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Thread: Hard Start, stalling, stumbling when hot

  1. #11
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    Default Re: Hard Start, stalling, stumbling when hot

    Good update and neat find.

    PSA though: DO NOT USE CLEANER ON YOUR AIR SENSOR!!!! Even if the cleaner states sensor safe.

    The 7MGTE uses a Karman Vortex optical sensor that WILL be damaged by sensor safe cleaners. It is never intended to be cleaned.

    https://en.wikipedia.org/wiki/Mass_f..._vortex_sensor

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    Default Re: Hard Start, stalling, stumbling when hot

    Thanks suprarx7nut. didn't know that about the afm, glad you told me before I fubared it.

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    Default Re: Hard Start, stalling, stumbling when hot

    Quote Originally Posted by bestsupraever View Post
    Thanks suprarx7nut. didn't know that about the afm, glad you told me before I fubared it.
    Absolutely. Every now and then a thread will pop up on the forums that says something like "My car runs rough (or won't run) after I cleaned the AFM."

    It probably would have saved some people if Toyota had put a warning sticker on there or something. Then again, plenty of people would just do it anyways, haha.

    The bulletin is odd to me. They say the newer TCCS ECU should not be used with the updated temp switch. Yet, the old temp switch appears to be discontinued. If there is some incompatibility it seems easy for a customer down the road to get the wrong combination of parts. It also makes me wonder how that works with JDM ECUs like I've got in my car.

    Again, thanks for finding the bulletin, that's cool to see.

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    Default Re: Hard Start, stalling, stumbling when hot

    Hi Guys, new update. Still haven't received the new CSI Time Switch yet, but I tried again unhooking the vac line from the fuel regulator when the car was hot and wouldn't start and run , before I pulled the vac line it catches within seconds, but stalls out within a second or two. So I pulled the vac line and plugged the hole with my finger( I could feel the vacumm pull on my finger), while my wife started the car, started right up and ran, idle was a bit low for a few seconds but then smoothed out and ran fine, I gave it some blips from the gas pedal to see if it would take it and it reved up just like it should without stalling. I did the vac pull a few more times after running around doing some errands, and each time pulling the vac line worked. So pulling the vac line does let it start and run while hot. I also noticed that after I reinstalled the vac line usually within a few seconds of the engine running smoothly, it would drop the idle down to 500 for a few seconds before gradually coming back up to 750 and staying there. So what does this mean, is the vsv bad, or is it doing what it is supposed to. Isn't it supposed to drop the pressure when activated, is it supposed to activate right away when you start. Is this maybe why the Toyota Engineers came up with the modified CSI Time switch, to give it a bit extra gas when starting even while hot.
    Any further ideas--

    Yes I agree Suprarx7nut. It is curious. It seems they changed the software to fix this problem in the later ecu's. And didn't want the modified csi time switch used with the newer programming. But the modified time switch wasn't produced very long, and has long been discontinued, the old time switch is also discontinued but replacements are still available in the lower heat range. It does make for a replacement nightmare. As for the JDM ecu's there were differences in a few systems between the American version and other countries versions. I guess you would have to look at the number on the CSI to know if it is compatible with the JDM ecu, if it was originally on the car before you got the jdm ecu. But as i wrote in the above paragraph, I wonder if the extra shot of fuel that the modified csi system will give to a hot engine was toyotas' way to fix what appears to be a fuel starve on a hot engine. I don't feel that either CSI Time switch will hurt the running in any way as it only activates when starting. At most with the modified one, it may run rich for a few seconds. IMO.
    Semper Fi.

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    Default Re: Hard Start, stalling, stumbling when hot

    Hi Guys, thanks for all the help, I am 99% certain that the vsv #17690 in the TSRM online catalog, which is toyota stock # 9091012024 is the bad part causing my problems. Now the problem is where to get one. Of course it is a discontinued part, and a search of many toyota dealers has gotten me the same answer, basically "SOL", I might find one on ebay, but that one may be no better than the one i have. Is there any new one possibly aftermarket that you guys know of that will do the job. I figure I may have to reroute the wiring and vac tubes if the part doesn't fit in the exact location of the original, but that is not a big deal, just need a working VSV that will hold up and work right. I was looking at the Dorman 911-604, it looks the same, anybody here have any insight on that one
    Thanks, Semper FI

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    Default Re: Hard Start, stalling, stumbling when hot

    Did you test the VSV? It's a very basic part that doesn't fail very easily

    http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=116
    (simply apply battery voltage to it and verify that air flows from pipe E to the air filter on it)

    When I had a similar problem my car would be hard to start, but it wouldn't outright stall out like yours is.. I dunno.. Have you checked stuff like timing and spark plug wire/coils resistance?
    Quote Originally Posted by supraman7mgte View Post
    I kept asking myself while i was taking the bumper apart,"why do i keep doing this?" I replied,"because my therapy makes me happy"

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    Default Re: Hard Start, stalling, stumbling when hot

    Quote Originally Posted by MK3pizzadriver View Post
    Did you test the VSV? It's a very basic part that doesn't fail very easily

    http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=116
    (simply apply battery voltage to it and verify that air flows from pipe E to the air filter on it)

    When I had a similar problem my car would be hard to start, but it wouldn't outright stall out like yours is.. I dunno.. Have you checked stuff like timing and spark plug wire/coils resistance?
    Hi Guys, thanks mk3pizzadriver, yes I tested the timing, tps, and fuel pressure, they all test out to specs. No I haven't pulled the vsv out yet to test it, because it is in a tough place to get at, so when I do bite the bullet and get at it I want to have a replacement on the ready to put back in. If I pull it out and test it and it is good, I can always reinstall it and take the uninstalled new good one back to the store. as I posted in my last post, after doing the vac line to reg pull a few times last week, and the car started right up, I am now 99% convinced that I need a new VSV for FPU. I got one yesterday at advance, it is Dorman #911-604.
    The OEM ones are not available anywhere that I could find, so I am going to use the Dorman. It looks almost Identical, but there may be some slight mounting rigging that I will have to create. Not a Problem, the function of it is exactly the same as the oem. I tested it yesterday on the bench and it performs exactly like the manual says it should. It is in a knuckle buster place on the car to get at , otherwise it is about a 3 minute job. I will install it this week, and post my results, but as I stated, I am 99% convinced that this is the fix. Thanks for all the thoughts and suggestions, I do appreciate them.
    Semper Fi.

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    Default Re: Hard Start, stalling, stumbling when hot

    Lot of over complicating still going on here. Again, the VSV is easily tested without removal. It's nothing more than a 3 way solenoid valve. Any 12 vdc 3 way, automotive or not, will work if plumbed correctly. That said I doubt it'll solve your problem even if it is bad.
    In memory of Rimma Kiselitsa

  9. #19
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    Default Re: Hard Start, stalling, stumbling when hot--SOLVED

    SOLVED---Hi Guys, Today I installed the Dorman 911-604 VSV. It was no pleasure getting the old one out. It's not that it is that difficult, it is just in a place that is rough to get large arms and hands into. There is one 12mm bolt to remove under the intake manifold on the drivers side between the engine and the wheel well. Then there are 2 vacuum hoses attached to the nipples. They are only a few inches long, and then attach to metal tubes that take them to their destinations. One goes to the Fuel Pressure Regulator, and the other goes to a Vacuum source nipple. Then the only thing left to remove is the connector. Just squeeze the locking tab, and it should slip off. Thats it, the VSV comes out with the small attaching bracket. You could take it out by removing it from the bracket leaving the bracket attached, but I found it easier to remove the bracket and VSV at once, plus you need to mount the bracket to the replacement, which is not an exact match.
    I then tested the old VSV, it measured 4 ohms on a 200k scale, and did not have any short to body issues, just as the manual says it should be. BUT when I applied 12v to the terminals, it did nothing. The solenoid did not click at all, and the airstream that i was applying went from the in nipple to the out nipple going to the regulator. So that proves that it was inoperative in redirecting the vacuum towards the filter side as it is supposed to do.
    I then tested the New Dorman, it measured 3 ohms and no short to body issues, AND when I applied 12v to the terminals, the solenoid clicked. The airstream then went from the in nipple to the filter side, thereby depriving the Fuel Regulator of Vacuum, allowing it to pass the full pressure coming from the fuel pump to the Rail. That is exactly what it is supposed to do.
    So here is what I had to modify to install the Dorman. It is very close to the oem, ( which I found impossible to get a new one), but the way you have to mount it to the oem bracket is different. I needed to use a small nut and bolt to hold it to the bracket, (the oem uses a small screw which mates to a threaded portion of the VSV Metal Housing). Not a big deal at all, the new one then fit right back where it was supposed to. Put the Vac tubes back on, I used new tubes, and then the connector, and then bolt the bracket back on. ONE CAVEAT The connection nipple on the Dorman is very slightly different than the oem, There is a small locating tab on the Dorman on the opposite side of the connection nipple from the lock tab. Unfortunately it is not exactly where the oem tab is. It is offset a few mm's, so the slot in the oem wire connector won't slip over it. My solution was to simply cut it off of the new dorman with a pair of snips. That was all that was needed, slipped the connector over the connection nipple, and it locked in place--Done Deal. The whole job took me about 20 minutes, and that was with standing up to stretch my aching back and groaning a few times.
    I did finally receive the Modified CSI Timer, brand new from Toyota, but I did not install it, because I do not think that my car has the lukewarm starting problem. So I will just have to eat that mistake. But I do believe that the modified CSI timer is appropriate for some cars that have a hard time starting when midway between hot and cold.
    Last but not least I took the Supra out for a long drive, highway, ac on and stopped at a few stores along the way, spaced my shopping out at about a half a dozen locations, I would come back out in 10, 15, 20, 25, 30 minutes to start and go to another location. SUCCESS She started every time with no fuss, just hit the key, and go, just like when it was new.
    Thanks again for all of your suggestions, It's now Miller Time.
    HOORAH---
    Semper Fi

  10. #20
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    Default Re: Hard Start, stalling, stumbling when hot

    Next time remove the alternator and alternator belt and then it won't seem to hard to get to it.
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