Sometimes my 1987 MR2 will idle funny. I will be driving, come to a stop, and the idle has a surge, it goes from normal to 15/1600 to normal, as if I were reving it slightly over and over. The car will run fine, once I start moving the problem either goes away or is not noticable(I am VERY sensitive). Once again, it does not seem to affect performance in any way aside from an inconsitent idle, any thoughts?
BTW, this only happens once ina while, once in a GREAT while, like once a month
may wanna take a look at your coolant's condition (re: bleed it as per BGB method). you might also consider the condition that your IAC (idle air control) valve is in and/or your TPS (might check its adjustment). ah! you might also try spraying the throttle body clean and the linkages and springs.
you know, i have an '87 and it too has an idle problem, however, instead of it sounding like its overreving, it drops to about 8/900 rpm. this rarely happens when i drive it for a while and just sit idle. when this does happen, i can hear the sound like im going to stall and everything that comes with stalling, ie all the lights go dim, the engine makes that stalling sound, and the whole car just shudders like its going to blow or something. i really wish i knew what was wrong but it doesnt happen enough for me to get worried
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1987 MR2
power nothing
15" ALBA's
custom paint
"Swearing shows a lack of creativity"
happened to me a few times, seems only on hot days. i just checked all linkages to see if any were sticking. heard a few mention AFM and TPS, burp cooling system(air pockets are NO BUENO), vac leaks. i bumped up the idle a tad and it went away.
1. The ISC may be sticking, so the ECU tries to get to stock idle and can't, so it cuts timing. The ISC has very small ball bearings in in that can get dirty and dry, causing the sticking problems.
2. Probably not the case here, but I wanted to point it out to you MK1 owners: the two power tranistors inside the ECU that control the ISC have nothing holding them onto the main circuit board except their three leads. Over the years, vibration cracks the leads and the ECU can't make the engine idle correctly any more.
There are two transistors, one for idle up, one for idle down. (A split coil on the ISC, three wires.) If one transistor fails and the other doesn't, the engine will either have a very high idle or a very low idle.
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Yes, it's an N/A. It IS a 3.0 liter V6 though. Does that matter?
Had you done a search in the Corolla forum, you would have noticed us guys with AE92 Corollas and 4AGE's have already dealt with this problem before.
Find your idle screw, crank it up to make your idle go up... leave it there for a few seconds, then you turn it down until you reach your desired idle speed. this should get rid of your idle problems.. trust me it did with mine.
Had you done a search in the Corolla forum, you would have noticed us guys with AE92 Corollas and 4AGE's have already dealt with this problem before.
Find your idle screw, crank it up to make your idle go up... leave it there for a few seconds, then you turn it down until you reach your desired idle speed. this should get rid of your idle problems.. trust me it did with mine.
1. I doubt too many of you know what to look for when you open up an ECU.
2. If you are going to crank your idle screw, you should first put an E1-TE1 jumper in the diagnostic connector. This only works for a correctly operating system. I am referring to "broken" systems.
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Yes, it's an N/A. It IS a 3.0 liter V6 though. Does that matter?
Mitch--i assume that you do ECU repair work? if you do, do you have access to some transistors? i'm having difficulty in locating a transistor and a particular resistor.
I don't make it a point to fix ECU's. I make (and sell) V6 swap circuits (Tach Adapter and Temp Sensors) and I repair things on MR2's that most people don't venture into. Hence, I know about the ISV's, ISC's, and ECU's that break from vibration.
I've been an electronics Design Engineer for over 25 years. I have seen lots of transistors and resistors.
What are you looking for?
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Yes, it's an N/A. It IS a 3.0 liter V6 though. Does that matter?
cool deal, mitch! here's what i'm looking for:
Resistor is a wire wound, rated at 1watt and 3.9 ohms marking on it is 3R9J.
Transistor is an NEC C2516A, secondary marking
is a 3K74S and it's a TO-220 case. (this one could also be a voltage regulator)
Have you tried NTE yet? What you have there for a transistor is likely a 2SC2516A. (Whenever you see something like "C2516A", assume that you can add a "2S" to the beginning, a typical Japanese prefix.)
Go here and put in "2sc2516A": http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm
The resistor is not so hard to find. Try Digkey, Mouser, or Newark. You will need to spend more than what one resistor will cost. You might try going to a TV repair shop first and ask if they have one to sell you. Or, you could ask for a "sample" part from one of the distributors.
Since the transistor is a high voltage part, are you trying to repair a monitor by any chance?
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Yes, it's an N/A. It IS a 3.0 liter V6 though. Does that matter?
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