P38A Diesel cutting out

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rover75lover

Active Member
Posts
210
Location
newport.wales.uk
98 diesel auto, had problems with her not starting but she starts OK cold or warm now.
however took her out on the road today and she cuts out ar Nything over 2750 revs. I. E. Engi e stops have to pull in restart her, starts no problem. Will rev freely, hold 2750 and above when in neutral or park. Attached the nanocom, needle and rpm pretty close until she cuts out, then the rpm dissapears but needle valve still has a value. Nanacom records needle lift sensor invalid value.
All, any help gratefully received. Idles beautifully, modulation 49 at 93 degrees
 
Does the Nanocom not have any more EDC faults stored? The engine will be shut down by the ECU if an implausible signal or no signal at all is being received from the quantity servo feedback pot. It will restrict RPM if the needle sensor signal is implausible or missing. But if modulation at idle hot is 49% that seems ok. Only if the static timing was vastly advanced or retarded would you expect to see a lift sensor fault. Bit of a strange one this.
 
Hi yes it also says fuel flow value out of range
I know of 3 P38's that always show fuel flow value out of range and they run fine. I may be wrong but I always suspected that this was a fault with the diagnostics rather than a fault with the car.
I don't know, but would a dodgy CPS cause the problem? Wammers would know for sure.
I suppose the in tank pump is working?
 
98 diesel auto, had problems with her not starting but she starts OK cold or warm now.
however took her out on the road today and she cuts out ar Nything over 2750 revs. I. E. Engi e stops have to pull in restart her, starts no problem. Will rev freely, hold 2750 and above when in neutral or park. Attached the nanocom, needle and rpm pretty close until she cuts out, then the rpm dissapears but needle valve still has a value. Nanacom records needle lift sensor invalid value.
All, any help gratefully received. Idles beautifully, modulation 49 at 93 degrees

Can you take a trace from the EDC page in the Nanocom? I'm wondering if the CPS signal disappears.

I am also wondering if the reason it is 49% modulation is that it is using some sort of default value?
 
Not on mine. Not using Nanocom anyway.
Wammers said the same, I don't have enough P38 diesels around to be sure if it a bug in the Faultmate diagnostics or a genuine fault, the cars certainly run well. I have in the past reported a couple of bugs in the Faultmate that BBS fixed, so it is possible it's a bug.
 
I know of 3 P38's that always show fuel flow value out of range and they run fine. I may be wrong but I always suspected that this was a fault with the diagnostics rather than a fault with the car.
I don't know, but would a dodgy CPS cause the problem? Wammers would know for sure.
I suppose the in tank pump is working?

Bit of an enigma this one Keith. If the modulation is 49% at idle warm i am wondering why Nanocom would say lift sensor invalid value. it would only say that if static was miles out in either direction. CPS signal disappearing is a concern. But of course the ECU will if CPS fails, take info from lift sensor but engine would run very fast at idle. Can't recall what the original problem was or what he has done to it.
 
Thanks to all. Never had a problem with the injector light previously. She just would not start one morning, no fuel bei g injected. Checked pump output, flattened two batteries, changed and synced the ecu on the engine, no start. Stop solenoid clicking. Changed cps, flattened two more batteries. Replaced original cps, no start. Re checked pump output after filter, 180 ml. Removed filter checked output 200 ml. Tank is 3/4 full anyway. Screwed filter back on, watched her as mate turned her over and hey presto, fuel spitting everywhere and she started with three cracked open injectors. Faultless starting since. Idles superbly, sounds gorgeous. Revs in p or n but on road over 2750 engine cuts out
 
Hmm, been working so decided to try the lady up our lane. Surprisingly she will rev to 2750 and above in low box. I'm beginning to wonder if the cutting out occurs when warm only?
Also I've connected the nanacom to two of my friends diesel p 38. Their modulation are 72 and 85 yet both seem to run fine. Question is my nanacom out? If it was and the two others were actually 45 and 50, mine would be 25 to 30 would that explain my symptoms?
 
You would need to move pump away from engine , normally when the chains have worn and the modulation is going up in the 80s you push pump towards engine to allow for stretch and bring it back to original 45-55.
yours is correct best left alone.
 
Hmm, been working so decided to try the lady up our lane. Surprisingly she will rev to 2750 and above in low box. I'm beginning to wonder if the cutting out occurs when warm only?
Also I've connected the nanacom to two of my friends diesel p 38. Their modulation are 72 and 85 yet both seem to run fine. Question is my nanacom out? If it was and the two others were actually 45 and 50, mine would be 25 to 30 would that explain my symptoms?
Check the connections to the fuel shut off valve on the FIP
 
Hmm, been working so decided to try the lady up our lane. Surprisingly she will rev to 2750 and above in low box. I'm beginning to wonder if the cutting out occurs when warm only?
Also I've connected the nanacom to two of my friends diesel p 38. Their modulation are 72 and 85 yet both seem to run fine. Question is my nanacom out? If it was and the two others were actually 45 and 50, mine would be 25 to 30 would that explain my symptoms?

No. I think the value might even be out of your ECU rather than calculated by the Nanocom as the base values aren't present.

If you take a trace of the 3 EDC screens by saving to SD card you can open in Excel as semi-colon separated file (used by Europeans more than comma) and paste into one of these spreadsheets to visualise.
 

Attachments

  • EDC.zip
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I'm tempted to adjust the pump to 75 80 as the other two ranges. If so do I adjust the pump towards the engine or away?

Ridiculous. As it is your modulation is near perfect. The other two are both retarded and need static timing doing to advance them. Sense should tell you if you get three different readings on three different cars the Nanocom is accurate.
 
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