High Idle - IAC Valve

[DPDISXR4Ti]

As far as connections this is what I apply to every connector I pull apart on any car:
https://www.specialized.net/cp8-tb-thom ... -8-oz.html
Stuff is magical and a container will last your lifetime.

Note to self, get some of this ^^^.

[MarkM]

Also along those lines is Stabilant 22 (concentrate) and Stabilant 22a (pre-mixed). Expensive, but getting rave reviews for at least 35 years. Interestingly, it's only conductive under certain conditions. But generally the ones where you want it to be.

https://www.stabilant.com/NoteList.html#appnotes

https://www.micro-tools.com/products/22

[Ed Lijewski]

I've used this for some time too after Pat Goss (Goss's Garage/Motorweek, et al) cited it.

YMMV

[andyofcolumbusmerkur]

Oh ya those non-conductive amorphous-semiconductive polyoxyethylene-polyoxypropyline polymers are pretty cool.

[brokencase]

The Kopr-Shield is the stuff. I received a half used bottle of it a long time ago from a friend of my dad's who worked at Peach Bottom nuclear power plant. They used it on all their electrics.

I used it mostly on my Sprite restoration. All those Lucas bullet connectors that always turn into green powder.

The bottle was later lost and for the longest time I would search on the internet and couldn't find it. I figured the company was out of business.
The problem was I was searching for "Copper Shield". Only very recently Google gave me a break and it showed up in the search results.

The only word of warning regarding Kopr-Shield - If you are doing a multi-contact connector, don't bridge the stuff across the contacts - you will create a short. It literally is fluid conductive copper. Best to use a small wire to apply it into the female part of the connector...and it does not take much.

[Ed Lijewski]

More Merkur sufferers suffering EEC-IV high idle blight

Screenshot_20210810-103002_Lite.jpg (843.14 KiB) Viewed 3999 times

Screenshot_20210810-103024_Lite.jpg (540.99 KiB) Viewed 3999 times

YMMV

[brokencase]

Sounds like the EEC-IV detected a problem and went into "limp mode" to me...

[DPDISXR4Ti]

Sounds like the EEC-IV detected a problem and went into "limp mode" to me...

I don't think that's what is going on. When I've experienced this issue - many times with the 2.3T and twice with the Scorpio 2.9 - the engine ran fine otherwise and was in closed-loop. Over the years LOTS of people have experienced this problem.

As I may have noted in this thread in the past, I've not experienced this symptom ever since switching over to the later 2.3 PCM's (exp '94 2.3 Ranger). My theory is that Ford evolved their strategy as time went on to account for this common issue.

[DPDISXR4Ti]

As far as connections this is what I apply to every connector I pull apart on any car:
https://www.specialized.net/cp8-tb-thom ... -8-oz.html

Stuff is magical and a container will last your lifetime.

I wonder if KOPR-KOTE is a less expensive version of KOPR-SHIELD?

Found this review of KOPR-KOTE....

"Customer Review
John Dinger
5.0 out of 5 stars KOPR-KOTE By Jet Lube
Reviewed in the United States on August 30, 2012
Size: 1/2 pound
I have been using this product, and a variation of it called Copr-Shield by Thomas & Betts, for about the last 20 years. My business is heavy equipment maintenance. This is one of the greatest spin-off products of the space industry.

As an anti-seize it cannot be beat. Granted, it's the most expensive one on the market, but worth its weight in gold. Used in demanding situations such as high temperature exhaust studs it has no equal. Years after application, nuts and bolts can still be easily removed. Not only does it provide an excellent anti-seize, but it also acts as a lubricant so that the proper torque can be attained on fasteners. I have seen too many techs installing dry bolts in a steel to steel, or aluminum, situation without using a proper lubricant for a good and accurate torque setting.

Used in electrical work, which of course is the specialty of the product, it again unequaled by any other. Being highly conductive it is the perfect medium to apply to electrical connections. Care must be taken to use it sparingly to avoid creating an unwanted electrical path. Used on battery terminal clamps it can bring an end to corrosion problems associated with the deadly green fungus growth on these terminals. As long as the battery is charging properly, without acid leaks, the product acts like a sacrificial metal that gives itself up in order to save the connection.
I have found that even in the worst case scenarios the treatment on battery terminals will last at least a year. With a reasonable maintenance program any problems should be caught long before corrosion issues arise. Likewise it is very effective on smaller connections such as a starter, alternator, etc. I use it on virtually anything with threads.

I can't say enough good things about this product. It has saved innumerable hours of labor and unnecessary road calls, and provided a means toward better craftsmanship. The extra care you give by its use may not be readily apparent to your customer. But in the long run, the added reliability of the equipment makes itself known."

[Ed Lijewski]

How can one square a diagnosis of limp home mode as the explanation for RHIS (random high idle syndrome) when the high idle is at or even above cold start rpms, the engine will respond to normal accelerator pedal depression above the high idle level on resuming motion in traffic or just revving it, the syndrome will disappear (IME) after shutting off the ignition and then immediately restarting (although it might reappear not long after)?

I've searched in the past for a good description of engine performance response while in limp home mode. Anecdotes about it suggest at least compromised throttle/power response. I didn't experience that, nor do others' RHIS experiences indicate it.

So logically, what might the ECU be responding to? The base assumption is the ECU commands the IACV to fully open (the RHIS engine speed never seems to exceed what that can produce).

--ECT severely out of range

--TPS continuously reading say 1/4 pedal depression

--02 sensor signal way lean

--RPM info received by ECU below what it had been expecting during that operating cycle

--Other (you fill in)?

One would expect a code or several to be recorded after these events that if/when resolved would eliminate recurrence of them. That doesn't seem to have permanentky worked in reported cases.

RHIS hasn't appeared on my '89 but did on my '88 with its original engine a handful of times over a couple of years. For other reasons I replaced that engine with one from a parts car (~100K miles) with no RHIS events to date.

Would love to get the EEC-IV Chief's input on this.

YMMV

[brokencase]

How can one square a diagnosis of limp home mode as the explanation for RHIS (random high idle syndrome)...

Plain and simple Ed. The vehicles did not exhibit this behavior off the showroom floor.
So it is not some innate problem with the programming of the EECIV.

This "syndrome" (as you so incorrectly call it, in an effort to somehow legitimize as some sort established defect of design) is a situation occurring with old examples of the cars that have something wrong with them for which the owners have not found the root cause.

The only time I have observed this effect is when my A/C diode failed the A/C clutch cycled and the power glitch forced the EECIV into a high idle state. Turning the car off and restarting (as well as turning off the A/C) allowed me to continue on my merry way. See? No mystery.

There are many limp mode failure cases where the EECIV will raise the idle in an effort to keep the car running and get you home or to a mechanic.
It is quite possible you may not get an error code indicating what the problem was. If anything this might be a design flaw in that it does not tell you what the problem is.

But rest assured, that if your Merkur jumps into a high idle state there is something wrong with your engine or it's sensors (or the electrical system).

So therefore "ERHIS (Ed's random high idle syndrome)" is a mental state of some owners of old Merkurs who are frustrated in that they have not found the problem with their cars.

It's quite a problem, because it leads these owners to automatically jump to this insane conclusion anytime someone comes onto this forum and complains that they have an high idle situation. Thereby bypassing all normal and sane troubleshooting procedure discussions that should occur first to assist that individual.

So for example...the following forum exchange accomplishes NOTHING, and only leads to DESPAIR and is NON-PRODUCTIVE.

New Poster: "Ah...I have a high idle situation...Can someone help me?"
Ed's response: "You have RHIS (random high idle syndrome)... Nothing we can do about it. You are screwed!"

So I ask kindly that you please refrain from doing this, and allow normal troubleshooting procedures to be discussed before moving the discussion to ERHIS.

[andyofcolumbusmerkur]

See what you started Fresh Air Inspector

[brokencase]

I find no mention of this syndrome in the old IMON archives.

But there are many who have experienced the high issue and have resolved...

"For the last year I have been plauged by an intermediate
high idle. Basically every once in a while it would jump
up to about 2000 rpm and stay there until the car was
turned off and on again. To make a long story short it
was not a dirty intake mainfold, a faulty TPS or the air
bypass valve. It appears that the idle problems were caused
by corrosion on the pins in the wire connector going to the
TPS."

"thanks to everyone that gave their advice on my recent high idle problem.
turned out that the TPS was bad and after a quick trip to a Ford dealer
(they actually had one in stock) the problem was fixed."

"I have had the same problem. It is my impression that an occasional
high idle can be caused by a bad connection to the air bypass valve. What will
happen is that normally the idle will be fine until the EEC temporarily looses
its connection to the air bypass valve, once it makes a connection again I guess
it figures something is wrong and kicks the idle way up and keeps it there. If
you turn the car off and start it again it the EEC then goes back into "normal"
mode and it idles ok until it makes a short again."

"I have found two things which result in irregular idle speed. They both
involved the throttle linkage. First, I found the fiber liner attached
to the underside of the hood was hanging down and interfering with my
linkage...causing it to occasionally hang up with a high idle. The
second item is the linkage itself. Sometimes, all of the springs in the
system will not return the throttle plate back to the idle position. It
seems that there is some combination of slop, friction, etc. which
causes this. I found that I could move the throttle plate without moving
the rest of the linkage and it would just sit there without going back
to the "idle" position."

"after getting info from the list about where to find it, I discovered my XR
still had the original (plastic?) PCV (valve). Popped in the new one
(metal) and now, my idle is @ low/normal, from high normal (best estimate I
can do without a reliable tach). I'd say it went from 1000 rpm down to 650.
Certainly less cost and work than ohauling the throttle body w/no effect.
The spring in the old valve was completely ineffective."


Here is a case of the Syndrome that Ed and other owners have...

"If you're in NJ and interested in a scorpio, please check mine.
Condition is much better than what you describe, my main problem is a
high idle which has frustrated me and I have no time to deal with.
Let me know."


Note that it is a "dead giveaway" of limp mode kicking in when the problem resolves after stopping and restarting the car.

Not only a momentary glitch in the connection to one of several sensors can cause the idle to go high, but a glitch in the power distribution will also cause this problem, i.e, the aforementioned A/C diode failure, bad diodes in the alternator, broken/intermittent power connections, failing filter electrolytic capacitors etc...

[brokencase]

I wonder if KOPR-KOTE is a less expensive version of KOPR-SHIELD?

Couldn't say Brad. But I did not think KOPR-SHIELD was very expensive, especially considering that 8oz would last you a lifetime.
I do know that KOPR-SHIELD has very low resistance when measured with a meter.

[Ed Lijewski]

This is the only technical definition of Limp I've found so far.

"The EEC gets one and only one timing signal from the TFI unit. It is called the PIP (Profile Ignition Pickup). The PIP signal is 45 - 55Hz @ 1000 RPM, for 4, 6 and 8 cylinder engines and, with the exception of SEFI, has a duty cycle of 50%. SEFI uses Signature PIP where the #1 vane on the PIP reluctor is roughly 35% duty cycle and the rest are roughly 50%. The EEC uses this to detect cylinder #1. On a stock car, the leading edge of the PIP signal is @ 10 BTDC.

The EEC controls the spark timing. The TFI's function at this point is to basically clean up the PIP signal, charge and fire the coil. The TFI module conditions the hall sensor output and sends it off to the EEC. The only delay is just propagation delay through the TFI electronics. The EEC sends out the SPOUT signal which starts the TFI modules charging the coil. Depending on what advance the EEC is looking for, the falling edge of the SPOUT can vary. The coil fires on the falling edge. Since the EEC 'knows' where 10 BTDC of each
cylinder is, by using timers and things, it can calculate when to drop the SPOUT signal. The MCU uses the previous PIP value to determine where the crank was.

The TFI module can handle acceleration rates of up to 250 HZ/sec. Another function of the TFI modules is to provide LOS spark (limp mode). If the TFI detects a loss of SPOUT, it will generate its own 'SPOUT' to coincide with the rising edge of PIP (10 BTDC...assuming you haven't moved the distributor)."

https://www.merkurencyclopedia.com/EEC-IV/EECTEC10.PDF

YMMV