WHITE EXHAUST............., After warming for 60+ seconds, starts to run very rich, exhaust turns white Options

[ctc911ctc]

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!

[JeffBowlsby]

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.

[ctc911ctc]

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

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.