THE ROVER SD1 FORUM

ramon alban · Posted: Fri Apr 18, 2008 12:52 am Post subject:

tommosredone wrote:

Could my over-rich start up be "ruining" the plugs?

Hard to say but someone is bound to know. One thing for sure an overrich mixture will produce a really inefficient bang so that could be deemed as a misfire. Wet Plugs, loadsa carbon, the plugs wont know if its good friday or half past three.

Could this be the route cause?

One of them - I reckon!

Temp on way home (including the section of journey on less than 8 cyls) was between 60 and 83°, mainly dead on 70°. It sometimes goes up to 80/83° then drops back to 70°. Sometimes as low as 60°.

These symptoms alsom suggest air locks in the cooling system.

So maybe two issues:
a) Overfuelling when cold
b) engine running cool, giving duff info to ECU.

The Temp sensor if its working properly, gives good information. It's just that the engine wont like the answer it gives. The root cause in this area seems to be over cooling - thermostat??

One note, tonight, in car park at work, I took the wires off the CSI while it was running VERY roughly seconds after start-up, and it made NO difference, I.e. the CSI is not stuck on at any point.

Leave the CSI permanantly disconnected - you dont need it unless its very cold in the mornings.

A very puzzled Roverist.

I'm not really surprised, because there has not been a lot of logic to this investigation. You tell us that the Efi components are all OK but there is very little evidence of you actually doing any actual component tests that are recommended, yet the car is clearly quite sick. Confused

Thermostat? Could be! I don't even know if there is one fitted, I certainly haven't checked!

Oh Dear! When you get this fixed take great care to eliminate air locks when refilling with coolant.

I've just been outside and changed the ECU back over to the original one, and blimey what a difference! Cold starts are MILES better; no rough running, not overfuelling etc.

ECU's can give the intermittant problems you have suffered on fueling mainly due to dry joints on the circuit boards. I had the same thing in 1994 and bought a new one having proved the old one was intermittant by running in a friends car where it displayed similar behaviour.

It wasn't totally cold, as I got in from work at about 5.45 (I changed the ECU at about 8.10), so I'll see what difference it makes in the morning.
I think I'll order a thermostat tomorrow!

Good thinking.

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Ramon

tommosredone · Posted: Sat Apr 19, 2008 10:31 pm Post subject:

UPDATE!
I've taken the heads off today, and I've found it has STD SD1 heads, without the waisted valves. One valve guide is totally worn out, which will be the horrible rattle I've suffered since I've owned it. At least one valve is leaking too, so I've just been to get a pair of TP heads, so I should be back in action tomorrow.
Also there are NO stem oil seals, so that could explain the oil burn on start-up.
The plenum chamber was full of engine oil too!
The bores look good, and all the pistons feel tight, so I think I'm heading in the right direction. I should think I'll notice the difference!

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I wish I could make my own petrol.

Punx0r · SD1 Regular Joined: 05 Nov 2006 Posts: 231

If the plenum is full of oil does that indicate oil is being blown through the breather system by crankcase pressure?

Are TP heads different to SP heads?

chris_derby · Posted: Sat Apr 19, 2008 11:39 pm Post subject:

Looks that way! More than likely the vacuum created by the airflow through the induction system will have sucked the oild through the breather pipe...

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Auto Vitesse, gonna be a beast!

tommosredone · Posted: Sat Apr 19, 2008 11:45 pm Post subject:

I don't think TP heads are any different, but at least they are off a Vitesse, which is better than the ones I've been running for the last 15,000 miles!
I'm hoping that pressure from the leaking valves/guides is pumping oil up into the plenum, otherwise it's deeper down trouble...
I've got to get it running by tomorrow night, as I need to drive it to work on Monday morning!!!!

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I wish I could make my own petrol.

tommosredone · Posted: Tue Apr 22, 2008 5:46 pm Post subject:

Well, I managed to get it finished in time to get me to work on Monday morning!
It really is miles better; all the faults have been cured. I'm very pleased, if a little sore and bruised.

Back on the temperature, there WAS a thermostat in (82°), but I replaced it anyway. It has made no difference, and the engine still runs at 70° at all times.
I have spent a long time getting the airlocks out, and I'm confident that the level is now correct.
When I bought the car, it was sold as having a re-con Hi-capacity rad (Rimmers I think the ad said). It has NEVER used a drop of coolant in 15,000 miles, and NEVER looked like overheating, even when towing a big caravan through mid-Wales last summer.
How do I get it running at optimum temp, and will it running at 70° feed duff info to the ECU via the temp sensor?
Cheers,

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I wish I could make my own petrol.

Chris P · Posted: Tue Apr 22, 2008 6:46 pm Post subject:

tommosredone wrote:

How do I get it running at optimum temp, and will it running at 70° feed duff info to the ECU via the temp sensor?
Cheers,

Are you reading the dash temperature gauge at 70°C, or have you got an IR thermometer?
I wouldn't rely on the dash gauge! There were two types - 50-130C and 60-140C and
they seem to have used different senders to get this reading. My Vitesse gauge reads 100C,
but I know it's actually 85-90C as the gauge is 60-140C but I think the sender is for a
50-130C. Before the sender broke and was changed, I had a rock-steady 85-90C reading.
If you have the opposite, a 50-130C gauge and a 60-140C sender, I would expect you'd get
a reading of about 70C at running temperature. If the thermostat is working correctly, I can't
see how the engine would run cool.

The ECU will fuel according to engine temperature, so will cope with 70C. The ECU temperature
sensor is totally separate to the dash gauge sender.

ramon alban · Posted: Tue Apr 22, 2008 7:35 pm Post subject:

Tommo,

I thinks Chris' analysis is correct. If the thermostat is working properly then it would be mostly closed below 82° and if your temperature is now steady this means that the airlocks have gone and the stat is OK.

That only leaves the temp sender and/or gauge combo which is no big deal in the short term.

One way to check if your system is hot enough would be to go on a belter and get it as hot as poss, then whip off the coolant temp sensor cover and measure the sensor resistance, Check it against the chart. If its in the order of 150 to 250 ohms I would reckon thats a good temp.

If its between 250 and 450 ohms I would say that was running too cool.

Whadya think Chris?

Ramon

Punx0r · SD1 Regular Joined: 05 Nov 2006 Posts: 231

Would a thermocouple taped to the head or block casting give a good indication of true engine temp?

ramon alban · Posted: Tue Apr 22, 2008 11:58 pm Post subject:

No. water temperature is the measurement, tape a tc to the inlet manifold near the temp sensor - maybe.

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Ramon

tommosredone · Posted: Wed Apr 23, 2008 1:17 pm Post subject:

I'll try and measure TS tonight.
I have a temp gauge that I keep in the driver's shin bin, it's plumbed into the thermostat cover. On dash it is always bang on the line after the 60° one, the more accurate one reads 70°. It occasionally goes up to 80°, but goes back down to 70° pretty quickly!
All will be revealed on the sensor check, I guess!
Thanks for the help so far!

_________________
I wish I could make my own petrol.