That voltage is wrong.

The battery is new, charged, and starts the car just fine. Must be a loose or bad connection somewhere. ECU is below the passenger seat isn’t it? Pins and sockets probably need a clean. I can sort that and test the voltage at the connector.

It could explain the lack of kickdown maybe. I still think I’ve got a misfire under load too. I thought it was chugging a bit today.

Thanks for that, a good place to start….!
 
Last edited:
pwood999 said:
Fuel seems to be going open loop every so often ? Might be worth checking the O2 sensor connections.
Click to expand...
Does it go open loop during wide open throttle? The open loop bits (roughly) line up with me putting my foot down where there would be an uphill I think.
 
with the gems titiana 02 sensors they fault to 5v and it'll run very lean, which will cause your issue, a quick look at the o2 sensors with an obd will tell you what going on with them..
 
Henry_b said:
with the gems titiana 02 sensors they fault to 5v and it'll run very lean, which will cause your issue, a quick look at the o2 sensors with an obd will tell you what going on with them..
Click to expand...
The live data from the Nanocom shows them swinging from 0v to 5v up and down up and down, so I think they’re good.
 
MrGorsky said:
That voltage is wrong.

The battery is new, charged, and starts the car just fine. Must be a loose or bad connection somewhere. ECU is below the passenger seat isn’t it? Pins and sockets probably need a clean. I can sort that and test the voltage at the connector.
It could explain the lack of kickdown maybe. I still think I’ve got a misfire under load too. I thought it was chugging a bit today.
Thanks for that, a good place to start….!
Click to expand...
Did you sort out that low voltage issue?
From what you say, the battery voltage is OK, but presumably there is a dodgy connector?

I have to confess particular interest in this thread as my P38 is in V8 Developments right now....
 
Last edited:
MrGorsky said:
I'm slowly going down the rabbit hole of doom!
Click to expand...
At the risk of winding you up, which is absolutely not my intention, at this stage perhaps you should step back and formalise your fault diagnosis.
Bertrand Russell's concept of meta-level works for this - or "the helicopter view" to use a dumbed-down term for it.
Occam's razor is also important: think carefully about symptoms before leaping to a conclusion. Another measurement might mean that a particular solution is not possible with those particular symptoms.
To quote the philosopher Datatek: "leaping to conclusions does not generally work and can be very expensive"...
(Well it was something like that - I am sure he will correct me...)
Measurement is clearly critical to this planned diagnosis:
~ Your P38 should do 0-60 mph in a little under 10 seconds. No doubt you can test this safely and with consideration for other road users, and if sluggish you will find it performs in nowhere near that time.
~ I would have thought that an MoT Test Centre will run an emissions test without a full MoT. That could give interesting results.
~ Check colour of spark plugs.
~ Although a rolling road (particularly a 4WD one) may not be convenient, it could provide valuable information.
~ As previous suggested, it is probably a good idea to have a chat with V8 Developments and even get the car back to them. Whilst out of warranty, I am sure they would want to help you solve this.
Apologies if all the above is a privileged glimpse of the bleeding' obvious, but I mean well.....
 
Last edited:
P38 Monkey said:
At the risk of winding you up, which is absolutely not my intention, at this stage perhaps you should step back and formalise your fault diagnosis.
Bertrand Russell's concept of meta-level works for this - or "the helicopter view" to use a dumbed-down term for it.
Occam's razor is also important: think carefully about symptoms before leaping to a conclusion. Another measurement might mean that a particular solution is not possible with those particular symptoms.
To quote the philosopher Datatek: "leaping to conclusions does not generally work and can be very expensive"...
(Well it was something like that - I am sure he will correct me...)
Measurement is clearly critical to this planned diagnosis:
~ Your P38 should do 0-60 mph in a little under 10 seconds. No doubt you can test this safely and with consideration for other road users, and if sluggish you will find it performs in nowhere near that time.
~ I would have thought that an MoT Test Centre will run an emissions test without a full MoT. That could give interesting results.
~ Although a rolling road (particularly a 4WD one) may not be convenient, it could provide valuable information.
~ As previous suggested, it is probably a good idea to have a chat with V8 Developments and even get the car back to them. Whilst out of warranty, I am sure they would want to help you solve this.
Apologies if all the above is a privileged glimpse of the bleeding' obvious, but I mean well.....
Click to expand...

You mean like having a cuppa or 2 before deciding to take a grinder to that bugger 10mm nut ;) .

I would also agree that the low voltage readings need further investigation. If ECUs are really seeing a low voltage they could be doing allsorts of weird things.

But dont know where the Nano gets the voltage from when it is checking an ECU.

But I would imagine the engine is correct and more to do with other issues. Our V8tuner engine was spot on, both companies have been doing it a while and know their stuff.

J
 
marjon said:
I would also agree that the low voltage readings need further investigation. If ECUs are really seeing a low voltage they could be doing allsorts of weird things.

But dont know where the Nano gets the voltage from when it is checking an ECU.
Click to expand...

Nano instructions says it's just the voltage at the ECU as provided by the BECM. There's 2 pins with voltage on, 1 and 39 I think. Anyway, if the voltage is what the Nanocom syas it is then I suspect the wiring, if the voltage isn't what the Nanocom says, then maybe the ECU is duff.... I'll go and test it when I find an hour or two.

The engine sounds sweet as a nut on tickover..... its just under load.
 
Last edited:
P38 Monkey said:
At the risk of winding you up, which is absolutely not my intention, at this stage perhaps you should step back and formalise your fault diagnosis.
Bertrand Russell's concept of meta-level works for this - or "the helicopter view" to use a dumbed-down term for it.
Occam's razor is also important: think carefully about symptoms before leaping to a conclusion. Another measurement might mean that a particular solution is not possible with those particular symptoms.
To quote the philosopher Datatek: "leaping to conclusions does not generally work and can be very expensive"...
(Well it was something like that - I am sure he will correct me...)
Measurement is clearly critical to this planned diagnosis:
~ Your P38 should do 0-60 mph in a little under 10 seconds. No doubt you can test this safely and with consideration for other road users, and if sluggish you will find it performs in nowhere near that time.
~ I would have thought that an MoT Test Centre will run an emissions test without a full MoT. That could give interesting results.
~ Although a rolling road (particularly a 4WD one) may not be convenient, it could provide valuable information.
~ As previous suggested, it is probably a good idea to have a chat with V8 Developments and even get the car back to them. Whilst out of warranty, I am sure they would want to help you solve this.
Apologies if all the above is a privileged glimpse of the bleeding' obvious, but I mean well.....
Click to expand...
Shouldn't a rebuilt engine be "run in" before, using full performance?
 
aj1954 said:
Shouldn't a rebuilt engine be "run in" before, using full performance?
Click to expand...
Well yes, but I managed the terrifying "cam break in" proceedure without issues.

It's just not even got the ooomph to drive gently, so I'm having to try other things in short bursts. Not ideal I know.
 
aj1954 said:
Shouldn't a rebuilt engine be "run in" before, using full performance?
Click to expand...
Yes and no
Piston rings bed in over at max 20 miles, after that, the seal won't improve.
Bedding in is done by use of full load to push the rings against the cylinder walls
 
MrGorsky said:
Well yes, but I managed the terrifying "cam break in" proceedure without issues.

It's just not even got the ooomph to drive gently, so I'm having to try other things in short bursts. Not ideal I know.
Click to expand...
Yes, the "cam break in" sounds quite a scary procedure but, I would have thought V8 Developments would have bench tested
it before handover.
 
kermit_rr said:
I didn't know about it first time around. Didn't have a problem
Click to expand...
I was aware of it but, when I had my V8, I never needed to even remove a rocker cover, I have since learned I must have been
very lucky with it in the 4.5 yrs I owned it!
 
aj1954 said:
I was aware of it but, when I had my V8, I never needed to even remove a rocker cover, I have since learned I must have been
very lucky with it in the 4.5 yrs I owned it!
Click to expand...
how did you change the cam without removing the rockers?
 
Henry_b said:
with the gems titiana 02 sensors they fault to 5v and it'll run very lean, which will cause your issue, a quick look at the o2 sensors with an obd will tell you what going on with them..
Click to expand...

Judging from the smell I would say it is running rich rather than lean, especially on startup.
 
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