P38A Thor engine RPM

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kermit_rr

kermit_rr

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I'm officially stumped now and don't know where to start.
I've mentioned before that nanocom reports the correct engine RPM at all times and the engine runs fine, idling at around 720 when hot.
The problem is the target rpm is completely out of whack. I thought it was a big in the nanocom display, but my new LPG system reports the same rpm as the bosch says is the target. At idle, the target is around 2800 ish and can go up to 10,000rpm if i hoof it!
It's obviously wrong, but the engine runs as it should.
How is wrong, why does the engine not try to reach the set target and how can i fix it?
Help!!
 
Have you got anybody with a nanocom to double check.

hummm target= +/- 4x. Why?

Does it come from crank or cam?
Why doesn’t the car actually try and get there?
Double check diagnostics for me to start as it seems the thing that’s off
J
 
marjon said:
Have you got anybody with a nanocom to double check.

hummm target= +/- 4x. Why?

Does it come from crank or cam?
Why doesn’t the car actually try and get there?
Double check diagnostics for me to start as it seems the thing that’s off
J
Click to expand...
I don't know anyone else near by with a nanocom. I figured the fact the LPG ecu showed the same value was close enough to rule out a bug.
I connected the lpg to pin 17 on connector 4 of the Bosch ECU which is labelled (by nanocom) as 'engine speed - output'
 
I don't know where it gets the signal from, but if someone has swapped things around then i can't see the engine would start.
I wonder.. if it is a bug in the nanocom AND the pinout is mislabeled.. maybe I've tapped into the cam sensor? Hmm
 
Just as a thought, my old lpg system tapped into the same wire and that ran ok though i don't know what rpm it actually saw as i couldn't connect to it
 
kermit_rr said:
I don't know where it gets the signal from, but if someone has swapped things around then i can't see the engine would start.
I wonder.. if it is a bug in the nanocom AND the pinout is mislabeled.. maybe I've tapped into the cam sensor? Hmm
Click to expand...

Yeah but the Pinout is for petrol as well so that doesn’t really explain the nano reading?
I wouldn’t assume you have tapped in wrong as you get the same on both.

Have you asked on the BBS forum?

J
 
marjon said:
Yeah but the Pinout is for petrol as well so that doesn’t really explain the nano reading?
I wouldn’t assume you have tapped in wrong as you get the same on both.

Have you asked on the BBS forum?

J
Click to expand...
I've not, i did see someone else presenting a similar issue but i don't think it got resolved. Will post on there and see what turns up
 
I must admit, I'm confused. Target Revs? What are you referring to? You say the car runs OK, and the tacho reports the right revs. What are you looking to do?

@oakey what do you mean by crank revs for one crank and not crankshaft revs?
 
I've just re-read the bosch pdf and actual RPM is measured from the crank sensor. maybe i should tap into this instead of the 'engine speed' wire.
Target engine speed is the value which the IACV uses and will increase or decrease the airflow to achieve this value.
Target engine speed is calculated is calculated from various factors including coolant temp and time since engine start.

Maybe this is the issue in that nanocom is mislabelled, it's not target RPM, but just a 'value' which the bosch ecu understands and can use.

I think I should connect the LPG engine speed input to the crank sensor input and see if that gives a better value. I can't see it could harm the LPG ecu even if its a wrong value.
 
Ok so have you tried to change it "RPM input" and see what you get?

Not sure what you mean by "ignition input" where would you get that signal? coils?

J
 
There's 2 options for rpm input, standard and weak, whatever that means but both give the same wrong value.
The loom goes inline to reach petrol injector so it knows exactly what is going on, i presume that's how it works out the rpm. It doesn't have any connection to the coils
 
My dvm is at a friend's house, i need to get it then do some probing, it's got a setting for Hz which i hope should get readings from the crankshaft sensor input and also camshaft sensor input, might shed some light
 
Does it piggy back 1 injector or all?

But going back to the original reason I would still want to check the Nano. But if the LPG is giving the same then something is going on.

What system have you got maybe somebody else has and could advise:) I know its all questions but sometimes you can hit upon the obvious by asking simple/stupid questions.

J
 
marjon said:
But going back to the original reason I would still want to check the Nano. But if the LPG is giving the same then something is going on.
J
Click to expand...
if its connected to the same wire the nano reports from then it makes sense its reporting the same value.. i know thats stating the obvious but might be that simple..
 
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