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Hi, my 1986 Toyota Cressida will start up fine but then "sometime" if I let it sit idle too long it started to miss, rough idle and loss probably half the power. It will get back to normal again if I park it for day or two. Car is not overheat in anyway and it's well maintained. I wonder if certain sensor get too hot while car at idle. When the engine is acting up I can smell excessive unburned gas from tail pipe. I like trying to fix this problem myself since I don't have time to take it to auto shop. Thank you.
 

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Cressida nut
91 Pickup (Hilux)2wd
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We've got Sherlock Holmes' apprentice apparently...

It could be several things...
I'd start by checking the fuel pressure. could be the pressure regulator is on it's way out and when warm, it leaks resulting in your fuel pressure dropping like a stone. Could also be the pump overheating again resulting in poor/no pressure. I assume it's fairly warm in Cali already (relatively speaking lol. 70s? 80s?)
Another good possibility is a bad temp sensor, the engine will run richer the colder it is. if the sensor is reading colder than actual temps the engine will run richer.

This one's gonna involve a lot of time with you, a multi-meter and your car's wiring. here's a good reference: http://cygnusx1.net/Supra/Library/TSRM/MK2/manual.aspx?Section=FI&P=8 yes it's for the supra but the engine electronics and mechanicals are nearly identical. If you want to get really fancy, watch ebay for a big green book, the toyota service and repair manual or TSRM for your car. (the link is to the mkii supra TSRM
 
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Thanks for pointing me to the right direction. I heard hissing sound around pressure reg. when the problem happened (after shut off engine)and thought that's odd. The problem now is getting to the unit, I can barely see the unit and can't even touch it. I'm just gonna replace with new one and not wasting time testing it. The engine does run rich and it seem worst everyday. I don't have people tailgated me anymore lol. I'll change out temp sensor as well. My another question is my 5mge has another temp sensor right underneath distributor and is required removal of distributor to get to. What's that sensor for? Is it just for temp gauge? PS. 70F is not considered as warm here, may be 80. Gonna take a month for me to work on it and will post once fix.
 

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This sensor is for transmission, possible, overdrive delay switch
 

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My another question is my 5mge has another temp sensor right underneath distributor and is required removal of distributor to get to. What's that sensor for? Is it just for temp gauge? fix.
I think it's just for temp gauge.. my gauge didn't work it wuz that sensor..
 

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If it has 1/4 inch wide spade terminal for single wire that probably a coolant temperature sender
 
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Discussion Starter #8
My car is an automatic so may be it's both. This is a single wire. Anyway, I'm just curious since I didn't see in the book.
 
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I got fuel regulator coming in so may be this weekend I can change it out. Do I have to remove the whole fuel rail ? If you around La Habra area and doesn't charge too much and want to do it let me know. I gonna change out regulator, thermal sensor, fuel filter, throttle position sensor and may be AFM box (have not order yet) got to wait till next pay check. After that muffler will be next to go.
 

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Cressida nut
91 Pickup (Hilux)2wd
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The transmission shifting is electronically controlled. the coolant temp sensors are for the gauge and ECU (make sure you swap the ECU sensor, not the gauge sensor. test by letting the car warm up and unplugging one of them (key on engine off so the gauge is working) if the one you pull kills the gauge, the other one is for the ECU)
 

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Reviving an old thread again.
Checking in with a 90' with a lil over 100k. Sometimes when I start it up the idle jumps back and forth vroom vroom 500 to 700 back and forth and today it would start but promptly drop to zero and shut off. No check engine lights. But once the car is running it drives fine only when I start it be it warmed up or cold it does this maybe once a week but first time it shut off promptly after starting thanks guys
 

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Cressida nut
91 Pickup (Hilux)2wd
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4,586 Posts
Reviving an old thread again.
Checking in with a 90' with a lil over 100k. Sometimes when I start it up the idle jumps back and forth vroom vroom 500 to 700 back and forth and today it would start but promptly drop to zero and shut off. No check engine lights. But once the car is running it drives fine only when I start it be it warmed up or cold it does this maybe once a week but first time it shut off promptly after starting thanks guys
First thing to check when a 7M stumbles is the head gasket.
 

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I did jus add a bit of water to top off the system. Now I do have a question how far gone would u guess it is? I'm inexperienced when it comes to head gaskets it hasn't been overheating and there is no milky stuff under the cap other then the funky idling is the only symptom I have seen any other advice for me? Thanks
 
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