Bogging at 4000 rpm

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DARK STAR
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Bogging at 4000 rpm

Post by DARK STAR » Tue Nov 14, 2017 10:46 am

Found it!
BUT before I mess about with something that hasn't been touched for 25 years ...

Is it possible that the problem is in the distributor cap, bearing in mind that the collapsed gearbox mount had jammed it hard against the bulkhead ... :?:
I have had the thing off once but only gave it a cursory inspection, could it be deformed/hairline cracked?

It's rather inconvenient having two faults at the same time, the relay certainly needed replacing but hasn't provided a full cure :roll:


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Bogging at 4000 rpm

Post by AJL Electronics » Tue Nov 14, 2017 10:53 am

You need to set the throttle plates, that is what 25 is telling you. The plates have been moved to set the idle speed which is wrong and so has thrown up the error because the throttle pot can see that it is partly open at rest.

You could have an issue with the distributer cap of course, but deal with what you know first.


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Bogging at 4000 rpm

Post by DARK STAR » Tue Nov 14, 2017 1:06 pm

OK but I know the throttle plates have not been touched since the motor was installed, and it worked very well until recently.
The idle speed (cold or hot as Phil says) has always been around 1100 rpm so already not correct 8)

Meantime I had a rummage and came up with not one but three distributor caps :shock:
On the left 2,9 as on Dark Star, middle 2,9 with male terminals wtf, on the right 2,8.

I also have a genuine Coupé speedo if anyone needs one, very clean and I would check it works before selling!
And so many gaskets for which I have no idea of the use.
And a trunnion, and, well you get the idea.

EDIT - middle one is a 2,8 injection distributor cap, no idea where that came from
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Bogging at 4000 rpm

Post by DARK STAR » Tue Nov 14, 2017 8:32 pm

I managed to get my brain into gear briefly.
It can't be the throttle plates whatever the fault code reader thinks.
It is something that has gone wrong gradually and not completely.
Looking at the throttle position sensor I notice a vacuum tube to/from the fuel pressure valve, adding another possibility :roll:

1/ distributor missing under load
2/ TPS not reading correctly
3/ fuel pressure regulator not passing enough fuel
4/ fuel filter blocked
5/ fuel pump tired

Any other thoughts?


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Bogging at 4000 rpm

Post by AJL Electronics » Tue Nov 14, 2017 9:00 pm

DARK STAR wrote:
Tue Nov 14, 2017 8:32 pm

Any other thoughts?
Sort out the issues that you know about, before going off at tangents.


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Bogging at 4000 rpm

Post by DARK STAR » Tue Nov 14, 2017 10:02 pm

I have read and re-read the Ford manual and the Haynes manual, they disagree on many points.
One interesting point from Haynes is that on a 2,8 injection engine, fault code 25 = TPS voltage too high.
I know mine is a 2,9 - but I'm not sure what is the 'knock sensor circuit' that they list for this.
Oh and Haynes differentiate between 2,9 catalyst and non-catalyst motors.
Haynes say you should blip the throttle when you receive the code 10, Ford don't.
One thing they agree on is that it 'can' be useful to bridge the input terminal to earth (though Ford know there is an extra terminal for this, Haynes don't :wink: )
That doesn't seem very logical but anyway I tried it and it doesn't change anything.

Haynes mention that the throttle plates can be reset by the ECU but that bit is completely beyond my comprehension.
Anyhow, as I've said, the throttle plates have not been touched since the engine was installed and they have been ok for 25 years ...
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Bogging at 4000 rpm

Post by DARK STAR » Thu Nov 16, 2017 7:29 pm

Huge advance today, thanks to Peter who sent me an article on exactly this subject which I can understand ;-)

I noticed immediately that according to this source ’there is no knock control’, whereas the Ford manual says fault 25 is the knock sensor circuit.
There is so much conflicting and incomprehensible information on the subject, I bet Ford garages just keep fitting new parts until it works.
Andy insists I should adjust the throttle plates but the article says the throttle stop (which is a lot easier ;-)

It looked as if the fault might be in the vicinity of the TPS so with this article I checked the voltages to see what’s going on.

It is the first time I have understood the instructions in this long-winded affair and they are spot-on.
It says that a fault code reader is of limited use … mind you it did come up with 25 which is the correct fault code - for a 2,8 :roll:
Anyway, the voltages check out with a smooth transition from 0,70 to 4,46 (near enough to 4,50 ?)
So the TPS is favourite, though there is also the vacuum pipe and probably other things that might be at fault.
Didn't someone say ’TPS’ at one point ?
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Bogging at 4000 rpm

Post by Coupe Racing » Thu Nov 16, 2017 10:06 pm

Coupe Racing wrote:
Sat Sep 23, 2017 6:30 pm
Just flicked through this and don't have time to read it all .

Has the fuel pressure been checked at the entrance and exit of the fuel rail
Have the injectors been removed and the spray pattern checked
Has the door opening electrical path been checked via an oscilloscope to check for breaks in the track inside the air flow meter
Is the throttle position switch reading full throttle
Didn't someone say ’TPS’ at one point ?

Yes I believe so on page 7 of the post :D


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Bogging at 4000 rpm

Post by DARK STAR » Thu Nov 16, 2017 11:02 pm

Nice one Steve :mrgreen:


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Bogging at 4000 rpm

Post by toolmanchris » Fri Nov 17, 2017 9:14 am

Will it run with the TPS unplugged to test your theory?


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Bogging at 4000 rpm

Post by toolmanchris » Fri Nov 17, 2017 9:16 am

Also for the TPS, stick a pin in the centre wire and measure the voltage - should go from about 0.7 Volts up to 4-5 with the throttle pressed.


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Bogging at 4000 rpm

Post by DARK STAR » Fri Nov 17, 2017 5:43 pm

Haven't tried running without the TPS, should it work?
Voltages as above, 0,70 - 4,46 which seems ok.

Looking at TPS available I cannot believe the Jenvey offer by Burton's at 81,41 sterling is worth the money, even if there is a wiring loom with it (which I don't need).
On the other hand, the Mobiletron at 26,53 € is probably a chinese reject.
Next up is the Ridex at 36,63 €, also sold under a different name at about 45€.
Or should I lash out on a Metzler at 67,27€ ?
Anybody know these items please ?
TPs 81,41 livres.jpg
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tps 67,27€.jpg
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Bogging at 4000 rpm

Post by toolmanchris » Mon Nov 20, 2017 8:54 am

Not sure if it will run with it disconnected, some cars will some wont but I don't think you would brake anything if you tried it.
Was the move from the lower voltage to the upper a smooth transition when you moved the throttle plate or did it fluctuate?
If it was smooth then I would say that this is not your problem :)


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Bogging at 4000 rpm

Post by DARK STAR » Tue Nov 21, 2017 8:34 am

Trying to work simultaneously on two cars with ECU issues I am as usual getting confused (see Two Scimitars and a Calibra thread).

This one will start and idle with the TPS disconnected, the engine will not turn any faster under any circumstances.
The voltage transition seemed smooth but it's difficult to tell when you are lying in the passenger footwell with an ECU and voltmeter in one hand and a long stick to push the accelerator pedal in the other :lol:

Just for fun I tried disconnecting the idle speed module.
This lowered the idle speed by 100+ rpm, the car runs exactly the same but idles at under 1 000 rpm, which is a novelty.


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Bogging at 4000 rpm

Post by toolmanchris » Tue Nov 21, 2017 10:31 am

Could this be the cause of your high idle speed ?

https://www.ecrater.co.uk/p/26171037/id ... -iac?gps=1


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