Lexus Troubleshooting Questions? Ask a Lexus Expert
First off I would like to thank you Billy for you help concerning this matter, and before we go any further I want to let you know that I am also an A.S.E. Certified Automotive Technician with over 20yrs in this field . With so much experience, why am I on this page ? Simple, because while I am GOOD, I am NOT the ABSOLUTE BEST mechanic in the world; nor am I one not to seek the advice of other's who may have more knowledge about a particular vehicle than me . I use whatever mean's are at my disposal to help me with a problem that I am not familiar with or that I can not solve ....
Let me give you alittle background to my problem . I puchased the LS earlier in the year because I got a GOOD deal on it . It wasn't running when I got it, but I figured that I could fix it . The previous owner parked it because it kept blowing the no. 2 coil every few months . When I got the car and started doing diagnosis on it, I found out that it didn't have an ECU, so I purchased the CORRECT one and a spare just in case. I did a COMPLETE tune up (plugs,wires, caps,rotors and igniters) . Then I changed the fuel pump and all the related filters, as well as changed all fluids . And because I didn't know the history of the car, I also changed the timing belt and water pump . When I finished, the car ran fine for about 2 weeks, and then on my way to work one day, I noticed white smoke pouring out of the tail pipes . A check revealed that the vacum pressure switch on the p/s pump had gone bad and was letting the p/s fluid be sucked back into the intake . I fixed that problem, and then on my way to work the next day, the car started to loose power . I had it towed home and did some diagnotic on it . I ran a fuel pressure test, a leak down test and a compression test . All were within specs, except for # 8 compression being down and some leakage in that cylinder as well . When I drove the car the next day it was fine for about 20 miles then it started loosing power again . Since that time, all the car will do is idle . If you try to give it gas, it stalls; and the ONLY way that you can get it to idle again is to take out a spark plug and let it idle before replacing it back; the car runs SUPER rich .
I also have a 90LS that runs just fine, and I have been swapping parts between the two vehicles to try and find the problem because none of my diagnostic skills are working . I have swapped the ECU, the Mass Air Flow sensor, the Intake Air Temp sensor, and the TPS between the 2 vehicles with no change . All these parts work just fine when switched to the 90LS.
The diagram that you sent me was not the right one, thanks anyway . When I requested that, I had those 2 codes in the ECU; they must have been old ones, becase after I cleared the ECU and let the car run for 20 mins or so, and I kicked the computer back in diagnostic mode; no codes were to be found . I have taken the upper intake manifold off to clean the throttle body, because it was gummed up bad from the p/s fluid being sucked back into it . I will install it tomorrow after I find another Idle Air Control Valve; I ohmed mine out today, and it was not within specs.
You have given me some advice, and eventhough I have already done these things, I will recheck tommorow; but I believe my problem lies elsewhere . Any additional feedback or asisstance that you can give me concerning this matter would be gratefully appreciated . Thank you very much for your time, patience and help with this matter .
Thanks for your response Billly..I think that we may have a miscommunication here . The p/s fluid that I refered to in my reply to you, actually came from the valve on the back of the p/s pump . That valve feeds off of the intake manifold via two vacum lines to provied the asisst for the steering . When the valve went bad, it leaked internally and the p/s fluid was sucked back into the intake manifold via the same two vacum lines, which caused the smoking out of the tail pipe .....
I will replace the fuel pressure regulator as you suggested, and replace the vacum line(s) as well since the fuel regulator feeds off of vacum . And I will also replace the Idle Air Control Valve, as soon as I complete these repairs, I will report back to you with my results .
Once again, thank you for your time and asisstance .
(Note : It may take a day or so for me to locate a Idle Air Control Valve . Do I have a time limit in which to respond back to you ?)
First off I want to thank you for your time and advice concerning my issue . I have found my problem ,after I started to look at the LS as a car instead of this Mysterious being .
I didn't get a new IAC, I switched the one from my running 1990 LS, and after getting the same results, I finally sat down and use my mechanical common sense to come up with the proper diagnosis . I redid the compression and leak down test's; with the cams and ALL spark plugs pulled . On the leakdown test, no.s 6 & 8 were leaking, with no.6 leaking back into no.8 . At that point I knew what was wrong, but I did the compression test anyway just to verify my therory . All cylinders were up to par, except for no.8 again . I then tore the engine down and found out that I had a blown head gasket between the no.6 and no.8 cylinder ,