1.9 td Poor cold starting (CURED!!!!!!!!!!)

pete woods · Post by **pete woods** » 10 Apr 2003, 00:02

Hmmm? Toms tight valve clearance theory sounds very plausable to me.
its been a while since I had to mess about with cars but I seem to remember that if you got a low comp reading on a cylinder you injected a little oil into the plug hole & tested again. I think the theory was that the oil would seal a leak down the bores but not one via the valves so if the next test showed a higher reading it pointed to the piston rings & if not then the valves were prime suspect.
This was for petrol engines. Does the same hold true for a diesel?
If so is it an expensive test to get done?

wheeler · Post by **wheeler** » 10 Apr 2003, 03:54

if tight valve clearances were causing difficult cold starting would'nt it be even harder to start when warm ? doese'nt the clearance get tighter (and push down on the valve more) as the engine heats up ?

tomsheppard · Post by **tomsheppard** » 10 Apr 2003, 14:30

No, it doesn't. This, as I have been told is a peculiarity of the XU engines. they start tight and loosen up as they warm up. I wonder if this is because the cam carrier expands more, being alloy so the camshaft finishes up higher. This is what I have read, but it sounds possible.

KAD · Post by **KAD** » 10 Apr 2003, 21:48

Dave..... So the fuel return pipe should be submerged inside the tank. If this is not so, it could cause the fuel to 'run back'.
When I took the sender unit out I think it was well above the fuel level, I'm not sure, so I'll have another look. If it is I'll extend it and see how it goes. Incidentally, the end of the return pipe in the tank looked factory finish, but once again I'll give it some closer inspection.

Dave Burns · Post by **Dave Burns** » 12 Apr 2003, 23:48

I'm not sure if the return pipe should or should not be submerged, but it is on the ZX, and I think over a long enough period of time might cause problems if it were not.
The tight valve theory sounds likely, depending on how much the head expands and contracts in the vertical direction, and if the valve clearance is below spec to begin with.
A cold head would be at its smallest hight, so the valve seat will be closer to the camshaft by a few thou, this could prop the valves open slightly.
When hot, the head is just a gnats taller, so the valve seat and camshaft are further apart.
Having said that I would expect the valve stem to expand more than the head, so would'nt the problem be there regardless of temperature.
Easy enough to check when cold though, just whip the rocker cover off and shove some feelers in to check the clearance.
An air leak in the supply line does'nt neccessarily mean the engine will stop or even run poorly, it depends on how much air gets drawn along with the fuel, beyond a certain amount the engine will of course stop, and unless primed wont restart.
Where the engine was running ok just before it was switched off, there is no reason why it would not restart even with such an air leak in the supply, though if it can't pull enough fuel along before the level in the pump drops to the critical point it will then faulter and stop.
Dave

mark_sp · Post by **mark_sp** » 13 Apr 2003, 01:15

this is probably not going to be of much help to you but i bought a xantia 1.9 td 2 weeks ago and it turned out to be a poor cold starter. the car is a 1998 model with 59k miles and its immaculate. it did not start very well on the test drive but as it had been stood for a number of months on a garage forecourt i paid no attention to it. after a week of poor cold starts [say 3 attempts, 40 seconds of churning and the obligatory cloud of white smoke] i began to think i'd bought a problem car, viewing the topic on this forum made me feel even worse as did the fact that my 12 year old bx tzd still starts first twitch of the starter however cold. i have however resolved the problem at little cost. i replaced the battery which was a 300 amp unit with a new 600 amp unit, however this did not improve the cold starting. the hand primer was very squashy, pumping this until it was solid also made no difference. a visual inspection of the pump and pipes revealed that the fast idle cable was excessively slack and not providing a fast idle for cold start, i left it alone at this stage but on the next cold start depressed the accelerator a third of the way down and the engine fired first turn of the keys in approximately 4 seconds, and continues to do so. it may seem an obvious thing to do in hindsight but on all of the cars i've owned over the last decade this was not required. however i now think that my assesment of the fast idle cable is wrong and would like some advice. my car has engine management and i now think that the fast idle is permanently on and that the cable should actually switch it off. the other end of the cable goes to a vacuum unit which is solenoid activated. i can't get a good look at the pump end because of all the pipework but it appears that the fast idle and idle screws have been adjusted to clamp the fast idle lever, it does not appear possible to push it. the car drives perfectly so i don't want to fiddle but its bugging me.

Dave Burns · Post by **Dave Burns** » 14 Apr 2003, 01:58

Clock this thread for vacuum controled idle speed problem.
http://www.andyspares.com/discussionfor ... IC_ID=1769
Dave

mark_sp · Post by **mark_sp** » 14 Apr 2003, 16:12

Dave
Thanks that was usefull. I did a little more investigation and there is 12 volts into the electrovalve with the ignition on and 14.5 volts in when the engine is running at normal temperature. There is also vacuum in but no vacuum out [there is vacuum out of the egr valve]. the pipes are clear of obstruction and in good condition so it looks like either the valve itself or possibly not enough vacuum in. The suck from the pump appears week but I've no way of measuring it other than sticking my finger over the pipe, if I obtained a vacuum tester does anyone know what the reading should be ? If it is the pump then presumably the EGR system won't be working properly either ?
The tickover on my car is a constant 900 rpm regardless of engine temperature or aircon usage.
The cable to the fast idle lever is very slack so much so that it doesn't look like it could be adjusted out and the fast idle lever can not be moved by hand, it's solid. As I said before it looks like its clamped in position by both the idle screws, I'm wondering if this has been done deliberately.
thanks
Mark

pete woods · Post by **pete woods** » 15 Apr 2003, 14:33

Right, last night after the car had been standing for about 26 hours I got in & started it with the throttle about 1/3 open. It started within 2 secs!! This morning I tried again using about 1/4 throttle & it started almost instantly!!!! This car NEVER starts with less than 20 secs of starter. I also only waited for the dash light to go out before starting.
I don't know what this means is wrong but I don't care I've got a car that STARTS!!!!:)
I hope this works for the rest of you

tomsheppard · Post by **tomsheppard** » 15 Apr 2003, 15:39

OK so the problem is fuel starvation. Sounds as though there may be a setting for idle fuelling that is a little out of sorts. Either way, you will be saving wear and tear on the battery and starter.

pete woods · Post by **pete woods** » 15 Apr 2003, 19:40

It may well be a fueling issue but it is odd that it only manifests it's self if the cars been standing for 8+ plus. Even when it was freezing it always fired up even after 6 hours at 0 degrees but leave it more than 8 & forget it!
I wonder why it starts on 1/4 throttle but full throttle doesn't help? Dave? Any Ideas?

Dave Burns · Post by **Dave Burns** » 16 Apr 2003, 05:17

Very strange but at least you can get the bugger going now Pete, I think if there were anything wrong with the start quantity lever or its spring inside the pump, then full throttle would give you the same setting of maximum delivery, but as you say applying full throttle doesn't help.
So why does 1/3 or 1/4 throttle get the job done, well your car being a 96'er will have an ECU to interfere with the pump will it not, as my 97 td does.
My thoughts turn to the potentiometer on the pump accelerator lever, this will give a throttle position input to the ECU.
There are several things that can be tried in an effort to pinpoint the offending device, but now you have a car that starts when you want it to you may think bugger it.
Anyhow first thing to would be cracking the injector union again, only half a turn, and unplug the glow relay so it wont fire.
Crank her over while cold at different throttle settings to see if there are noticably differing amounts of fuel being pumped, there should be a short spurt of about one to two inches at starter motor speed and with half a turn of the union.
If there is a definate difference I would be inclined to suspect the inner workings of the pump.
If there doesn't seem to be any change, it could be a timing fault brought about by the ECU, pump, pot. or a temp. sensor, injector lift sensor or the like.
You could mark the position of the pot. on the lever and then mechanicaly disconnect it so it would'nt turn with the throttle lever, then try the 1/4 throttle trick, no joy then would make a stronger case for the timing theory.
Or as above but this time position the pot. to the 1/4 throttle setting and try starting without applying throttle, if it started easey then, even more credibility to the timing theory.
There are three connectors on the pump if the car has an ECU, blue, black and brown IIRC, the black square one is the pump immobiliser if you have a keypad, don't unplug that, the blue one goes to the pot. and the brown one goes to the bottom of the pump, this one transmits ECU signals for timing purposes, if you disconect it while the engine is running the timing should go towards advance in a big way and the engine will knock louder.
You could try disconecting the brown one and try a start, no throttle of course, and the same with the pot. plug.
Hehe now you are going to come back and say it doesn't have an ECU after all this.
Dave

NSP · Post by **NSP** » 11 Aug 2003, 20:32

I can relate to the Xantia start problem and many more. I suspect a more sinister fault causing the starting issue though. My Xantia has now got nearly 190k on the clock (so don't give up on yours yet!). My cold starting got progressively worse until the damn thing burnt it's combustion chambers clean out of the cylinder head! A loud clacking noise and a very gentle drive back from Scotland, and a new complete refurb head got it starting perfectly!
I would stress to anyone with one of these 1996-1999 Xantias or the 406 with an identical under-bonnet arrangement, to check those electro-valves & vacuum cables. I wonder if my motor running on cold-start for a long time cause the head to run hot, and the centre two combustion chambers to seperate from the head. Anyone who noticies a ticking noise getting progressively worse over a few thousand miles, get the centre injectors removed and the combustion chambers checked, cause if one falls out completely then I imagine you'll be collecting your engine in bits over a large area!
I now have an unpredictable turbo boost problem. When I went through the learning curve with these electro-valves & vacuum system, I found the gas-recycling vacuum cable had been left disconnected. This seemed to cause an unpredicable turbo boost at times. Also a leak in the turbo pressure sensor hose that sends the pressure from the turbo output (rigid hose) to the top of the injection pump will cause a loss of, or unpredictable boost (presumably the pump will not fuel the engine too much if it detects a lack of pressure. Any ideas? I have checked the electro-valves are both functioning, and the turbo hoses all seem sound. I am going to have the exhaust system examined though as it is starting to sound a bit "blowy" and I guess exhaust back-pressure is quite important for these beasts.
Hope this has been of some use.
Another useful hint is to note when the LHM pump cuts in during driving that it runs for one burst not several short bursts. My Xantia had a failed accumilation sphere (mounted on the front of the engine), which was causing the pump to click in and out three or four times (sounding very frog-like). This eventually led to pump failure.

vanny · Post by **vanny** » 13 Aug 2003, 00:47

My engine is a '96 model from a Xantia Estate, and doesnt have any engine control unit (nice and simple like me).
Does the pump have a little BOSCH hydraulic lift on the side (to stop the turbo suddenly cutting out and stuffing the bearing i pressume)? Ive got one on mine, and when i first got the engine it would hold the throttle open even with foot off the accelerator. It also wouldnt allow the throttle to fully open (couldnt get it past about 60mph in 5th).
Reading through this thread, there is a trend to suspect the fueling (especially if it starts with foot on gas). My problem was the lickle hydraulic lifter sticking open (worrying when i pull up in a serive station behind a police car, ragging it something rotten!), the solution was a big hammer, cold chiesel and can of WD40, basically i sprayed the lifter body and smacked the bottom braket something good and proper, turning the lifter a little and freeing the travel.
Would the reverse of this cause problems on start, if the lifter was stopping fuel being injected by not resting properly??
just a vague thought

MarkB · Post by **MarkB** » 23 Oct 2003, 03:18

I had starting problems with a 1.9TD Xantia with 125K miles on the clock. 1996 but no idea whether it has an ECU. There were serious clouds of white smoke filling the neighbourhood.
I had new glow plugs - no difference.
Had the injectors refurbished - no difference.
Had a compression test and its fine.
Had the camshaft clearances checked (yes I have heard that the clearances change on heating up) they were fine too.
Took it to a diesel expert and for £50 (I had spent at least £200 already) they reset the pump timing and stuck a valve in the fuel pipe - no smoke and again a pleasure to drive.
Apparently the pump is slightly worn so the timing was out.