Intermidiate backfiring
#81
09-02-2018, 10:41 AM
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Sometimes you simply have to keep digging, repair faults as you find them, and then move on if needed.
Cheers
DD
#82
09-02-2018, 10:53 AM
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No reason to spend on Magnacor this time though...I bought OEM 'Rists" wires for my XJS and had no problems whatsoever over the years. On my present V12 I bought a set of Bosch wires for about $45 and the engine "purrs like a tomcat in a dairy"
Magnacor is high grade stuff, no doubt. I often wonder, though, if the owner benefits more than the engine does. The engine doesn't seem to care too much.
I suspect the biggest advantage of Magnacore wires is long term durability...which is certainly a worthwhile consideration.
Cheers
DD
#83
10-04-2018, 07:42 AM
So, I ordered the new ignition amp and ignition leads in the end of August. I was goin g on 3 weeks vacation to China and UAE from September 13th, so parts should arrive well in time for installation and test.
Well, DHL decided to first send the parcel to Jersey, then return it to sender and finally the parcel turned up after 3 weeks, while I was not at home.
I mounted the amp today. Changed 2 male spades to female, then it fitted my 89 HE engine
It seems to have solved the issue. We had around 16C today, and that is as hot as it gets this time of year. I drove a good long round and then tried driving really slowly to provoke the error to occur, and it didn’t !
Thanks for all your input. I believe Greg was the one to point on the amp, so I owe him a drink
Well, DHL decided to first send the parcel to Jersey, then return it to sender and finally the parcel turned up after 3 weeks, while I was not at home.
I mounted the amp today. Changed 2 male spades to female, then it fitted my 89 HE engine
It seems to have solved the issue. We had around 16C today, and that is as hot as it gets this time of year. I drove a good long round and then tried driving really slowly to provoke the error to occur, and it didn’t !
Thanks for all your input. I believe Greg was the one to point on the amp, so I owe him a drink
The following 2 users liked this post by leo_denmark:
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Greg in France (10-04-2018)
#84
10-04-2018, 08:09 AM
Veteran Member
#85
10-11-2018, 02:25 AM
Well, a few more runs has proved it's NOT fixed.
First 2 runs I got very slight missing at ultra light throttle. I doubt anyone else would have noticed, but I was looking for issues and found them. Runs were around 20 miles, included some motorway, and missing occured after motorway, i.e. when engine bay was warm. Temperature was not high, 12-16°C.
Then yesterday it was a bit warmer, 18°C. Still not warm at all. I did a 25 mile backroad drive, gentle and with light throttle. I got more missing, but it was far from undriveable, which it would have been at similar conditions before changing the ignition amp. I stopped and touched the amp: Pretty warm, but not boiling warm. I guess maybe 60-70°C on external faces. Much warmer than the inlet manifold though, so it is for sure warming up.
Based on the theory of ignition amp overheating at low RPM due to power being absorbed by amp instead of coil, I tried to use 2nd and even 1st gear. I was approaching my destination, so I didn't have time for extensive testing of this, but I believe it helped.
Return run was in 10°C and on motorway. 10 minutes at 100 MPH and then 3-4 miles slowly: Zero issues at all. It ran really sweet, both on motorway and after.
I must admit I'm tempted to move the amp out front just to see if it helps. I know some of you run original position and no issues at much higher ambient temp, but I also know many amps are giving problems. Mine is new and better than the old one, but is it good enough ?
Any advise on the extension leads to move the amp forward regarding routing and/or shielding ?
First 2 runs I got very slight missing at ultra light throttle. I doubt anyone else would have noticed, but I was looking for issues and found them. Runs were around 20 miles, included some motorway, and missing occured after motorway, i.e. when engine bay was warm. Temperature was not high, 12-16°C.
Then yesterday it was a bit warmer, 18°C. Still not warm at all. I did a 25 mile backroad drive, gentle and with light throttle. I got more missing, but it was far from undriveable, which it would have been at similar conditions before changing the ignition amp. I stopped and touched the amp: Pretty warm, but not boiling warm. I guess maybe 60-70°C on external faces. Much warmer than the inlet manifold though, so it is for sure warming up.
Based on the theory of ignition amp overheating at low RPM due to power being absorbed by amp instead of coil, I tried to use 2nd and even 1st gear. I was approaching my destination, so I didn't have time for extensive testing of this, but I believe it helped.
Return run was in 10°C and on motorway. 10 minutes at 100 MPH and then 3-4 miles slowly: Zero issues at all. It ran really sweet, both on motorway and after.
I must admit I'm tempted to move the amp out front just to see if it helps. I know some of you run original position and no issues at much higher ambient temp, but I also know many amps are giving problems. Mine is new and better than the old one, but is it good enough ?
Any advise on the extension leads to move the amp forward regarding routing and/or shielding ?
Last edited by leo_denmark; 10-11-2018 at 02:27 AM.
#86
10-11-2018, 06:15 AM
Veteran Member
Leo, just a few things to ask before you move the amp, as it does not sound hot enough to fail to me:
Greg
- Have you checked the dreaded white wire and stripped it back to where the insulation is not flaky and renewed it?
- Have you checked wiring for the low tension feed to the coil?
- Is the coil certainly 100% OK?
- Are the connectors onto the coil definitely OK? I mean, have you renewed them? Quite often the copper wire under the insulation fractures?
Greg
#87
10-11-2018, 06:25 AM
Hi Greg
Thanks for your input once again
I have looked closely at the dreaded white wire and decided it was OK. I find it hard to understand how it should fail only at low RPM combined with minor throttle opening and a certain level of temperature, but maybe I shall forget about understanding and just check it properly...
Same goes for low tension feed and other connectors in the ignition setup.
The coil is quite new, and I had similar problems with the original dual coil setup. That puts the coil a long way down the list of possible causes, if any logic applies to finding the fault...
I will go over this again and get a test drive done before temperatures drop from Monday...
I had to Google your greeting
Thanks
Thanks for your input once again
I have looked closely at the dreaded white wire and decided it was OK. I find it hard to understand how it should fail only at low RPM combined with minor throttle opening and a certain level of temperature, but maybe I shall forget about understanding and just check it properly...
Same goes for low tension feed and other connectors in the ignition setup.
The coil is quite new, and I had similar problems with the original dual coil setup. That puts the coil a long way down the list of possible causes, if any logic applies to finding the fault...
I will go over this again and get a test drive done before temperatures drop from Monday...
I had to Google your greeting
Thanks
#88
10-13-2018, 06:33 AM
Veteran Member
Leo
Just had a further thought. It could be that you have an injector that is not 100%. It might be that when going faster it works, but at low "clicks per second", as you might say, it is not 100%.
Does your slight miss show at tickover? If so, you could pull one injector plug at a time and see what happens. If removing one injector plug makes the miss regular, and the intermittent miss disappears, that would indicate the problem injector.
If it only misses when under some load, you could still try it, but it would be a longer process!
Greg
Just had a further thought. It could be that you have an injector that is not 100%. It might be that when going faster it works, but at low "clicks per second", as you might say, it is not 100%.
Does your slight miss show at tickover? If so, you could pull one injector plug at a time and see what happens. If removing one injector plug makes the miss regular, and the intermittent miss disappears, that would indicate the problem injector.
If it only misses when under some load, you could still try it, but it would be a longer process!
Greg
#89
10-13-2018, 10:07 AM
Great input, thanks. I actually just came to something similar: if I have an air leak at for example an injector o-ring, this cylinder would run lean, and this would be worst at very light load and idl. I have my AAV fully closed to achieve 750 rpm idle with AC. Idle drops to 550 when AC turns off the extra air solenoid at RH front.
My idle is not perfect. My injector condition is not known, but I have checked that they are all clicking using a mechanics stethoscope, and I have used a few bottles of injector cleaner.
Injector and hose refurb is on my to do list, and based on the issues I face it will have to be a job for next winter.
I have done nothing since Wednesday, at least nothing XJ-S related. I hope to get a few hours in the garage and a drive tomorrow to try out your injector test suggestions.
My idle is not perfect. My injector condition is not known, but I have checked that they are all clicking using a mechanics stethoscope, and I have used a few bottles of injector cleaner.
Injector and hose refurb is on my to do list, and based on the issues I face it will have to be a job for next winter.
I have done nothing since Wednesday, at least nothing XJ-S related. I hope to get a few hours in the garage and a drive tomorrow to try out your injector test suggestions.
#90
10-13-2018, 01:34 PM
Veteran Member
#91
10-13-2018, 01:42 PM
#92
10-14-2018, 04:10 AM
Veteran Member
Leo
You definitely have a not-properly-functioning AAV / tickover system. With the adjuster tight sut the car should stall if all else to spec.
Once the car is warm, try blocking the airbox to AAV pipe so the AAV / tickover system is getting no air, except through the dizzy vent, and you can block this by removing the pipe from the dizzy and blocking it. If it still runs, you have either got over-large butterfly gaps or a leak elsewhere.
Greg
You definitely have a not-properly-functioning AAV / tickover system. With the adjuster tight sut the car should stall if all else to spec.
Once the car is warm, try blocking the airbox to AAV pipe so the AAV / tickover system is getting no air, except through the dizzy vent, and you can block this by removing the pipe from the dizzy and blocking it. If it still runs, you have either got over-large butterfly gaps or a leak elsewhere.
Greg
#93
10-14-2018, 06:50 AM
Started up the engine cold and removed both air filters
AAV for sure sucks air cold, and only bare idles if I block it
As soon as the engine warm up a bit, AAV air flow is close to zero
Butterfly flow is also close to nothing, and pressing them in closing direction does not stall the engine. Idle is 750 wi5 AC on and 550 with AC off.
The electric solenoid air valve on RH front end of air cleaner housing opens and closes with AC on/off and gives a clear audible air flow noise when open. I still have around 500 RPM even when blocking the solenoid with compressor running.
Blocking accessible vacuum hoses (LH FPR line, dizzy vent does not reduce idle. Opening the lines increases idle.
Spraying WD40 all over inlet manifold gaskets and injector o-rings makes no change in idle or sound. There is no obvious suction noise, which there should be in my opinion, when all the correct air ways are closed.
The ignition amp was by by the way pretty warm after 15-20 minutes idle.
I did not try pulling injectors at this point. I find these connectors a bit hard to remove, and access is not good. I will practice removal on other more accessible similar connectors, but after 20 minutes in heavy CO and CH fumes it was time to get out of the garage. I have open doors and a draft, but still....
AAV for sure sucks air cold, and only bare idles if I block it
As soon as the engine warm up a bit, AAV air flow is close to zero
Butterfly flow is also close to nothing, and pressing them in closing direction does not stall the engine. Idle is 750 wi5 AC on and 550 with AC off.
The electric solenoid air valve on RH front end of air cleaner housing opens and closes with AC on/off and gives a clear audible air flow noise when open. I still have around 500 RPM even when blocking the solenoid with compressor running.
Blocking accessible vacuum hoses (LH FPR line, dizzy vent does not reduce idle. Opening the lines increases idle.
Spraying WD40 all over inlet manifold gaskets and injector o-rings makes no change in idle or sound. There is no obvious suction noise, which there should be in my opinion, when all the correct air ways are closed.
The ignition amp was by by the way pretty warm after 15-20 minutes idle.
I did not try pulling injectors at this point. I find these connectors a bit hard to remove, and access is not good. I will practice removal on other more accessible similar connectors, but after 20 minutes in heavy CO and CH fumes it was time to get out of the garage. I have open doors and a draft, but still....
#94
10-14-2018, 07:15 AM
Veteran Member
A couple ideas to ponder. The actual EFI amp inside dissipates heat through the metal amp case. A thin layer of good thermal transfer paste on the mounting surface is necessary.
Barring any air leaks i’d suspect uneven fuel injector delivery. A backwards flow through them may flush any debris from the internal screen filters. Sending them out to be tested and a balanced set chosen is ideal.
Barring any air leaks i’d suspect uneven fuel injector delivery. A backwards flow through them may flush any debris from the internal screen filters. Sending them out to be tested and a balanced set chosen is ideal.
#95
10-14-2018, 07:50 AM
Thanks JigJag
Should I use the thermal paste just between amp box and inlet manifold, or should I open it to get paste in there as well ??
Overrun valves just popped up as something I had not thought about. Blocking both makes no impact on idle speed. They are not 100% tigh, they build up a small vacuum over time.
Brake booster line is tight. It still held a good vacuum after some time, and blocking it didn’t affect idle
Removing and blocking the vacuum line to the dizzy vacuum regulator did lower idle, but I suppose the later ignition timing will make idle drop ? I have tested the line earlier to hold a vacuum.
Next:I will replace balance tube with some temporary plumbing, I can use to determine which bank delivers the false idle air...
Should I use the thermal paste just between amp box and inlet manifold, or should I open it to get paste in there as well ??
Overrun valves just popped up as something I had not thought about. Blocking both makes no impact on idle speed. They are not 100% tigh, they build up a small vacuum over time.
Brake booster line is tight. It still held a good vacuum after some time, and blocking it didn’t affect idle
Removing and blocking the vacuum line to the dizzy vacuum regulator did lower idle, but I suppose the later ignition timing will make idle drop ? I have tested the line earlier to hold a vacuum.
Next:I will replace balance tube with some temporary plumbing, I can use to determine which bank delivers the false idle air...
#96
10-14-2018, 11:21 AM
Veteran Member
Hot amp after 20 mins is 100% normal. The lower the revs the more heat the amp generates (for reasons Warrjon can no doubt explain!).
You are on to something now with the unexplained idle. If you have not replaced the balance tube flexible connectors to the manifold they might be cracked.
Also the vac tube to the ECU might be leaking.
Also, block off the crank ventilation into the B bank airbox and see if that changes anything.
You are on to something now with the unexplained idle. If you have not replaced the balance tube flexible connectors to the manifold they might be cracked.
Also the vac tube to the ECU might be leaking.
Also, block off the crank ventilation into the B bank airbox and see if that changes anything.
#97
10-14-2018, 12:22 PM
1” Balance tube connecting hoses are new(ish)
ECU vacuum line holds a vacuum, so it’s tight.
Crank ventilation goes to air filter box, not inlet plenum, so I would say it cannot have influence on idle speed ?
I think I understand the reason for the amp heating up at low rpm, I just wanted to mention this as I was uncertain about just how warm it should get...
ECU vacuum line holds a vacuum, so it’s tight.
Crank ventilation goes to air filter box, not inlet plenum, so I would say it cannot have influence on idle speed ?
I think I understand the reason for the amp heating up at low rpm, I just wanted to mention this as I was uncertain about just how warm it should get...
#98
10-14-2018, 12:28 PM
Veteran Member
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#99
10-14-2018, 12:36 PM
Thanks JigJag. I might have some paste from my last computer build...
i just realized that that the crankcase vent connects to both inlet plenums as well through the small diameter balance pipe (or whatever it’s called...)
How does this work ? Is there a check valve in the connector to the air box ?
i just realized that that the crankcase vent connects to both inlet plenums as well through the small diameter balance pipe (or whatever it’s called...)
How does this work ? Is there a check valve in the connector to the air box ?
#100
10-14-2018, 01:50 PM
The positive crankcase ventilation system influences idle !
Blocking the connection to LH airbox reduces idle significantly, so I suppose it is defect ?
Engine was kind of cold now, so AAV was somewhat open. With AAV and PCV inlets blocked and AC off I still have 500 RPM idle, so the search continues, but I’m getting there...
Kirby tells there are loads of other PCVs, that will fit. Does anyone know of one of something European or Japanese, which is what is easy to find parts for here in Denmark.
Blocking the connection to LH airbox reduces idle significantly, so I suppose it is defect ?
Engine was kind of cold now, so AAV was somewhat open. With AAV and PCV inlets blocked and AC off I still have 500 RPM idle, so the search continues, but I’m getting there...
Kirby tells there are loads of other PCVs, that will fit. Does anyone know of one of something European or Japanese, which is what is easy to find parts for here in Denmark.