Engine: 2.5: missfire

[bernard1971]

ok dropped exhaust from manifold no start cat isnt the problem
cranking it over it wants to start but just wont go there is spark at plug and there is fuel pressure
could the coil pack be weak
if the ecu was was dead would i get spark and injection pulse as both seem fine
also noticed interior light not working as before does the 850 have a body control unit if so could i have damaged it by putting wire into wrong pin in the obdii socket by mistake if so would this also explain the car going from very rough running to non starter

how do i get into the ecu box under bonnet and what precautions do i need to take when buying a new ecu

[Jod T5]

Originally Posted by bernard1971

jod you still building flash readers
if so dam im in need of one

I am Bernard....

http://www.volvoforums.org.uk/showthread.php?t=52900

Originally Posted by bernard1971

ok dropped exhaust from manifold no start cat isnt the problem
cranking it over it wants to start but just wont go there is spark at plug and there is fuel pressure
could the coil pack be weak
if the ecu was was dead would i get spark and injection pulse as both seem fine
also noticed interior light not working as before does the 850 have a body control unit if so could i have damaged it by putting wire into wrong pin in the obdii socket by mistake if so would this also explain the car going from very rough running to non starter

how do i get into the ecu box under bonnet and what precautions do i need to take when buying a new ecu

Firstly have you checked the voltages as i mentioned before between 3 and 16 with ignition on and off?.
If your getting a spark then i would expect all the sensors are working, maybe incorrectly but you have a start....
Have you checked the plug gaps?...
What colour are the plugs after a lengthy crank?
How long do you crank for?..
Have you tried setting up a secondary engine earth using a jumplead?...
Have you checked the fuel pressure?.....
When was the fuel filter last changed?...
Do you know how to check resistance?..if so what is the resistance between the two bullets of your ECT sensor (coolant temp sensor)?....
Cheers
Jod

[bernard1971]

Originally Posted by Jod T5

I am Bernard....

http://www.volvoforums.org.uk/showthread.php?t=52900




Firstly have you checked the voltages as i mentioned before between 3 and 16 with ignition on and off?.
If your getting a spark then i would expect all the sensors are working, maybe incorrectly but you have a start....
Have you checked the plug gaps?...
What colour are the plugs after a lengthy crank?
How long do you crank for?..
Have you tried setting up a secondary engine earth using a jumplead?...
Have you checked the fuel pressure?.....
When was the fuel filter last changed?...
Do you know how to check resistance?..if so what is the resistance between the two bullets of your ECT sensor (coolant temp sensor)?....
Cheers
Jod

not re checked the voltage at socket not touched car today until it was dark but got young lad to drop exhaust to check cat
plugs are 2 weeks old ..... black and wet with fuel not checked gaps
10 to 15 secounds cranking
had jump leads to engine, body and base of coil
not checked fuel pressure but was hoping easystart would confirm fuel was good as it still made no effort to start
fuel filter is at the workshop to be fitted tomorrow
is the temp sensor combined with the temp gauge

[bernard1971]

sorry workshop is full of trucks undergoing body repairs so no room for my car
will get voltage readings from socket tomorrow
if coil amplifier was failing would that cause an ignition timing fault

[Jod T5]

Originally Posted by bernard1971

sorry workshop is full of trucks undergoing body repairs so no room for my car
will get voltage readings from socket tomorrow

Read the ECT sensor resistance while your at it Bernard...
If its nice and cold expect IRO 6-7k ohm.....
Cheers
Jod

[Jod T5]

Originally Posted by bernard1971

if coil amplifier was failing would that cause an ignition timing fault

If your getting a spark i would put this bottom of the list......
Cheers
Jod

[bernard1971]

ok got some strange voltages from obd socket
had jump leads from another car onto volvo as battery is getting low after all this cranking so actual readings under vehicles own battery may differ
ok pin 16 to 3
ign off -10.30v
ign on -12.33v
link 3 to 5 no flashing of led
the car tries to start but it is like timing is way out

[Chris_Rogers]

Looks like pin 3 is being held near gound potential for some reason.

There is either a short circuit on the diagnostic line wiring or the ECU / immobilizer is holding the level low.

Try disconnecting the battery for an hour or so (I guess you are going to have to anyway to recharge it).

It's better to measure the voltages on the socket relative to a good ground connection.

If I remembar correctly this is a 20V car with Jetronic 3.2.

Pins 4 & 5 should be gound, pin 16 = +12V not switched by ignition.

Ignition off; pins 1, 3 & 7 near 0V

Ignition on Pos II; pins 1, 3 & 7 near 10V

[bernard1971]

Originally Posted by Chris_Rogers

Looks like pin 3 is being held near gound potential for some reason.

There is either a short circuit on the diagnostic line wiring or the ECU / immobilizer is holding the level low.

Try disconnecting the battery for an hour or so (I guess you are going to have to anyway to recharge it).

It's better to measure the voltages on the socket relative to a good ground connection.

If I remembar correctly this is a 20V car with Jetronic 3.2.

Pins 4 & 5 should be gound, pin 16 = +12V not switched by ignition.

Ignition off; pins 1, 3 & 7 near 0V

Ignition on Pos II; pins 1, 3 & 7 near 10V

cant understand why from 16 to 3 i get minus voltage

[bernard1971]

have i shoved a wire into wrong pin when i first tried to gain flash codes