To all ECU/MPS/TS2 people!

I have a '74 2.0L that I am resurrecting to be original equipment with the exception of all of the Hell-Hole parts which are Rest-Design or other vendors.  The problem that I have been admiring for 2-3 weeks is one of White Smoke, or richness that begins after the engine has been running for 1-2 minutes.

Background: ’74 2.0 barn find, 20K miles all indications are this is accurate (brake pedal wear, rotor wear, seat wear, all other used car tricks, etc….)
Replaced fuel system tank to injectors
Replaced all vacuum hoses
Replaced all other fluids
Replaced Hell hole, longitudinal, floor pans.
Body – perfect, really, really good.
Engine started, sounds like a swiss watch – no mechanically ‘noise’ just mechanical music….
A little rough, however – too much engine motion in the bay

As the engine warms, the injectors are told to put way too much fuel into the system, white smoke and rich exhaust smell start after 40-60 seconds of operation.

Here is what else I did so as to learn as much as possible about the process. I bought a second MPS from a 911World - great guy, very engaged and supportive (THANKS!). I also bought an ECU from him. When I received them, both checked out as ’74 2.0 numbers. Great, though the new MPS is a bit leaky, it compares to the numbers of the one I had which I replaced the diaphragm

I put the two MPS units (the one I  got with the car and the one I bought) on the bench and here are the numbers - very similar - My H meter is not calibrated so I believe since the two are VERY similar that I have a calibration problem…

 Setting____Reference__New Diaphragm___Purchased though leaky
0 inHg._____1.45_______1.06______________1.15  
4 inHg--------1.24_______ .94_______________ .96  
15 inHg______.75_______.66_______________ .66  
 
1. I have tried both MPS units – operates the same, white smoke starts after a minute or two.
2. I Swapped the ECU units – operates the same, white smoke starts after a minute or two.
3. Replace the TS2 with a rheostat (variable resistor) tried it at 1K/500/300 - I believe it changed the time before the white smoke….takes a bit longer, have not timed this effect yet.

I have not done anything with TS1 (Air temp sensor) since it has a marginal effect on mixture (see https://members.rennlist.com/pbanders/ecu.htm Common Questions)

Talked to the guy who rebuilt the injectors and he has never seen a stuck injector which would stop being stuck when the car is off. (The fuel rail holds 30lbs for hours so injectors close when off).

I am centering the MPS/ECU/TS2 part of this equation.

Will keep digging, ANY advice would be very welcome!

is the smoke coming out of the tail pipe? if yes, probably old oil burning from your Heat exchanger/headers/muffler.
If smoke from headers/heat exchanger, same that old oil on the outer surface of HE/headers Or some oil leaking that is dropping.

Smoke is white, passes the paper test (white paper against the exhaust, no residue), pretty certain it is not oil related. Tail Pipe yes, that is where the smoke is coming from, actually, WHITE EXHAUST.....may change the title......

THANK YOU,
CTC

White smoke is usually from water or antifreeze. Assuming your car is still air cooled, oil is the more likely cause. Especially since the smoking starts after a little heat has started to generate. Do you know when/if the top end has been rebuilt? Have you done a compression / leakdown test? Could be rings or valve guides. The rich running may be unrelated to the smoke.

When
the heck did white smoke equal running rich? Running rich is black smoke. Oil is blue smoke. White smoke is generally caused by ignition in an air cooled car

You may not be aware that the Anders reference MPS numbers need altitude correction for calibration, and because the numbers are very sensitive, the meter you use is unknown in how its calibration compares to Brads Wavetek which could be significant. I see major differences with even a 0.01 calibration difference. They are raw numbers before altitude correction, which depends on your location. As is they feel like they are too lean, especially at WOT. Fatten up those 0 in.Hg numbers to be about 1.52 for a 74 2.0L, leaving the other numbers alone. But those are numbers for my altitude at about 500 Ft above sea level.

Setting____Reference__New Diaphragm___Purchased though leaky
0 inHg._____1.45_______1.06______________1.15
4 inHg--------1.24_______ .94_______________ .96
15 inHg______.75_______.66_______________ .66

Needless to say, your New Diaphragm and the leaky one are way off. I don't understand how the engine would even run with these numbers. Are these 043 MPS?

TS1 does not have marginal effect, it richens the mixture if left unconnected.

TS2 richens the mixture when its cold only. Once it warms up it is not critical but must be left in the circuit.

Jeff,

Thank you for the reply,

1. I believe those are the sea level numbers - will double check
2. there are 2 sets of numbers that are VERY close, hence I am leaning towards the Henry meter, 7% difference at 0 Hg, <2% at 4 Hg and the same at 15Hg. Am I correct to assume that two MPS units (both 043) would be that close together but so far away from the standard.....I am centering on getting a new meter.

Before I adjust the MPS, one other question......after the car runs for 2 minutes, the smoke starts, until then runs just fine.

Are there timer circuits in the ECO? is there something happening at the 2 minute mark I should investigate?

Thank you!
Respectfully,
CTC

Thank you for the reply, what part of the ignition would you chase for this? The smoke starts right at the 2 minute mark.

Will get more information ASAP,

Last, the Bosch mechanic that rebuilt the injectors advised that the white smoke is fuel not burnt or rich running.

I have confirmed it is not a stuck injector.

Thank you again!
CTC

Whoa! A mechanic rebuilt the injectors? Your first post indicated fuel system had been replaced from tank to injectors. So they are not new, but rebuilt? I'm a mechanic, but i don't rebuild injectors. That's done by a specialty shop.

Clay just posted that front transmission seal went out on Betty‘s car and white smoke came out from under. Transmission fluid dripping down on the exhaust ??

the cold start valve would close after 1-2 minutes, cutting off the extra air that creates high idle for warm up. You can just unplug it to test the theory - it heats up to close.

Only the reference MPS numbers are close but the 0 inHg is too lean. The new diaphragm and leaky MPS numbers, though close, are patently wrong and require calibration.

There are no timer circuits in the ECU. The cold start info in the post above is not correct. The CSV, which is a 5th injector, only sprays during cranking, and only when the air temp is cold. Let go of the key and no CSV fuel spray.

The post above describes the Aux Air Valve, which allows free air in when cold, then closes after a few minutes as it warms up. The AAR is not the CSV.

Bosch Guy, German - Hurst Injectors. Has a calibration station, check out the website. Rebuilt and calibrated. Local here in MA. Great guy, super helpful and resourceful. Had trouble finding 4 new proper injectors. May have to buy a set to swap them out for testing.........

UPDATE - tested various items, no change. Cylinders 2-4 are all 130+, number 1 is 125. Good! Tomorrow will go through entire ignition system, coil, points, rotor, cap, wires, plugs. Will scope the injector signals Saturday.

Here is a video of the exhaust smoke, started the video at 1:30minutes, smoke starts about 30 seconds into video.

https://youtu.be/uyxESjam9PU

Sure looks like oil smoke. Does it smell?

I think you mean the auxiliary air valve.

How cool is it where you are?

Does it smoke after driving it down the road for 10 mins?

Depending on the temp outside mine would smoke a little and I believe a minute or so after starting due to the condensation that would collect inside exhaust.

If it was a real hot day I wouldn't see any. If I drove around for a few minutes it would be gone as it had cleared it all out.

Does the idle change when it starts smoking? The idle should drop and get rough if it's going that rich.
Have you driven the car?
If it was too rich, enough to cause smoke, the engine would run poorly and have low power.
Have you tried adjusting the idle mixture knob on the ecu? If it has a noticeable effect, the mixture is fine.

Sometimes oil collects in the exhaust pipes or muffler and when they start to heat up after a minute or two, the oil starts smoking. The way to eliminate the smoke is run the engine long enough to burn it all off. It may take 5 or more minutes of driving to completely eliminate the accumulated oil.

Looks like oil smoke to me. does it ever go away? As Chris noted, have you driven it? if you have oil build up in the exhaust system, it will take a while to burn off. You could also have some oil seeping by the rings.

Run it for a while - drive it, not just idling.

We get white smoke on Huey after it sits a while. Takes a while to go away but it eventually does.

After I posted the video I realized that the car in the background (my daily driver) with its blue background makes the smoke look Blue....sorry about that, but the smoke is white and smells like very rich exhaust.

I tested the exhaust using a white clean sheet of paper, then held it against the exhaust for 10-15 seconds. If it is oil (this test I remember from high school so it could be a complete failure) then there will be residue on the paper. The paper is clean after 15 seconds.

Thank you for the post CK.

CTC

It was in the 60's when I took the vid, the car has not been on the road since 1988, calipers are in Idaho being rebuilt - cannot drive it until I get them back....grin. pretty certain it is NOT condensation nor oil/gas/lubricant that had collected in the exhaust system. First time I started the car all of that (including mice nest material) blew out of the 4 pipes.

Thank you NDITIZ,

CTC

Tangerine Chris,
Great to hear from you in this thread!

Yes, a few seconds from the smoke starting there is a drop in RPM.
Cannot drive the car until I get the calipers back ( and weld some panels into the floor so I can re-install the seats...grin)

Good tip as to the idle fine tune knob on the ECU - will try that today,

Thank you, Chris,

CTC

The exhaust needs to be up to full operating temp before all accumulated oil inside burns off.

If the AAR is working, there will be a drop in rpm when it closes.

Simple test for auxiliary air valve, pull the hose from intake box to aux air valve off at the intake and put your thumb over the end of it. When the engine is cold doing this will drop the idle, if the valve is working correctly when the engine warms up there will be no more suction on the hose and blocking it will cause no drop in idle.

UPDATE

Today I changed the plugs with new ones. Here is what happened. The car started and ran clear and crips for about 10 minutes. THough, while it ran it smelled very rich.

About at 10 min the car started to miss a bit and then started to smoke. I looked at the old plugs and now I have a hypothesis.

My guess is that all of the cylinders are running rich but one is running extra rich or the injector is being held open. THis is flooding the cylinder and then the smoke is the un burnt fuel going out of the pipes.

Here are the plugs I pulled out, all of them are rich, one was wet and very rich...None had any oil.

Will update again tomorrow.

CTC