Over revving and other issues

[TristanC]

Well I’ve covered 430 trouble free miles in 11477..... but today that changed.

First some background, as I think it’s related to the over revving.

I finally found somewhere to regas the car with a drop in gas.
Amazingly, the AC kicked right in and the system was blowing cold.

That was yesterday.
Fast forward to today, where I took 11477 on a 90 mile round trip.
As I completed the first 45 miles smoke started to billow from the rear.
I immediately stopped to inspect - but it was NOT overheating. It was in fact the AC belt being shredded and covered my engine bay in rubber.

On inspection the compressor pulley is not aligned with the lower pulleys. It looks like the garage overtightened the belt or bent something?? What should I look for to get that sorted?

NEXT issue is the main one.... over revving to 2100 rpm ALL the time. Now this only started after the AC belt issue above. Has the AC system enabled something to increase revs that is now stuck??
I’m stuck, and am not sure where to look first......

NEXT issue is the speedo. It stopped working on my journey home with just 5 miles to go.
I could hear ticking coming from the speedo before hand and it started bouncing a little.
When this happened in the past, I pressed the trip reset and pulled back out and it resolved it. But not today. Instead, the speedo just stopped working in its entirety.
Could the trip reset have broken something inside the binnacle?
The lambda box connection looks good as does the angle drive at the wheel.
I hope it’s not the angle drive..... 

On the plus side I’ve now covered 500+ miles and all is relatively well with 11477.....

Tris

[Chris Williams]

Quote:On inspection the compressor pulley is not aligned with the lower pulleys. It looks like the garage overtightened the belt or bent something?? What should I look for to get that sorted?

Possible it was over-tightend but may be one or both of the idler pulley bearings have failed. Cant think what would be out of line.

Quote:NEXT issue is the main one.... over revving to 2100 rpm ALL the time. Now this only started after the AC belt issue above. Has the AC system enabled something to increase revs that is now stuck??

I’m stuck, and am not sure where to look first......

Odd, are you sure it's not just old bits of belt stopping the return on the throttle spool thingy, or bits elsewhere. Cant see re-gassing the A/C would affect the revs in any other way. I think it's more likely to be belt related myself.

Quote:Could the trip reset have broken something inside the binnacle?
The lambda box connection looks good as does the angle drive at the wheel.
I hope it’s not the angle drive.....

Possible but doubtful
Try disconnecting the input cable from he lambda box, with the front wheel jacked up spin it and see if it (the cable) turns freely.
Chris

[Nick H]

As Chris has stated these are all likely common faults apart from the high revs.
Double check none of the wires to the idle micro switch are damaged or have disconnected.
Most likely some rubber jamed in the throttle mechanism.

Nick H

[Chris Williams]

This is the A/C belt you need BTW: https://www.ebay.co.uk/itm/Gates-Alterna...SwKRJZb3iI

[TristanC]

Thanks very much guys.

I’ll be on it today. It was a new AC belt too....

I can’t see a regas being related either.... just a coincidence when it chewed the belt.

The throttle spool is freely moving and seems to be clicking back to position. But will be investigating today.

Cheers
Tris

[TristanC]

Angle drive is still in working order, except for the wire that goes through the hub!
That’s sheared in two, leaving part of it in the dust cover.
Can that be repaired? Seems a shame as the angle drive turns freely.
I also hand turned the remaining cable and it still moves the speedo. So all good there.

On further inspection of the belt, it looks spot on with regards the pulleys. It seems the belt itself has a kink in it making it look out of alignment. So new belt and I’ll tighten it myself. Lol

Engine idle...... I’m still at a loss there.
No rubber is gumming anything up. The spool turns freely and the micro switch is clicking and all wires connected. That’s not say it hasn’t failed of course.
The idle speed motor is getting power and I can hear it buzzing.

I’ve read about testing the thermistor...... but I must admit I do not know how to go about that?

Thanks again,

Tris

---

So, back to the belt.......

I actually think it’s just come loose..... just restarted the car, turned AC on and the burning rubber is the compressor not getting a grip on the rubber belt, it’s just slipping!!! Doh.

[Nick H]

Tris, Just has a thought. Check the idle speed thermistor connection.
It’s the sensor in the side of the water pump. It’s right in “the line of fire” of the
AC belt.

Nick H

[TristanC]

Hi Nick,

I think I have the right connection. All seems fine to me.
Unless the themister itself has packed in?
I disconnected it and started the car and it was the same high idle.



Cheers
Tris

[Nick H]

That looks ok. Worth a try.

Nick H

[Nick H]

Tris,
Re-reading your initial post. The fact that the car is reving to 2100 rpm. Sounds like a vacuum leak.
Just behind the area shown in your photo a vaccum line runs from the charcoal canister to the throttle body. Is it still attached or damaged?

The speedo drive wire that runs through the hub is replaceable on certain aftermarket replacement speedo drives. My only thought is what caused it to fail? Normally the gears jam and the wire is sheared.

Nick H

[TristanC]

Hi Nick,

The vacuum hose from the charcoal canister hasn’t been connected since I had the car.
I only recently found out what that hose was supposed to connect to.
I’ve not put it on as yet. 
It’s been idling perfectly until yesterday without that connected...... do you think that the extra load of the AC compressor has made it relevant?

Is it difficult to connect? I couldn’t figure it out earlier lol !

With the cable on the angle drive, I’m guessing something further up the line is jamming, because the trip hasn’t never liked going past 99miles and I also used to get a “ticking” in the binnacle and the speedo would bounce, until I reset the trip or fiddled with the trip by pushing in and out a couple times.
Is there something in the binnacle around the trip itself that’s causing a “snag” maybe?

Cheers
Tris

[Nick H]

Hi Tris,

          That’s interesting. It’s a bit tricky to attach. If you look at the curved horn pipe on the left of the intake. You can just see the white label on the vacuum line in the picture. There is a little spigot under there that the line pushes on.


   


Reference the speedo drive. It might be the speedo if everything else checks out. Dash is not that hard to remove but it’s a bit awkward to do laying on your back. The drive cable has a little spring clip that you have to push to remove the cable from the speedo. 

Nick H

[TristanC]

Ok cool - I have something to aim for to get that back on. See if it helps.

Now the angle drive is out, I’ve manually turned the cable and it activates the speedo needle as I turn.
Doesn’t seem to be any resistance. But perhaps now my trip is reset, the resistance has gone.

Oh well, she’s laid up for a wee bit now while I get these jobs sorted. No stress.
(Perfect time to remove the seats for my leather guy to restore...) 

Thanks Nick, appreciate the input and the pic there.

Cheers
Tris

[TristanC]

I took the horn pipe off to reattach the canister pipe.
But still over revving.

Just before all this and excluding the regas - she over revved at 1,000 when I stopped at lights. A quick blip of the throttle brought it back down to the 750 mark....

Would would make it stick like this and I stick at a throttle blip?
(This no longer rectifies the issue)

The search continues.....

[Rissy]

I've had a similar issue with my accelerator ever since i did my VOD work in 2015. I've been fettling with it, and had others, like Rich H fettle with it too - over the past 3yrs! Despite this, it still gets stuck. It's the best it's ever been now, but i'm going to continue to fettle until i can get it right. Right now, my accelerator gets "stuck", and revs at around 2,100rpm. Blipping the pedal brings it back down to about 950rpm-1000rpm (before 2015 my car used to idle around the 800rpm mark! - i just can't get it back like that at all). It's only an issue once the engine is warmed up. When it's cold, it's perfect. The problem that is being considered is that the spring behind the stover nut arm assembly is just not strong enough (any more!?) to retract the butterflies back to the fully closed position when it has even the smallest amount of force acting in the opposite direction. Even the pushing force from the idle speed microswitch when trying to be depressed is enough to stop the butterflies fully closing! It seems to be a new (or stronger) spring in there which is required, but the situation right now is that you can't get that spring separately, as it's part of the butterfly assembly. An expensive way to get your hands on new spring if you don't need the rest of it!

You can help your situation by ensuring the following (presuming all parts are proven to be working):
1. The idle speed microswitch is ONLY JUST made and no more when the throttle is at resting position.
2. The is NO push back to the arm to take it even the slightest minuscule amount away from the fully closed rested position
3. Your throttle spool is returning to the completely rested position (against the end stop) - this is tricky because you must also be able to get full gas position against the other side of the end stop when the accelerator is fully depressed.
4. Ensure the accelerator cable is clean and free moving inside the sheath from the pedal to the spool. No fraying at all, otherwise it could catch.
5. The three brass screws on the throttle body should be tight down.

Good luck and let me know if you find a trick that helps, because i'm fed up tearing my hair out over this. It's just ridiculously sensitive and needs infinite precision it seems to make it work correctly.