Stupid?? Coil question.
Discussion
Hello everybody. I'm currently doing some fault finding on the Cerbera. After fixing an oil leak and fitting an electric power steering pump the car now runs like crap. It seems to only be firing on 4-6 cylinders. My coils have been relocated to the inner fender and need to be removed to access the front "panel" thing to get to all the stuff in front of the motor. I'm wondering if I knocked one a bit and it's died on me.
Question: when the coil fires does it fire all 4 leads at once, or is it split into two?
Question: when the coil fires does it fire all 4 leads at once, or is it split into two?
Sorry for the crappy diagram, but you get the picture.
The ECU pulls the voltage on pin 1 to zero, to fire plugs 1 and 7, and then on pin 2, to fire plugs 3 and 5.
It is a “wasted spark” setup, so each pair of plugs look like they’re firing together, but only one is at TDC. This means the TDC plug gets all the energy (as the other one doesn’t need much to achieve spark).
Hope this helps.
I have had no-end of coil pack issues (awaiting my 4th set to arrive in the post) and have not figured out a good way to test a faulty coil pack.
Good luck.
Well it turns out it was plugs! I put a timing light on each lead and found that it was running on 3 cylinders, with a fourth kicking in and out.
I swapped the coils and found the dead cylinders didn't move with the coils. So I pulled the plugs, swapped them for new ones and she's sweet.
I guess over the past year of rebuilding the suspension, fuel system and so on she's had a few too many cold starts and idling in the shed.
I swapped the coils and found the dead cylinders didn't move with the coils. So I pulled the plugs, swapped them for new ones and she's sweet.
I guess over the past year of rebuilding the suspension, fuel system and so on she's had a few too many cold starts and idling in the shed.
QBee said:
Good one Sherlock - nice piece of deduction.... 
Haha yeah I'm a TVR detective!So I took it for a spin and she's way better, but I'm still showing zero on both lambdas. One of the jobs I've done was running a fatter wire from the fuse box to the fuel pump, so I will check and make sure I haven't misplaced or blown a fuse.
I also occasionally see a dthrottle fault (or something written in red) flash up. I know the plug to the left hand throttle pot is a little on the loose side, could this be the cause of the fault?
And when I give it heaps it still breaks down and sputters a bit. Could this be because of the dead lambdas?
mrniceguy351 said:
I also occasionally see a dthrottle fault (or something written in red) flash up. I know the plug to the left hand throttle pot is a little on the loose side, could this be the cause of the fault?
And when I give it heaps it still breaks down and sputters a bit. Could this be because of the dead lambdas?
dThrottle isnt so much of a fault as an indication that the ECU has detected movement of the throttles and is applying acceleration enrichment. Of course a noisy throttle pot could trigger that when you're not actually accelerating.And when I give it heaps it still breaks down and sputters a bit. Could this be because of the dead lambdas?
If your throttle pots are set incorrectly, or the adaptive maps have been screwed up my the missfire/lambdas then you can expect running issues.
CerbWill said:
dThrottle isnt so much of a fault as an indication that the ECU has detected movement of the throttles and is applying acceleration enrichment. Of course a noisy throttle pot could trigger that when you're not actually accelerating.
If your throttle pots are set incorrectly, or the adaptive maps have been screwed up my the missfire/lambdas then you can expect running issues.
Yeah next step is work out whats wrong with the lambdas. I can see the adaptives are up to 34% at certain points, this seems like a lot of extra fuel.If your throttle pots are set incorrectly, or the adaptive maps have been screwed up my the missfire/lambdas then you can expect running issues.
I wasted a day chasing a lambda that wouldn’t respond, after I replaced my throttle pots.
I learned the hard way, that the lambdas are narrow-band, therefore won’t respond until and unless they sniff the correct AFR (stoichiometric). Eventually, I turned up one of the pots and the lambda began to respond.
Pull the plugs on the lambda’s (one at a time, on top of bell-housing) and check for 12V. You can go further and check continuity back to the ECU connector.
Then, you can reset your adaptives and and see if the ECU enriches (max adaptive) trying to achieve stoichiometric.
I learned the hard way, that the lambdas are narrow-band, therefore won’t respond until and unless they sniff the correct AFR (stoichiometric). Eventually, I turned up one of the pots and the lambda began to respond.
Pull the plugs on the lambda’s (one at a time, on top of bell-housing) and check for 12V. You can go further and check continuity back to the ECU connector.
Then, you can reset your adaptives and and see if the ECU enriches (max adaptive) trying to achieve stoichiometric.
I have reset the adaptives a few times. On my test drive tonight I could watch the adaptives slowly adding more and more fuel at low throttle openings with the lambdas both at zero.
One thing I didn't mention is that I blanked off the breather tube from the intake manifold to the air intake next to the crankcase breather (which I have also removed). I did this to pull more of a vacuum on the fuel tank as the stink of fuel in the car was quite noticeable, and that's with no leaks, and all new fuel lines. Obviously with this vacuum source plugged I've had to up the idle a bit. This means she is now idling around 21% on the throttle pots. I'm guessing I should adjust the pots back to the more typical 12-15% >
One thing I didn't mention is that I blanked off the breather tube from the intake manifold to the air intake next to the crankcase breather (which I have also removed). I did this to pull more of a vacuum on the fuel tank as the stink of fuel in the car was quite noticeable, and that's with no leaks, and all new fuel lines. Obviously with this vacuum source plugged I've had to up the idle a bit. This means she is now idling around 21% on the throttle pots. I'm guessing I should adjust the pots back to the more typical 12-15% >
Imran999 said:
I wasted a day chasing a lambda that wouldn’t respond, after I replaced my throttle pots.
I learned the hard way, that the lambdas are narrow-band, therefore won’t respond until and unless they sniff the correct AFR (stoichiometric). Eventually, I turned up one of the pots and the lambda began to respond.
Pull the plugs on the lambda’s (one at a time, on top of bell-housing) and check for 12V. You can go further and check continuity back to the ECU connector.
Then, you can reset your adaptives and and see if the ECU enriches (max adaptive) trying to achieve stoichiometric.
Yeah that could be it. I will play with the pots.I learned the hard way, that the lambdas are narrow-band, therefore won’t respond until and unless they sniff the correct AFR (stoichiometric). Eventually, I turned up one of the pots and the lambda began to respond.
Pull the plugs on the lambda’s (one at a time, on top of bell-housing) and check for 12V. You can go further and check continuity back to the ECU connector.
Then, you can reset your adaptives and and see if the ECU enriches (max adaptive) trying to achieve stoichiometric.
The adaptives are tipping in bulk fuel with the lambdas both at zero, see above post.
Since resetting the throttle pots to 12.3% at idle when I put my foot down in neutral the car sputters and the wideband goes to 16:1 (the max limit).
This is what this Cerbera sherlock thinks:
The zero lambda readings could be a legit lean situation.
Having the throttle pots at 20% at idle was actually helping me
I need to check fuel pressure and clean injectors.
This is what this Cerbera sherlock thinks:
The zero lambda readings could be a legit lean situation.
Having the throttle pots at 20% at idle was actually helping me
I need to check fuel pressure and clean injectors.
mrniceguy351 said:
So it turns out my fuel pressure was 38psi. After jacking it up to 50 she seems to run a lot better, but lambdas are still stuck on zero.
I'm starting to think a haltech and a couple of widebands could be the go.
Hello,I'm starting to think a haltech and a couple of widebands could be the go.
How did you jack up the pressure? This is an interesting thread
Well the cerb fuel pressure reg is 3.5 bar so about 52psi. I wonder if someone has fitted a rover v8 2.5 bar reg at some point ?
So now you know the fuel pressure is about right, you could even raise that a little bit more to the correct 52psi (presumably you have a proper reg in there and haven't just restricted the return line?).
It seems you have a 4.5 so set your airflows even and the tickover around 950rpm and the throttle sensors to around 15-16percent and you should be somewhere near. Mind you your afr gauge shows lambda1 so your lambdas should have shown as switching at that point.
So now you know the fuel pressure is about right, you could even raise that a little bit more to the correct 52psi (presumably you have a proper reg in there and haven't just restricted the return line?).
It seems you have a 4.5 so set your airflows even and the tickover around 950rpm and the throttle sensors to around 15-16percent and you should be somewhere near. Mind you your afr gauge shows lambda1 so your lambdas should have shown as switching at that point.
Gassing Station | Cerbera | Top of Page | What's New | My Stuff