Over revving and other issues

[TristanC]

Check on all those 5 items Chris. Thanks for that.

I also removed the micro switch to be sure it was operational... and it was.

I’ve read that it could be no resistance on the thermistor, which is in the depths of the valley.
But to test it you do something with “white plug to the idle ecu”

Now I am not sure what white plug. There are 2 on my idle ecu and 3 in the fire wall.

Oh well...

Mine is at 2100 rpm hot or cold......

[TristanC]

So I was rechecking the idle speed motor. And whilst there is power to it and it is buzzing - could it be sticking? I tried tapping it, but nothing happened.

I read on DMC talk that you can test the resistance as follows:
“Another way to test the idle air motor is to measure the resistance with your multimeter. A good motor should read +/-20 ohms resistance between any two pins that are next to eachother and +/-40 ohms resistance between the two outside pins.”

Now I get 12ohms and 22 ohms. Does that mean my motor needs replacing?

Who knows. Either way I’m laying the car up until I can resolve it. It’s not great driving at that high an rpm. It just keeps wanting to pull when you don’t want to.

But now I am stuck and confused as to what changed......

Bummer

[Rissy]

I've not measured my idle speed motor pins, i'll admit, but i have a new idle speed motor on there, which to be fair, i put on suspecting my idle issues were related to my original idle speed motor, but now i'm not so sure. I could measure my pins and report back, for BOTH my motors. I could also try putting back my original motor again, and see what happens, but to be honest, i've already proven that the whole mechanical leverage on that butterfly assembly is MY sticking point of concern, and it's THAT which needs to be resolved.

If you pull your idle speed motor off the pipe work and look into the air flow nozzle, you can watch the valve rotate inside according to turning on the ignition and starting the engine. If you also try gently pushing the valve closed before you start, then you know that it's got to open when starting from cold. Over the course of warming up, it should slowly close that valve more and more. So this is a good visual check to see that your valve is operating at least mechanically. I did all this years ago when i was determining a sticky valve, which i then corrected with carb cleaner and a good shaking (years before i had my high idle issue). This is why i bought another, in case it had become damaged. As i say though, now i suspect it's still fine.

[TristanC]

Hi Chris,

Well, I’ve just had some advice from the FB group about disconnecting the cable from tbr idle speed ECU to see if that increases the RPMs even more.
I think to test if the ECU is working.

However, the car didnt want to start. I reconnected it and still didn’t  want to start, without a pedal in the carpet and then she started.....
What I had forgotten is to reconnect the idle motor from my previous investigations...... but guess what?
She idled around 800 and crept and steadied at 1000. Not perfect..... but a damn site better!

I then shut off, reconnected the motor and boom, same high idle. Proceeded with the original ECU disconnection (cable nearest the centre of the car) and she shot up to 2500 rpm....

So for me at least it seems like it “could” be the idle motor...... I’ll wait to see what the FB crowd think of it.

I’m not sure if any of what I’ve performed will help you in any way, but thought I’d report back as I go.
It does seem that your issue is elsewhere, but you never know....

Cheers
Tris

[Rissy]

Right, I've taken some measurements for you. Incidentally, you can tell what it is you're measuring. It's basically just two windings joined together with a centre tap. Energise one winding and the motor opens the valve, and energise the other winding and the motor closes the valve. So measure across the two windings at once and the result is just the sum of the two individual windings.

so here's my results.

For my original motor:
9.7ohms
10.8ohms
20.4ohms

For my replacement motor:
22.5ohms
24.1ohms
46.5ohms

I'd say if you're measuring something sensible, electrically, then the motor is probably ok, electrically. You could do as I said before to check good movement. You could lubricate it and clean it up a bit by spraying some carb cleaner into it and giving it a shake a few times and check again if you're not convinced. Next check is to start checking the plug feeds to the motor.

[TristanC]

Great stuff - I’ll try cleaning it as my next step.

Thanks Chris - appreciate it

Tris

[Rissy]

Well, after taking some measurements for you last night, i was left inspired to look into my own idling issue again last night. I know that my idling issue is not the same as yours, but it's maybe still an area you should check to make sure.

Last night I took off my throttle body. I literally had it in my lap. I took the throttle arm off (removal of the stover nut), and pulled the spring from it. I did indeed have some deformation in the profile of the spring, meaning i think it was a bit too relaxed. The spring was also gummed up with lots of gunk and dirty with age. I thoroughly cleaned all that up by literally going right round the entire windings with a fine wet and dry paper and brake cleaner. I decided this time to leave the spring dry and clean rather than grease it up again. I also gave the spring a bit of stretch out to help correct some of the deformation.

The other thing i noticed was that the idle speed microswitch arm was bent slightly inwards. So i gave that a bit of a slight bending back out the way again. Not too much, just enough to make it look straight again.
I then assessed the rebuilding of the arm piece by piece.
I had actually bought a new arm earlier in the year, as my original's ball joint was all loose and wobbly, so now that's been rectified. The other thing was that due to the nature of the squared hole in the arm, slotting over the M8 threaded spindle where the stover nut winds down, there was seemingly a bit of play in that, meaning that there was movement of the arm whilst being pushed or pulled by the throttle spool link arm, BEFORE any movement from the butterlies themselves. I rectified this upon rebuild by applying a serated locking washer, then instead of reusing the stover nut, i just used two thin M8 nuts in its place, first one to tighten right down on to the locking washer, and hold the arm tight and still in one place wihtout any loose waggling this time, and the second to lock off the first in place so that it couldn't back off. I'd like to have just used a nyloc nut, but it seems i either couldn't find one in my stash, or i don't actually have one. So i may still replace my double nut setup later in time with a nyloc once i have one. For the time being now though, this will form a good test.

Next, was to get the two adjustment screws in place properly. Holding the butterlies completely closed, I then wound down the bottom screw to touch the plate, but without pushing the butterflies open. locked it off. Then, continuing to hold the butterflies closed, I then wound in the top screw to the point where it was only JUST clicking the microswitch and no more. Locked it off. I then tested moving the arm back and forward against the newly cleaned spring force to make sure that the butterflies were free moving to full open position, and rested back at fully closed position, AND clicking the microswitch.
Once happy, i put the whole lot back together again on to the engine.

The adjustment arm and throttle spool came next.

It's a bit of a process to adjust both of these, but i did the link arm first. Made it the length so that I was sure the recoil action was still pulling back to make sure that microswitch was being clicked.
Then, i moved to the cable tensioner and adjusted that. The way i've left it, i've proven i can get the butterflies completely closed and the microswitch clicked, (but it's not at the idle end stop), and I can also get full gas right up to the end stop with the accelerator pedal. For idle, it's about 3-4mm shy of the end stop. I could relax off the tensioner more if I wanted to, to allow that contact, but that means i may not then get full gas at the end stop at the other end of travel for the pedal. I'm happy though, because even if the idle is not right at the end stop, i know for definite my butterflies are fully closed and the idle speed microswitch is clicked in.

I quickly ran the engine to test it (it was getting late and dark by this point), and it all seemed good. Engine idling again at about 870-900rpm, even with quick and slow release off the pedal from giving it some gas. Everything seems a lot more solid and purposful now. Before, it was all loose and floppy and waggly in nature. Not now though. So i'm quite pleased with a few hours efforts last night.

The real test will be to drive the car tomorrow morning to get everything fully warmed up and see if the idle continues to behave itself through all the thermal expansion stages of cold to hot engine. I'll report back and let you know how i've gotten on (feeling postively hopeful this time though. I think it really needed this sort of attention to do it properly).

I know my adjustments may not be necessary on your car for your idling issue, but if you exhaust everything else, then maybe you'll have all this to consider looking into as well...?

[Chris Williams]

Nice write up, well done. You should have taken some pics at the same time for a magazine article.
Chris

[TristanC]

Wow, yes excellent !

I’ve got a few more things to investigate before a tear down like that.
(Pipe of agony is loose on mine)

Sounds like you may have sorted your issue - let us know how you get on

Tris

[Rissy]

(10 Aug 2018, 09:30)Chris Williams Wrote: Nice write up, well done. You should have taken some pics at the same time for a magazine article.
Chris

Yes, i'll admit it's always an after thought with me. But also, until it's proven to be successful, then there's no point doing a write up on anything. Then if proven successful, but if you haven't taken photos, then do you really want to be upsetting the fix to start again for the sake of taking the missing photos!? Maybe i just need to be more proactive in taking photos as I go along, "just in case".

---

(10 Aug 2018, 09:46)TristanC Wrote: (Pipe of agony is loose on mine)

Surely you mean "Pipe of Pain" ;-)

[Rissy]

Just had Lexi-baby out for an extended spin (to Coventry B&Q and back home, which is a round trip of about an hour or so, including a couple of stretches along the M6).

Sooo happy! She's driving like I used to remember all those years ago again! No high idle, no sticking, no over fuelling, or under fuelling. Just perfect!

I can finally say, it's fixed!

[Chris P]

Good for you Chris.......I'm ok with a big hammer or cleaning stuff up, but that would be too fiddly for me to get right!

[Nick H]

Nice one Rissy!    

Same here with LJH, Took her out for a run today, no problems  .

Don’t want to jinx it so enough said  .

Nick H

[TristanC]

Glad to hear you’ve resolved the issue after all that time Rissy.

Unfortunately for me, I may have a long road to travel myself to resolve my issue. 
The “pipe of pain”   is now located properly (rather easy) and it’s still high revving.

Something is making the revs increase. As I say when the idle motor is disconnected, she idles normally.
So something is telling the idle motor to open and therefore increase RPMs.

People tell me vacuum leak - but I can’t find one..... also still quite a coincidence that this all happened when the AC belt started to play funny beggars with me.....

The search continues......

[Nick H]

(11 Aug 2018, 23:46)TristanC Wrote: Glad to hear you’ve resolved the issue after all that time Rissy.

Unfortunately for me, I may have a long road to travel myself to resolve my issue. 
The “pipe of pain”   is now located properly (rather easy) and it’s still high revving.

Something is making the revs increase. As I say when the idle motor is disconnected, she idles normally.
So something is telling the idle motor to open and therefore increase RPMs.

People tell me vacuum leak - but I can’t find one..... also still quite a coincidence that this all happened when the AC belt started to play funny beggars with me.....

The search continues......

Tris, 
Sounds like your getting nearer to the source of the problem. When you say idle motor disconnected. I take it your just pulling the electrical plug off the top? 

The idle motor provides a route for air to enter the engine when the throttle plates are shut. 
So it’s possible your getting unmetered air from somewhere else which is enough for the engine to idle correctly. If you connect the idle motor it’s also trying to add air and the engine idle’s to high.

Also have you been testing with the AC on or off? Bare in find that the heater/AC is all vaccum controlled. So if it idles high with the AC on you could have a leak in the control hoses/mode switch. Do you hear any “hissing” in the cabin?
Vaccum hose diagram 

Check the charcoal canister inside the pontoon. And the connections. One of them is supposed to blanked off (see diagram in link).
 I’m suspicious of that area as one of those vacuum lines was disconnected. You may have had a P.O. playing around in there before.

Another check is to make sure the 3 brass screws and throttle body are snug. 3 brass screws

Nick H