Rough idle, sudden misfire during cruising and hesitation

ive done some major rebuilding and had the Def 2002 running pretty sweet for a while though the slightly rough idle remained. Suddenly today i started feeling severe hesitation at cruising speed on all gears. Still pulls strong and no hesitation when under heavy load. But slight load and cruising start to jerk and misfire. I have replaced injectors, head gasket, everything in fuel line way including filter housing which solved bad start at low tank. Injector loom etc all replaced. I was thinking about giving the injector seals one more go and see where it takes me but otherwise clueless. The idle has funny sporadic raspy sound to it coming and going, could be the misfireing. Any clues, could something else but injection cause this?

You really need to use a diagnostic tool too instead of replacing everything just like that...it can be a crank signal issue (sensor or wiring) but without a proper diagnosis it's just a guessing game

I use nanocom and everything that has been replaced has been replaced because it has been faulty and diagnosed so. So nothing has been done just in case. This is a new issue but i cannot figure it out since i get no fault codes.

Maybe you use nanocom but it seems not as it's necessary. You can't diagnose the head gasket or fuel related parts with nanocom cos the fuel delivery system is not covered by diagnostics, if some management parts are not 100% gone open or short circuit or if the fuel presure is low there will be no fault codes and a live data log is needed to catch all the readings when the symptom occurs... that was what i meant with proper diagnosis... so if you have nanocom go for a ride and record ''input's fuelling" on SD card to catch the missfire then post the result here and i'll tell you more

Yeah i know the fuel system is not covered. The head gasket leaked cooling fluid so i replaced it. I recorded a drive but forgot the sd card in the car, will get it later today and post the result.

Ok, here is the file. There are a few HUGE numbers in the injector compensation, that happens just as I lift the throttle to completely stop the car.

1. EGR still on?
2. check the clutch switch and the N/C brake switch inputs with nanocom to see if they react to the pedal or not
3. How old is the air filter
4. 2002 was transition year, is it 10P or 15+P engine?... if it's 15P the CAT is still on?

EGR removed, mid muffler/can replaced with straight pipe, P15, air filter a K&N i put there last year which seem still clean. I will test the switches tomorrow. How should i test them to know if they react to pedal?

Edit: was there something off with the readings or did they seem normal?

With nanocom - Inputs, watch brake switch 2 and clutch switch while you depress pedals... you said it's OK under heavy load but according to the data log that engine has low power like underfuelled, did you repace the FPR too ?

I cleaned it and replaced the round canister on it. That sounds real interesting. Could underfuelling couse rough idle too?

It's like the fuel supply is restricted somehow and it gets too little fuel at idle but more though still not enough under throttle

Ok. The fuel pump is a new oem as the old one broke. The filter and housing is new as the old one corroded away. I have blown thru and cleaned the fuel lines. Seems like the regulator is the last piece on the way. Worth replacing that if the switches does not give a result? Or you recon there is some other possible place to dig into first? You dont think injector seals and washers could be the issue? The thing is, it had a really bad and rough idle and i remapped it with the latest standard map fom nanocom website. It got a 100 times better only leaving a slightly bad idle but otherwise ran ok. Do you think low fuelling could be a mapping issue?

A bad fuel map can cause various symptoms, was that fuel map a dedicated one for Eu 3 setup? what's the part number of your ECU?... BTW, you said you changed the injectors, did you save the codes in the ECU and set well the clearances also was the injector loom genuine ? the rough idle is visible in the data log and can be fuel related or crank sensor missbehaviour... you should measure the fuel pressure in the FPR with a gauge instead of the FT sensor

we'll speak again tomorrow

Yes it was a eu3 map. I saved the codes and set the clearance to one turn out from lightly seated. I replaced with a genuine injector loom. The crank sensor is also replaced with a new one as i suspected the same.

In 2002 the original ECUs on Td5s were the last MSB (transition) modell 000080 which can't be remapped via OBD port, did you change the ECU and if yes what number? ... is your VIN's last number higher than 2A622424 or below ?

2A630861. I remapped with the nanocom and it made a huge difference. Before the idle was lumpy now its just lightly rough, clutch and throttle behaviour was erratic, now they work smooth and nice.

Where is the best place to measure the fuel preassure, should i remove the fuel temp sensornand take i from there or the regulator output line?

northernbobber said:

2A630861.

Click to expand...

then it's NNN000120.... it seems that you covered almost everything mechanical so check those switch inputs and if OK then i'm running out of ideas, eventually try with MAF sensor unplugged cos the air flow readings are low... another suspect can be the flywheel cos if it has excessive play it mixes up the crank signal

northernbobber said:

Where is the best place to measure the fuel preassure, should i remove the fuel temp sensornand take i from there or the regulator output line?

Click to expand...

yes, insert the gauge instead of FT sensor... when you worked on the FPR did you check the filter in the head ?

I attached the preassure gauge to the outcoming hose leading to fuel cooler. That gave me 8bar which is double of what it should be right? I cleaned the small filter yes. Maybe new fuel regulator would be the thing.

Usually the pump should deliver around 6 bar but can be more... though if you start the engine that pressure should drop cos the FPR must keep 4 bar in the rail and let the excess to the return port so if the pressure on the return is too high it means there is a restriction in the rail or the pipes are connected wrong at the pump or filter... are you sure you connected well the pipes at the pump and filter cos i've seen cases when they were accidentally mixed up , they should be white-green-blue-black at the pump