daffy

Hi,

I use my 1991 Ls400 all year round and found that a good set of winter tires reduces that amount of trac lock usage. With all season tires, the traction control was working more than I wanted it to. Hugh difference with winter tires. First set were Blizzacks and now Nokian (studded from the factory). Both good tires. Studs gives me a little edge though... My two cents worth. Daffy

Hi everyone,

I have decided to keep using Amsoil in my tranny. I am at about 200,000 kms now and will change it out in the very near future. That's how much trust I have in Amsoil. I also use it in my engine with a bypass filter and good success. At 390,000 kms I have compression of 190psi on 6 cylinders, 200 on another and 210 on the last cylinder. Manual says anything over 178psi is good. The lowest allowed is 142psi. So I feel that Amsoil probably contribute to these good compression readings. And that was with two different "Mac" compression guages! Again, I will keep using Amsoil. Great forum! Thanks for all the input.

Daffy :D

I didn't know Toyota Type IV had synthetic additives either.    Good to know I guess......how low does it flow in the cold?    It's MUCH colder for a longer period in Alberta than say the Toronto area right daffy?    :)  What year is your LS?    I changed the tranny fluid in my Maxima to Mobil 1 synthetic & never had a problem sk......I wouldn't do it in the Lexus mind you.  ;)

 

←

Hi Lexusfreak,

It's a 1991 ls400 with 395000kms so far. I would only use Amsoil as they were one of the first to come out with synthetics. So far 200,000kms with Amsoil. Seems to work well. It gets to 40 degrees below here in Edmonton at times.

Daffy :)

Hi,

I flushed out my tranny about 3-4 years ago and installed Amsoil synthetic transmisson oil. Reason being that it flows better in the winter time (here in Canada), and doesn't break down as easily. Now I read that you should only use toyota transmisson oil. It seems to be working fine. I want only the best for this car. What should I do now? Thanks, Daffy

I've determined that my power steering lines are leaking.  I called a garage and they said with parts and labor around $400.  Is this pretty fair?

←

Hi calean007,

I don't know what year your Lexus is, but I bought one that was 8 years old with what looked like a leaking power steering hose. I replaced it myself. It wasn't that, it was the pump itself, leaking onto the hose. I would suspect it's your pump.

If you are handy with mechanical stuff, you can rebuild the pump yourself for around $100. Cdn. It just needs seals and bearings. I have already put over 170,000 kms on mine and it still works good and dry as a bone. I found this pump very easy to rebuild. Needs no special tools. The hardest thing was taking it out of the car and reinstalling it. If you take it to Lexus, they prefer to replace the pump. If you leave this problem for too long, then the power steering oil starts to drip into the alternator and can fry it. Alternators are expensive, so look at it fairly soon. I am not a mechanic by trade but have worked on my own cars in the past as a hobby. Hope this helps. Daffy

the exterior driver's door handle on my ls400 has issues. When I pull on it to open the door, it is loose and feels rough as it lifts. The top of the handle visibly scrapes the frame around it. The rest of the car's door handles open smoothly and are not loose at all. Can I just take apart the door and tighten up some screws, or would a fix be more complicated than that?

←

Hi ec437,

My back door handle broke. I was able to take it out and very carefully glue it back together with epoxy, because it is plastic. It's been good for a year so far. You can add extra glue on the backside where nobody can see it, for extra strength. It works just like new. I'd give it a try, you have nothing to lose.

Daffy

Everyone's here to help. I'm glad you tackled the job yourself and saved yourself hundreds of dollars. Nothings more satisfying then doing it yourself huh? I love that feeling.

←

Hi, 92Lex

I agree, so why does Lexus here have a scope? They should have picked up my problem really easy, fixed the car properly and kept a satisfied customer. Now it's likely I will never go back. I didn't feel to good to hear from them that it may need a valve job at about $5,000+ when it really would have taken less than $150 for parts to fix it. Well I sure learned a valuable lesson here. Thanks, Daffy :)

I agree.

Excessive carbon build up is usually because of an engine that has been running too rich for an extended period of time. Another cause would be worn piston rings or leaky valve seals.

←

Hi 92Lex,

I just finished putting my engine back together. I changed out the waterpump, timing belt and two idlers, fan support housing, spark plug wires, rotors and distributor caps. I also cleaned out the throttle body. To my surprise the engine fire right up and got no airbag light on the dashboard (because the battery was out for a few days). I took it down the road and the car worked perfectly!! I guess the scope doesn't always work. I and very happy now and will probably work more on my car myself rather than leave it to the "experts". I was so close to taking the heads out, I have to thank my one mechanic friend for convincing me to do my own compression test. I would like to thank this forum for giving me some insight to my problem. I will be back next problem I get. Thank-you

Daffy :D

Agree 

that's 240,000 miles  -  fuel filter is usually changed every 60k /5 yrs...

Did you mean the filter in the first place?

←

Hi,

I meant the fuel pump itself, I think I would be better off replacing it in the convenience of my garage rather than getting stuck on the road somewhere. I am curious though, how long they last? But it looks like nobody really knows.

daffy

Hi,

Just curious, I have 390,000 kms on my 1991 LS400 and pretty sure the fuel pump has never been changed. Should I change it now to be safe or do these pumps last a lot longer? Thanks,daffy

Hi,

I just picked up some Nokian Hakkapeliita 2's and had a chance to try them. I think they are awesome on my 1991 LS400 and that is without weight in the trunk.

The studs are from the factory and so should stay in better. And noise, my friend stated and I would agree that they were more quiet than the Blizzaks I had before these. I was happy with the Blizzaks as well. Good snow tires will beat all season tires in the winter anytime.

daffy

this is baffling, im thinking the carbon is your issue though, especially if you run ~89 octane or less on a regular basis.

←

Hi,ArmyofOne

I bought the car at 186,000 kms and since that time I used Esso at 92 octane, but this year they dropped it to 91 octane. Which I still use. So this car has been getting the proper fuel for a long time now. It's never seen less since I owned it.

Daffy

The compression is fine - that has been established.  Don't forget that for 99% of driving, the throttle is nearly closed, and the engine does not see maximum compression because you are limiting the amount of air to control power.  Cranking compression is high as a function of the test itself, but operating compression is not while the throttle is less than wide open. So carbon or compression is not responsible for whatever may be wrong.

←

Hi SRK,

Well, I am relieved that the heads don't have to come off. And it is nice to know that at 390,000 kms, the compression is pretty good. I just finished taking the throttle valve body off and cleaned it out. Boy was it ever dirty! I don't think that's the problem, but might idle better now. So what's left? I am going to replace distributor and rotor because they are probably original. Thanks for your input, it confirms that this engine is in pretty good shape. I am not giving up on it just yet. I'll bet it is something simple that is wrong with it. I am back to work tomorrow so I probably won't get it back together until this weekend. I sure miss it already.

alwyas start with the cheapest first, plugs/wires (just cause they look ok, doesnt mean they are!) ;)

im sorry if i sound too pushy, i just hate to see people waste a TON of money.

←

Hi, ArmyofOne

I have new plugs and wires already installed. I am going to change distributor cap and rotor next. Thanks, Daffy

Never assume when it comes to reparing these vechicles because it can get costly very quick. Honestly, I don't think the compression in that cylinder is high at all.

To help remove some of the carbon build up from your combustion chamber go buy a can of SeaFoam.

←

Hi 92Lex,

I just had another mechanic drop by and inspect what I had done. Looking at the spark plugs and compression, he sees nothing wrong with the engine mechanically. He isn't concerned at all about the cylinder that reads high. He thinks it may be a bad sensor, computer is a possibility. He also pointed out that the water pump needs to be replaced, it's leaking (just what I need more work).

Of course the water pump has nothing to do with the problem, but has to be done anyway.

So he is willing to look at it, but needs to have it running before he can say for sure what it might need. I have to put it back together after I clean the throttle body valve, replace waterpump and might as well replace timing belt even though it has only 60,000 kms on it. I am so close at this point.

It's nice to know that the engine is good! :D

I will let you know what we find... ;)

Daffy

You may want to spray some Throttle body/Intake Manifold Cleaner into that cylinder, this is not generaly a safe practice on a clean engine, because it is unfiltered, however in this case, it sounds liek the piston is already dirty.

1. Pull the plug wire and plug off the cylinder that is high and look at the piston with a flashlight...see anything?

2. if so, Spray the cleaner SPARINGLY in the cylinder. (1/2 a second ofspray)

3. Replace Spark Plug and Wire.

before you restart the engine, do this.  disconnect the main wire from the distributor get in the car and crank for 5 seconds, 3 times.  replace main wire, and put gas pedal halfway to floor, start the engine.  IMMEDIATELY take your foot off the gas once it is going.  let idle for 3 seconds, then floor it for a second (bring it to 5,000 or so RPM's) then bring it back down slowly.

**THIS CAN BE PERFORMED WITH GASOLINE, WHICH IS GENERALLY SAFER, HOWEVER, IT IS HARDER TO REGULATE THE AMOUNT OF FLUID GOING INTO THE CYLINDER THIS WAY, TOO MUCH FLUID AND THAT CYLINDER WILL HYDRO LOCK**

so use the TB/IM cleaner.  it burns just the same, but it also cleans.

now do a compression test.

if all is OK, do an oil change (to get whats left ot the TB cleaner out of the oil) and enjoy.

i have done this many times on engines of all kinds, it works like achamp.

the other idea is to stick a toweldown inthe cylinder with a flathead screwdriver to rub offthe carbon, but that only flakes it off into your oil and leaves lint and stiff in the cylinder, this method will DISSOLVE the carbon, so you can burn it.

←

Hi ArmyofOne,

I would be concerned about getting a big chunk of carbon coming off and damaging the valves. I will try a slow way first over many miles. Thanks, Daffy

If you feel strong about your theory then pull out a spark plug...use a scope to look at the top of your piston(s). If you see excessive carbon build up then use a top engine decarbonizer.

I think that if there is excessive carbon build up in your combustion chamber that you'd hear a "pinging". I doubt that you have excessive carbon build up in one of cylinders...when you did your compression test you warmed it up to normal operating temperatures right?

←

Hi 92Lex,

I cannot ever hear pinging because I wear two hearing aids and even with hearing aids, hearing is still below normal. Also the Lexus is so quiet, I would probably not hear it anyway. I would have to assume that it is pinging when it jerks. What about the anti-knock sensors, would they not prevent this pinging? Why else would one cylinder be so high?

Yes, I took the car down the highway to get it to operating temperature before compression testing.

What would you recommend for a top engine decarbonizer? I would prefer some product that does it in a slow way to prevent any damage to the valves. Thanks, Daffy

If it had something to do with the ignition you would be able to see it on the scope. Does your rpm change when it jerks? If it had something to do with the clearance of the valves it would of showed up when you did the compression test.

Try what lexus400 said....clean your throttle body. Try that first and if the problem is still present then just repost.

Torque converter, intermittent maf sensor, low fuel pressure, malfuntioning fuel pump?

←

Hi 92Lex,

The more I get into this, the more I am thinking... that one cylinder with high compression (because of carbon build up) is probably what is doing it. Carbon glows when hot and when I let up on the gas a little, it must sort of diesel at this time only on that one cylinder. When I step on it, it seems ok, so the extra fuel must prevent this dieseling action on acceleration. If I let my foot right off the gas, there's not enough fuel for it to diesel. and so it doesn't jerk. Am I on to something here?

I have notice my temperature guage is reading lower than it used to and so could make the engine carbon up easier? I have told Lexus to check into this for me awhile back, but they though it wasn't necessary. I think I will install a new thermostat anyway. Opinions?

And the throttle body to my knowledge has never been cleaned in 390,000 kms. I notice a little rough idle, so I will clean up the throttle body by taking it right off and do a real good cleaning.

Any safe way to remove carbon from my cylinders?

I feel I might be onto something here! Thanks, Daffy :)

Have the plug wires, distributor caps and rotors ever been changed? With OEM replacements? If not, they are long overdue.  Also, have the valve clearances ever been checked and adjusted if necessary? If not, they are long overdue.

←

Hi Monarch,

The wires have been changed and I just finished checking the resistance and they appear ok. The distributor and rotors may not have been but wouldn't that show up on the scope? I don't think excessive clearance on the valves would cause a problem like that, again would that not show up on the scope?

Daffy

Does it jerk when your foot in on the pedal or off?

←

Hi 92Lex.

It jerks with my foot on the pedal(holding it still). It does it with cruise control on as well. Again this is most pronounced between 70-80 kms. Only when coasting.

Daffy

I'm not sure what the "cause" of the problem your having is but those compression readings are fine. I would not be pulling off the heads.. anything within 10% between cylinders is more than acceptable. I have had good luck spraying throttle body cleaner into the throttle body while someone else keeps the engine running. The Gen I's are carbon prone and this would certainly help. I assume that Lexus did all the obvious checks (plug, plug wire, etc.) on this cylinder right ?

Bob

←

Hi Bob,

Yes Lexus checked everything and come up empty. Their solution was to take the heads off. I don't think so...

Daffy

92lex,

I don't think it is fuel related for a couple of reasons. (1) the spark plugs are a chocolate brown, all 8 of them (2) I can cruise down the highway at 120 kms/hr all day and this car seems to run just fine. and good gas mileage. An easy 30mpg + (canadian gallon). So I conclude that the fuel system is working fine. But can anyone tell me how long the fuel pump last in a Lexus? Maybe I should be thinking of changing it before it gives me trouble?(390,000 kms.)

Back to my problem, it is most annoying when I let off the gas a little when at about 70-80 kms/hr and it starts to jerk. step on it, it seems to go away. Let right off the gas, no problem. When I cruise around town, I have to shut the overdrive off to get the rpm up to prevent this jerking motion. I thought maybe fuel mixture isn't quite right, but the plugs indicate that it is. Thanks

Daffy

Hi,

I am not taken these heads out with compression like I have. I believe this engine mechanically is perfect! I have been using Amsoil oil since 186,000 kilometers and it now has 390,000. I just recently had new plugs and spark plug wires replaced. So my problem must be electrical elsewhere, corrosion of some connector, bad sensor or something else. Lexus had it on their scope and found nothing wrong with anything. I guess the only thing left is to put it on a dyno and scope at the same time to see if anything shows up. What do you think?

Is it possible that the cylinder with the highest compression has too much carbon and when the engine warms up it begins to glow and starts to act like a diesel?

Is it safe to run some kind of cleaner through the throttle body? I would be concerned about a large piece of carbon flaking off inside the engine and damaging the valves. Thanks

Daffy

Hi,

What I did was picked up some used steel rims that fit my LS400(off some van-don't know which one) and installed Nokian Hakkapellita 2's which come studded from the factory. At first snow fall, I install these winter tires(4) and either keep the tank full of gas or add a little weight in the trunk. I just can't believe how well the LS400 with traction control works in snow and ice. Nokian also has Hakkapeliita 4's now which have a triangular stud and improves traction by another 8% over my Hakkapeliita 2's.

Winters don't scare me now. :D

Daffy

Hi,

Well the reason I was going to take the heads off was because at a Lexus dealer they had done a compression test with these results: 1-170, 2-200, 3-210, 4-210, 5-220, 6-210, 7-215, 8-200. They stated that #1 cylinder was too low and causing my jerking(like it's missing). It is most pronounced at about 70 to 80 kilometers when I am coasting. It also idles a little rougher than it did when I got the car. This jerking was barely noticeable when I got the car, and now is so annoying. The Lexus mechanics thought that the heads needed to come off for a regrind.

I then talked to a retired mechanic and he came over and said to me "do your own compression test". I thought he was nuts! Why would I repeat this procedure?

Anyway I looked in the manual under compression test and did exactly what they said. My results are, with two different compression testers (both Mac made) : 1-190, 2-190, 3-190, 4-190, 5-200, 6-190, 7-210, 8-190. My mechanic friend was tickled pink! He said this engine is perfect mechnically. If I were to add oil to the cylinders, this would only make the readings higher, so I could see no point in doing this. The high readings are probably due to carbon build-up. Further reading the manual, says that compression should be 178psi or higher with a min. 142 psi allowed. The range between cylinders- 14 lbs.

So the only concern I have is one cylinder reading high. But this shouldn't cause my engine to run like it does. Anybody know?

Daffy