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Discussion Starter · #1 ·
In 1989 626 non-turbo with 102,500 miles, I've had problems recently with idle holding at 1500 rpm. Sometimes idles perfectly at 650 rpm and runs well. Another start, another day and for some hours will idle at 1500, sound slightly "thick" (not rough) at 3000 rpm on highway. Milage drops from usual 26 avg to about 20 avg city/hwy. Excellent mechanic cleaned idle switch etc. But unpredictable problem persists. O2 sensor? Mass air sensor? Other? Any thoughts?
 
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Discussion Starter · #2 ·
High idle

I have a 89MX6 Turbo and it started to idle high, 1500 or so. Soon after, my distributor went out, I had to replace it, and that fixed the idle problem and it ran much smoother.

PS- If you decide to replace distributor, buy a new one,not a refab. They work much better.
 

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The distributor on the nonturbo is 100% different than the turbo's. However, check to make sure the vacuum hoses going to the distributor are in good shape. Because extreme advances of ignition timing can cause the idle speed to go up. You also may want to try spraying the throttle body liberally with a carb/throttle body cleaner, as the IAC valve on our cars tend to gum up causing erratic idle problems. In any case, the idle can be manually adjusted by turning the screw on top of the throttle body, while grounding the green connector by the drivers side strut tower. Hope this helps.
 

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After I put the new engine in my car, and got it out of the shop, ever since, in the morning, when the engine is cold, my engine idles high, I think around 1500. Once the engine is warm it drops to >1000.
 

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The engine is supposed to idle at 1500 when cold. That's a normal function. Your IAC valve was probably clogged before you re-did the engine. Same thing happened to my old '89 mx6 that I gave to my friend. The car didnt have a fast cold idle, so it wanted to stall half the time until it warmed up. After we re-did his cyl head and replaced the IAC valve, it idles at 1500 when cold.
 
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Discussion Starter · #6 ·
Many thanks to each of the above posters for their thoughts. I'm passing these on to the mechanic working on the car. anarchyx34, I've wondered about vacuum hoses to ignition--but then convinced myself that ignitions are driven by computer these days rather than the old, mechanical vacuum advance. Is is vacuum/mechanical on the 89 626 or electronically-driven? Again, many thanks.
 

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anarchyx34 said:
The engine is supposed to idle at 1500 when cold. That's a normal function. Your IAC valve was probably clogged before you re-did the engine. Same thing happened to my old '89 mx6 that I gave to my friend. The car didnt have a fast cold idle, so it wanted to stall half the time until it warmed up. After we re-did his cyl head and replaced the IAC valve, it idles at 1500 when cold.
Hmm, thats good to know. I thought something was amis. Thanks.
 

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one other thing

It may have something to do with your thermostat, or Temperature sendig unit. The reason I say that, is cause if the computer "thinks" that the car is cold, it will run a richer fuel to air ratio, and idle higher. The rich fuel to air ratio would explain the poor gas mileage.

Does your temp guage register warm? Mine was always about halfway up.

My sister's car (1991 MX6 LX)was idling @1500rpms also, and her heater never would get warm, although the temp guage always was in the middle too. We pulled out the old thermostat, and someone had taken out the spring, and valve (bascially all that makes it a thermostat). We put in a new thermostat, now the car idles good, and the heater is warm. The temperature guage still goes to the "halfway" mark. I don't understand that, but oh well

Just a thought, good luck.
 

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Fred Rose said:
Many thanks to each of the above posters for their thoughts. I'm passing these on to the mechanic working on the car. anarchyx34, I've wondered about vacuum hoses to ignition--but then convinced myself that ignitions are driven by computer these days rather than the old, mechanical vacuum advance. Is is vacuum/mechanical on the 89 626 or electronically-driven? Again, many thanks.
yep, believe it or not, the nonturbo engine uses an old fasioned mechanical/vaccum advance system. It dosent use points though, it has a hall effect sensor type ignitor built in. It's generally a pretty reliable setup.
 

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jiffy6969 said:
one other thing

It may have something to do with your thermostat, or Temperature sendig unit. The reason I say that, is cause if the computer "thinks" that the car is cold, it will run a richer fuel to air ratio, and idle higher. The rich fuel to air ratio would explain the poor gas mileage.

Does your temp guage register warm? Mine was always about halfway up.

My sister's car (1991 MX6 LX)was idling @1500rpms also, and her heater never would get warm, although the temp guage always was in the middle too. We pulled out the old thermostat, and someone had taken out the spring, and valve (bascially all that makes it a thermostat). We put in a new thermostat, now the car idles good, and the heater is warm. The temperature guage still goes to the "halfway" mark. I don't understand that, but oh well

Just a thought, good luck.

Temp reads cold until about 5min after being run. Then the guage will never go past the hlaf-way mark, but it is usually there when the car is running. And my heater works great, as does the AC.
 

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Oh yeah

By the way, the correct idle should be 750 RPMS (when engine is warm). There is a sticker under your hood that tells you what your idle, timing, refrigerant, and other things should be.

And temp guage should not go past halfway--like Rendell said.
 

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I would recomend u replace your PVC valve its only like 5$ or so and it controls the air preassure. too much air ant it will idle high so or too low or sometime 2 both It mostly a sign of it . Try it out see ifit make a difference
 
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