The high idle problem however was not fixed. So I was left with the idle control module under the passenger to deal with. I took it out, knowing how people said this thing is faulty mainly due to aged solder, so I bang it a couple times on the ground. Put it back, presto, idle is normal again.
However, the idle problem came back after about a hour or so, thus I know, that's the culprit.
So, if I were you. I would do the opposite of what I did. Change the idle control module (unit) first, then check your timing before change out the EZL. The reason I didn't go with the idle control unit was the first shop put in a supposedly known good used unit and it made no difference, thus they declared the ICU was not the problem.
The lesson is unless you pulled the ICU off a car that you know idles perfectly, you have no way of knowing if that ICU is good or not. Also, make sure you get the correct ICU specfically for your car, appearntly, they are not interchangeable.
Yes. Before I went ahead and purchased the EZL, I took my car in to another shop to do a proper diagnostic. The first thing they questioned about my assumption of the faulty EZL was what's causing the timing to be off. Their belief was there was something obviously feeding the signal to EZL to advance the timing and possibly causing the high idle. When they did the duty cycle test, it turns out I had a combination of faulty air flow sensor and idle control module. A very expensive prospect, as they told me the air flow sensor needs to be replaced as a whole unit eventhough only poientometer was faulty. I was fortunate as Bosch as recently just brought the poientometer back to market. I had it replaced, and immediately I know that was the culprit, because ironically the car went back to the slightly rough state rather than perfectly smooth when the idle was hugely advanced.
Hi, I have read you thread about EZL vacuum line and high idle, I have exactly the same problem and I have bought a second hand ezl, but the problem doesn't goes away. Have you solved your problem already?