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2.4 jtdm injector data

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Hi guys,

To briefly sum up I've been having a engine judder with a spike in RPM at idle when the car reaches water temp 90degC and not a degree less, not even at 89. Inlet Manifold replaced/ EGR replaced/ MAF unplugged/ MAP cleans/ Air duct to turbo tightened/ DPF = Normal clogging & no fault codes. Still no difference. For anybody who is interested in detailed trouble I've been having see this thread...

It has got worse in the heat and the other day I had a scary juddering at 70mph, 2000rpm in 6th gear. This has happened once before after the manifold was replaced but I thought it was a DPF regen.

I've taken some data using ECU scan and an excel spread sheet. I've monitored the injectors and I wondered if any tech'ies can interpret the data....

Below is a graph taken seconds after start up...

Text Line Parallel Diagram Slope

This one shows the injectors seconds after I watched the water temp sensor gauge reach 90degC. It was accompanied by juddering, and a repeated increase and decrease in RPM. Injector 4 seems interesting

Text Line Font Parallel Plot

I have the free version of ECUscan so I can only monitor 4 injectors (parameters) at a time. (plus I forgot to save the other 2 graphs. :rolleyes:

However I did take this data at warm:

Injector Cyl. 1: minimum reading -52mm3/i to max reading -32mm3/i
Cyl. 2: min -36 to max -22
Cyl. 3: min -0.99 to max -75
Cyl. 4: min +2.54 to max +2.72
Cyl. 5 min -82 to max-68

Can anybody interpret what these readings say about the state of my injectors? Particularly Injector 4 which gave a plus 2.5 - 2.7 reading when all the others read between 0 and minus 1.

Would this be causing the symptoms I am experiencing?

Do any need replacing/ reprogramming/ reconditioning?

I would appreciate any views.
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· Registered
233 Posts
Discussion Starter · #4 ·
Thanks for the reply sussexa & for looking in to the maps for me.

I have data recorded of the injectors at 2000rpm from cold start & at 90degC. I haven't had much laptop time to convert them to graphs as of yet but injector 4 doesn't change from cold. However it does comes back in to line with the others when holding the car at 2000rpm. Strange.

I really hope that by replacing the injector the issue is sorted.

On the bright side this is not a exclusively Alfa issue. Today I drove works 12 plate, diesel Ford Kuga with 40k on the clock and it did the same thing! Although the only evident common denominator at the moment is me! :rolleyes:

· Registered
233 Posts
Discussion Starter · #6 ·
if it doesnt get any better with injector sorted you may be looking at valves or piston rings or head gasket issue on that cylinder maybe worse case, not read any similar issues so i hope its not.
Number 4 & 5 injectors were swapped by Motormech. Now number 5 (was number 4) injector is playing up.

To be honest I fear those things listed above. How do they fail & how would I diagnose them?

If it's not the injector then I may have to question the longevity of the car and whether it is financially viable to keep it and replace those parts. Sad really because I do love it when it's on form.

Sent from App

· Registered
233 Posts
Discussion Starter · #11 ·
Cheers Bre,

I hand an injector replaced today and initially it seems that has gone a long way to resolving the issue. It is there but drastically reduced to a point you would not notice unless you were looking. If it stays this way then I am happy. Power delivery is smoother, gear changes from 1st to 2nd seem better, and the car is much quieter not sounding so much like a tractor.

I understand you troubles, and although you seem to have bigger problems, mine has come out of my own wallet. I am considering getting rid of the car while the going is good as I have lost some confidence in it. Especially as the main car for a young family!

Just out of interest, what is your replacement?
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