erattic idle and hesitation on initial accelerator movement

Mosser · Unread post by **Mosser** » 08 Dec 2006, 14:42

Right, Next problem with my car !!!

Its a Citroen Synergie 1998 model with a 2.0i petrol XU10J2 engine (dinosoar engine that citroen seem to have raided from the peugeot 405!!!)

The head gasket blew on me between cylinders 2 and 3 about 3 weeks ago, so i duly replaced the head gasket, had the head on a flat plate and it was fine so didnt skim it, and since i changed the head gasket the idle has been very erratic and sometimes the engine cuts out and is very reluctant to start afterwards, it will only start after about 2 minutes of cranking and playing with the accelerator

I thought the idle control valve was failing so duly purchased and installed a new one, and there was no improvement at all so that ruled that out and wasted some of my money !!, then i thought it might be an air leak around the inlet manifold so i have sprayed wd40 all around the inlet manifold whilst the car was running, but that made no noticeable change to the engine note or speed, but i took the whole inlet manifold off anyway and washed it in the bath and carefully inspected it for holes/leaks/cracks (there were none), but i used silicone gasket compound on all the joints just in case, and when i put it back on, it seemed very slightly better, but its still not right,

Then!!, I took the throttle body off (its a cable operated one, and cleaned the whole assembly paying particular attention to the idle bypass hole and the throttle butterfly, all the seals and everything else were in place and this want disturbed during the head gasket change anyway, but when i put it back on the idle was still erratic and still had a big hesitation when the throttle was initially pressed

So, i then checked the cambelt timing and that is still spot on ( i thought it might be a tooth out, and no the crankshaft pulley hasnt slipped on its rubber insert !!!)

So, now i am stuck for ideas ?, can anyone think of anything else that might be causing it ?, or anything else can try ?

I'm running out of ideas on this one and my wife is not happy with me spending this much time fixing the car

HELP !!!!!!!

AndersDK · Unread post by **AndersDK** » 08 Dec 2006, 17:07

I have exactly the same problem on my newly aquired XU9J2 (DDZ) monopoint engine powered BX estate

So far I'm preparing myself to get under the rear of the car and repair a small (dripping) leak from the fuel line pulse damper.
It will be replaced by a piece of straight tubing

I suspect that the leak is causing a fuel shortage on coldstarts. Thus the engine initially springs into life (by the small amount of fuel in the fuel pressure regulator) and then dies immediately after.
Result is pr instinct that you buttom the pedal, while cranking engine again, and then the engine is flooded, and reluctantly thereafter is caughing and smoking into life again.

Note : the leak is only visible while fuel pump is running and pressurising the fuel line.

PS : any chance of a butterfly flap end stop adjustment on your engine ? (the "old style" idle setting)
There is on mine, and I had to adjust this up a wee bit ...

More to follow ...

Mosser · Unread post by **Mosser** » 08 Dec 2006, 17:57

I was thinking that the fuel pressure regulator could be suspect because when i open the throttle manually on the throttle body, i can hear the engine suck the air, but its like the fuel isnt being delivered quick enough to keep up with the demand and this is why the revs dip i think as it goes lean for a second or 2 before picking up and running properly, and rather than buy a new one, i might just get one from my local scrap yard to test it with,

As sods law goes, my engine is now running and idling fine at the moment, but it can be different each day and sometimes even on each start of the engine !!

there is a butterfly valve end stop on mine, but it is fully shut and already at the end of its limit so i dont think it is that, when i had the throttle body off, i filled up one side of it with water and left it for 10 minutes and none leaked through so i dont think there is an air leak problem anywhere

citronut · Unread post by **citronut** » 08 Dec 2006, 19:14

i would have said belt timming,you need to go back over what you have disturbed,and check it all again,vaccum pipe,i have never heard of anyone useing wd40 to find an air leak in the induction,it is best to use carb cleaner,did you check the valve clearances whilst you had the head of
regards malcolm

Mosser · Unread post by **Mosser** » 08 Dec 2006, 19:27

citronut wrote:i would have said belt timming,you need to go back over what you have disturbed,and check it all again,vaccum pipe,i have never heard of anyone useing wd40 to find an air leak in the induction,it is best to use carb cleaner,did you check the valve clearances whilst you had the head of
regards malcolm

I would have said belt timing too, but i put the timing tools back in this morning and it was spot on, I painted a line across the crankshaft nut and pulley to see if the rubber insert was slipping round and putting the timing hole out, but in the last 8,000 miles of driving, the mark hasnt moved a single millimetre so i cant see how it could be that ?

I didnt check the valve clearances because the car was running and idling fine before the head gasket change and i didnt even remove the camshaft when i did the head gasket !!

Unread post by **alan s** » 08 Dec 2006, 20:02

I'd say there's a fair chance the answer lies here:

http://www.aussiefrogs.com/shane/

If you don't want to read it all through, scroll down to the last item and I think you'll find problem solved by someone who had the same problems after doing similar jobs.
I won't spoil it for you, but it's a simple solution and one I even got caught on when I did my cambelt even though I was aware of it.

Alan S

Mosser · Unread post by **Mosser** » 08 Dec 2006, 20:14

Thanks Alan, I'm dying to read it now, but unfortunatly that link doesnt work as that site uses frames in their web page design, to get the link you need to right click the text that you want to create a link to and then left click on create shortcut

I really do hope its just something simple i have overlooked, because i have to drive to Dordrecht and back on monday which is a 700 mile round trip !!

Unread post by **alan s** » 08 Dec 2006, 20:24

There's pics involved, so try this.

Click on link.
Go down the side bar (left hand side) to "96 Xantia VSX"
Click on that and look at top of page.
Click on Changing Xantia cambelt

Look for pics associated with this:

*************************************************************
I counted the teeth on those belts about 5times each to ensure the lines were correct, then fitted the new belt.

The motor ran like a dog ... Obviously the cam timing was out ...

Back to the internet message groups, no-one had anything to suggest. I suggested the old belt was incredibly loose (I mean enormously loose, it's a wonder it didn't skip teeth and destroy the motor) so maybe with the correctly tensioned belt I need to rotate the camshaft 1 teeth one tooth anti-clockwise ?? No-one seem to buy that though.

In desperation I'd removed and refitted and counted the teeth on that belt another few times. How the hell can the cam timing be out ????

The answer ?? I finally decided it wasn't the cambelt and started searching for something else...

This bloody hose was off and hanging down the back of the motor (grrrr). As soon as I found it and plugged it back on the motor ran perfectly.

**************************************************************

See how that goes.
I'd download it and post, but I'm having major computer problems at present and my system locks up if I even try.

Alan S

Mosser · Unread post by **Mosser** » 08 Dec 2006, 20:51

Thanks!, read it and seen the picture now, unfortunatly my manifold pressure sensor is properly plugged in both electrically and with the vaccum pipe, I pulled the pipe off this morning to check it was working and the engine almost stalled and ran really rich when i reved it

Thanks for the suggestion thought !

AndersDK · Unread post by **AndersDK** » 09 Dec 2006, 18:28

Mosser -

Try out the info found here :
http://www.tramontana.co.hu/citroen/fuel/diags.php
Even if it is for the BX engine range, the information found here is very valuable for standard injection systems.

Note that the AFS referred to is the long discontinued air flap controlled Air Flow Sensor found on early EMS systems.

Bet you've been there before in the past

Mosser · Unread post by **Mosser** » 09 Dec 2006, 18:34

Thanks Anders,

I will read through it all and see if it helps,

I bought a brand new Citroen BX TZD Turbo estate in 1993 and kept it until it had nearly 300,000 miles on the clock !!, so i certainly remember the BX well, I never owned a petrol one though, and if i had a choice with my synergie, it would be diesel powered too, but the diesel ones are too expensive so i am stuck with a petrol car until i can save enough to buy an HDI version of the synergie

I also owned a Citroen XM 2.5TD Exclusive which i bought as exdemo +1 with 27k on the clock, and only got rid of that when it had 332,000 miles on the clock too !!

I also owned a Xantia for a couple of years, but never really liked it, the XM was the best citroen car i have had, followed by the BX, followed by the Synergie and the Xantia comes last !!

Unread post by **philhoward** » 10 Dec 2006, 19:42

I'd go with the fuel pressure regulator as a start; a lack of willing to pick up on a change of manifold pressure (i.e. blipping the throttle at idle) could be caused by an FPR which gets stuck - actually happens more than people will admit. If its then stuck either shut or fully open, then that would also tie in with the lack of starting afterwards (i.e. no fuel or flooding).

I hate to say it (now!) but whilst an ISCV failure would result in stalling, it will start pretty easily with some throttle - I know! Great fun with an auto - especially when it does it as you pull onto an island. You're looking for the oncoming traffic, not the tacho and the alternator light...

AndersDK · Unread post by **AndersDK** » 10 Dec 2006, 22:38

Righty -

Got under my BX today (was rather frightened by the stormy wind though) and removed the leaking pulsation damper. The fuel filter was renewed as well.

Now THAT helped with instant coldstarting and stable cold idling

I had a feeling that the problem was a wrong (too low) fuel pressure because of the small leak.

Out of interest I dismantled the pulsation damper. I got pretty mad to see how simple a device it is and Citroen demanding some £50 for a new part

As I thought its nothing but a membrane controlled cavity, the membrane being held by a very strong spring. It will never come into action during normal circumstances, but must be some kind of a fuel temperature dependent volume compensator. Otherwise I dont see any function of this device.

Conclusion : always be suspicious on the fuel pressure if the engine suddenly gets erratic coldstart/idling.

Mosser · Unread post by **Mosser** » 17 Feb 2007, 23:22

Just thought that i would update my post here,

My Synergie is still hesitant on initial acceleration after idling or coasting along, I still havent got to the bottom of it, and it is slowly getting worse as about 2 mornings a week it will fail to start, i can crank the engine for ages and it wont even hint at firing,

I'm pretty certain it is a lack of spark problem now as a plug held against the head has no spark when i am having the problem, but i am stumped as to where the problem is comming from, but i do have recurring problems with moisture getting into the ecu connector despite me using electrical cleaner and silicon spray on it liberally, and the bitron unit connector gets moisture in it too and gets hot and drains the battery flat overnight so i have to constantly dry that connector out too,

One thing i have noticed, is that it pinks like made going up hills with foot flat on the floor, its like the ingition is way too advanced, and i wonder if this is part of the hesitation on initially pressing the accelerator problem and the problematic starting in the mornings,

Does anyone have a picture of the plug leads on a synergie 2.0i 8v engine ?, as i'm wondering if they are not connected properly and firing out of phase ?, the fuel economy (if you can call it that!!) is about 19mpg, and it use to do way more than that before i changed the head gasket !

AndersDK · Unread post by **AndersDK** » 18 Feb 2007, 11:08

Note that severe pinking can be caused by too lean a fuel mixture as well.
Also a (too) hot running engine will pink like mad.

I think its about time you start a serious checking for false air (lean mixture syndrome). On engines seen many moons you have a rather fair chance of rotten rubber hosing all over, twisted inlet manifold, faulty inlet sealing etc etc.

All recent engines have a vacuum sensor delivering a voltage for the ECU reading the vacuum after the throttle flap. This effectively reads the Manifold Absolute Pressure (designated the MAP sensor) for the ECU.
Its directly responsible for ignition advancing - jut like the earlier vacuum capsule devices.
And just like the early devices it suffers from a split or leaking vacuum connecting hose - or the opposite : a gunked up vacuum hose holding the ignition erratic advanced for a time.
The MAP sensor can of course be defective itself.

X-ing my fingers for you. Sounds like a very simple problem indeed - you just have to stumble over the solution I'm sure.