CA SMOG inspecton blues

(Carl Hutchins, Jr. ) #1

A better title might be California SMOG Inspection Black.

I’ve procrastinated getting to it. A recall of the last near miss.

M<Y 83 and it’s 94 LT1 are running just fine according to the seat of my pants.

I took the precautionary run on the freeway awith as much throttle as I dared. It was a lively as ever.

Went to the last station that passed my Jeep just fine. But the on that I had an issue with over a “snap throttle” test.
It did not work. And, true enough, on revving and backing off it did indeed smoke from both pipes. Black particulates. Against the shop['s advice, I asked they continue the test. Two of the techs admired the installation. The tech on the machine, not so much ,just did the hookup and the visual and the two dyno runs.

I was asked to open the gas caps! That needed exam was done by pressing the spring loaded diaphram and noting that they were lined.

Well, as I expected, the numericals and the visuals were in compliance. But for the black smoke, it passed. But, because of the smoke, it was marked a fail. ,

Why does it smoke.

  1. It is carbon loaded. I’ve not done much freeway run ning at speed, almost all put/put around town. Run it long and hard AKA blow out the carbon. The “smoke” is not really the black denoting an overly rich mixture, but carbon loosened along the
    entire system and being cleared out. Induced by the pre test run by me on the freeway.

  2. It is an overly rich mixture. Sticky injectors. Add some Chevron Techronic in a rich mix to the fuel and drive it a lot in a "spirted fashion. D2 in lieu of D1. To get the rpm’s up.
    Objective "cleanse the injectors.

  3. Remove the injectors and have them serviced. S.D. Faircloth in FLA. Long time lister here and good guy. cloth

Complication; Registration due by 10-22!!! Best, fi before, fall back, go on non op and get dispensations to run for short times.


(Carl Hutchins, Jr. ) #2

No success yet, either here or in my garage.

Enthusiastic freeway runs seem to have made it smoke even more. And, wow, it sure does run great!!!

Registration has expired. I put it on non-op status til I find the issue and fix it or find it not to be done.

  1. Remove the air cleaner. Examine and try the car sans the K& N “knock off”.

  2. Disconnect the canister purge. Plug the vacuum line and try it.

  3. Visual exam of the MAF. Check it’s conection.

  4. Visual for loose or damaged vacuum lines.

  5. Check electrical connection at the coolant sensors. Think of a way to test them.

  6. Break out my OBD I scanner for functions of stuff. EGR, O2 sensors, etc.

  7. Pull the injectors and send them to Dave Faircloth for cleaining

Unproven working theory. The engine is getting a false signal l of cold and/or lean and the PCM responds by enriching the mixture.

Or, merely, lousy old gas???


(Carl Hutchins, Jr. ) #3

Sure is quite in lumpdom!!!


(Mark SF) #4

How old is the gas exactly?

(Carl Hutchins, Jr. ) #5

Thanks. Mark.

No exact answer. But, years, no. Months, for sure.

But it fires right up and runs great. Not a symptom of aged fuel.

Procrastinated. Errands in the Jeep and cleaned the leaves from it’s wind shield and the jets that wash it. Very strong spray from both nozzles now. My electric leaf blower worked well for that. And, while at it power swept the breezeway. Some locals agin power sweeping. My old shoulders eschew the brooms !!!



(Paul Wigton) #6

It is nasty stuff, but a pint of MTBE will very likely , excepting the smoke, get it to pass.

Back in the 80s, Wynn’s sold it as “Smog Chek,” and it works. However, getting it in Cali may present s bit of an issue…:stuck_out_tongue_winking_eye:

(Mark SF) #7

Another question. Does the black smoke happen during the full throttle, or is it afterwards during overrun, or both?

(Carl Hutchins, Jr. ) #8

Paul :

Not as such, and probably under no other “moniker”. I checked the snake oil shelf at the local hardware and NAPA stores.
CA flipped it’s lid at the refinery use of it early on. Leaking tanks fouled the aquifers! So, CA sent the oil companies to ethanol Quirky, but far safer.

My first run was with a pint of Techron in each tank. The labels had no mention of t’s “real” name. No better.

Then, a lister on JF suggested Toulene. Sunrise, a paint thinner marked as a substitute for toluene. I checked at the local hardware. Not stocked there as such. I exam9ined the label of various brands of oil paint thinner. Nope, no “chemical” name there either.

On to their auto snake oil shelf. I selected “Gum Out”.
It and Techron proclaimed as injection system cleaners.
The run, with now an added pint of gum Out in each tank did nothing.

Subjectively, possibly a bit worse !!!

The car’s “numbers” on the dyno at the required 15 and 25 mph pass !!! Albeit the HC at the limit. Same number at each RPM.

And, again, the car revs up smartly and has lots of power. It runs great


The black comes on at roll out. Ie, a quick stomp on it. Much, much less at steady, barely visible.

Two working theories.

  1. Combustion chambers and pipes coked up from “lolly aging” around town, sans a good freeway run And, even the latter limited. 2;88 x .70n OD, it loafs at 70!
    For my runs I drove at D2. Sans OD.

  2. The engine management system has a sensor flaw. It is receiving a “false” signal that the engine is cold and enriches the mixture. Or another sends a “false” signal that the mixture is lean and enriches the mixture.

I hurt my back and may have to delay further messing for a day or two. But, I’ve formed a plan to check it out from the simple to the more complex. Hoses and wires first. The, the gas tank purge valve and cannister. And, the MAF in the intake pipe. And, bone up and relearn to run my OBD I scanner for functions.

Thanks to the both of you.


(Mark SF) #9

That’s the most important clue. The HC being at the limit all the time. This should not be the case, you should be able to very easily pass the HC specs. My XJS does it by a factor of 10.

So I think it’s always marginal, but when you stomp on it, the ECU will go open loop and go deliberately rich. But it’s already rich, so the result is way too rich and lots of smoke. Fix the rich running at 15 and 25 mph, and the stomp test will follow.

It isn’t carbon buildup. It’s rich running. Forget about the evap system.

What can cause rich running? Too much fuel, not enough air. This is back to basis stuff. You have a simple too rich condition.

Blocked air filter (those K&Ns are are a common problem, people over-oil them), dodgy MAF, MAP sensor, or dirty or even faulty (dripping) injector(s), faulty O2 sensors (your lump install did include the O2 sensors, didn’t it?)

Does this have OBDII? Is the system happy with no fault codes?

(Carl Hutchins, Jr. ) #10


Thanks a lot. I like the logic of your response.

Indeed, as required, it has all the stuff that went with the donor engine. Including an O2 on each down pipe of the V8. My purchase of the engine package included O2 sensors. But, in an abundance of caution, I used new ones.

As the engine and management system is 94 Cadillac, it is an OBD I system. In actuality, an SBC.

I will start by removing it’s K& N knock off trying it. If no better, run a scan. Limited to some functions only. No trouble codes to translate.

Somehow, I hurt my back. So, I placed myself on limited duty. So, getting after the Jaguar will have to wait a bit. New field, I’m used to shoulder problems, My back has behaved fairly well over the decades???

But, your XJS is still a V12 ???

Thanks again.


(Carl Hutchins, Jr. ) #11

I think I am on to something. I did a lot of research and learned how to test the MAP and MAF. With a Mitty VAc and a meter!!!

but, before embarikng on those, I went "easy first’. . I removed the k & N knock off. It doesn’t show any signs of dirt unlike white ate paper filters do?

So, I fired up the engine sans filter. Alas, I can’t rev it and look at the pipes. No one around ! Then the lady across the street came home. I enlisted a helpful, but a bit perplexed lady to do three quick on/off throttle stabs.

Much different. No black smoke. But a gray like exhaust. Not squeaky clean.

So, my new working hypothesis is that the filter is restrictive and choked the engine, and it produced a rich mixture. Clean or replace the filter should address that. I have the kt to clean it and another different cone filter, the latter a “real” K& N, unused. Affixing it will take some fabrication.

And, in my stuff, I have a Semi genuine paper holding box. I used it way back to “please” the referee.

As to the lack of “squeaky clean”. Merely remaining debris in the pipes and some clean running should blast it out.

As my registration n expired, I have it on “Non OP/”. So, more scheming to fix that.

I’ve learned some more abut my lump nd it’s stuff.

Day off today. One trip to the store and then watch to foot ball games at once. Raiders and Niners! Although, I am a bit … at some players antics.


(Carl Hutchins, Jr. ) #12

Lost morning !!! Raiders and 49er’s lost big time.

  1. Expected. Worse team in the NFL vs possibly the best!!

  2. Yeah, Cold and rain OK for a NY team, not so much for a CA team.

Son says I complicate things. Jaguar included.

Not to mention, did we go from daylight saving time to standard time ? Research seems to say, no?


(Paul Wigton) #13

Next Sunday…

(Carl Hutchins, Jr. ) #14


Thanks !

Clocks seem to confirm. Son says no.

I was wondering why he news was not full of warnings, as is their wont.

Sleeping habits to readjust.


(Carl Hutchins, Jr. ) #15

Status of the lump!

Son was over to improve on Billy’s acomodations. Most done.
He is off the tether and free to roam the entire back yards. he had a ball exploring and taste testing here and there. Not to mention, pleased to see his real steward.


Agreed. The K & N knock off is really dirty. Rough fix. I put it in a pail of hot water laden with detergent. Later this AM, I’ll rinse it with the garden hose and let it dry in the sun.

Sans filter, the smoke is much less, but present. The SMOG folks not likely to OK it. Son says too much moisture, smells rich and with a hint of antifreeze odor!!! An jus a tad of blue oil from he left pipe.

Signs of an “experienced” engine. Who knows how many miles it really has.


  1. Proceed with sensor tests.
  2. Check canister/purge for source of extra fueling.
  3. PCV valve check,
  4. Run the OBD I scan. Functions only, no DTC’s here.
  5. Change oil to synthetic. Not to thin. DIY or quick change place. Research coming up.

Might give myself a day off. Yesterday was a busy day…


(Bob Loftus) #16

One more suggestion. Remove the MAF sensor and clean the inside with MAF cleaner. The oil from the K&N type filters can accumulate on the hot wire sensor and not allow it to work correctly. I have used a MAF cleaner made by CRC which I bought at Autozone. It comes in an aerosol can. Easy to use. Just spray it into the MAF (with MAF removed from engine) and the solvent ‘washes’ the grime off of the sensor wire. This may not solve your issue but it’s good maintenance while the filter is off.

(Carl Hutchins, Jr. ) #17


Good to hear from you !!

How is the status of your well planned and executed lump ?

I “shimmed” the cap stand with a bit from my table saw. Up to about 1700 RPM. Let run there a bit. The pipes cleaned up a bit. Bluish smoke described by son at his visit, no longer visible,.

I enlisted the assistance of another neighbor lady. She revved it up and down a few times, but less RPM’s than the other lady. Black smoke still there, but significantly less.

Progress, possibly. But, perhaps only subjective.

And indeed, cleaning the MAF makes a lot of sense.
Next up Post rain…

Thanks, Bob.



what do the spark plugs look like?
perhaps spark plugs are wrong heat range. try a hotter plug?
injector hanging open?
can you put a wideband on it temporarily to see AFRs? or a scanner, i assume you kept an obd port?

(Carl Hutchins, Jr. ) #19


It is on hold. I’ve a really bad cold. When I’m well and the weather is tolerable, I’ll go at it again.

  1. The spark plugs were new on the install. Not that many miles on them, fat short of the mythical 100K ! And they are not easy to remove and check.

  2. true enough on a hanging injector.

  3. I did keep the OBD port. CA AMOG rules required it. I do have a means to scan it. The case with the device is on my dining room tavble, at the ready.




the lt1 had reverse cooling. is it plumbed correctly?
is the engine getting warm enough to properly burn the fuel?
perhaps someone stuck a 160 degree thermostat in it or no thermostat in hopes of a few more horses?
i like the above post about checking open/closed loop mode as well.