P38A 1995, p38, diesel, manual: Engine won't rev sometimes

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Jerseyp38

Active Member
Posts
240
Hi All,

Sorry to trouble just before Christmas but after some ideas and possible directions to look. I have an alternator fault showing regularly but as has been discussed before probably an earth fault (but have noticed the error message doesn't come up unless I let the glow plugs go their time. I have fitted a new in-tank pump and recently had the injectors serviced.

Additionally, I do have a hot start fix fitted and a PSI power box.

So when driving along having lifted my foot from the accelerator say to slow for a bend when I put my foot back on the accelerator the engine doesn't rev but if I drop down a gear and give the engine chance to go back to idle it will then rev up again. It doesn't stall and ticks over at 750 rpm. I don't have a nanocom (and cannot afford one at the moment, I have asked to borrow one but cannot locate one on Jersey).

Any suggestions for places to start to look? Guess I had better start saving for a nanocom.......

Thanks in advance.
 
Hiya, yes, saving for a nanocom is your number one priority, they are invaluable.
As to your current issue, my knowledge on the diesels is limited but what I've seen on here to check are (in no particular order)
Leak off pipes
MAP sensor pipe.
Turbo hoses delamination
Fuel pump timing.
@wammers is the guru on these and I would strongly advise you to follow any advice he gives TO THE LETTER!
Nobody knows more than he about the p38 diesel.
Good luck.
 
I'd start with the fault you know about before looking for a second, especially with it being an earth fault. Heavens knows what readings it is getting with an earth fault. I think the throttle is fly-by-wire, isn't it? Low revs = low volts = spurious reading = no power?
 
Grrrrrr said:
I'd start with the fault you know about before looking for a second, especially with it being an earth fault. Heavens knows what readings it is getting with an earth fault. I think the throttle is fly-by-wire, isn't it? Low revs = low volts = spurious reading = no power?
Click to expand...
It is fly by wire and pretty reliable compared to the Transit throttle potentiometer.
 
Thanks for the replies, fuel filter is a couple of years old but can pull well when I put my foot down (as much as you can in Jersey). The engine light (looks like an injector?) comes on regularly on lifting foot from accelerator but cannot say I have noticed it particularly when the engine goes flat. Despite the £750 injector rebuild cost! Have some time over the Christmas break so will look at the earths will find out how much the local indie (is that the right word? and if so what does it stand for?) guy will charge for a diagnostic. Was thinking about making up a long lead for the multimeter so it can be on the battery negative and then check the resistances on the BeCM as a start point. Did have a period of leaking heater matrix O rings which I did recently (year/18months)?
 
Jerseyp38 said:
Thanks for the replies, fuel filter is a couple of years old but can pull well when I put my foot down (as much as you can in Jersey). The engine light (looks like an injector?) comes on regularly on lifting foot from accelerator but cannot say I have noticed it particularly when the engine goes flat. Despite the £750 injector rebuild cost! Have some time over the Christmas break so will look at the earths will find out how much the local indie (is that the right word? and if so what does it stand for?) guy will charge for a diagnostic. Was thinking about making up a long lead for the multimeter so it can be on the battery negative and then check the resistances on the BeCM as a start point. Did have a period of leaking heater matrix O rings which I did recently (year/18months)?
Click to expand...

Injector lamp coming on as you lift off is a quantity servo fault. You need diag on it i am afraid. £750 for refurbing injectors are you being serious. That is bloody ridiculous. Costs about £32.00 per injector around here exchange. £250.00 should cover all six.
 
Wammers: Yes, well joys of Jersey. I offered to let the guy keep the injectors and said I would buy some more, we negotiated down in the end but it was still a lot. Was a bit difficult the guy really though he was doing me a favour! Will follow up with the diagnostics then, (says sucking in on my teeth)! Thank you.
 
Jerseyp38 said:
Wammers: Yes, well joys of Jersey. I offered to let the guy keep the injectors and said I would buy some more, we negotiated down in the end but it was still a lot. Was a bit difficult the guy really though he was doing me a favour! Will follow up with the diagnostics then, (says sucking in on my teeth)! Thank you.
Click to expand...
Wasn't the price of these injectors talked about a while ago on another thread?
Could be wrong..:)
 
Yes, my fault a bit as I didn't check how much he was going to charge........... But had asked him just to reshim as I had changed the nozzles and pop tested them but didn't have shims to get the right crack pressures. I think he thought I worked in finance and had $$$$$$ to spend. Haven't managed to get the car diagnosed yet but am going to fit a new filter this weekend and check flow on in tank pump and fuel pipes for softness. Then make a start on cleaning any earth points and checking the earth connections on the BeCM.
 
Jerseyp38 said:
Yes, my fault a bit as I didn't check how much he was going to charge........... But had asked him just to reshim as I had changed the nozzles and pop tested them but didn't have shims to get the right crack pressures. I think he thought I worked in finance and had $$$$$$ to spend. Haven't managed to get the car diagnosed yet but am going to fit a new filter this weekend and check flow on in tank pump and fuel pipes for softness. Then make a start on cleaning any earth points and checking the earth connections on the BeCM.
Click to expand...

Have you been told before you need diagnostics on this. Guessing will cost you a bloody fortune. Already has to a great extent.
 
Hi Wammers,

Yes, I am not ignoring the advice given. One person came and had a look and then their snap on didn't do the job. I refrained from saying anything. Spoke to a local indie guy today who was helpful but not keen on the diagnostic route so will do some simple things first. Would buy a nanocom but simply don't have the spare cash at present. Will ring main stealer and find out how much................. Otherwise might wait until I get to the UK........
 
Jerseyp38 said:
Hi Wammers,

Yes, I am not ignoring the advice given. One person came and had a look and then their snap on didn't do the job. I refrained from saying anything. Spoke to a local indie guy today who was helpful but not keen on the diagnostic route so will do some simple things first. Would buy a nanocom but simply don't have the spare cash at present. Will ring main stealer and find out how much................. Otherwise might wait until I get to the UK........
Click to expand...

You're coming to the mainland? Permanently?
 
Try this quick trick.

Unplug your diesel engine ecu, check the pins on the ecu & connector. Refit the connector to the ecu making sure it's fully home as you're locking it in.
 
Yes indeed, after spending a fortune on what it can't be he needs to be looking for what it can be. Good diag would have sorted this long ago.
 
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