Tii Run On

[BCbryan]

Appreciate that there are some threads out there on this subject, but curious if anyone current can chime in on some possibilities.

 

1974 tii with 60K original miles.  Excellent mechanical shape.  It has been in the family since 1976. 

 

If the car is warm and has run for a bit, it will run-on when I kill it.

 

Thought it was likely timing.  Put a 123 in it to see if that helped.  Seems like over the car runs smoother, but still diseling.  Running a pretty stock tii curve.  28 degree's max, 8 degee's at idle (seems to want to start better hot with a tad more advance).  123 has been checked with a timing light off mark on pulley and line on kugelfisher.  Idle has been adjusted per spec for speed, but not touched air/fuel adjustment.

 

Runs really well for the most part.  Good cold start, 900rpm smooth idle once warm, solid power and seems normal on engine temp and oil psi.  I can't really say it runs poor at all, but if the car is warms it will run on when I try to kill it.

 

I have tried the following and they have made no real difference...

 

Switching plugs to a slightly colder range

Tried both 91 Octane Shell and 94 Chevron (both non ethanol in Canada there are the two choices)

Slightly lower idle 

 

I'm thinking my next steps or things to figure out are...

 

Is fuel pump delivery correct fuel pressure to kugelfisher

Is all linkage correct (the car is mint and this stuff has very low miles)

Is the air/fuel ratio screw in tuna can set correct

Are the injectors all working properly

 

Just curious if anyone has insight on the issue and where the typical culprits are.
 

 

 

 

 

[rstclark]

Seems like you have tried the basic fixes  Can you lower the idle a little more to see what happens ?

What engine temperature does it run at ?   You could try a 71 degree thermostat but it wont help if your radiator is not cooling enough to keep the car in the 1/2 to 3/4 range on the temperature gauge  Heat makes a difference here.  The other culprit could be carbon build up raising compression and encouraging dieseling.

There may be specific issues with a Tii and the injection system, but others would have to chime in here

You can always resort to leaving the car in gear with the brake on when you shut it off and letting out the clutch simultaneously   Not a real fix, but it does avoid the embarrassment of having the car run on and be more difficult to restart  

[conkitchen]

It's possibly too lean-check throttle/pump linkages 

Timing- too advanced 

Carbon deposits inside combustion chamber 

 

I have in the past shut 'er down whilst in gear to thwart run-on condition but that's not a solution. 

 

 

 

[ray_]

Yeah. and then invest in an AFR gauge.

 

GL,

[Simeon]

Remember, it cannot directly be ignition timing because the ignition has been turned off. Unless you have something like an MSD box which can be falsely energised by the alternator, the dieselling is not related to ignition. 

 

An engine still needs fuel, a source of ignition and compression to fire. The fuel can come from residual line pressure in the KFish system. If the engine keeps turning, it will keep spraying. A source of ignition may be too hot a plug or carbon deposits in the head. It may also be a sharp edge that runs hot and may not normally be an issue without one of the other factors. What you may may find is that your car needs a general tune up (including timing) that may effect these factors in other ways. 

 

Generally a lower idle speeds may help (though 900 rpm doesn’t sound excessive). Maybe it needs a good ‘Italian tune’ by taking it out and working it out up to the red line a few times. Give it a good blast. It might not help but at least you will be smiling. 

[BCbryan]

Thanks guys.  It does not seem to be running hot by the stock gauge.  1/2, maybe 2/3 if I'm climbing hills.

 

Seems like I can play with timing some more, then get an AFR gauge and try to figure out if it is running lean.

 

Carbon I'm hearing a lot.  Motor has 60K original on it.  The last 10 years it did not see much daily action.  Is there a solution to carbon?

[02Pilot]

Late to this, but carbon would be my first thought as well.

 

If you want to get more aggressive than just driving hard, here's the old-school method. Get about a quart of water and a very small diameter hose (1-2mm orifice). Get the engine hot, then insert the hose into the airflow pre-throttle plate and run the engine at fast idle. The suction will pull the water slowly into the cylinders and steam-clean the carbon more effectively than any chemical. DO NOT LET THE ENGINE STALL. Continue until the water is gone and the steam cloud from the exhaust abates. Your cylinders are now cleaner than they've been in years.

 

You can use lots of things besides water - some swore by Windex, some people like the Seafoam cans made for this sort of cleaning for their convenience, but water works just fine.

 

[Dudeland]

I have a bottle of Lucas gas treatment in the trunk.  I give it a little squirt with every fill-up.  It keeps things clean and lubed on the fuel side and may help prevent carbon build up.  

[j2002tii]

May I suggest running a can of 44K fuel additive through the engine?  Usually works well cleaning up the fuel system and upper engine very well.  Cleans the injection system, valves, combustion chamber, fuel pump, etc. and all sorts of gunk.  Also, use only ethanol free fuel.

[02Pilot]

I hate to be the negative voice here, but nothing you put in the tank is going to clean decades of carbon out of the ring lands and piston tops. Take a little bit off the top? Sure. But the really hard stuff is still going to be there. Inspect the cylinders with a borescope before and after if you don't believe me.

 

If you've ever had a head gasket dump coolant into a cylinder and torn the engine down, you know very well how effective steam is in cleaning the piston - the cylinder(s) with the leak are spotless. You need something that will thermally shock the deposits to get them off without tearing down the engine and doing it mechanically.

[PaulTWinterton]

On 8/25/2018 at 10:32 PM, rstclark said:

he other culprit could be carbon build up

 

On 8/25/2018 at 11:11 PM, conkitchen said:

Timing- too advanced 

Carbon deposits inside combustion chamber 

 

I'd go with these guys first.  A good hour of highway driving to clean out the cylinders (some) and slightly retard your spark. Book is 7° BTDC at idle iirc.

 

On 8/26/2018 at 5:59 AM, Andrej said:

Get about a quart of water and a very small diameter hose...

 

Another technique I've never heard before.  Very interesting.

 

My personal experience with run on was ignition-based.  Once I had my timing sorted there was no more run on.

 

Your fluctuating temp gauge is another story though.  Probably time for a block flush and a re-cored rad,  OR a replacement high volume W&N replica rad.  I just happen to have an extra. ?

[Mike Self]

+ 1 on the "waterboarding" trick.  I've done that many times with carbureted cars, and have always been amazed at the black stuff that comes out the tailpipe.  Just follow Andrej's instructions for doing this on an injected car (not sure I'd want to do this on an EFI system, but the mechanical K-fish doesn't have any sensitive electronics). 

 

And I'd also set the idle down.  If you don't have the sudden load of an A/C compressor, 750-800 rpm is just fine--just fast enough to keep from stalling.  And I've found that even a hundred or two rpm is enough to make a difference between dieseling and not dieseling.

 

mike

[02Pilot]

6 minutes ago, mike said:

+ 1 on the "waterboarding" trick.  I've done that many times with carbureted cars, and have always been amazed at the black stuff that comes out the tailpipe.  Just follow Andrej's instructions for doing this on an injected car (not sure I'd want to do this on an EFI system, but the mechanical K-fish doesn't have any sensitive electronics).

 

FWIW, I've done it on modern EFI cars with multiple catalytic converters in the system with zero problems. The only thing I haven't tried it on is a very modern DI motor. Given their reputation for carbon build-up on the intake valves, I suspect I'll have occasion to soon enough.