Chimaera rough idle confusion
Discussion
Hi all
I'm hoping someone will kindly share their wisdom because I've run out of ideas/knowledge on this one!
Long story short(ish)...
I have a 1997 Chimaera 500 that would not start due to a lack of spark on the king lead. Tried new coils/amps and swapped leads, no joy, even bought a new hall sensor for the dizzy, but still nothing. I did manage to create a spark manually by rolling a screwdriver over the hall sensor so I figured there was a problem somewhere in the dizzy preventing the spark triggering. I broke a plastic part in the dizzy trying to investigate further (doh!), so bit the bullet and splashed out on a 123 Ignition, hoping never to have similar issues again. After fitting the 123 dizzy the car started fine and I was hoping to get it on the rollers to set it up properly, but unfortunately it still wasn't/isn't running right...
I bought 4 x sparkrite plug testers and checked the sparks on each bank. This showed that plug #6 occasionally had a weak to no spark when the rough running occurred - there would be a drop in rpm and the motor would struggle to keep running until a few seconds later when something corrected itself and the rpm jumped up. I thought 'ah ha' and changed #6 HT lead (and plug) with the neighbouring one that was running fine. It made no difference. #6 still bad. My confusion really set in when I disconnected #6 HT lead and held it to the engine block to see the spark and I saw the same behaviour i.e. rough running when the spark quality dropped or disappeared - even though it wasn't connected to the plug! I thought it was the mis-fire causing the rough running, but it's almost like something else is causing the rpms to drop at the same time as affecting the spark to #6.
Things I tried along the way:
New AFM
New Flame-Thrower coil (recommended for the 123 ignition)
Cleaning the stepper motor (proved working using RoverGauge)
Cleaning around the butterfly air inlet flap (not sure of its proper name)
Checked the ECU for connections/dampness
Checked the ignition (and fuel) relay
The timing is set to roughly 8 degrees BTDC.
RoverGauge shows everything as normal (AFAIK) with no fault codes - apart from 100% long term trim on both lambdas, but I'm thinking that's down to the mis-fire(?)
Would anyone be able to help me with next steps or let me know anything I've missed please?
Maybe take it somewhere for a vacuum leak check??
Many thanks in advance.
Tim
I'm hoping someone will kindly share their wisdom because I've run out of ideas/knowledge on this one!
Long story short(ish)...
I have a 1997 Chimaera 500 that would not start due to a lack of spark on the king lead. Tried new coils/amps and swapped leads, no joy, even bought a new hall sensor for the dizzy, but still nothing. I did manage to create a spark manually by rolling a screwdriver over the hall sensor so I figured there was a problem somewhere in the dizzy preventing the spark triggering. I broke a plastic part in the dizzy trying to investigate further (doh!), so bit the bullet and splashed out on a 123 Ignition, hoping never to have similar issues again. After fitting the 123 dizzy the car started fine and I was hoping to get it on the rollers to set it up properly, but unfortunately it still wasn't/isn't running right...
I bought 4 x sparkrite plug testers and checked the sparks on each bank. This showed that plug #6 occasionally had a weak to no spark when the rough running occurred - there would be a drop in rpm and the motor would struggle to keep running until a few seconds later when something corrected itself and the rpm jumped up. I thought 'ah ha' and changed #6 HT lead (and plug) with the neighbouring one that was running fine. It made no difference. #6 still bad. My confusion really set in when I disconnected #6 HT lead and held it to the engine block to see the spark and I saw the same behaviour i.e. rough running when the spark quality dropped or disappeared - even though it wasn't connected to the plug! I thought it was the mis-fire causing the rough running, but it's almost like something else is causing the rpms to drop at the same time as affecting the spark to #6.
Things I tried along the way:
New AFM
New Flame-Thrower coil (recommended for the 123 ignition)
Cleaning the stepper motor (proved working using RoverGauge)
Cleaning around the butterfly air inlet flap (not sure of its proper name)
Checked the ECU for connections/dampness
Checked the ignition (and fuel) relay
The timing is set to roughly 8 degrees BTDC.
RoverGauge shows everything as normal (AFAIK) with no fault codes - apart from 100% long term trim on both lambdas, but I'm thinking that's down to the mis-fire(?)
Would anyone be able to help me with next steps or let me know anything I've missed please?
Maybe take it somewhere for a vacuum leak check??
Many thanks in advance.
Tim
Yep, I have the leads with the ceramic extenders which have always been great. I have just bought a new (cheaper) set as the next thing to try actually, so I'll give it a go, thanks.
When I tested the spark against the block I had no extender on though, so I'm not expecting that to be the problem.
When I tested the spark against the block I had no extender on though, so I'm not expecting that to be the problem.
> You happy it's wired right ?
I believe so. It's pretty simple. Just 2 wires + an earth (optional).
> Does the dizzy spin ok when cranking?
The rotor arm? I haven't cranked it with the cap off to watch, but I presume so as the engine starts no problem and the other 7 cylinders seem fine.
I believe so. It's pretty simple. Just 2 wires + an earth (optional).
> Does the dizzy spin ok when cranking?
The rotor arm? I haven't cranked it with the cap off to watch, but I presume so as the engine starts no problem and the other 7 cylinders seem fine.
Thanks Pal, have PM'd you.
Yeah, I forgot to mention I have all new plugs too. I've also tried my original lucas coil and two new viper coils along the way! The 123 ignition has an internal amp, so that's out of the equation.
I tried some local old school auto electrician types but they are all waiting on hip ops or have bad knees so 'don't want to be crawling in and out of a TVR' I'm just left with the local bosch garage at £120/hr for diagnostics - It may well come to that!
I also spoke to the 123 supplier who gave me a bunch of tests to try. Can't remember all of them off the top of my head, but only some seemed relevant and others I didn't have the equipment for. I did suspect the 123 unit, but the engine dipping without #6 lead connected makes me think it's something else.
Yeah, I forgot to mention I have all new plugs too. I've also tried my original lucas coil and two new viper coils along the way! The 123 ignition has an internal amp, so that's out of the equation.
I tried some local old school auto electrician types but they are all waiting on hip ops or have bad knees so 'don't want to be crawling in and out of a TVR' I'm just left with the local bosch garage at £120/hr for diagnostics - It may well come to that!
I also spoke to the 123 supplier who gave me a bunch of tests to try. Can't remember all of them off the top of my head, but only some seemed relevant and others I didn't have the equipment for. I did suspect the 123 unit, but the engine dipping without #6 lead connected makes me think it's something else.
Thanks all for your replies.
Andy:
> Do a vacuum or smoke test before doing anything else
Yep, I think definitely worth doing once I've ruled out the further checks I can do myself, thanks.
Andrew:
> king lead from coil direct to a plug which is resting on the block
I did this but without the plug. I can try with a plug to see if it makes a difference.
Mark, many thanks for your detailed and well thought out response. Please see my replies to your questions below...
> have you routed the HT leads correctly?
Not looking at the diagram, no. Mine do cross over in several places. I'll sort that out as the next step. That said, I have closely monitored for sparks in the dark several times and haven't noticed any sparks or blue glows, but will check again.
> it only becomes specific between the rotor arm and HT lead number 6 so you can discount anything "upstream"
This is why I was really confused when I saw the same problems occurring even without #6 lead connected to the plug - in that situation there is nothing else "downstream"
> cut a hole in an old distributor cap
I could maybe try and mark the exact position of the copper post on the dizzy body and hand-crank to see if the rotor range is aligned. (BTW, I didn't mention, but I also tried a Distributor Doctor rotor and cap)
> find someone who can look at several cylinder traces at the same time
Yeah, this is where I was heading with the "local old school auto electrician types" because one of them advised me to hook it up to an oscilloscope, but I haven't found anyone yet.
> spark arc voltage depends on the combustion chamber condition
Great suggestion, but I believe this was ruled out by observing the spark when not connected to the plug. I will definitely pull plug 6 out and take a look at the condition though.
> long term trim, is it adding or removing fuel
100% adding on both
> Short term will also spike at 100% adding fuel during a misfire
Makes sense, but didn't observe that
> showing on both banks yet you say its only plug 6
Very good point. I hadn't thought of that. Not sure where that leave me though. Presumably I have a fueling/lambda issue too then??
> have you put a test meter on the coils 12v ignition supply to make sure its not dropping
Not while running, no. I'll give that a try too, thanks!
> Definitely got + and -ve the correct way around on the coil
Pretty sure, yes.
Andy:
> Do a vacuum or smoke test before doing anything else
Yep, I think definitely worth doing once I've ruled out the further checks I can do myself, thanks.
Andrew:
> king lead from coil direct to a plug which is resting on the block
I did this but without the plug. I can try with a plug to see if it makes a difference.
Mark, many thanks for your detailed and well thought out response. Please see my replies to your questions below...
> have you routed the HT leads correctly?
Not looking at the diagram, no. Mine do cross over in several places. I'll sort that out as the next step. That said, I have closely monitored for sparks in the dark several times and haven't noticed any sparks or blue glows, but will check again.
> it only becomes specific between the rotor arm and HT lead number 6 so you can discount anything "upstream"
This is why I was really confused when I saw the same problems occurring even without #6 lead connected to the plug - in that situation there is nothing else "downstream"
> cut a hole in an old distributor cap
I could maybe try and mark the exact position of the copper post on the dizzy body and hand-crank to see if the rotor range is aligned. (BTW, I didn't mention, but I also tried a Distributor Doctor rotor and cap)
> find someone who can look at several cylinder traces at the same time
Yeah, this is where I was heading with the "local old school auto electrician types" because one of them advised me to hook it up to an oscilloscope, but I haven't found anyone yet.
> spark arc voltage depends on the combustion chamber condition
Great suggestion, but I believe this was ruled out by observing the spark when not connected to the plug. I will definitely pull plug 6 out and take a look at the condition though.
> long term trim, is it adding or removing fuel
100% adding on both
> Short term will also spike at 100% adding fuel during a misfire
Makes sense, but didn't observe that
> showing on both banks yet you say its only plug 6
Very good point. I hadn't thought of that. Not sure where that leave me though. Presumably I have a fueling/lambda issue too then??
> have you put a test meter on the coils 12v ignition supply to make sure its not dropping
Not while running, no. I'll give that a try too, thanks!
> Definitely got + and -ve the correct way around on the coil
Pretty sure, yes.
Thanks again all for taking the time to post on this.
My latest updates on trying the suggestions so far are below...
> have you routed the HT leads correctly?
I have now. Unfortunately problem still present.
> spark arc voltage depends on the combustion chamber condition
Great suggestion, but I believe this was ruled out by observing the spark when not connected to the plug. I will definitely pull plug 6 out and take a look at the condition though. – please see photo of plug #6
> Short term will also spike at 100% adding fuel during a misfire
Makes sense, but didn't observe that – This was observed after leaving at idle after the 15min run to gather the RoverGauge logs for Frank.
> have you put a test meter on the coils 12v ignition supply to make sure its not dropping
Not while running, no. I'll give that a try too, thanks! – The voltage across the coil terminals was ~13.93V, it did increase during the periods where the engine dips and runs rough, but only to ~13.98V
I haven't had chance to look at the lambda sensors yet, although I'm not sure what to test on them.
I have generated RoverGauge logs for Frank and will send for analysis.
My latest updates on trying the suggestions so far are below...
> have you routed the HT leads correctly?
I have now. Unfortunately problem still present.
> spark arc voltage depends on the combustion chamber condition
Great suggestion, but I believe this was ruled out by observing the spark when not connected to the plug. I will definitely pull plug 6 out and take a look at the condition though. – please see photo of plug #6
> Short term will also spike at 100% adding fuel during a misfire
Makes sense, but didn't observe that – This was observed after leaving at idle after the 15min run to gather the RoverGauge logs for Frank.
> have you put a test meter on the coils 12v ignition supply to make sure its not dropping
Not while running, no. I'll give that a try too, thanks! – The voltage across the coil terminals was ~13.93V, it did increase during the periods where the engine dips and runs rough, but only to ~13.98V
I haven't had chance to look at the lambda sensors yet, although I'm not sure what to test on them.
I have generated RoverGauge logs for Frank and will send for analysis.
Finally had chance to pull the plugs...
This is the passenger side/good bank.
This is the driver side/bad bank.
Not much difference, but of course RoverGauge did say 100% long term trim on both banks (for whatever reason).
The plugs are B7ECS (as recommended to me).
I tried changing all the plug leads to brand new ones and if anything it was worse.
Vacuum test on Monday.
This is the passenger side/good bank.
This is the driver side/bad bank.
Not much difference, but of course RoverGauge did say 100% long term trim on both banks (for whatever reason).
The plugs are B7ECS (as recommended to me).
I tried changing all the plug leads to brand new ones and if anything it was worse.
Vacuum test on Monday.
Finally had chance to pull the plugs...
This is the passenger side/good bank.
This is the driver side/bad bank.
Not much difference, but of course RoverGauge did say 100% long term trim on both banks (for whatever reason).
The plugs are B7ECS (as recommended to me).
I tried changing all the plug leads to brand new ones and if anything it was worse.
Vacuum test on Monday.
This is the passenger side/good bank.
This is the driver side/bad bank.
Not much difference, but of course RoverGauge did say 100% long term trim on both banks (for whatever reason).
The plugs are B7ECS (as recommended to me).
I tried changing all the plug leads to brand new ones and if anything it was worse.
Vacuum test on Monday.
Finally had chance to pull the plugs...
This is the passenger side/good bank.
This is the driver side/bad bank.
Not much difference, but of course RoverGauge did say 100% long term trim on both banks (for whatever reason).
The plugs are B7ECS (as recommended to me).
I tried changing all the plug leads to brand new ones and if anything it was worse.
Vacuum test on Monday.
This is the passenger side/good bank.
This is the driver side/bad bank.
Not much difference, but of course RoverGauge did say 100% long term trim on both banks (for whatever reason).
The plugs are B7ECS (as recommended to me).
I tried changing all the plug leads to brand new ones and if anything it was worse.
Vacuum test on Monday.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff