S2/S3/S4 2.9 Engine Diagnostiics

[tvrgit]

Chaps

I found an old workshop manual for the Granada 2.9 I had years ago, and tucked inside was a photocopy of an article from "Car Mechanics" February 1995. I remember following this through at the time with a voltmeter to try to find why the engine was "surging" and managed to diagnose that it was the ISCV at that time.

However, this article specifically mentions surging and uneven idle as a well known problem, and the areas to look at, mainly the ISCV, throttle pot and a diode in the wiring loom alongside the plenum chamber.

It also explains about disconnecting the throttle pot (not the ISCV as I have said before) to get the engine into "service" mode for adjusting timing etc.

The article is available for download on my web site. It's not great quality, it's a scan of a 15-year-old photocopy, but it's perfectly readable:

http://www.andrewc.org.uk/tvrgit/ford29diagnostics...

Edited by tvrgit on Monday 18th January 18:48

[MCS4]

Thanks for this Andrew, my S4 has been 'playing up' recently so I have printed off a copy.

AS you know I live just up the road from you, I will let you know how I get on at next Scottish TVR meet

Regards
Michael

[jimed]

What an interesting article - now printed and in with all the rest of my 'useful stuff'. The bit about the throttle pot disconnection for 'service mode' is interesting as I'm about to have a go with the timing of the S3C and was wondering why the change in timing on Tony's car hasn't made as much difference as I would have expected; perhaps that is the answer. I'll post the results with the timing at 15btdc when I've had a go - it'll be next week though now unless I can get hold of the strobe earlier ...
Jim

[tvrgit]

Mike

I was going to bring you a copy if you didn't see it here - I think it's worth working through for the problem you've got, I'm going to do the same.

I know you're away this weekend, but oif you need a hand, let me know.

[MCS4]

Hi Andrew

Thank you, I have now read the article, sounds like it could be very useful, a good find! I too will have a go. (Andrew, I may need your help!, I will have a go next week and let you know how I get on) I also will post the results.

Cheers

Mike

[Jed-S]

tvrgit said:

It also explains about disconnecting the throttle pot (not the ISCV as I have said before) to get the engine into "service" mode for adjusting timing etc.

I tried this today and it does appear to achieve the same result as entering service mode. The strobe showed rock solid timing at 12 degrees.

[tozerman]

Nice one, when I recently reset my timing (which was about 6 degrees over advanced) it did not make any real difference which might be due to the fact that I didn't put the car in to service mode, I will have another go and see how I get on.
Also the way it explains how to set the throttle stop is a real help, how many of our cars have it set properly with a voltmeter on the throttle pot ??
can't wait for my next day off now so I can have a play1
Cheers.....Tony..

[tozerman]

Couldn't wait until my day off so last night I thought I would have a go at setting the throttle stop using the method described with a voltmeter, the first thing which was tricky was exactly where to connect my meter to!! what I had to do was strip a bit of wire bare so I could connect my meter to the middle wire which is green and brown on my car, the range read from 0.51V to 4.7V. (the low reading might explain the sometimes jerky low speed running)
I adjusted the throttle stop screw and stopped it at exactly 0.6V, it then went up to 4.55V at full throttle, the only concern is thet I had to screw the throttle stop about 1 turn in thereby possibly raising the idle speed outside the parameters of the ECU, If I get time tonight I will start her up if it is early enough and see how she goes, while I am there I will check the timing with the throttle pot disconnected this time and see what happens !!!
Cheers.....Tony..

[tozerman]

Started her up last night and just as I thought the idle speed was too high so had to back off the throttle stop screw, also when I went to disconnect the throttle pot to put the car in "service mode" in order to double check the timing the revs went right up to about 2000rpm !! all I can conclude is that it does not apply to the S3C.
Cheers Tony..

[jimed]

Just seen Tony's post but my experience in trying to sort the timing is different.
Just had a go this am; car wouldn't start/run when stone cold with throttle pot plug off so warmed it up and then removed plug. The revs dropped from the usual S3C tickover of 1k to 850 or so although a small bit of hunting. The strobe was steady but the timing appears to be well over 20btdc and maybe even towards 25!! Despite that the car isn't going badly (just not quite well enough I suspect) so I wondered if I was missing anything here as last people to have a go with it was TVR when they fitted a new T Pot some time ago and they set if up as far as I'm aware on their STAR tester. Had a ponder and decided to try 15btdc but even after slackening the bolt on the dissy clamp on the drivers side the dissy won't move and can't see another bolt; quick poke around didn't show another bolt so all is stopped for now. (I've deleted some of the old post here as superceded by info from Tony re right bolt so will have another go later when I can see how to get at it) - in the meantime I'd also welcome any thoughts re how it seems to be so far advanced and yet no sign of pinking at all ...
Jim

Edited by jimed on Thursday 2nd October 11:43

Edited by jimed on Thursday 2nd October 13:02

[mikee boy]

You'll only notice pinking when the dizzy advances with the car under load, and I'm not sure how obvious it'll be in such a noisy car anyway. Pinking can easily destroy pistons so be careful and keep an eye on the engine temp too.

[jimed]

Had another go this afternoon and set at 15btdc - result it was awful:
- tickover a lot lower
- very hesitant
- hardly any go at all
- the above after a drive of a few miles to see if the ECU learned it all. Came home and had a go at setting it back to near where it was before - difficult as it was off the top end of the scale but guessed a bit and the tickover was so much smoother in service mode so decided to try that. Tightened the dissy up and it stopped and wouldn't start. Looked around and one of the connectors had come off the coil - mine has one of the funny square coils on it - couldn't see where to connect it, as the connectors are in an oblong box on the side and you can't get to see inside, so got a mirror out and found the spade had got bent in (how did that happen - must have been with the pulling about to get at the dissy bolt!) so straightened it and reconnected and all well so had another run - the car was hot (fans on/off) and it pulled like a train far better than before. I've no idea what it is set at but it does seem fine so in the absence of a better idea will leave it at that - very strange!!
Jim

[mikee boy]

Keep an eye on the temperature as hot running can indicate incorrect timimg (advanced OR retarded).

[jimed]

It was fine on the move as per usual and at the normal temperature so no sign of anything there - the fan only came on in the garage when it was sat there ticking over whilst I was fiddling with the timing. If anything I suspect it may be a little retarded from where it was before which would help with the cooler running I suspect although that has not been an issue before; as you suggest Mikee I'll keep an eye on it anyway.
Jim
Later: I've been wondering why the timing should be so off the scale and wonder if it could be the strobe? The one I've used is a Gunson with an adjustable setting which is supposed to allow you to slow and stop the light in a prism thing on the side - a line was supposed to move in it (as per a record turntable) and the idea is to stop the line and then its synchronised to the engine speed; this didn't seem to make much difference so I set it on the lowest rev range and the flash was steady - but could the adjustment/lack of cause an offset?? Has anyone any experience with one of those?

Edited by jimed on Thursday 2nd October 20:20

[tozerman]

Hi Jim, I used to have one of those, it's called a Gunsons Tachostrobe,a and the prism thing on the side is purely to set the engine rev speed at idle, in my experience that part of it never worked properly my advice is to forget that bit and just use it as a timing light only and you should be ok. If you are struggling to know where you are timing wise why not just set it with the throttle pot connected
(like I had to do)? and you should then gain control of the static timing from there.
Sorry I havn't replied to your email jim but I got it just as I was finishing work, I will be back at work on Tues. good luck with your tinkering over the weekend.
Cheers.....Tony..

[jimed]

Hi Tony - the timing was really strange - with the throttle pot connected it was about 12btdc or so but disconnect it and it flew up to over 20btdc. I did use the strobe as a timing light having wound it right back to the low end of the rev scale on the side and it appeared to work fine but I can't understand why it all changed so much when it was in service mode. There isn't a vacuum advance or anything else I should have disconnected is there - not as far as I'm aware but then maybe I'm a bit ignorant about that? I'm still puzzled as it was certainly going very well after my reset to approximate where it was before (which was off the timing scale on the engine); it would be nice to know what it is though and why it should appear to be so far from what it should be as 5+ more advanced from what it should be (or so it appears) is what it was at before as well and it had been set up some years ago and not touched since - can't believe its moved itself so much either.
Jim

[tozerman]

Hi Jim, back at work now, I think we are both missing a trick somewhere here ref service mode, what I am going to do is to have another go at the throttle stop setting and time the car at 15btdc with the throttle pot connected and leave it at that until I can find concrete info on how to do it properly or possibly get a code reader/service mode thingy.
Cheers.....Tony..

[jimed]

The timing on mine is still as I left it at the end of last week and it does seem fine - I'm hoping to go to Oulton on Saturday (anyone else going?) so will be able to give it a better run then.
Jim

[Roy C]

jimed said:

I'm hoping to go to Oulton on Saturday (anyone else going?)

Yep. Coming up from London.

[jimed]

I said I would update where I was with the timing after the last fiddle. Recap - setting it in service mode (Throttle pot disconnected) and to 15btdc (this effectively retarded it by a large chunk if method is correct) the performance was terrible so had to try and set it back to near where it was before which was difficult as off the engine timing scale so set it where I thought was the previous but maybe a little bit retarded and it seemed to be OK but only a very short trial. So last Saturday off to Oulton Park - I have to say it is running much smoother when cold or hot with no hesitation (which was an occasional thing before) and in cruise on the M6 foot was fairly well backed off or so it seemed. So overall I'm pleased with it as it is running better but still don't know how to set it correctly as the S3C does seem to be different to the S3 from what I can see in terms of service mode but the timing does seem to be about 13/15 btdc (little bit of a range on tickover so need to clean the idle valve I think) when idling normally with TP connected. Hmm! All very strange.
(As an aside Roy said above that he was going to Oulton. He was there but left soon after the last race and I didn't get to meet up but from an email contact he said he left London at 5.30am to get to Oulton but had to get back for the evening so had to leave smartish. He also said he had the roof off until he was nearly home and had to give in to the relentless rain - what a star!!)
Jim