Hey CLers,

I've been having a lot of trouble with my 1994 SC400 on warm starts. I bought this car a few months back when it (unknownst to me) had this problem. Since then I have spent of the order of 2 grand trying to fix it (at the local lexus mechanic). I know I've been paying top dollar for my repairs, but I was hoping that they knew what they were doing. I'm fast starting to lose faith . After my fourth trip to Lexus it reared its ugly head again today.

The basic symptoms are (it seems) after driving the car for a while (30-60 mins) and stopping it such that it's still warm (30-120mins) when I turn the car over it chugs and dies (perhaps as if starved of fuel). After trying to start 3 or 4 times it will finally start up. On the bad starts flooring the throttle does nothing and the engine always just seems to cut out (chug chug chug, die). I've noticed the faint smell of something when this happens too, perhaps a slight petroly smell. It's a nasty intermittent problem that's very hard to show a tech.

In an attempt to fix i've had:
- The throttle position sensor replaced.
- The idle air control motor replaced (diagnosed by a lexus tech as the problem). This seemed to work for a while, but a couple of weeks after they replaced it a check engine light came on and I took it back and they said it had a bad connection. Since then the warm start problem has been getting bad again. (Could it be a bad part? -- it's new). I don't seem to have any variance in idle RPM.
- A faulty O2 sensor replaced (about a week after it got back from the Air flow meter jig, the check engine light came on again and apparently this time it was my O2 sensor).

I also had the EGR plates on my motor replaced (unrelated) because apparently they were missing (and it passed smog?).

After cruising the forums the problem seems as if it could be the FP ECU. This is probably the next thing I take a look at (after I call up Lexus and whinge tomorrow). By the sounds I can probably replace it myself (without paying hundreds of dollars labor)?

Does this sound like a reasonable avenue to persue? Anything I (or the well paid lexus mechanics) could be overlooking? Any help would be very much appreciated (between this and the whining differential the SC400 is starting to drive me insane).

t.

 

Sorry you spent so much money on replacing parts and labor. It sounds like the classic fuel pump ECU problem. Sounds like you got taken for a ride like so many other people that have had this problem.(Dealerships make me sick, they should ONLY be used for warranty work ONLY...nothing else.)The fuel pump ECU is located behind the drivers side back window panel. Very easy to remove, (a monkey could do it blindfolded)check forums on how to remove back seat. I just picked up a used FP ECU for $40 from my local junk yard. Stealership wanted $325 plus tax!)(Many salavage yards are asking $100-150 for this part...be smart, shop around and/or wheel and deal when purchasing used parts!)Any SC 300 or 400(1992-99) uses the same fuel pump ECU. Dimes to donuts this is your problem. Please let other forums members know what fixes the problem, (I bet it is FP ECU)everyone on this forum and other forums as well, are sick of throwing money out the window on parts and labor that DOES NOT fix the problem ,especially to dealership that have the diaganostic equip to check things PRIOR to charging labor and replacing perfectly good parts. BTW the "Soarer" web site is a good site to check out.

 

Thanks very much for the heads up! After reading back through the threads this was my gut feeling too. Unfortunately looking back over the archives it's very frustrating that there are so many open posts, with solutions suggested and no feedback about whether the problems were fixed or not.

I'll make sure to post when I finally manage to fix this issue (and my weird differential whining). The most painful aspect is the $900 idle air motor. I guess my O2 sensor probably went, and the TPS was probably bad too)

t.

(And for search system optimization purposes I'll just make sure to mention: warm start and starting problems, fuel pump ECU, fuel starvation, engine cut out, idle air control, IAC, stealing dealers )

 

My guess is that those parts you replaced where probably O.K. Did you ask for the old part to be returned to you upon pick-up/replacement. I ALWAYS ask for my so called "worn-out" or bad part back whenever I place a workorder(have them write this in BOLD LETTERS on the workorder AND watch them do it!!!!)(its yours you know). ALWAYS do this BEFORE the work gets started. (I also feels that it keeps these guys honest...yeah right)This way, if the repair is done AND you still have the same problem well then there is a good chance that the part MAY NOT have been bad to begin with and is still usable/saleable/refundable/or can be used as a "core" etc.I am always amazed by how many people do not do this. As for your differential. I had a differential whining noise that started at about 35mph. (original diff with 140,000 miles, auto trans)Turned out that the small differential vent hole on top of my diff. had clogged up causing pressure to build inside diff ,thus putting pressure on the diff axle seals causing them to leak, unbeknownsnt to me. (Should have checked the diff fluid and seals more often but didn't...my mistake) Anyway this lead to permature diff wear(i.e. whining at 35mph+) very annoying. Tracked down a used one from a junk yard for $250 with around 100,000 miles on it(good price). Watched them remove it from the car(not a big deal really) and decided I could replace it myself. Took several hours to remove and replace and the problem is fixed. If you are a DIYer this is not that difficult of a job and I did it by myself. Let us know how your repairs go.

 

The replacement FP ECU went in this morning -- hopefully I'll be able to report in a couple of weeks whether it fixed my problem. As other people on this forum have mentioned the install is very easy, remove the back seat, the panel behind drivers door, and bolt the new one on (I decided not to just override with a paperclip).

Now that I've got the old one out is there anyway I can test it to determine if it's bad? Or is there any way I can tell whether it's old? I only bought this car recently and the one I took out looks *exactly* the same as the one I put in. Are there serial numbers or model revisions since 1994?

I immediately noticed the car driving quicker and having lower idle RPMs (which seems a little weird). Perhaps that's just a side effect of having disconnected the battery (and maybe resetting another ECU)?

t.

 

wow... 2 grand at Lexus and they didnt fix the problem? I would make a complaint. Good luck with the new fuel pump ECU man. Hope it all works out

 

trystanu: I'm having the same problems with my 92 sc400. Did the FP ECU replacement fix the problem. I tried the paperclip override but no luck, I'm leaning more towards my IAC. Do you know how to test the IAC stepper motor?

 

Yeah, when you're working w/ the dealer and they don't fix it..call 800-25 LEXUS, tell them your story and they will follow up. Lexus cares alot about their post-sale and dealership experiences.

I agree with the frustration of incomplete posts on fixes... the questions keep coming, but sometime the solutions don't get followed up...BUT!! This is still the best site to get answers..so mods don't lock me out

 

I had an intermitant cold start problem(very annoying) on my SC 300 auto 1992, (with 160,000miles) Decided to get a used FP ECU from my local junk yard to try and fix the problem(I beleive it came out of an 95 SC400), I removed it myself from the junk card($40) very easy to do(remove rear back seat panel) and this diffinity fixed my problem. It has been in the car now for over 50,000 miles and runs perfect. Give it a try and save yourself a bunch of money and do it yourself. I also, ALWAYS,ALWAYS shop around junk yards and get a price quote BEFORE I get the part, you will be shocked how many different prices you get quoted. ACT like you are a PRO (don't act stupid) and that you want a fair price. I got prices from $40(my local friendly junk yard guy )to $150 from some of the rip off junk yards. Always have them put their mark on the part so that if it is faulty ,you can bring it back for a replacement. Good luck.

 

Yeah, replacing the ECU fixed this problem.

Now if only the whine I get at 20 and 45 mph on cold mornings would go away. The lexus mechanics swapped my diff out, but now that the weather is cold it's started up again.

Aaargh!

t.

 

Warm start problem corrected by replacing Fuel Pump ECU. Thanks for the help friends.
Garage on second attempt wanted $800 parts and labor for the IAC. While I was thinking about it, did some research here. Spent $100 at a junk yard for the ECU and installed myself.

92 sc400

 

i've got same prob with my 91, will bridging the port in diag box harm anything until i can locate a new one

 

while i'm on here is it possible to repair TEMS struts or are they a throw away i've got a small seepage in one stut would like to keep TEMS but if to costly will replace with ;any suggestions

 

check the coolant temp sensor ect sometimes that can cause a no start because it thinks its hot when its not or cold when its warm