Question about no start condition
#121
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
#122
#123
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
Auto range: that should work fine. Somewhat better than my $15 Amazon special...
I wonder if it might be easiest to check on the injectors first. Choose a cylinder we know is firing (so any of 1A 2B 3B 4A) and connect the meter +ve to the Black/not red) wire, -ve to ground.
With the ignition on & motor not running, you should read B+ with the meter on Volts. Start the motor and switch the meter to Hz. Do you get a steady reading now?
I had to probe around a little with the blunt needle in the back of the injector plug to get proper contact.
I wonder if it might be easiest to check on the injectors first. Choose a cylinder we know is firing (so any of 1A 2B 3B 4A) and connect the meter +ve to the Black/not red) wire, -ve to ground.
With the ignition on & motor not running, you should read B+ with the meter on Volts. Start the motor and switch the meter to Hz. Do you get a steady reading now?
I had to probe around a little with the blunt needle in the back of the injector plug to get proper contact.
The following users liked this post:
Gus (05-27-2022)
#125
Auto range: that should work fine. Somewhat better than my $15 Amazon special...
I wonder if it might be easiest to check on the injectors first. Choose a cylinder we know is firing (so any of 1A 2B 3B 4A) and connect the meter +ve to the Black/not red) wire, -ve to ground.
With the ignition on & motor not running, you should read B+ with the meter on Volts. Start the motor and switch the meter to Hz. Do you get a steady reading now?
I had to probe around a little with the blunt needle in the back of the injector plug to get proper contact.
I wonder if it might be easiest to check on the injectors first. Choose a cylinder we know is firing (so any of 1A 2B 3B 4A) and connect the meter +ve to the Black/not red) wire, -ve to ground.
With the ignition on & motor not running, you should read B+ with the meter on Volts. Start the motor and switch the meter to Hz. Do you get a steady reading now?
I had to probe around a little with the blunt needle in the back of the injector plug to get proper contact.
The following users liked this post:
Gus (05-29-2022)
#128
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
#129
#130
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
OK, perhaps I can hear the TB or some other background noise.
That wild variation doesn't make sense
The meter should strictly be on DC Volts, but that wouldn't explain the erratic readings. Switch it to DC just to make sure.
Can you get a stable display by moving the probe to the Brown/Red wire on the injector plug? I'd expect a steady B+ there.
What is the symbol on the very top left of the meter display?
That wild variation doesn't make sense
The meter should strictly be on DC Volts, but that wouldn't explain the erratic readings. Switch it to DC just to make sure.
Can you get a stable display by moving the probe to the Brown/Red wire on the injector plug? I'd expect a steady B+ there.
What is the symbol on the very top left of the meter display?
#131
OK, perhaps I can hear the TB or some other background noise.
That wild variation doesn't make sense
The meter should strictly be on DC Volts, but that wouldn't explain the erratic readings. Switch it to DC just to make sure.
Can you get a stable display by moving the probe to the Brown/Red wire on the injector plug? I'd expect a steady B+ there.
What is the symbol on the very top left of the meter display?
That wild variation doesn't make sense
The meter should strictly be on DC Volts, but that wouldn't explain the erratic readings. Switch it to DC just to make sure.
Can you get a stable display by moving the probe to the Brown/Red wire on the injector plug? I'd expect a steady B+ there.
What is the symbol on the very top left of the meter display?
1A- 3.6
2A- 0
3A- 3.1
4A- 3.1
1B- 3.1
2B- 3.1
3B- 3.1
4B- 0
#132
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
#133
The meter should be on DC...
Poke the black lead into the little crevice in the springed hood latch where the hood/bonnet locks down. There is a spot where you can PIN the lead and leave it there so you have a ground and can use your other hand and move around... You have to find a good ground point.
Then, if you can, remove the connectors and take the readings from the connector contacts. You need to be seeing a solid steady battery voltage or youre doing something wrong.
Poke the black lead into the little crevice in the springed hood latch where the hood/bonnet locks down. There is a spot where you can PIN the lead and leave it there so you have a ground and can use your other hand and move around... You have to find a good ground point.
Then, if you can, remove the connectors and take the readings from the connector contacts. You need to be seeing a solid steady battery voltage or youre doing something wrong.
#134
So sorry, trying to do to many things at one time. The last set of numbers were with the engine running. I'll do it with just key on tomorrow.
#135
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
No worries
We're trying to confirm that we can get a stable Hz reading from the meter.
To recap, we want to 'see' the injector firing approximately 5.75 times each second, and we know that the ones for 1A 2B 3B 4A are good since the car isn't reporting any codes for those cylinders.
With the ignition on, motor not running, I'd expect to see B+ or around 12V DC on both the black/red and black/not red wire on an injector. Choose one of the above working cylinders, and place the meter probe at the black/not red injector connection. You should see B+.
Now switch the meter to 'Hz', start the engine and note the meter reading.
If you don't see B+ on the black/not red wire in the first step, move the probe to the black/red wire and check for B+ again (meter on DC volts). This should confirm whether or not the injector is receiving power.
We're trying to confirm that we can get a stable Hz reading from the meter.
To recap, we want to 'see' the injector firing approximately 5.75 times each second, and we know that the ones for 1A 2B 3B 4A are good since the car isn't reporting any codes for those cylinders.
With the ignition on, motor not running, I'd expect to see B+ or around 12V DC on both the black/red and black/not red wire on an injector. Choose one of the above working cylinders, and place the meter probe at the black/not red injector connection. You should see B+.
Now switch the meter to 'Hz', start the engine and note the meter reading.
If you don't see B+ on the black/not red wire in the first step, move the probe to the black/red wire and check for B+ again (meter on DC volts). This should confirm whether or not the injector is receiving power.
#136
How about just swapping the injectors from the suspect cylinders around? See if the problem follows the injectors.
edit:
I plowed though some of the original posts and did find the injectors were replaced.
The problem arose with coil replacement and now three cylinders show consistently misfire and a couple others occasionally. Since injectors, coils, plugs, ECM and even harness have been replaced, about the only two original items remaining are the engine and chassis. The resistance from the coils joint grounding point is 0.1 Ohms, What is the resistance from that lug to the battery ground? I have added ground wires on engines and chassis that did resolve problems numerous times. You might take a few minutes out to wire brush that lug and terminal then add a temporary ground wire from that ground lug directly to the battery terminal.
edit:
I plowed though some of the original posts and did find the injectors were replaced.
The problem arose with coil replacement and now three cylinders show consistently misfire and a couple others occasionally. Since injectors, coils, plugs, ECM and even harness have been replaced, about the only two original items remaining are the engine and chassis. The resistance from the coils joint grounding point is 0.1 Ohms, What is the resistance from that lug to the battery ground? I have added ground wires on engines and chassis that did resolve problems numerous times. You might take a few minutes out to wire brush that lug and terminal then add a temporary ground wire from that ground lug directly to the battery terminal.
Last edited by jrnsr; 06-01-2022 at 10:17 AM.
#138
No worries
We're trying to confirm that we can get a stable Hz reading from the meter.
To recap, we want to 'see' the injector firing approximately 5.75 times each second, and we know that the ones for 1A 2B 3B 4A are good since the car isn't reporting any codes for those cylinders.
With the ignition on, motor not running, I'd expect to see B+ or around 12V DC on both the black/red and black/not red wire on an injector. Choose one of the above working cylinders, and place the meter probe at the black/not red injector connection. You should see B+.
Now switch the meter to 'Hz', start the engine and note the meter reading.
If you don't see B+ on the black/not red wire in the first step, move the probe to the black/red wire and check for B+ again (meter on DC volts). This should confirm whether or not the injector is receiving power.
We're trying to confirm that we can get a stable Hz reading from the meter.
To recap, we want to 'see' the injector firing approximately 5.75 times each second, and we know that the ones for 1A 2B 3B 4A are good since the car isn't reporting any codes for those cylinders.
With the ignition on, motor not running, I'd expect to see B+ or around 12V DC on both the black/red and black/not red wire on an injector. Choose one of the above working cylinders, and place the meter probe at the black/not red injector connection. You should see B+.
Now switch the meter to 'Hz', start the engine and note the meter reading.
If you don't see B+ on the black/not red wire in the first step, move the probe to the black/red wire and check for B+ again (meter on DC volts). This should confirm whether or not the injector is receiving power.
#139
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
I couldn't find any 'banana skins' where Jaguar had changed the pin-to-pin wiring between the two years.
We are trying to establish whether the injectors on the 'bad' cylinders are firing. One of the default actions taken by the ECM when P035x codes are thrown is to inhibit injector firing for that cylinder. My take there is that if the ECM can't detect a sucessful spark, it will shut off the injector to the offending cylinder to prevent raw fuel being dumped out the exhaust and into the cat.
The codes indicate a coil or spark feedback issue, yet moving the coils around makes no difference. The grouping of the three failing cylinders suggests to me that there is a problem with the spark 'OK' signals getting back to the ECM (or, for some reason, the ECM isn't responding properly) since they are aggregated into two groups of four:- two from each bank per group.
Last edited by michaelh; 06-01-2022 at 06:38 PM. Reason: spelling, sigh
#140
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,157
Received 2,391 Likes
on
1,551 Posts
So as not to complicate things, I'm working on only injector 1A, right side first cylinder. Key on, I get 12v on both black/not red, and black/red. Switch the multimeter to Hz, engine on, I get no reading. The probe is working because I get 12v with key on, engine off, as well as engine on.
Last edited by michaelh; 06-01-2022 at 04:55 PM.