Tii good cold start, terrible warm running - PROBLEM SOLVED!

[jgerock]

Your engine ancillaries are in good shape compared to most.

[Swiss 2002Tii]

OH JOY! It's alive!

 

I replaced the tee hose between the breather and throttle body with a good silicon hose, re-set the tuna can to baseline and took the FunMobile for a spin.

 

Once warmed up I had to dial up the idle screw to get an idle of 1000rpm.  AFR was reading rich around 10.6.  I made a couple of small adjustments towards lean between revs.  Idled steady and at 3000rpm AFR was between 13 and 14, ranging up to 16.x when running up and down the hill.  With the sensor at the tailpipe, there is some delay, so I am just going to keep watching it and making small adjustments over time.  It is still rich at idle, 10.8-11.0, but the car revs much better, has plenty of power, so I'm looking forward to fine tuning when I have more time.

 

My heartfelt thanks to Paul, Einspritz, Jim and All who encouraged me to start from the basics and work through the problem.  I know the KF system much better now.

 

And a sincere apology to Pat Allen... I dislodged the tacho connector as I was re-installing the cluster after the clock repair.  Tacho is working fine.

 

[PaulTWinterton]

23 minutes ago, Swiss 2002Tii said:

It is still rich at idle, 10.8-11.0,

 

That's not uncommon.  Your adjustments sound very close to optimum.  You probably even have proper cold start performance now that the WUR adjustment is on spec.: high idle, dropping steadily as the engine warms up.

 

Love it when the work has positive results.  Enjoy.

 

 

[Swiss 2002Tii]

It'll be a few weeks around travel before I can come back for the throttle body inspection.  I ordered the plastic cup for the intermediate shaft and the throttle return spring, along with gaskets for the throttle body, riders, and the tuna can (missing).  The idle and mixture screws are now so close to baseline that I am confident that I can disassemble and reassemble and easily get back to where I am now.

 

I'll do a deep clean on the tuna can and check the bushings and bearing for wear.  If I understand correctly, the only grease should be on the D-cam where it contacts the intermediate lever? A drop of oil on the bushings?  yes/no?  I recall reading that the butterfly should be opened and cleaned  with a light oiling of the bearings on a regular basis?

 

I'll look at the intermediate flange to see about that 6mm deflection from the service bulletin.  Would this require changing the length of the connecting shaft?  Should be just a minor geometry change, right?

 

After I run it in for a while and I'm satisfied that all is stable, I'll replace the plugs and start checking them for hopefully the mocca brown coating, instead of the black buildup I have had.

 

Edited June 4, 2018 by Swiss 2002Tii
additional info

[PaulTWinterton]

I believe that service bulletin refers to linkage interfering with injection lines on certain VIN sequences.   Read it again and visually inspect your linkages.   May not be relative.  FAQ opinions please.

 

I put a dab of lithium grease on any location where there is metal on metal friction.  Can't hurt.

[Einspritz]

28 minutes ago, PaulTWinterton said:

I believe that service bulletin refers to linkage interfering with injection lines on certain VIN sequences.   Read it again and visually inspect your linkages.   May not be relative.

 

I provided this so you could check for interference on your system. You can choose to do it or not if there is no interference. My Turbo has it, my '72 Tii tribute does not.

 

1 hour ago, Swiss 2002Tii said:

If I understand correctly, the only grease should be on the D-cam where it contacts the intermediate lever? A drop of oil on the bushings?  yes/no?  I recall reading that the butterfly should be opened and cleaned  with a light oiling of the bearings on a regular basis?

 

From the 2002 Turbo technical pages:

Every 8000 miles:

 

"Oil joints and bearings  of the injection pump and Throttle valve actuation mechanism."

 

That's all I could find.

 

Yes, a bit of grease on the cam. I use Krytox on the bearings, bushings and cam......as I just don't want to mess with it so often. You might also consider teflon plumber's grease, though that can be a bit "sticky".

 

You mentioned using a tail pipe sensor; I have used a Heathkit CO meter successfully which I built when they first came out. I plugged it in and set the meter on the dash so that I could see the effects. The sensor was on a wire that I closed the trunk on to secure it. Afriend gave me the one that was from England, but I haven't used it...sort of a spare.

 

The thing about tail pipe measurements is that there is a lag time (in the sensor) and sometimes the air moving under the car can affect the sensor providing a "lean" interpretation. In addition, if there is a lot of water coming out of your tail pipe, it too will affect your readings. That's not all bad, you just have to know about it.

[Swiss 2002Tii]

A Heathkit CO meter!!! Memory lane... I went to DeVry Institute in Atlanta back in the '70's when it was just a few classrooms in a former printing factory.... they had taken over (actually evolved from) Heathkit, and some of my earliest electronic lab projects were Heathkits.  Good education, though; I was working on a particle accelerator for the physicist at Emory University by the time I graduated. 

 

One day while working on that accelerator I had an epiphany: I was working on a complex vacuum assembly deep inside the bending magnet.  The only way I could use my right hand to reach and disassemble it with a special wrench was to stand with my back to it and reach behind my back.  I worked on that thing for a coupe of hours and it occurred to me: "If I can do this, surely I can work on my little '68 1600!" Started working on it from that moment on.  Then I had a world travel gap of about 30 years without even seeing an '02, so I'm just catching up!  Never lost the itch, though.

 

I am getting used to the tail sensor.  Yes it's a slow response, but I'm getting so much use out it on multiple cars.  Now that the FunMobile is running reliably again, I can take it out on country roads for long runs at different constant rpms and see how everything behaves.  I have to drop the tranny this winter to fix a leaking front seal.  I'll add the bung to the downpipe then.  Maybe I'll mount a sensor permanently and get another if I still want to use the tailpipe mount.

 

I can search, but if anybody has a photo of where that honker CO sensor can go through the firewall, I'd appreciate it!

Jim, didn't you cover that in your rebuild blog?

 

best,

 

Tom

Edited June 4, 2018 by Swiss 2002Tii
additional info

[PaulTWinterton]

So I don't hijack this thread I'm starting a new one because Einspritz brought up "vacuum gauge".  Thanks.  I've had my own issues with rich and lumpy idle.  I'm on a quest for smooth 850rpm idle at 12.5AFR and no lean issues in the higher ranges.  Good luck...

 

Great discussion here.  I'll be back.

Edited June 5, 2018 by PaulTWinterton

[Swiss 2002Tii]

Thanks Paul, and I'll start a new one if I can't find that hole in the firewall!

 

I wanted to wrap this one up (until I pull the t-body) with a thanks to you all and an observation:

I think I went from "normal" running to crazy lean when that little tee hose popped off the first time.  The trouble-shooting of the fuel system was a good exercise, setting up the K-F system was a GREAT exercise.  I think where things got confusing for me was that little gremlin knocking off that tee hose each time I set up for a trial run.  I now have a slightly longer hose that puts a positive pressure on the breather so that it deflects slightly; kind of wedged in there.

And... very small increments on the mixture screw!?

Edited June 5, 2018 by Swiss 2002Tii
additional info

[Swiss 2002Tii]

Grrr.  I thought I would come back to this thread to report that all was well, but...

 

I finally had a chance to take my Tii for a good romp after fixing the throttle body/breather hose problem thinking that with everything KF set up properly, I would report that all was well, but not so much!. 

 

The car ran OK for a while, but once I got out to my favorite country roads where I can loop around over the same terrain to test performance, it started going sideways again.  Increasingly I started getting bucking when starting from a stop, changing from 1st to 2nd gear, then 2nd to 3rd.  As I got the car really warmed up it started missing again.  Not as bad as the first episodes before all of this trouble-shooting, but still pretty bad, and again had difficulty making up the hill to home upon return.

 

I tried going into tune mode to change timing while driving, but didn't detect any obvious gains from this.  I still get some pops and bangs when backing off of a hot run or engine braking (not running above 3500 RPM, though).

 

I put the AFR meter on it when I got back to the garage; idle was really rough upon arrival, but as I let it run at idle for a while it steadied slightly, enough to continue running, but with noticeable misses and some pops from the exhaust.  At idle the AFR reading is pretty steady around 12.x, and if I run at 2000 rpm it holds at 14.x-15.x, so I don't see why the engine is running so rough.

 

Looking for false air, I tried shooting carb cleaner at various points around the intake runners, no change.  I sprayed at the little breather hose and I might be getting a slight change when I spray at the hose joint, but it's hard to say, as it's not running super-smooth.

 

I have to say that running today after the KF setup and before the performance faded after hot running, my impression was that I was getting more speed from less RPMs than prior to KF setup when my throttle setting was way off.

 

Any thoughts on other sources of false air, other ideas?

 

 

 

Edited June 21, 2018 by Swiss 2002Tii
spelling

[Einspritz]

Take a look at the plugs to see if there is any variation, and if there is any one that is much different. It might show one offending cylinder's spark. e.g. could be a bad plug resistor arcing to the head.

 

1 hour ago, Swiss 2002Tii said:

and some pops from the exhaust

 

running rich in that instance and / or you may have a gasket leaking air into the exhaust from the manifold-head gaskets and probably not from the primary.

 

But that is separate from the running problem.

 

AFR is very different running at a certain RPM in neutral as opposed to running under load. It sounds lean. In which case you should richen it up a bit. If you can get an AFR / CO% / Lambda reading at full throttle, full load that is where you start, regardless of your method of measurement.

 

Here is how you "Self Dyno":

 

Drive along say, at 3000 RPM in say 2nd or 3rd gear. Apply the brakes easily and at the same time increase the throttle to full; keeping the RPM steady and then take your reading of your AFR. Release the brake to let them cool, then do the same at 3500 RPM, and every 500 RPM all the way up to 5500 RPM if it will go that far. Take notes of your results.

 

Now you know where you need to adjust, particularly if it starts bucking; pull over to the side of the road, make an adjustment, then repeat until you zero in on the AFR you seek.

 

I, being old skool use %CO or Lambda via voltage in Mv, depending on the car. I have even used this method to identify that my S14 runs 1&4 cyl lean and 2&3 run rich.

 

Measurements for partial throttle / part load are a little bit trickier, but you should start with the above.

 

Ted

[Swiss 2002Tii]

 

Great advice Ted. 

I can look at lambda, but as a wideband, I cannot see Co or CO2 specifically.

I don't think I can get back to it this week as I leave on a trip Saturday, but That will be my starting point!

 

Tom

Edited June 21, 2018 by Swiss 2002Tii
additional info

[Einspritz]

Here's a start:

 

https://www.mgexp.com/article/co-afr.html

and:

A/F ratio or Lambda = Calculated Air/Fuel Ratio or Lambda value based on the HC, CO, CO2 and O2 concentrations. Remember the ideal (Stoichiometric) A/F is 14.7 liters air to 1 liter fuel or 14.7/1. The ideal Lambda value is 1(one) below that the A/F mixture is rich and above - lean. For example, lambda=0.8 corresponds to an air/fuel ratio of (0.8x14.7):1=11.76:1 ( e.g. lambda 0.8 = A/F ratio of 11.76/1 or very rich air fuel mixture )

 

If you are at 14.X-15.x at 2000 rpm not under load, that is OK; that would be as if you were decelerating.....where you normally see the AFR spike lean.

 

What is important is if the engine is under load because if it is lean, then it is prone to knock. If the settings are rich enough e.g. 13.38 AFR - 3.0%CO that is more like it at the lean side to 4.0% on the rich side. Shoot for 3.5%. Of course, if the gas has Ethanol in it, then it changes the CO and you will have to "tune around" that; so just get a baseline at 3.5% for now.

 

Don't worry about the AFR at idle, unless it is for SMOG reasons. Get everything else correct, then let that be what it will be, or fiddle with it later.

 

I will look for my tables in the next few days.

 

Ted

[Swiss 2002Tii]

Thanks Ted, I was just using my meter set to Lambda to set the mixture on my MBZ oldtimer today.  That looks pretty straightforward.  I hope to have a few minutes tomorrow to make a few passes.  I take it that a good steep hill would substitute for the brake/dyno process?

[Einspritz]

The usage of brakes represents the maximum of load, and it is only for maybe 10 seconds so that you can take a reading, it won't harm them.

 

Just give one run at 3000 RPM a try.

 

Separately, does your MBZ have an oil cooler next to the radiator? I am looking for the proper black paint color. I was told by the MBZ restoration shop in California that it was "black, not shiny, not flat" but that is a bit vague for me. Insight or pictures would be helpful.

 

Thanks,

 

Ted