lexus082

You have to remove the back seat to gain access to the fuel pump "service panel".

The amp is located in the trunk, right hand side.

Figured out it comes of igniter #1. So I got the tach speed off of that (basically inspecting the condition of the wires). After I found that tach signal to be correct and the one at the diagnostic port next to the engine, I swapped out guage clusters and found that the tachometer was displaying the wrong rpm's. At 700 rpms the tach was showing 250-500 rpms. Now I just have a misfire to resolve. :cries: Damn Misfire :chairshot:

I am trying to find out where the tach signal is created/generated? Does it come from the ignition coils?

Does anyone know where the tach. signal comes from. Does it come from the ignition coils?

I have a 94 sc400. It has the same engine as the LS. Here's my problem: I have a misfire that occurs I think just at idle. So basically to sum it up, I have replaced the plugs, caps, rotors, and the wires are only two years old. I pulled each wire (One by One) to make sure I didn't have a dead cylinder. So heres the symptoms: --The idle speed is within spec. approx. 700 rpms in park and 583 in gear. --Tachometer is not getting the proper tach. signal. --Have a random misfire. --Car shakes slightly after it warms up when the idle comes down to 700 rpms. --Engine mounts have never been replaced. Any thoughts after reading those symptoms? I have read that a misfire can be caused by a vacuum leak, leaky egr valve, weak fuel pump or fuel pressure regulator, dirty injectors, water in the gas...

Sounds like the sensor is bad.

I also have an improper tach signal. What does your tachometer read at idle and at cold start. My tach reads 750 at cold start idle and then drops to like 200-400 when its really around 700 rpms. Like the question was already asked does the tach signal come from the camshaft sensors? I looked in my parts book and there's nothing listed as a camshaft sensor. There's only crank position sensors listed.

It should put out a code 41 if the tps sensor is going bad. No precautions, but you should re-calibrate the tps sensor. Go to: www.lexls.com you'll find how to re-tune it there under the engine tutorial section I believe. Even if you don't have a code it may be starting to fail. Especially if its the original sensor from a 92 model.

You should stick to the Toyota Type IV. I would go ahead and do another drain and refill. And if your tranny fluid isn't red/pink and dark then I would continue to do drain and refills every oil change until it cleans up. Some members have had bad luck with tranny flushes.

Not sure where that came from. But that squeak may very well be from the drive belt tensioner. I had to replace mine when it started squeaking. I would go to www.partsamerica.com Here you go: http://www.partsamerica.com/ProductDetail....819&PTSet=A One of the few non oem parts I have used. Haven't had any problems with it since and that was about two years ago. Pretty good deal for that price.

Could be the tps sensor. I have a new Lexus tps sensor, part number (89452-22090) that I could let you have cheaper than what the dealer wants. You can e-mail me if you find you need a new one: OBRIE00@comcast.net Does your check engine light, or TRAC OFF, or TRAC light come on at all? Just asking in general.

lextech.org

Tonight I ohmed all the plug wires and they were all within spec. So I'll be pulling each plug wire one by one to make sure they're all working properly.

I had a toyota dealer check for a vacuum leak. They didn't find any. Checking the resistance on the two year old oem lexus plug wires. Maybe I'll get lucky.. I doubt it.

I plan to check the resistance of all the plug wires and or check for spark also. Alot of people are suggesting it may be a faulty coil, but would a bad coil leave me running on just 4 cylinders? I haven't really noticed any change in horsepower. Someone else suggested it could be a faulty injector and of course the great idle air control valve. I plan to buy a used working iacv and swap that out as well. Thanks alot for the quick replies. If anyone can think of anything else please reply to this post. I have been trying to fix this for a really long time. I haven't noticed the cats getting hot. I'll check them again at night to see if they glow. Its been so long since the car was running properly that I am able to tell any change in exhaust odor. Thanks again for the help!

Is it a constant squeak? My wheels bearings are shot in the rear but they make a low pitch sound. Its like waa-waa-waa-waa on the highway. A good indicator is if your on the highway move the wheel back and forth slightly and if you hear the noise make a change of pitch its most likely the wheel bearing(s).

I have searched alot looking to resolve this problem. I have a 94 Lexus SC400 (CA emissions) 200,000 miles. I have a low idle to the point where the car shakes. It looks like it idles at around 200 rpms in drive and 400 in park. And no check engine light. So far in attempt to fix this problem I have changed air filter, pcv valve, spark plugs, distributor cap and rotors, fuel filter, mass air flow sensor, swapped out throttle bodies, tps sensor, checked for vacuum leaks, cleaned iacv I believe thats it. When I first start the engine (cold): the cold start idle is around 750 rpms then it will gradually decrease down to 400 rpms in park. Sometimes after driving for thirty minutes and then putting it in park the idle won't even get back up to 400rpms. The car shakes due to the low idle. I also have a misfire. I have just recently tried to fix the misfire by replacing the plugs, caps and rotors. The oem plug wires are only two years old. I am lost with the low idle. I don't know what is causing it. The only thing I have left to try myself that I know of is to replace the idle air control valve (iacv). And with the misfire the only thing I know of to check would be to check each plug wire to make sure it ohms within specs. Other than the low idle and the misfire, the car seems to drive fine. So here are my questions: A. What else could cause an engine to misfire B. What else could cause this low idle to occur all the time? C. Could the low idle and the misfire be related? D. If my spark plug seals are starting to leak would that cause it to misfire? Sorry for the long post, I was trying to describe it the best I could.

I have searched alot looking to resolve this problem. I have a 94 Lexus SC400 (CA emissions) 200,000 miles. Same engine as LS400's. I have a low idle to the point where the car shakes. It looks like it idles at around 200 rpms in drive and 400 in park. And no check engine light. So far in attempt to fix this problem I have changed air filter, pcv valve, spark plugs, distributor cap and rotors, fuel filter, mass air flow sensor, swapped out throttle bodies, tps sensor, checked for vacuum leaks, cleaned iacv I believe thats it. When I first start the engine (cold): the cold start idle is around 750 rpms then it will gradually decrease down to 400 rpms in park. Sometimes after driving for thirty minutes and then putting it in park the idle won't even get back up to 400rpms. The car shakes due to the low idle. I also have a misfire. I have just recently tried to fix the misfire by replacing the plugs, caps and rotors. The oem plug wires are only two years old. I am lost with the low idle. I don't know what is causing it. The only thing I have left to try myself that I know of is to replace the idle air control valve (iacv). And with the misfire the only thing I know of to check would be to check each plug wire to make sure it ohms within specs. Other than the low idle and the misfire, the car seems to drive fine. So here are my questions: A. What else could cause an engine to misfire B. What else could cause this low idle to occur all the time? C. Could the low idle and the misfire be related? D. If my spark plug seals are starting to leak would that cause it to misfire? Sorry for the long post, I was trying to describe it the best I could. I just recently learned of the misfire. Not sure how long its been missing.

Its a little more complicated than that. You have to remove the intake manifold to gain access to the starter.

If you bushings are shot the ride quality is going to suffer dramatically. You'll have more noise coming from the front suspension while driving. Its certaintly something you should change/replace. I personally went with the supra control arms. They are cheaper than the lexus arms. If the ball joints are shot then there is no point in replacing the bushings. I would just buy new supra control arms and be done with it. Haven't heard of lower control arms bending due to worn bushings.

If you do a search you should find what you need. Its a detailed post with instructions and pictures.

Try searching. Its not fun.

I myself have a very low idle and have yet to figure it out what is causing it. So low the car begins to shudder/shake at stop lights. If I replace all the vacuum hoses is there still a chance I have a leak somewhere besides the hoses? Is there any way to test to see if I might have a vacuum leak. When I first start the car (cold) it idles were it should when warm/hot in park at around 700 rpms. It then drops even lower as it warms up. I hope its just a vacuum leak.

If you lift your foot off the brake and gas how fast do you coast in gear on a straight road? Make sure your throttle cable isn't adjusted too tight.