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I Could Really Use Some Help!


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I have a 98 ES300 with 242K miles It has been an incredible car for our family.

It recently began surging at higway speeds, and severely at idle as well after warming up. It only does this after about 10 minutes of driving. It runs great when it is a cold engine.

My first action was to catch up on a little overdue maintenece... I had a little ove 100K on the plugs, so i replaced them, along with putting new wires on as they were original. This made no difference... but the plugs did have a little wear on them, so no harm done.

I then chose to do some reading here on the forum, and after a lot of searching and reading, i deciced that i should check the throttle body. It was definitely in need of a good cleaning. I went after it with using the seafoam "Deep Creep" spray. It did a very good job. I scrubbed inside as far as i could with a toothbrush, and it cleaned up nicely.

I started the engine, and it ran smoother than ever, and took her for a test drive. Aceleration was very good, in fact i cant remember the car running this well. However, at about 100 yards from our driveway i could feel it starting to surge again. It was then i knew that it was taking about 10 min. for the symptoms to show up. I repeated this 3 times and it repeats the problem.

I figured the next thing to check was probably the EGR valve. I pulled it out, cleaned it, checked it to hold vacuume, tested the ohms at 5.0, pulled the sensor out of the bottom of it and cleaned the carbon off of it. Re-installed, again it ran great cold... but after about a 10 minute drive... back to the surging...

Out of curiosity i started checking electrical connections and vacuum lines, and interestingly enough when i pull the vacuume line off of the EGR valve the motor instantly smoothed out. Put it back on and the surging came back again. Pulled it off, and pefectly smoothe. So, i took it for a test drive this way, and without the vacuum line hooked up it never did the surging thing.

Any advice on what the heck is going on would be greatly appreciated!

Thanks,

Ron

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It sounds like you are on the right track with the egr valve, the tests that you have done for the valve sound valid. Your next step would be to check the solinoid that controls vac to the egr valve. Trace the vac line back to the solinoid valve. To test this valve 1) measure the resistance of the two connections for the solinoid. It should read 22 to 34 ohms, or close to that. (remember, do not disconnect the electrical connector while the engine is on. HAVE THE KEY OFF!

Next, there are three hose connectors on the solinoid, two that are close together, and one at the far end of the solinoid. With no voltage applied you should be able to blow air from the center fitting, and it should exit out the fitting at the far end.

Next apply 12 volts to the solinoid, now when you blow air thru the center fitting, it should come out the fitting next to it. I would quess one of two things, either the valve is sticking/leaking. Or there is a problem with the ECM. The most likely issue is the solinoid. Remember to turn the power off before removing any electrical connector. Also driving with the EGR valve disconnected is a valid test, will tell you important information, make sure that you do not drive for any length of time with it disconnected. Long therm, it will cause engine damage

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It sounds like you are on the right track with the egr valve, the tests that you have done for the valve sound valid. Your next step would be to check the solinoid that controls vac to the egr valve. Trace the vac line back to the solinoid valve. To test this valve 1) measure the resistance of the two connections for the solinoid. It should read 22 to 34 ohms, or close to that. (remember, do not disconnect the electrical connector while the engine is on. HAVE THE KEY OFF!

Next, there are three hose connectors on the solinoid, two that are close together, and one at the far end of the solinoid. With no voltage applied you should be able to blow air from the center fitting, and it should exit out the fitting at the far end.

Next apply 12 volts to the solinoid, now when you blow air thru the center fitting, it should come out the fitting next to it. I would quess one of two things, either the valve is sticking/leaking. Or there is a problem with the ECM. The most likely issue is the solinoid. Remember to turn the power off before removing any electrical connector. Also driving with the EGR valve disconnected is a valid test, will tell you important information, make sure that you do not drive for any length of time with it disconnected. Long therm, it will cause engine damage

Hi George,

Thank you for your response. I had 29 ohms on the solenoid that controls the vacuum to the EGR valve. I unhooked the vacuum lines, and checked as you suggested, and found that the solinoid was very sluggish. it would shift, then stick in that position for a while and shift back... I tried to find the part a local parts stores with no luck. So.... I bent the tabs back, and took it apart. as soon as i released the last tab, i heard the valve click back from the tiny spring pressure. Took it the rest of the way apart, and cleaned it up, blowing any debris out with a little air pressure. After reassembly, i tested it as you outlined above, and found it to click back and forth with instant response... I just put it back on the car and am going on the "10" minute test drive... I will let you know how it works when i get back....

Thanks again!

Ron

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It sounds like you are on the right track with the egr valve, the tests that you have done for the valve sound valid. Your next step would be to check the solinoid that controls vac to the egr valve. Trace the vac line back to the solinoid valve. To test this valve 1) measure the resistance of the two connections for the solinoid. It should read 22 to 34 ohms, or close to that. (remember, do not disconnect the electrical connector while the engine is on. HAVE THE KEY OFF!

Next, there are three hose connectors on the solinoid, two that are close together, and one at the far end of the solinoid. With no voltage applied you should be able to blow air from the center fitting, and it should exit out the fitting at the far end.

Next apply 12 volts to the solinoid, now when you blow air thru the center fitting, it should come out the fitting next to it. I would quess one of two things, either the valve is sticking/leaking. Or there is a problem with the ECM. The most likely issue is the solinoid. Remember to turn the power off before removing any electrical connector. Also driving with the EGR valve disconnected is a valid test, will tell you important information, make sure that you do not drive for any length of time with it disconnected. Long therm, it will cause engine damage

Hi George,

Thank you for your response. I had 29 ohms on the solenoid that controls the vacuum to the EGR valve. I unhooked the vacuum lines, and checked as you suggested, and found that the solinoid was very sluggish. it would shift, then stick in that position for a while and shift back... I tried to find the part a local parts stores with no luck. So.... I bent the tabs back, and took it apart. as soon as i released the last tab, i heard the valve click back from the tiny spring pressure. Took it the rest of the way apart, and cleaned it up, blowing any debris out with a little air pressure. After reassembly, i tested it as you outlined above, and found it to click back and forth with instant response... I just put it back on the car and am going on the "10" minute test drive... I will let you know how it works when i get back....

Thanks again!

Ron

That was it!.... The car runs as smooth as silk!.... took 3 test drives with no symptoms whatsoever. Runs better than i can remember!

This has without a doubt been the best car we have ever owned. I have yet to have to put any money into it other than 3 sets of brakes, 2 sets of tires, and just put the second set of spark plugs, and changed the plug wires this time. I replaced the original lexus battery last winter as well. Everything else is original...

The next project is to replace the radio LCD. I also have a few of the backlight bulbs that are out in the heater controls, so i will replace all of them while i have it apart working on the LCD.

I also have a 92 ES300, and i am certain that it will benefit from the IAC/Throttlebotty/EGR cleaning. It is our backup car, and has 239K on it... still a fine driving vehicle!

Thank you again for your help George! I sincerely appreciate it!

Ron

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I would suggest maybe checking some slightly later model cars to see if you can find a replacement. The important specs should be the coil resistance and the terminal configuration. From what I can tell of the circuit, and it's description in the factory manual, the ECM uses a pulse width modulation to control the egr. The ecm receives feedback as to the actual position. My experience with working with these types of solinoids has been that for the most part trying to repair one usually does not give a long term reliable solution.

I think you did a very good job isolating and verifying the problem, but I would recommend looking for a replacement as a long term solution.

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I would suggest maybe checking some slightly later model cars to see if you can find a replacement. The important specs should be the coil resistance and the terminal configuration. From what I can tell of the circuit, and it's description in the factory manual, the ECM uses a pulse width modulation to control the egr. The ecm receives feedback as to the actual position. My experience with working with these types of solinoids has been that for the most part trying to repair one usually does not give a long term reliable solution.

I think you did a very good job isolating and verifying the problem, but I would recommend looking for a replacement as a long term solution.

I completely agree with replacing the Vacuum control valve, and plan on doing so. Now that i know what the problem is, it can be swapped out with a new part in about 10 minutes total. I am over an hour drive away from any dealerships, so i will be ordering the part today. Its a shame that its not available at the auto parts stores...

Thanks again!

Ron

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I would suggest maybe checking some slightly later model cars to see if you can find a replacement. The important specs should be the coil resistance and the terminal configuration. From what I can tell of the circuit, and it's description in the factory manual, the ECM uses a pulse width modulation to control the egr. The ecm receives feedback as to the actual position. My experience with working with these types of solinoids has been that for the most part trying to repair one usually does not give a long term reliable solution.

I think you did a very good job isolating and verifying the problem, but I would recommend looking for a replacement as a long term solution.

I completely agree with replacing the Vacuum control valve, and plan on doing so. Now that i know what the problem is, it can be swapped out with a new part in about 10 minutes total. I am over an hour drive away from any dealerships, so i will be ordering the part today. Its a shame that its not available at the auto parts stores...

Thanks again!

Ron

Glad to have helped, you appear to have a good basic understanding of how it was working, I am glad that I could help fill in a couple details.

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I bought from Orailly for $35. they have life time warranty.

LCD is not really hard to replace. parts runs about $110.

Hi Camlex,

We just had an O'Reilly store open locally. I was on hold for about 10 minutes while he "looked in the book" since it didnt come up in the computer...

Do you have a part number?... or do you remember what you asked for when you purchased yours?... what year was yours for?

I am going to wait to order till i hear some feedback from you. I also called Autozone, and Advanced Auto. They also said it was a "dealer item"...

I look forward to hearing from you. Thanks for jumping in and letting me know this!

Ron

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97 and 98 use same EGR sensor part# EGR500(Orailly part#) for $35.99

please call your local rep. and ask for this part#

I am not needing the EGR Sensor... I need the EGR Vacuum Control valve. (it is a solonoid w/ 3 vacume ports on it)

I dont think this is the correct part... Do you have anything on the one i need?... I called again and they say "dealer only"...

Thanks,

Ron

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I have looked at a couple different auto parts stores, but have not located the part that you need. You might save a few dollars by going to toyota instead of lexus but otherwise I do not see any other viable options. I would suggest the dealer because when you consider the time that you spend researching alternatives you it would effectively cost you more. You have allready saved major dollars by diagnosing the problem yourself. So you can rest assured that you have saved enough.

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