bubbaz28

Just got my E4ME back from being rebuilt. Starts right up, but the idle stop solenoid (I think that's what it's called) plunger pushes out and runs the idle up to around 1500 rpm.
A kick of the throttle doesn't drop it back down, but if I unplug it, of course, it'll de-energize and retract.
I read that I can screw it in to adjust how far it comes out, but I'm not sure if that's the answer. Also I read to "apply 12v. to the contact" to see if the solenoid itself is the issue... dumb question I guess, but how do I get 12v. directly to it?

Thanks for your help,
Bubba

sofakingdom

iTrader: (1)

Unplug the wire; use an alligator clip lead from batt to the terminal. Big post on the alt is a convenient spot close by to get batt from.

Yes you can (and obviously need to) adjust how far it comes out. Set the idle to something around 1300 RPM with it extended as described above, and the curb idle screw on the carb to about 650. Goal of the exercise should be that if you rev the motor up a bit, 2500 or so should easily do it, it should extend; then when you let go of the throttle it should drop back down against the stop, then in a short time as the RPMs fall off the solenoid should release and let it drop all the way to curb idle. May take acoupla tries to get it to act just like that.

Of course, DO NOT use the tach-shaped "sport" trim object in the dash for this; use a piece of actual test equipment.

bubbaz28

Thanks for the help sofakingdom.

sofakingdom

iTrader: (1)

Didja get it to work like that?

bubbaz28

I didn't get a chance to try it yet. I will let you know though- probably thurs. the way work has been going. Too busy...

bubbaz28

So I did as you said. (It took me a while b/c of endless other projects.) Anyway. the plunger holds the throttle to around 1200-1300 rpm when cold, but doesn't always back off when it warms up.

When I disconnect the alligator clip the plunger retracts, but it doesn't throttle down... think I need a new return spring, but that will be a different post-

paulo57509

Back in the old days before CC carbs, there used to be two idle speed specs; with and without the idle solenoid energized.

The idle speed was first set with the solenoid unplugged, using the screw that's up against the carb body. Then the solenoid was plugged in and the idle speed adjusted by twisting the plunger.

I don't recall if this is true (probably not) with the CC carbs.

sofakingdom

iTrader: (1)

Good troubleshooting, you've got to a point where you've eliminated the thing you "thought" was the problem. Very good.

The throttle return spring system for our cars is IMO very poorly designed. In a perfect world, it would be mounted in front of the carb, up high, and would EXACLTY oppose the throttle cable. Where it is, there's always force pulling the throttle shaft rearwards: ALWAYS. Both the force of your foot AND the force of the spring. That ends up causing wear to the rearward face of the shaft (started out life Teflon-coated) and the base plate. Can get pretty severe.

Plus, THIMK about "vacuum" for a minute: if your engine makes, say 15" of vacuum (roughly half of atmospheric pressure), that puts around HALF of 15 psi on the throttle blades, AT ALL TIMES the engine is idling. I've never calculated the pri throttle area but I'd bet it's something on the order of ¾ sq in of area; ¾ of half of 15 is around 6 lbs of force pushing the throttles DIRECTLY DOWN AT ALL TIMES INTO THE MANIFOLD, × 2 since there's 2 blades, for a total of around 12 lbs of static load. Which causes.... you guessed it... wear on the throttle shaft and base plate. There's EVEN MORE force than that when you're shifting or you just let off the throttle while cruising or something, since vacuum is even higher then; can get to as high as 90% of atmospheric sometimes.

You may need to send your throttle plate off to The Carb Shop or the like, or trade it in as a core on a "rebuilt" one, with new bronze bushings and re-coated shaft, to get rid of the friction from all the wear that has accumulated over the years.

Paulo's point is largely true as well: there's a "spec" for both "curb" idle, and idle with the solenoid engaged, for the CC Q-Jets as well as the older ones. If memory serves they were around 650 and 1350 - 1400 RPM respectively. However after all these years, setting it to the "new car" " spec" may or may not produce exactly the desired results, if for no other reason than because fuel nowadays is different from the early 80s. Seems to me, as time has gone on, the solenoid has needed to have slightly less "authority" for optimum behavior; which is why I gave you the idle speed #s I did. It's a TUNING thing anyway, not a "spec" thing, ultimately; tweeeeeek it until it works smoothly the way YOU like it, not, be a SLAVE to "book".

bubbaz28

Thanks again for your time Sofakingdom. The throttle bushings are new... I had it rebuilt by a reputable carb shop...

I haven't had the throttle sticking problem in the past couple hours of running it. However there are still a couple of issues-

still sputters/ hesitates when I hit the throttle. Even when warmed up. I have searched the boards here for answers of course. Timing is good. I have an Actron OBD1 to analyze dwell, and it's at about 80%. This goes to about 76% with IAC 4 1/2 turns out, but then idle drops to around 500. I should be looking for 30% duty cycle?

From what I've read, if I can get a handle on this dwell issue maybe it'll run smoother...

Other issue is from a cold start, it sometimes dies and I have to restart a couple of times. Probably a choke issue...

Rhp454

The throttle stop solenoid is there to speed up the engine when the A/C is turned on at idle. It should be adjusted to bump up the rpms 3-4 hundred over idle speed. Once the A/C is turned off it should de-energized. This mainly is for when the engine is at idle so the engine does not stall. If it continues to be energized with the a/c turned off then there may be a problem through the computer not telling it to shut off. If it stays energized all of the time you will have a fast idle

sofakingdom

iTrader: (1)

I hate to be a buzz-killer (well, maybe I don't, but...) EVERY WORD of Rhp's post is WRONG, as applied to our cars.

That solenoid has served 3 different functions that I know of, over the years.

In some cars, especially underpowered early 70s smogger motors with very slow late timing curves (one of the things that "emissions" specs did that nutted those cars so bad back in the day), the solenoid did in fact do that. By the mid 70s they had moved on from that.

In some other cars (I have a 74 Caprice 454 like this for example) the solenoid is active AT ALL TIMES that the key is on, and is used to set the normal curb idle speed. Then the idle stop screw on the side of the carb is used to set the idle to some lower value, like 400 - 450 RPM. In that design, it was intended to stop run-on or "dieseling", another major shortcoming that plagued 70s cars, when the key was shut off, by allowing the throttles to close so far below normal idle.

In our cars its function is primarily a "soft" throttle return. When you pop your foot off the gas and the throttles slam shut, vacuum goes VERY high, and since the idle system delivers fuel in proportion to vacuum, that causes a VERY rich condition that results in a YUUUUUJJJE blast of unburned fuel out the exhaust (hydrocarbons and CO emissions) every time that happens. Stick-shift cars IN PARTICULAR are bad about this since that condition happens every time the gears are shifted. In fact I suspect, although I have no way of knowing for sure, that this is THE ONE emissions parameter that prevented a 350/T-5 combo from ever being offered in our cars... no way to get that managed well enough to get it emissions-certified. The solenoid is under control of the ECM, and holds the throttles open (idle speed higher) until the engine RPMs drop down to some moderate point, under these conditions; should be something in the 1300ish range (don't know the exact RPM but it's somewhere near there). Its proper operation then is, hold the throttles open to raise the engine RPMs to 2500 or so (some sort of cruising type speed); let off the throttle quickly; the solenoid should pop out and hold the linkage up a bit, until the RPMs fall to the ECM's set point as described above; the ECM should then drop the solenoid out, allowing the throttle to return the rest of the way.

It DOES also operate at all times when the AC compressor is being called for, even if not necessarily on: if either the low-pressure cutoff or the high-pressure limit turns the compressor off, the solenoid will still be operated. But the AC function is totally secondary to the soft throttle stop one. Furthermore the connection for the AC operation is simply hardwired from the compressor control line, and is not under control of the ECM.

It's an emissions device, not a "convenience" of some sort, in our cars.

naf

iTrader: (7)

the bump solenoid will energize with AC and during deceleration.

first check your TPS voltage. if the TPS has failed 'high' the ECM will not command the bump solenoid 'off'. when this failure occurs, the bump solenoid will not engage upon start-up until the motor reaches a set RPM, then it will engage and not release.

if your TPS voltage is correct, start trouble shooting the AC switch.

naf

iTrader: (7)

and, at least for some 87 LG4s, the bump solenoid is engaged by a low pressure switch on the power steering line. this feature is not installed when AC equipped but the wiring connector can be found next to the gear box.

AC equipped cars route the power that engages the compressor through a normally closed power steering pressure switch.

gotmud7

Could you explain the "dieseling" part better? My 86 with the E4ME diesels. I just got it and it drives my nuts. I was reading this post to better understand the actions of the Idle Solenoid.
Thanks

naf

iTrader: (7)

the idle solenoid should not be engaged at idle except when the AC is on, providing everything is functioning correctly.

dieseling, or run-on, is typically caused by a throttle that is open too much at idle. a vacuum leak allowing in excess air can also lead to run-on. both of these issues also typically cause a higher idle speed than specified (around 600-650 depending). a poorly running engine (timing, fuel mixture, etc.) can have a low idle speed AND still have too much throttle opening as the throttle must be opened more to account for the mis-tune.

if your idle speed is above spec when it runs-on, find out what is keeping it up. if the idle speed is normal and it still runs-on, chase the tune.

sofakingdom

iTrader: (1)

= "run-on"; where, when you turn the key off, the engine keeps on going anyway, roughly and slowly and unevenly and making a bunch of spark-knock sounding racket that somewhat resembles the sound of a diesel engine, sometimes even eventually turning backwards and blowing a cloud of fuel out the top of the carb at which point of course it stops

As naf says, usually caused by the idle speed being set too high; hence the "cure" for it in certain early-mid-70s applications by way of a similar solenoid, which in that system holds the idle speed up to "normal" and then drops the throttles farther closed when the key is turned off. But that's not how it works in our cars. Read and understand post #11.