:: Diary - October 2013 ::

:: Sunday, October 6, 2013 ::

I had another wee run in the car earlier this week, just to see how it was running. The misfire has gone, but it's still hanging on to a high idle speed for a few seconds after you stop, then it drops to normal.

Anyway, today is TVR Car Club day, so as usual, it's off to meet with Jim and Dave - and Marcus too, in his wedge. After a bit of a blether we set off to follow a route that only Dave and I understand, because we use a code that mentions places more than 5 minutes from Jim's house.

Half-way through Inverkeithing, Jim's car splutters to a stop. Dave diagnoses the fuel pump relay, and just happens to have a spare with him, so we're soon on our way, to catch up with a shit-brown Kia toddling along at 45, and no chance of overtaking in the face of 45mph toddlers coming the other way. At least it's metallic brown (which reminds me that you can't polish a turd but you can roll it in glitter).

Eventually the Kia driver stops, so we can catch up to a dawdling Toyota Previa that takes a couple of miles to pass.

There are days where I am tempted to hand in my licence and get the bus. I don't remember there being this number of dawdlers a few years ago, there seems to be a law against getting within 15mph of a speed limit, and overtaking is a bigger crime than murder. Maybe it's just that when I was driving a variety of shitboxes before, the number of vehicles within my overtaking range were a lot more limited - but I don't think so, my 30-year-old record time for Inverness to Perth in a 1.2 Nova remains unbeaten (at least by me) to this day, despite using supposedly faster vehicles now.

We eventually reach the meeting, a wee bit late after our unexpected stop and funereal convoys, but not too late for food. Their attention to service the past couple of months is suddenly explained - they have now put their prices up. But at least you get a decent plateful, not the pretentious "designer cuisine" they were doing for a while.

Dave has unfortunately forgotten to take the trophies he won at S-Club and at Back Home in Blackpool, out of the car. This of course means that, despite his obvious embarrassment, people ask him about them, and he has to explain how his car won against stiff and close competition. He's almost relieved when the rain comes on, and I cover them with an umbrella to keep them in good nick for other future winners.

Then it's time for the drive home, through a bit of rain, bit of sun, lots of mist, wet roads, dry roads, you name it. No snow yet though.

I'll need to get to the bottom of this "fast-idling" problem though - even in third gear, you get pulled along in built-up areas faster than most people want to go (slower than 30 but too fast for some). I've checked all the mechanical side, so I'm sure it's something to do with ecu signals. It could be the cold start system, temperature sensor, ignition module, or the wiring or connectors to any of those. It could be a sticky idle speed valve (despite cleaning it twice) but my bets are on the favourites: either the throttle position sensor, or the MAP sensor.

I can't use my fault code reader because I discovered years ago that (1) the car has a non-standard OBD connector - most Ford looms used a 3-pin triangular connector, with only a few using a 3-in-line connector - guess which mine has?), and (b) the connector doesn't work anyway, as I discovered when I tried to use the "paper-clip and test lamp" method to read the codes (basically, you short two of the 3 pins together, and then use a test lamp on the 3rd pin to "flash" the codes. I got sod all.)

I don't want to do the "substitute and see" thing that most garages do, because those bits are fairly expensive. That might still be cheaper than taking it to a garage who might only "substitute and see" anyway, and charge me for the privilege. The oracle of spare parts procurement (aka ebay.co.uk) says that they are available at about £30 each, so maybe worth a punt, for less than an hour's garage labour… I could also test the TPS with a meter, to see if it reads evenly across its full range - what usually goes wrong with them is that the contact strip breaks inside, so you suddenly get a duff "zero reading" in the middle of a range of positives, so the ecu goes into meltdown for a second while it figures out that it should ignore it. BY the time it's worked that out, the sensor has moved over the broken bit back to a positive reading again so the ecu over-compensates, and it doesn't take long for the idle and acceleration settings to be all over the place.

So - test the TPS and if that's ok, change the MAP sensor. If that doesn't work then I think I might take it to the wee man in Edinburgh, underneath Edinburgh Waverley Station (almost), who has been tuning cars for 40 years that I can remember, and is apparently quite good at it. At least he might have a machine that the ecu will speak to.

:: Thursday, October 10, 2013 ::

Well today I got around to testing the throttle position sensor. This is what you do:

Unplug the connector from the TPS.
Push a pin down the back of the connector, between the centre wire and the rubber seal, so that it touches the terminal.
Put the connector back on.
Connect a voltmeter - black wire to a good earth (I used the battery) and the red wire to the pin to the centre wire.
Switch on the ignition. The voltmeter should read at least 0.4 to 0.5 volts - any lower and the ECU gets no signal, too high and the signal says the throttle is open, when it isn't.
Now open the throttle very gradually, so that the voltmeter steps up by 0.01 or 0.02 Volts at a time. The increase should be smooth and linear - if there are jumps, or if the voltage drops at any stage, the TPS is kaput.
Meter should read about 4.5 Volts when the throttle is fully open.

Mine is absolutely bang on, so the TPS seems to be ok.

I go indoors and order a MAP sensor. There are a few that look the same, with similar part numbers, so it takes a while to track down true right one - for £28. I order one for delivery by Monday.

:: Friday, October 11, 2013 ::

The MAP sensor arrived today. It's quicker to order stuff from Ebay and wait for the postman, than it is to wait in the queue at a Ford parts counter.

Fitting is easy: unplug the wiring connector, and pull off the vacuum hose, then undo the two screws that hold it on the bulkhead, and swap them over. I don't have time to try it out though.

:: Saturday, October 12, 2013 ::

Tried out the MAP sensor today - started the car up and left it to get hot. It's still holding the higher idle for a few seconds though, before it settles back. While I am wondering if I need to disconnect the battery so that the ECU can "learn" a new MAP sensor, the engine suddenly starts to hunt and surge, in a steady cycle. It doesn't come on gradually, it just suddenly starts. Then it stops, and goes back to its normal idle.

Very mysterious. I decide to try disconnecting the battery and re-starting the ECU tomorrow.

:: Sunday, October 13, 2013 ::

Today I reconnect the battery and start the car, and leave it ticking over. It gets hot, the fans cut in and go off again, all seems ok. Except that it's still taking a couple of seconds to return to idle, when you rev it.

Then the hunting and surging starts again, just for a minute. I connect up an accurate (digital) rev counter (i.e. my multimeter) and its normal idle is about 1100 revs - that's where it has sat since I got it. When it starts hunting, the revs surge between about 800 and 950, then it clears and goes back to 1100. When I rev it, it sits at about 1700 for 2 seconds before it drops down.

It takes ages for it to start hunting, much longer than you would be sitting in normal traffic, so that's not really a problem - the "sticky idle" is.

Another problem is that the exhaust manifold is leaking at cylinder 6 - just a slight ticking, but you can definitely feel it blowing. It's a never- ending mission this… I order a set of exhaust manifold gaskets for a tenner, again from the 'bay. What did we do before the computer came along, eh?

I'm going to go through the system and check every sensor connector - if that doesn't work, then I'm going to sit behind the exhaust and inhale deeply. Or I might take the car to the tuner in Edinburgh - I've looked up his phone number just in case.

:: Monday, October 14, 2013 ::

First task for today is to remove the coil, and disconnect the big loom connector underneath it. I clean that out with electrical cleaner, and then blast it dry with my airline. I also clean the connector to the fuel temp sensor. The idle speed valve and TPS look ok.

Then it's on to the exhaust manifold. The last time I tried this, it took me 3 days to get 6 bolts out - that was after 16 years of rust though, and these bolts have only been in for 7 years (time flies eh?). A couple of them are a wee bit sticky, but with a bit of easing to and fro, and a wee bit of lubrication, they all come out no problem. No need for a 6 foot extension bar and a 35-stone weightlifter on the end - and people wonder why the bolts break…

So here's the manifolds detached, waiting for the new gaskets;

and here's the old gaskets - the one on the right was leaking, but they are all pretty knackered.

Just have to wait for Postman Pat to bring the new gaskets now.

:: Wednesday, October 16, 2013 ::

The gaskets arrived yesterday, but motivation didn't.

So today, I'm just contemplating going out to the garage, when I hear a familiar noise outside - it's Dave's S.

So we have a blether while I put the gaskets in, with a wee smear of gasket silicon, and bolt the manifold back onto the cylinder head. It's fairly fiddly, but not that difficult. Wee spanners are the secret.

With the manifold re-fixed, I start it up. It sits and idles no problem, but is still sitting at a high idle when you rev it. When it gets hot, though, it starts hunting and surging again. Dave notices that there's a very slight "whistle" in time with the surging. It sounds as if it's coming from near the alternator. It might be the fan belt - it can be a bit noisy, but I don't think so… The car smells like it's running really rich when it's surging.

I try spraying some easy start around the idle speed valve (the vacuum would suck it in, and the engine would rev slightly as it burns). No sign of it being sucked in.

I decide to eliminate one possibility - I take the MAP sensor off, and put the old one back, then start the engine and leave it running for ages. No hunting or surging. £30 down the drain - I'd have been better blowing it (literally) on some Columbian marching powder.

The idle speed is still not right though. It idles perfectly, it revs perfectly, but when you shut the throttle, it takes a couple of seconds for the idle to stabilise.

Adrian texted me this morning suggesting lambda sensors. He's obviously doing well with the night classes. I think he might be right though… we'll see what it's like tomorrow.