Hi guys,

recently I began experiencing an uneven idle/hesitation every few seconds but only when engine gets hot (it is worst after long highway ride when engine is the hottest). During this hesitations it seems like engine would stop for a brief moment and then start again. Car doesn’t smoke at idle or during acceleration and accelerates just fine, hot or cold. Below is a clip of how engine idles when hot, because of image stabilisation (that i can’t turn off) you cannot really see engine moving when it hesitates but you can hear it (better to use headphones).

I have looked at the cylinder balance data in forscan when engine is hot and it shows the values below:, when I go oscilloscope view and the hesitation occurs you can see the imbalance in the chart (picture below)

Cylbal values when idling hot:

 

Cybal graph when hesitation occurs:

 

Video showing hesitation when hot -HESITATION CAN BE BEST HEARD ON HEADPHONES (hesitation occurs at 2 seconds and then again at 18 seconds and so on): 

Things that have been already done to the car previously (all were done before this problem started happening)

DMF replacement (10k km ago, LUK brand)

Glow plugs (5k km ago, Bosch)

Fuel filter (5k km ago, Delphi)

EGR blanking plate installed

L shaped turbo hose before intake/EGR replaced (10k km ago)

Fuel rail pressure sensor (in 2018, Metzger)

 

I have bought the injector leak-off test kit, but cant find instructions how to do the test except this one for Mondeo mk3: https://www.fordwiki.co.uk/index.php/Injector_Leak-Off_Test. Anyone knows if this prcedure is ok for 1.8 tdci mk2?

 

Any suggestions what it could be and help is much appreciated!

 

 

Hey guys,

problems have stayed about the same since the previous post, I have just had all 4 injectors tested (on the bench) and replaced since they were out of spec and also the fuel filter replaced (no particles in fuel filter housing). The car runs smoother and pulls better. I have also done "Engine knock sensor reset" in forscan. But the problem with hesitation/ uneven idle is still here when engine is really hot, the hotter it gets the worse the hesitation. Below is a forscan Cylbal and EGR (egr is blocked but the value still changes since it was not coded out) snapshot when the hesitation occurs (hesitation occurs in the middle of the graph when you can se the egr value changed. When hesitation occurs you can also hear chain rattle, chain rattle can also be heard when quickly blipping the throttle. So I guess next move would be changing the chain, belt and both tensioner, since I think the car can be out of phase when this hesitation occurs? What do you guys think? Is there anything else I can test in order to diagnose this?

I have found the below comment on the forum, which mentions that the mk1 1.8 tdci (same engine with chain as mk2, only different fuelling system (delphi)), had hesitation and judder because timing was not spot on, since the problem only arises when engine gets very hot (after going up a long hill), i think some part of the timing system stretches because of heat and the hesitation start happening, it never hesitates when it is cold.

 

You can see the hesitation in the middle of the graph below

 

I AM RUNNING OUT OF IDEAS AND ALSO THE EXPENSES FOR THIS REPAIRS ARE VERY HIGH COMPARED TO THE VALUE OF THE CAR SO ANY TIPS WOULD BE GREATLY APPRECIATED!

 

THANKS!

Hello! 

Have you solved this issue? I have exact same problem driving me crazy. I have changed the timing belt, changed injectors, rail pressure sensor, camshaft sensor, measured compressions, valve clearance. Nothing helps

Hi,

since then I also replaced the alterantor freewheel pulley which was seized (didnt freewheel), which helped smooth out the engine but the hesitetion persisted. I see you said you changed the timing belt, have you also changed the lower timing belt in oil/timing chain, since I think stretched chain/weak chain tensioner may be causing the engine to go out of phase, especially when engine oil is warm and oil pressure that fills the tensioner is lower in idle than when the oil is cold due to lower viscosity of oil when hot. It could also be some type of seal/air leak which happens only when parts expand due to heat.

 

Since replacing the chain is another very expensive job (around 500 eur) and I also had some pretty bad rust problems on the jackpoints and fenders I've had enough and just bought a mk 2.5 focus today which recently had the engine rebuilt (due to broken wet belt tensioner not the belt - previous owner said so) and both timing belts repalced and will slowy transfer all the new parts (injectors, engine mounts, etc.) to it.

I sincerly hope you find the solution, if you do please report back.