Technical JTD jerky moves - constant acceleration

[B0yCk]

Hello,

For some time I face a persistent and nagging problem: my car goes jerky / interrupted.

The show starts just after the engine started to warm up, across the whole speed range (often there are areas that i can keep constant acceleration without jerky). I repeat, ONLY if i maintain constant throttle or accelerate very very smooth / easy it jerks. If you get in the way of stuttering and then accelerate, disappear, but reappears if i keep again constant.


I made several tests and replacement of parts:
- I cleaned and blocked EGR-> no change (EGR functional so I left, I removed the lock plate) - the tester comes out functional
- MAF, just stands in the tester parameters, no symptoms of a dead sensor
- MAP - cleaned
- I replaced the crankshaft sensor (I read that once heated can give all these symptoms-replaced with a genuine BOSCH)
- Changed the fuel filter
- I did a visual test of how the injectors spit, all the same.
- I have no hose broke, no smoke.
- I used over 80% the most expensive fuel at gas stations, the best ones
- i shift over 2500rpm after the engine warmed
- no symptoms of "eating" oil (about 500ml at 9000km)
- no lights on dash, no errors in FiatEcuScan.
- brake switch changed

The only thing I noticed when opening the hood is that I have some traces of oil from the intercooler and intake hose connection (at the throtle body).


Any ideas or opinions are welcome, I have no idea what to check anymore.
:bang:

Car: 1.9 JTD 8v 115bhp

 

[B0yCk]

I am still having those problems on my car.

Now i have changed de MAP sensor with a new one. No change.
I have tried to run with EGR disconnected, no change.

What piece is the problem? What should i check more? Boost solenoid can cause this problem?


Why it works like hell after 5 minutes of working, when the car starts to heat?

 

[roy lovelock]

to me that sounds like it could be map problem if you have done all that work with no improovements, have you remapped the car by any chance?
is your solonoid been moved to a dryer location?
roy

edit - have you checked the small plastic pipes that go to the solonoid? i remember having a similar problem and ended up replacing all my vaccume pipes an moving my solonoid at the same time, i was unlucky when i removed the pipe as i broke one of the lugs on the solonoid and we had a 300mile trip to complete the following day, luckly for me superglue held for the trip.

 

[B0yCk]

the solenoid is still under the battery tray, i haven't resite it.
i have not remapped the car.

the vacuum pipes seems ok.

i will try to resite the solenoid near the battery.

 

[Dcthebear]

Could be the crank sensor starting to fail. Our 1.9JTD started doing similar when warm then it got far worse and started stalling and wouldn't start until cooled. You may not get a fault light on it until it stalls though. Cheap to replace and rules it out if it don't work.

 

[B0yCk]

i replaced it with a new Bosch one. No change i hoped to be that sensor, but no result

 

[Dcthebear]

Sorry, just read in your first post you'd changed that! Worth checking the sensors wiring too. Same with the cam sensor but thats a bitch and expensive to change.

 

[B0yCk]

Well, i wouldn't like to change all the engine parts now )

I'm trying to understand what can cause the interruptions when the engine just starts to warm up/ or after automatically "shock" is off( i do not know if you understand this "shock", but i cannot explain in another way..."shock"= when the car runs on idle about 900rpm for about few minutes to warm up, and then the idle is always on 800rpm).

About black smoke, yes i have, but only on hard acceleration.