Flooding 88 XJS
#21
06-12-2015, 02:30 PM
Safari
You now have a few things to go at: The sump breather system (as Katoh says, this is quite a possibility given the blue smoke), the loom, the oxygen sensors, the enrichment timer system, and here is a fourth:
If the full throttle enrichment system is earthing all the time for some reason, this would make the engine run rich. On USA spec cars there are two devices that trigger the full throttle enrichment:
1) a microswitch on the rear of the capstan
2) a vac switch on the rear of the A bank manifold.
If the wiring to either of these is cracked and earthing unintentionally, or either switch is malfunctioning that would cause rich running.
Greg
You now have a few things to go at: The sump breather system (as Katoh says, this is quite a possibility given the blue smoke), the loom, the oxygen sensors, the enrichment timer system, and here is a fourth:
If the full throttle enrichment system is earthing all the time for some reason, this would make the engine run rich. On USA spec cars there are two devices that trigger the full throttle enrichment:
1) a microswitch on the rear of the capstan
2) a vac switch on the rear of the A bank manifold.
If the wiring to either of these is cracked and earthing unintentionally, or either switch is malfunctioning that would cause rich running.
Greg
Thank you for the additional info.
I am going to be working on this car most of the weekend. Hopefully I will discover the problem and get it fixed. I will report my findings as soon as I have something to report.
Mark
#22
06-12-2015, 11:12 PM
Today I did the following;
1. Replaced the ECU with a known good unit. NO CHANGE.
2. Jumpered the CTS harness. NO CHANGE.
3. Plugged the AAV line from the air cleaner. NO CHANGE.
4. Verified that vacuum is being provided to the ECU.
5. Replaced Oxygen Sensors. NO CHANGE.
6. Replaced Fuel Injector harness. NO CHANGE.
Nothing I have done so far has reduced the over-rich condition.
As I said before, all of the ignition components have been
replaced and the timing adjusted. Using a timing light I
have confirmed that all cylinders are receiving spark.
Obviously I'm missing something. Maybe I need to go back and
check the fuel regulators again.
The hunt continues.
Mark
1. Replaced the ECU with a known good unit. NO CHANGE.
2. Jumpered the CTS harness. NO CHANGE.
3. Plugged the AAV line from the air cleaner. NO CHANGE.
4. Verified that vacuum is being provided to the ECU.
5. Replaced Oxygen Sensors. NO CHANGE.
6. Replaced Fuel Injector harness. NO CHANGE.
Nothing I have done so far has reduced the over-rich condition.
As I said before, all of the ignition components have been
replaced and the timing adjusted. Using a timing light I
have confirmed that all cylinders are receiving spark.
Obviously I'm missing something. Maybe I need to go back and
check the fuel regulators again.
The hunt continues.
Mark
#23
06-13-2015, 12:28 AM
OK, finished work for the day.
Have a look down near the 5A inlet tract, and you should see/have a Blue/White vac switch. This is the fuel enrichment switch, and works in conjunction with the enrichment micro switch on the throttle turntable.
This vac switch requires vac to keep the contacts OPEN, and the ECU fuel map in the correct idle mode. When the vac drops, the contacts close, the fuel "mixture" is richened by about 15%. Now this enrichmnet will cause smoke on an engine that is idling, not under load.
I have had many of these with vac lines missing, so the engine is in constant enriched state, and also these valves do fail, and that also has the contacts CLOSED.
My suggestion, whilst the hunt continues, is to unplug this valve electrically, at the capstan micro switch, or very close to it. These 2 units are wired in common, so either can enrich the fuel as the demands on the engine dictate.
This will "force" the ECU to stay in idle fuel map below 900RPM, and un-richened (good Aussie word that) mode above that.
If that sorts it, then the "hunt" is narrowed big time.
If it dont sort it, I would then look seriously at fuel pressure. You have eliminated a lot of the obvious by swapping out.
You have checked the engine earth straps?????, and that bunch on the rear of the RH inlet manifold????.
Have a look down near the 5A inlet tract, and you should see/have a Blue/White vac switch. This is the fuel enrichment switch, and works in conjunction with the enrichment micro switch on the throttle turntable.
This vac switch requires vac to keep the contacts OPEN, and the ECU fuel map in the correct idle mode. When the vac drops, the contacts close, the fuel "mixture" is richened by about 15%. Now this enrichmnet will cause smoke on an engine that is idling, not under load.
I have had many of these with vac lines missing, so the engine is in constant enriched state, and also these valves do fail, and that also has the contacts CLOSED.
My suggestion, whilst the hunt continues, is to unplug this valve electrically, at the capstan micro switch, or very close to it. These 2 units are wired in common, so either can enrich the fuel as the demands on the engine dictate.
This will "force" the ECU to stay in idle fuel map below 900RPM, and un-richened (good Aussie word that) mode above that.
If that sorts it, then the "hunt" is narrowed big time.
If it dont sort it, I would then look seriously at fuel pressure. You have eliminated a lot of the obvious by swapping out.
You have checked the engine earth straps?????, and that bunch on the rear of the RH inlet manifold????.
Last edited by Grant Francis; 06-13-2015 at 12:30 AM. Reason: spelling sucks
The following 2 users liked this post by Grant Francis:
Greg in France (06-13-2015),
Katoh (06-13-2015)
#24
06-14-2015, 02:00 AM
Maybe a little of a long shot, on the A bank side on the coolant line under the air filter towards the rear of the motor is also a temperature switch that Kirby talks about in his book that enriches the fuel when its cold, his solution was to simply disconnect it, which I have done and I assume most others have done as well.
Have you looked at that? Sorry if my terminology is not exactly correct.
Have you looked at that? Sorry if my terminology is not exactly correct.
#25
06-14-2015, 09:33 AM
Maybe a little of a long shot, on the A bank side on the coolant line under the air filter towards the rear of the motor is also a temperature switch that Kirby talks about in his book that enriches the fuel when its cold, his solution was to simply disconnect it, which I have done and I assume most others have done as well.
Have you looked at that? Sorry if my terminology is not exactly correct.
Have you looked at that? Sorry if my terminology is not exactly correct.
I have decided to go back and double check everything again. I really think the issue is either excessive fuel pressure or a leaking injector.
I am going to pull the injector assembly off of the engine and test each one for leakage and flow. I will replace as needed and clean all of them before returning to the engine.
If I don't see any issues with the injectors then I'm going to replace the regulators and add a pressure gauge so I can see exactly whats happening.
I'm building a new injector harness today and that will be installed before trying to start the engine again.
Either way I will not be defeated. I WILL fix this problem eventually and consider it a good learning experience.
Mark
#26
06-14-2015, 10:01 AM
You can easily make a great injector cleaner/Tester out of two small spade connectors a 9v battery and a cheap push button switch, mine cost me $10 in total. Block off one side of your fuel rail fill it with fuel and fit it to a air compressor with 29PSI only. Use a clear 1.25lt PET bottle and go through and check each one, you will soon find out. This little tool also works wonders for cleaning the injectors out, but that’s for another day.
I was reading this afternoon if the fuel rail regulators are shot they can leak fuel straight into the manifold through a vac hose? Not sure on that one but sounds intersting enough to investigate further.
I was reading this afternoon if the fuel rail regulators are shot they can leak fuel straight into the manifold through a vac hose? Not sure on that one but sounds intersting enough to investigate further.
The following users liked this post:
Greg in France (06-15-2015)
#27
07-16-2015, 08:27 PM
Well, its taken a while but I finally resolved the rich running condition. Built and installed a new FI harness, replaced the FI hoses and cleaned the injectors.
The engine is now running but I have a problem with a hunting idle. If I turn the screw in on the AAV it will stop hunting but then it idles at 1200 RPM. Backing out the AAV screw below 1000 RPM the idle starts to hunt. Up and down.
I'm pretty sure the problem is a vacuum leak but I'm having a heck of a time trying to locate it. I can hear it sucking air but I dont think its coming from a bad or disconnected hose. With all of the noise coming from the engine and fan its hard to isolate where the leak is coming from.
Saturday is now reserved for leak hunting.
Mark
The engine is now running but I have a problem with a hunting idle. If I turn the screw in on the AAV it will stop hunting but then it idles at 1200 RPM. Backing out the AAV screw below 1000 RPM the idle starts to hunt. Up and down.
I'm pretty sure the problem is a vacuum leak but I'm having a heck of a time trying to locate it. I can hear it sucking air but I dont think its coming from a bad or disconnected hose. With all of the noise coming from the engine and fan its hard to isolate where the leak is coming from.
Saturday is now reserved for leak hunting.
Mark
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