temperature sensor. Also think that the FP may be on the decline.

Thanks In advance.

I am sending the diagnostic instructions for a 1992 LS400, since '90 thru '94 are all the 1st gens, I believe. Maybe this will help you resolve the problems you are experiencing. I think you probably should first check into #6 since you have already done some coil work - sounds like something may have been jarred loose.

The following steps are recommended if you have the diag code 14 (checking #1 igniter circuit; igniter #1 is wrapped with yellow tape in the 1992 LS400):

1. Check for spark; if OK, go to #2 (below); if not ok go to #4 (below).

2. Check harness and connector in IGF signal circuit between engine & ECT ECU and igniter; if OK, go to #3 (below); if not OK, replace/repair harness or connector;

3. Disconnect igniter connector and check voltage between terminals IGF1, 2 of engine and ECT ECU connector and body ground; if not OK check and replace ECT ECU; if OK replace igniter #1.

4. Check voltage between terminals IGT1, 2 of Engine & ECT ECU connector and body ground; if OK, go to #5 (below). if not OK, go to #9 (below).

5. Check voltage between terminal 3 of #1 igniter connectors and body ground; if OK go to #6 (below). If not OK, go to #8 (below).

6. Check harness and connector between ignition relay and ignition coil, ignition coil and igniter; if OK, go to #7 (below).

7. Check ignition coil; if OK replace igniter #1; if not OK replace coil.

8. Check ignition relay; if OK, check and repair harness or connector between battery and ignition relay, ignition relay and igniter; if not OK, replace ignition relay;

9. Disconnect igniter connector and check voltage between terminals IGT1, 2 of engine & ECT ECU connector and body ground; if OK replace igniter #1; if not OK go to #10 (below).

10. Check harness and connector in IGT signal circuit between engine & ECT ECU and igniter; if OK, check or replace the engine & ECT ECU; if not OK repair or replace the harness or connector.

HTH

Hi,

From my 1992 manual, engine diagnostic code 14 (15 is for igniter #2) indicates an ignition signal circuit - diagnosis: IGF1 signal from #1 igniter is not input to ECU for 8 consecutive ignition; Trouble area: 1)Open or short in the IGF1 and IGN1 circuit from the #1 igniter-ECU 2)#1 Igniter 3) ECU

The diagram shows a direct lead from the ignition switch to the igniter. Sorry I don't have the capability to post a picture, but there may be some pics available somewhere online.

From what I have found after spending time on the Australian LS forum circuit, they seem to think that around 15 years the capacitors begin breaking down, both in the display boards, as well as in the ECU boards. You probably should check your igniter circuits first - sometimes those connectors can be knocked loose, then the ECU. I believe they may be available on EBay.

HTH

...hehehehe; same thing happened to me! I had a fused lightbulb, switched it out and then (during the day) tested to see if the fix worked. Ran a multitude of tests and in frustration, left it till evening, when lo and behold, when I turned on the lights, a miracle - the durn thing worked!!!

:)

Hi Steve2006,

Thank you for the reply. Forgot to mention that the TPS is relatively new - replaced with OE from Sewell just about a year ago, so that is unlikely to be the cause; I will test it though to rule that out. One point, though, is that my TPS wire harness plug tabs that hold it onto the TPS snapped off and so I have rigged some electrical tape to hold it on. Would like to know if anyone else has this happen, and how they fixed the plug(?)

Thanks

Hi,

The vehicle is a 92LS400, and this appears to be a new hiccup - I would like to know if anyone has experienced this and what you think it may be.

I had been experiencing what I can only describe as a periodic disengagement of the engine while driving and then suddenly "catching" and continuing. It was not bucking or anything, but when I replaced my non-working Tach with a new one, I could tell that the RPMs had dropped by about 300 to 400 for a couple of seconds, then it would "catch" and carry on, then happen again. With Cruise control engaged, this does not happen as much. Anyway, my battery was dying so I started the car yesterday and let the engine warm up and idle for about 10 to 15 minutes. Then, on a hunch, I revved up the engine slowly and noticed that at around 1300 RPMS, it would sort of "miss" or something and the RPMs would drop, then come back up. I roughly timed the duration, and it seems like it would run for about 7 seconds before dropping, then catch and 7 seconds later drop again. After a few minutes of this, I found that the duration had dropped to about 4 seconds!

Has any one on this forum had this happen, and if so, what do you think the problem was and how did you fix it? I don't think its the torque converter, or the clutch, since I had the transmission completely rebuilt about a year ago, but I could be wrong. Also, about a year ago I had the timing belt, water pump, rotors and caps replaced, so those are new. Both coils and spark plugs, wires are new as well.

I have not cleaned the IACV or TB. Also have not changed the fuel filter, but am planning to do that as soon as the parts arrive. Can this be the last dying gasps of the Fuel Pump, and or the Fuel Pump relay? Or something else? I would hate to spend the $$ on a fuel pump ($$290+) if I don't really have to do that but will if it is indicated!

Thanks In advance

As mentioned earlier, with a single coil functioning well and no other electrical problems, four cylinders (in both banks), will fire and the engine will run, but sound really rough; also, more likely than not, your catalytic converter will glow cherry red from the unburned fuel igniting in there! If this is the case, Oxygen sensor CEL/MIL codes show up as well. In your case, you have #21 and #28 (main right & Left sensor issues). If both coils are on the way out, and it sounds very much like they are, then replacing them is called for. If you sign up with Sewell Lexus as a LOC member, you get slight discount on parts and a coil would run about $72+shipping. If you do identify that the coils are the culprits, the driver side one is a pain, but there are tutorials on here somewhere; the other one, just in front of the right bank of cylinders is a breeze and can be swapped out in about 30 minutes to 1 hour for a neophyte with the right tools.

On the other hand, and I am not too sure about this, so someone more proficient with the LS400 fuel system could chime in here (There are several very knowledgeable folk in here with years of experience!), since you mention a strong smell of fuel, something else could be the culprit - perhaps a faulty fuel pressure regulator, pulsation damper, or something in the fuel circuit. Sometimes even something as simple as a broken vacuum hose can affec the fuel system.

Was something done to the vehicle recently that may account for these symptoms?

By the way, for all the engineers in this forum, given the similarities of the problems we are running into, and the almost eerie predictability with which certain parts break/malfunction, what is the probability that these occurrences are purely random and not engineered?

Good luck and let us know how you resolve this :)

Hello! So I own a 1991 Lexus LS400 V8 and I just had the starter replaced. I drove it home and noticed some strange things happenning.

1. The oil light,battery light, brake light,temperature light, and trac light were all on.

2. The dash lights were on but when I press the brake they go completely off except for the P,R,D, etc...

3. The idle on the car is extremely low.....about 150 to 200 rpms.

4. Battery went dead after attempting to recrank.

Now I had the battery tested and it was good. Once I installed it all the lights in problem #1 went off except for the trac. Now I just have #2 and #3 to worry about. Now sure were to start because there is no CEL and no codes. Any suggestions?

Hi shatcher80,

Have you tried looking up the older threads for this issue? You may have what is a well known problem with the early models: the wire harness in the trunk leading to the tail lamps in the trunk lid was a tad short and over time, repeated opening and closing of the trunk lid would cause the wires to break inside their insulation, causing all sorts of odd/erratic behavior, including the #2 problem you have described.

Look up the threads, but in the meantime, here is something you could check out - open your trunk and look at the left hinge area. The wires are routed inside the hinge arm and are covered by a plastic cover; if your vehicle wiring in that area is pristine - does not look like it has been tampered with, then I would be inclined to believe that the problem in your vehicle has not been fixed, and you will have to remove the plastic cover to expose the wiring, then remove the insulating tape around the harness and methodically check each one of the wires to see if any are broken. This is not as simple as it may seem, since there is no easy way to tell if a wire is broken on the inside of the insulation. In the case of my vehicle ('92LS400), it was the Yellow wire and the White wire. I forget which colored wire was the ground, but in my case it was the ground wire. Others have also found that it was either the Yellow or White wires.

Good luck and keep us posted if you have more questions or answers!

Where can I purchase these two replacement lamps? I would prefer to buy them both from the same source (to save on shipping cost). Thanks in advance:

- Interior Dome Light: 3022 (31mm Festoon)

- Fog Lights: H3C

You may have a hard time finding the H3c fog lamp bulbs for a reasonable cost. I believe that there is a solution to using the the single lead bulbs (H3 instead of H3C) on LexLS website - lexls.com/tutorials/lighting/h3conversion.html. I followed the fix and am happy to say that for only about $5 or $6 bucks my fogs are now alive!

1990ls400,

Hey, thank you for your reply. I had seen these two on Toyodiy and thought perhaps there were specific models which each pump applied to, but it looks like I was wrong!

Thank you again.

Hi List,

I am getting ready to replace my Fuel Pump, and would like some input from experience in this forum - there are two types listed: Aisan and Nippondenso... which fuel pump would be the correct one for the '92LS400 without traction control and non-pneumatic shocks?

Any input would be more than I already have, and much appreciated.

TIA

fsuguy

hughes369,

What specification data are you looking for from a manual? I have a '92 and both the manuals, so some of what you may need should probably be common, and I can get you that if you want it. Just let me know.

Also, you have not mentioned (or I missed it) whether you did anything with the "messed with" TPS. I had been having some acceleration issues with my '92, including cruise control not working, and most of them went away once I replaced with a new one.

BTW, your notes on what you did to fix your car are very informative - thanks for posting.

Hi Steve2006,

Thank you for the reply. My shifter is pretty sloppy to the point where the indicator does not really point to the correct gear. I think this may be due to the bushings, or more likely due to the neutral start switch (not sure which one) since the problem began after I had my transmission redone.

Besides, it is a Lexus, and I feel the darn thing should be tight! I had redone the shifter (manual) on my VW GTi and it was worth it, although the VW seemed to be fairly straightforward. Not sure with the LS, though!

Thx

Good Morning List.

I have looked through many, many threads to see if anyone has attempted to tighten (or remove) the sloppiness from the gear selector in these first gen cars. My LS has about 200K miles and the shifter is sloppy, but I am not sure how one goes about replacing the bushings, or even if there is a way to do this. None of the other forums I checked have anything, so if there is any kind soul in here who has attempted this, can you post your experience?

I have gotten as far a removing the covering plate (wooden shiny bit), and the shift indicator plate, but that's as far as I can get without breaking something, I think! Do I need to get under the car and remove the neutral start shift switch also?

TIA

fsuguy

lex460,

it's been a while since you posted the information, so please accept my apologies. Thank you for posting this information. Will post what I find after my efforts.

Mike

I guess you missed this from the site :

"6 December, 2009

The diagrams are no longer available on this site."

I know of the site and have used it before. I did check it before I posted this request for information.

Register on http://www.toyodiy.com/ and you will be given access to the diagrams. You have to be logged on to see them. It sometimes takes a day or two for access to the diagrams to be granted.

Hey 1990LS400,

Was it you who was having a heck of a time with fixing your steering issue? How did that thing finally work out?

I guess you missed this from the site :

"6 December, 2009

The diagrams are no longer available on this site."

I know of the site and have used it before. I did check it before I posted this request for information.

Register on http://www.toyodiy.com/ and you will be given access to the diagrams. You have to be logged on to see them. It sometimes takes a day or two for access to the diagrams to be granted.

...also, there is no cost (thankfully!)to register.

Hi, I bought the OEM Bushings from Park Place.

part # 48674-40051 x 2 was 83.00 and I just press the old ones out and the new ones in.

Billy, you might have saved a little change if you'd bought those strut rod bushings at lexuspartsonline.com. By the way, parts.com is always cheapest for OEM parts, in my experience, but the part no. for those OEM bushings you bought doesn't register anything on parts.com. I hate it when that happens. Fsuguy was looking for the bushings for the UCA's. Don't know if there is an OEM part # for those.

NEITHER place has any references to a strut rod bushing,

like they never heard of one.... ??

Hi guys,

thank you for the information on parts and your experiences. FYI, the toyodiy.com website has somehow managed to get their parts diagrams and parts numbers back online. I had registered with them and got an e-mail from them letting me know about the availability. I checked it out and sure enough the diagrams were back!!!

fsuguy

914lps,

You can find detailed schematics/drawings and parts numbers at toyodiy.com. The site is back up and has a wealth of info for Lexus owners!

Good Luck

Fsuguy

(go 'Noles!)

dasha1,

I am considering revamping the UC arms in my '92 and, like you, face the prospect of expensive parts. Have you found out anything about just replacing the bushings alone? Or is your ball joint shot? I think LexLS or Lextreme have a tutorial on replacing the bushings, but I have not heard from anyone who has done this(?)

Fsuguy

KillerFatty and LA1,

Thank you for the info. KillerFatty, I will take the two you have off your hands for the $75.0 if you still want to part with them(?) Let me know how to get you the $$. You can send me an e-mail.

Thanks again.

Fsuguy

Andy,

Great post! Thank you for sharing your experience!

Fsuguy

Hi listers,

I think my front brake rotors are in need of replacement - let my brake pads wear out to where metal on metal occurred, and possibly the rotors warped. Now there is a heck of a lot of shuddering and thumping if I ease on the brakes, but not when I suddenly and forcibly step on them.

Question is does anyone in here have a preference for any alternative rotors beside Toyota ($135.00 each!). I have heard of Bembro, but don't have any experience with them and thought perhaps someone in here would have better knowledge and experience.

PS: I only use the ceramic brake pads (and plan on continuing to do so) so that I wouldn't have to go through this process, but...

Thanks in Advance

fsuguy

Mister Rupe,

I have a '92 with a similar problem, but more mild in that the car still runs reasonably, although it is obvious that performance is not at par. I have suspected the EGR temperature sensor, but have not as yet tested it - there is a test for it in the manual. I am not sure, however, since I also suspect the fuel pump, the fuel filter, or the fuel pressure regulator, since I find that sometimes the doggone car runs fine anyways, even if I have been driving for a while.

Unfortunately for me, there are no Lexus dealers within at least 200 miles of where I live, and the Toyota dealerships have bumbling !Removed! for mechanics - I say this based on direct experience with them !Removed! up things with my LS such as ripping out the wiring from Speed sensor #3 when I had asked them to replace #2 and even provided the OEM part!!!

Anyway, would surely like to know what you find out is the root of your problem.

fsuguy

Does anyone have a diagram of the parts and part numbers used in the rear suspension system for a 1994 Lexus LS400? I am having difficulty talking to mechanics and parts houses. Nomenclature is the problem. Some call them supports, struts, control arms, sway bars, etc. I need pictures to communicate my problem. No habla mechanix.

RexLexus,

Check out Toyodiy.com. They have an excellent reference resource with parts names, numbers, etc. If you register (no cost), you will be able to see the schematics; if you don't register, you will only see the part names and numbers.

HTH

Mike