Tuning Problems V12

Talk about the E-Type Series 3

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SESH
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#1 Tuning Problems V12

Post by SESH » Thu Jun 20, 2019 5:45 pm

Hi All.
Has anyone come up against this before.
I have a 1973 Series 3 V12 OTS.
Issues were that it wouldn't idle properly when hot and stalled with RPM falling below 500. Secondly re-start, after being left for 20 mins it was a problem to start - not firing at all. Then after a number of attempts it started. Doesn't like to sit in gear whilst idling (its an Auto).
So my mechanic who knows Jaguars well tested the emissions and the CO was up at 9.5 with the hydro carbon reading at around 2000.
He adjusted the needle height on all 4 needles but it made no difference. So started off again setting them lean and trying to find a good balance. Then all of a sudden we got 4 on the CO and 500 on the Hydro carbons. Great we thought. Took it for a run and measured when back and we were back at 9.5 and around 2400 hydrocarbon. Tried this a couple of times - same result.
Any ideas.
Thanks.
Mike
1973 Series 3 OTS Signal Red

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MarekH
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#2 Re: Tuning Problems V12

Post by MarekH » Thu Jun 20, 2019 8:03 pm

You've already answered your own question - you have told us there is a huge amount of hydrocarbons coming out of the tailpipe, so it sounds as though you are running on fewer than nine cylinders when this is happening, so next time shut the engine down and look at which plugs are soaked in petrol and/or black carbon and take it from there.

Your hot starting problem may be totally unconnected and so don't attempt to solve this until you have a normally running car. The typical way to start a heat soaked v12 is to simply floor the accelerator.

kind regards
Marek

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SESH
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#3 Re: Tuning Problems V12

Post by SESH » Thu Jun 20, 2019 9:13 pm

Hi Marek,
Thanks for your input. However the engine is running otherwise perfectly smooth and not missing a beat. That's the strange thing!
Mike
1973 Series 3 OTS Signal Red

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MarekH
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#4 Re: Tuning Problems V12

Post by MarekH » Thu Jun 20, 2019 10:21 pm

It's not strange - it's called an intermittent fault. You have to act when you catch it and the plugs won't lie if they are black or soaked in unburnt petrol.

My hunch is that the throttle sticks shut somewhere sometimes. I have a datalogger on my v12 and I can make it run happily at 500rpm at walking speed with my foot on the brakes and in first gear but the air-fuel ratio is super rich when I do this (~9:1). I can also do it by deliberately shutting down 4 cylinders (although it comes up lean in this case for obvious reasons - in your case, you can't switch off the petrol supply, so it'd do the same but be very rich before the cylinders die.) In either case, you'll see what the plugs look like and then you can stop wandering and start looking for what is the different factor on those cylinders.

kind regards
Marek

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Woolfi
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#5 Re: Tuning Problems V12

Post by Woolfi » Thu Jun 20, 2019 10:32 pm

I had such a problem for three years. If the hydrocarbons are 2000 ppm and the co is 9,5% maybe some ignitions ar failing and the motor is blowing out not ignited mixture from some strokes.
Such a problem can be ignition related or carb-related. Mine was ignition related. The timimg was much too early. At iddle in some different cylinder don't burn the mixture, because of too early spark, the mixture was not compressed enought, that the mixture starts to explode.

Maybe one carb is not working correct. Marek wrote, that you can check the sparks plugs and try to find the bad working carb or cylinder. If the 3 spark plugs of cylinder nr. 1, 2, 3, or 4, 5, 6 or 7, 8, 9, or 10. 11. 12 are dark, you have identified the bad carb.
Also you can buy a colortune spark plug and check the burning in the cylinder at idle. You can see very clearly, which cylinder is working bad.
Regards Wolfgang Gatza

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SESH
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#6 Re: Tuning Problems V12

Post by SESH » Fri Jun 21, 2019 10:23 am

Thanks Marek and Woolfi.
We will check the plugs and report back.
Probably next week now as currently have a lot on.
Thanks for your valuable help. Very helpful.
Mike
1973 Series 3 OTS Signal Red

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jagwit
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#7 Re: Tuning Problems V12

Post by jagwit » Fri Jun 21, 2019 7:26 pm

Mike, what ignition system does your car have?
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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#8 Re: Tuning Problems V12

Post by SESH » Fri Jun 21, 2019 10:02 pm

Hi Philip,
It has a new SNG Barratt Ignition Conversion Kit (Opus was removed)
Product Code : DAB113HE
Mike
1973 Series 3 OTS Signal Red

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#9 Re: Tuning Problems V12

Post by SESH » Mon Jul 15, 2019 6:34 pm

Update.
The four Carbs came off. Fitted 8 new butterfly rod seals, re-set floats, New Vacuum Pipes, New adjuster Screws. Colour Tuned, All Plugs running Blue!
Car is running much better and CO and Emissions at normal.
However, the idle is a bit intermittent so still working on that. It tends to now idle between 600-1000 RPM but it varies a bit.
Could this still be a leak somewhere?
Mike
1973 Series 3 OTS Signal Red

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jagwit
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#10 Re: Tuning Problems V12

Post by jagwit » Mon Jul 15, 2019 6:53 pm

SESH wrote:
Mon Jul 15, 2019 6:34 pm
It tends to now idle between 600-1000 RPM but it varies a bit.
Does the idle speed vary like that as it stands there, idling, just being left alone? Or does it choose a new idle speed every time after throttles were operated?
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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#11 Re: Tuning Problems V12

Post by SESH » Mon Jul 15, 2019 7:14 pm

It will idle at a constant RPM, then after a run it will change. It doesn't fluctuate at idle.
Mike
1973 Series 3 OTS Signal Red

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jagwit
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#12 Re: Tuning Problems V12

Post by jagwit » Mon Jul 15, 2019 7:18 pm

SESH wrote:
Mon Jul 15, 2019 7:14 pm
It will idle at a constant RPM, then after a run it will change. It doesn't fluctuate at idle.
Mike
That tells me that the butteflies don't return to the exact same position after they were operated by the throttle mechanism. Either they are sticking or play in the throttle linkages is not consistent.

An air flow gauge would confirm this - which you should have used to balance the carbs ;-)
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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#13 Re: Tuning Problems V12

Post by SESH » Mon Jul 15, 2019 11:10 pm

Thanks Philip.
Will check butterflies and throttle linkages.
Mike
1973 Series 3 OTS Signal Red

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#14 Re: Tuning Problems V12

Post by SESH » Wed Jul 17, 2019 9:26 pm

All linkages/Butterflies seem ok.
Took the car out to a classic meet this evening. Was quite warm around 25 deg C
Car ran very smoothly without issue for about 15 miles. I stopped to wait for some friends for about 30 mins. Tried to re-start the car and although the engine would turn without problem it wouldn't fire nor even an attempt to fire not even a splutter. Just span over. Allowed the car to cool for around an hour and it started! It ran perfectly again until we arrived at the meet. There were so many cars and a massive queue and the temp gauge went up to a fraction over the L of Normal. Car started to misfire and after flooring the throttle spewed a very rich mixture out the exhaust. Added to this one of the front brakes was binding and locked up! (It's an Auto and due to all the queues I had ridden the brakes hard to stop car from stalling). Car then stalled again and again wouldn't start. (Fortunately I managed to get into a bus stop layby)After about 2 hours with the bonnet up she fired up first turn and I got home in cooler evening weather and a good flow of cool air through the rad and engine. Fuel wasn't an issue, it was ignition. I am thinking that this could be an electrical fault with the Ignition circuitry, the car has a replacement non-Opus SNG unit. It's only a couple of years old and has probably run about 1,000 miles, However it is mounted in the middle of the V at the front of the engine where it gets very hot. Could this be the issue. I am considering moving the veined controller unit to the picture frame where it will be a little cooler. With all this the car didn't boil over.
Any thoughts please.
Thanks
Mike
1973 Series 3 OTS Signal Red

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42south
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#15 Re: Tuning Problems V12

Post by 42south » Thu Jul 18, 2019 3:17 am

Hi Mike
Very frustrating.
I have the SNG barratt opus replacement system on my V12. I have had it installed for 5 or 6 years with the amplifier in the valley the same as yours, it has not shown any problems. However the symptoms you describe sound like the failure mode of the original OPUS amp, so it may be the amp. You may have got unlucky and have a faulty amp.
Marek has suggested on several occasions that you could try to isolate the problem by putting a bag of ice or frozen veges on the amp to cool it, then see if it will start. I think you can also get a can of freezing agent to spray on the amp.
Your brake issue may depend on whether it is definitely only one front brake, it it is then a flexible line internal collapse; not readily visible from outside, or a caliper problem may be indicated.
If its both front brakes then the booster is indicated, you can isolate it by removing the vacuum supply from the inlet manifold.
good luck
mark
Mark Brown
1971 S3 Etype
Son: when I grow up, I want to be a pilot
Dad: You’ll have to choose.

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andrewh
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#16 Re: Tuning Problems V12

Post by andrewh » Thu Jul 18, 2019 6:44 am

SESH wrote:
Wed Jul 17, 2019 9:26 pm
All linkages/Butterflies seem ok.
Took the car out to a classic meet this evening. Was quite warm around 25 deg C
Car ran very smoothly without issue for about 15 miles. I stopped to wait for some friends for about 30 mins. Tried to re-start the car and although the engine would turn without problem it wouldn't fire nor even an attempt to fire not even a splutter. Just span over. Allowed the car to cool for around an hour and it started! It ran perfectly again until we arrived at the meet. There were so many cars and a massive queue and the temp gauge went up to a fraction over the L of Normal. Car started to misfire and after flooring the throttle spewed a very rich mixture out the exhaust. Added to this one of the front brakes was binding and locked up! (It's an Auto and due to all the queues I had ridden the brakes hard to stop car from stalling). Car then stalled again and again wouldn't start. (Fortunately I managed to get into a bus stop layby)After about 2 hours with the bonnet up she fired up first turn and I got home in cooler evening weather and a good flow of cool air through the rad and engine. Fuel wasn't an issue, it was ignition. I am thinking that this could be an electrical fault with the Ignition circuitry, the car has a replacement non-Opus SNG unit. It's only a couple of years old and has probably run about 1,000 miles, However it is mounted in the middle of the V at the front of the engine where it gets very hot. Could this be the issue. I am considering moving the veined controller unit to the picture frame where it will be a little cooler. With all this the car didn't boil over.
Any thoughts please.
Thanks
Mike
I just read this post for the first time. I Have an XJ12 series one ( on Carbs ) also with the SNG Opus replacement mounted in the valley as they always were. I have had exactly the same issue and it turned out to be the SNG Amplifier going the same way as the original OPUS system AMP. Namely when hot it would fail, then when cool it would get you home. I purchased a new Amplifier and a new coil to match, and all is now good again. I have not relocated the amplifier to the front over radiator location as SNG seem to think with their new specification Amplifiers this is not absolutely necessary. I think I would be asking if the amplifier you have is of the same design/specification as the ones they now produce. Inside the Amplifier is a standard GM HEI ignition module and a resistor I think . These are mounted on anti heat conductive cream. I got the impression that these modules will still fail with time. I think you need to have a conversation with SNG. If you are reading this Julian, I do wish you had a dedicated tech guy we could speak with at times. I know you have the technical knowledge internally to your company, but its very hard to get to speak with someone who really understands the tech. Just a thought.
If you do buy a coil and amplifier, make sure that you get the correct coil . I was sent an original fitment coil, i.e ballasted, when the SNG Ignition system is non ballasted. This resulted in me still having ignition failures when hot until I realised I had the incorrect coil. I am just about to fit this system to my 76 XJS so I do hope these Amplifiers are lasting a bit longer now. A lot of rich running will be down to intermittent failure of sparks not carbs, but it does sound that you have a few things going on there. As you will no doubt be aware the V12 on carbs are very susceptible to vacuum leaks which will mess up your running something rotten. Good luck.
1962 3.8 Series One FHC

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jagwit
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#17 Re: Tuning Problems V12

Post by jagwit » Thu Jul 18, 2019 2:22 pm

I have had exactly the same issue and it turned out to be the SNG Amplifier going the same way as the original OPUS system AMP.
That is really disappointing!! However, I am aware that modern IGBT's (transistors specifically meant for inductive kickback applications) have built-in self-protection mechanisms (over current and over temp etc). This is how I know....

I had a situation with the distributorless wasted spark implementation on my Jensen Interceptor (using dual EDIS-4) coils, where my car would just suddenly die. Parked with bonnet open for about 15min and off we go again. Long story short, it turned out that I was using non-resistored spark plugs where the the EDIS-4 coil packs "wanted" resistored spark plugs to reduce the amount of flyback current that was going back through the IGBT's during flyback causing the "ignition amp" to overheat and then shut itself down. Makes we wonder about how sensitive the SNG kit is to non-resistored plugs....
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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jagwit
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#18 Re: Tuning Problems V12

Post by jagwit » Thu Jul 18, 2019 2:33 pm

The bottom line is that mixing electronics and high heat is NEVER a good idea.

With a Series 3 rebuild I did for a friend, I mounted the AB14 amp (of an HE ignition system) right there inside the V where the OPUS amp was installed. This car drove faultlessly in > 38ºC temperatures with a tail wind.

BUT...

1) I mounted the ignition amp on an alu base plate of 3mm thickness AND I installed very good heat insulation between this base plate and the engine, to limit heat radiation from the engine to the ignition amp. And...
2) I had fitted 74ºC thermostats, made sure that the bypass circuits did fully close when the t/stats were open and the car was running on a brand new alu radiator.
3) Finally, the car was also fitted with vacuum advance module which reduces the heat production of an engine under partial throttle conditions (including idle) by significant amounts due to increased efficiency.

My point being: It all adds up...
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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Whitact
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#19 Re: Tuning Problems V12

Post by Whitact » Thu Jul 18, 2019 3:55 pm

Hi Mike,
Your description of the symptoms you have suffered sound very much like those that I had after an engine rebuild. In that case it turned out that the cold start mechanism in the carbs had been fitted 180 deg out so that in effect the cold start was always operating even with the control pushed fully in. Until that was discovered the car was doing only 10mpg and would not start when hot. Once the carbs had been rebuilt and tuned properly the car started easily hot or cold and returned 20+mpg. It may be that you have an ignition problem but from your description I suspect that your have an over rich mixture for some reason.
Cheers,
Adrian Turner
S3 OTS & FHC
S1 FHC
XK140 FHC

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#20 Re: Tuning Problems V12

Post by SESH » Thu Jul 18, 2019 10:52 pm

Thanks everyone for your thoughts and advice.
I am going more in the direction of the amplifier breaking down under heat.
I spoke with SNG Barrett today and they told me that they had problems with the replacement amplifier in the past and had re-designed it again in the lat 12 months. What we are looking at doing is re-locating it onto the picture frame. But to do that requires a longer wiring harness. The tech guy said he thought they did a longer harness and would investigate for me. I don't really want to shell out again for an expensive piece of kit if I can help it. Added to that the amplifier I bought (that has only covered about 1200 miles) isn't fit for purpose, not sure where I stand on any warranty as I bought it about 4 years ago. But will wait and see what can be achieved.
I also wondered if it was worth swapping out the coil for a new one.
Mike
1973 Series 3 OTS Signal Red

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