My home-rebuilt carb is set up exactly as you guys have suggested, but I still idle rich after warmed up. New computer temp sensor, new tps, new vacuum sensor, etc. Idle mixture needles are set very lean at 2 1/2 turns from seated position. Solenoid travel and positions are set [with micrometer] as instructed. TPS is set to correct voltage.

SO, I FINALLY ORDERED A REBUILT COMPUTER AND THERMOMASTER [ONLY ONE THAT SUMMIT HAD] CHIP. PLUS THE SUGGESTED 160 DEGREE THERMOSTAT.

Wish me luck. I recall reading that when one has exhaust work, the arc-welding machine can fry computer chips.

Read this years ago. Could this be what occured when I replaced the cat?

Seth

 

I installed the items.

Et Viola'!

We have closed-loop with a dwell reading that floats between 25 and 30 degrees on the six-cylinder scale.

(EDIT THIS EVENING!!!!!!
Idling in park was perfect, but driving down the avenue lead me to choke on the fumes at eack stoplight.
So, how did I screw up???????????)

Back to the upbeat post, before I discovered this bug-
Now I have to see how she drives, cold-starts, and if she continues to work properly. And, if she can still use 87 octane, as before. It is a pleasure to watch the dwell change while turning the idle-air-bleed screw, or when you create an artificial vacuum leak.

This was one big p.i.a. and thanks for your support.

One Q- It will not tolerate the idle mixture screws to be any further out than 2 1/2 turns. Any more, and the idle goes smelly. This o.k.?

Back to the edit: Where do I need to retrace my adjustment steps?

PLEASE HELP ME.

Seth

 

I edited my previous post, but none of the 50 people who read it know that I am still having trouble, because , well they don't. So please take a look at my post, with the edits.

Seth

 

Been waiting for you to post back with news...You should be able to drive the car with the dwell meter connected, wires running under the hood through the pass window. If your cables aren't long enough you can rig an extension. This will allow you to see what the computer's trying to do to the mixture when you smell fumes.

Carb should be fine at 2 1/2 turns out.

Keep in mind that the computer adjusts dwell based on oxygen reading not true A/F ratio. If it's sensing too much O2 in the exhaust stream on the driver's side bank it will richen the mixture. Sometimes a mis-fire or stumble will result in a dwell peak. I did a cam swap once and couldn't get the dwell to stay the same. Discovered my y-pipe collector had come loose (probably while running rough with cam break-in) and was intermittently leaking and confusing my O2. Course my O2 is in the Y because I have hedders.

I suspect you're just dropping out of closed loop though and the dwell meter should show that.

Good Luck and let us know how it turns out.

Mike

 

Mike,

Idling in driveway now.

Dwell is hovering around at 30 degrees.
Idle mix screws now at 2 turns.
Running rich.
You state that it all depends on the O2 sensor.
Newish Bosch unit.
I hear no miss at idle.

I have a leak, where?
Original iron exhaust manifold.

Seth

 

It's highly unlikely you have a leak that could affect your O2 readings without being aware of it, especially with stock manifolds.

With your idle mixture screws 2 turns out, how many turns out on idle air bleed? They're commonly around 3-4 turns out on each, but that's not a hard-fast rule.

You can check for a miss at idle by pulling each plug wire and noting if there's a change in idle quality.

O2 sensors can "report lean" as they fail but I wouldn't replace a new one until I'd checked everything else. Isn't this the second one already?

If driveability is fine and dwell is responding correctly you may want to put some miles on it, run a few gallons through and check your mileage.

There's also the off chance that something on the side of the carb that feeds the pass side bank is off. The ECM only looks at driver side bank for O2.

Keep in mind that this ECM doesn't come with a pre-programmed A/F map. It writes and re-writes one as it goes based on O2 readings. It uses TPS and MAP sensor readings to make instantaneous changes to mixture based on it's A/F map then re-writes it's A/F map if needed based on O2. This is a pretty quick process at idle but could take some miles driving for the full spectrum of TPS/MAP settings. So when test driving after adjustments be sure to give it a little more than a "once around the block".

 

Mike,

The air bleed screw is about one turn short of the bottom.
For six years, I have had an intermittant noise that sort of sounds valvish, and from only one at that. I still have no idea what it is, as it comes and goes w/o rhyme or reason. Not a peep all winter. I thought it was fan clutch, timing, heat stove flap, egr solenoid valve, heat riser flap, etc. Still have no idea.

One good thing---This Thermomaster chip provides excellent drivability.

Thanks,

Seth

 

IAB down is trying to richen mixture (allowing less air in), idle screws in is leaning mixture (allowing less fuel). You may want to average out the two by turning mixture screws 3-4 turns out and opening IAB a turn or two. This is closer to the stock settings. If the dwell is only happy where it's at I wouldn't fret too much about it.

I pretend not to hear funny noises when driving mine.

I've been chasing down a lean stumble all day and I think I've only been able to determine that it's NOT my carburetor. At least it only got to 90 degrees today.

Mike

 

Mike,

The rain cooled things down a bit, and with the windows down, A.C. off, I was gagging all the way home. Each stop light was a challenge to breathe.

***Yesterday, the solenoid was adjusted as per the posted instructions. They are on the shelf in the garage, but I can tell you that I used the steel rod that pulls out of the dial caliper to measure the plunger travel, after setting the, I think it was lean stop, four turns up from the bottom.

Does this need further tinkering? Perhaps beginning from a point one full turn lower? Or am I wasting my time with that? I still know so very little about this system.

WHY IS THIS SO FREAKING DIFFICULT??????

Thanks Again,

Seth

 

First make sure the ecm is controlling mixture and that the carb has the right amount of range before tinkering with the rich/lean stop. Hook up the dwell meter like I said before and set it in the seat next to you. When you notice the rich condition check it for:
1) If dwell meter is pegged full lean you'll know the ecm is attempting to correct a rich condition that is beyond it's ability to compensate for. Then play with rich/lean stop or look for a carb problem.
2) If the dwell meter is not ranging you've gone out of closed loop. If you see this, I'd look at CTS. It can be shorted out to tell the ecm temp's met.
3) If the dwell meter is ranging properly the ecm "thinks" the mixture is correct. If this is the case, I'd pull plugs and look for a cylinder(s) running rich.

Plug all the vaccuum ports and vent ports for the charcoal system before doing any more tests. It can fail and cause weird problems too.

Good luck, I'm still working on mine too.

Mike

 

Mike,

This deserves a bloody strong Bloody Mary.

Brought the mixture screws out to 3 1/2 turns.
Discovered the pigtail near the evaporator. Really never knew about it.
Chocked wheels, put in gear, set dwell to float around 30 degrees. Floats several degrees in either direction.

Back to stinksville, after a short drive. O2 sensor is most probably giving false reading, you have suggested. Put in brand new Bosch unit. Same s**t. It would seem that there is a leak anywhere from the exhaust ports to the O2 sensor.

The AIR pipe holes have been blanked off for years. The air pump pumps only into the cat, and the diverter valve is altered to work w/o a computer signal [to switch between the chrome pipes and the cat], simply relying on vacuum to prevent backfire.

Valve cover gaskets [crancase venting] are recent.
Did you know that this egr solenoid valve buzzes with car idling in gear [not neutral] ?

You say to pull the plugs. I think that this would be futile, as all are blackened by the rich mixture. When changed last year [along with H.T. wires] they were all clean after a long run and no idling to foul them. The computer issue did exist then.

Also, both sides of the carb dump into a common opening in the intake manifold. If the right side of the carb has issues, then it would logically affect both cylinder banks.

No wonder people go the Holley/ Mallory route, but I refuse to do that.

I would unhook the charcoal cannister, but the temp-valve that dumps it is busted, so it is sort of already not connected to carb.

Seth

 

Drive it with the meter hooked up. See what it's doing.

You can check your plugs on the driver's side to see if there's evidence of mis-fire.

Your stock manifold is dual-plane and although there may be a small cut-out between the two sides under the carb, they're essentially split.

EGR shouldn't cause a problem, but you can disconnect it so it doesn't buzz and take it out of the equation.

Your charcoal canister should be connected to the fuel tank vent and the bowl vent for the carburetor. If it's not hooked up, the fumes from one or the other (or both) have to go somewhere. Could this be what you're smelling?

Mike

 

Mike,

Gotta do the lawn. Will play after dinner. The evap cannister holds raw gas. What I smell is burned gas; lots of it. Canister vapors are in canister, but when I trick the temp valve into venting it, nothing seems to change.
A 'Q'- If there is a mis-fire, this would reduce vacuum, and leave unburned fuel, raising O2. If a valve, it would not change O2, but would reduce vacuum.

No?

Thank You,

Seth

 

I know the smell too, just shooting in the dark.

Yes a mis-fire will allow unburned fuel and O2 into the exhaust stream and will confuse the O2 sensor, vaccuum may be reduced slightly-the motors still working as an air pump. I'm deducing (or inducing?) here, never really hooked up a vaccuum guage to a mis-firing engine. A valve that does not open at all should have no affect on O2 readings (nothing in-nothing out either intake or exhaust), but the efficiency of the pump is lessened. A valve that is not opening completely or not closing completely can cause some weird things.

Let me know how the dwell thing goes while driving.

Mike

 

Because I was out all day ferrying my girlfriend around the city.

Now, back to something completely different. [Monty Python]

Exhaust was bad, right from start of closed-loop mode.
At g.f.'s house, dwell was good, exhaust was not.

While driving, check-engine light lit. Code 55.
From this time on, exhaust was seemingly clean; dwell hovering around 30 degrees. And get this- The computer was adjusting for FOUR FULL TURNS of the mixture screws.
Also, I found at this time, that tightening down on air filter nut kills dwell. A wire or hose is bad or loose. This does not solve the code 55, though. The engine light comes on immediately upon starting. No resetting for this problem.
My 'new' computer is bad? I still have the old one, which is possibly good, as I always felt in my gut that it was the chip. The new comp is Standard Motor Products and if faulty, I can possibly deal with them, as their location is within NYC. Got the computer from Rock Auto, over the 'net; they are not in NYC, for certain.

EDIT on Tues A.M.: Reinstalled old computer. No codes. The seller of the rebuilt sent a FedEx label, and is refunding my $$. Replaced all vacuum pipes and tees that connect to base of carb.Used whatever junk was in garage. Holds dwell in driveway. Will go to FedEx later to see if my eyes water.

Thanks,

Seth

 

But I need to say that my exhaust remained clean all day. No watery eyes or irritated throats. You can now smell exhaust from other vehicles.

So, I need to thank you all for your help, especially Mike.

I'll certainly let you know if the hydrocarbons return.

BTW, the Thermomaster chip rocks, but I am concerned that I have yet to experience the torque converter lock up. These early 700R4 trannys need it for full fluid flow.

Seth

 

Good to hear. Keep an eye on your mileage and let me know how it goes. You say you got the last thermomaster chip from Summit?

On your torque converter you can place a test light in the A and F terminal on the ALDL. It will light when power is being provided through the brake switch and go off when the ECM closes the circuit to engage the converter. (It will also go off when the brake switch is opened.) You can jump these terminals to bring it on manually. If your ECM was not seeing a good cts signal it could have been causing the engine to stay in warm up mode (rich) and not allow lockup.

Mike

 

Summit sent chip for '84. Didn't work, which led me to call the factory. Then I called Summit, who had the factory send the correct Thermomaster, and then had FedEx pick up the 'old' one. Great when people stand behind their product.

Will wire in test light. Also, might try to get to the parkway tomorrow, to see just how fast I need to drive to get lock-up.

Seth

 

The stink returned, even though the dwell remained steady at 35 [30 was too stinky].

I had an idea. Went to the one thing not checked. Sure enough, it is the vacuum reservoir. Pull the vacuum source hose, and hold finger over it, and dwell goes up FIVE degrees. The leak is in the can, not the hoses or the A.C. switch assembly. The in and out hoses are now just pushed together. Dwell is near steady at 35 degrees [readjusted the bleed screw].

Only a drive will reveal if this helped. Between this temporary fix, and the repair of the pcv hose assembly, well who knows. I will cross my fingers. Apparently this oxygen-sensor based system is very sensitive to air leaks, where they don't belong.

Seth

 

It only gets data from one bank. So if that's the bank that's running lean, it'll fatten up the mixture for the whole thing.

 

Yeah, I always like to plug all vaccuum sources at the carb to eliminate them when troubleshooting stuff like this. A vaccuum source on the right side of the carb=driver's side bank lean. Your code 55 had me worried that it wasn't the CTS (as I thought) as that's a lean trouble code too. Let me know, I'm losing sleep already on this one.

Mike

 

Mike,

Leave it to the engineers at General Moron [you like that one?], to devise a system that richens up the mixture when a vacuum leak occurs.

That CODE 55 left with the bath water. I am using my original computer, as that troubled rebuilt is now on its way back to the supplier. The vacuum storage can has a big, but hard-to-see, crack around the connection nipples. I will apply glue or silicone sealer to repair. The vacuum source for this plastic p.o.s. is common to both cylinder banks. Wouldn't it be a kick in the *** if two years of replacing or rebuilding all that crap [and spending $90 on each inspection], was a dumb waste of time/gas/effort/money, as this was the problem all along? Also, I cooked the original chip, by installing it ***-backwards, so I am now beholden to the Hypertech chip. Can't complain about the new chip, though. It works nice, and also eases the burden on the A.C., by working at 160* F. As long as the converter still locks up at some speed or other. I am taking a trip on Saturday, and will check that out then.

I will keep my nose alert, and report back soon.

You are a wonderful bunch of fellow car enthusiasts.

Thanks,

Seth

P.S.- I see that each time I used the word '***', it was replaced with three asterisks. So, in the future, I will use the word 'butt', instead.

 

The ECM shouldn't richen the mixture in response to a vaccuum leak anymore than the programmed (normal) A/F ratio. It's still only trying to meet O2 setpoints within the driver's side exhaust stream. A vaccuum leak allows extra O2 into the carb/manifold and the system will respond by adding fuel until the O2 levels are met-up to the richening limits of the system. If this leak is allowing more O2 into the driver's side it will richen the mixture past this setpoint only on the pass side, where no (or less) extra O2 is present. I'm going to have to check whether the vaccuum ports access both plenums or not.

Another possibility is that the extra O2 from the leak is not allowed to mix properly with the extra fuel, burning "lean" and allowing unburnt fuel and O2 past the chamber.

Let me know though. I'm still learning stuff everyday too.

Mike

 

Mike,

I drove around all day long.

Not even a whiff of hydrocarbons.

All that trouble over a hidden vacuum leak.

The great news is that it is fixed. Also, the car has never idled as smooth; just like a V8. Oops, it is a V8. Smooth as a baby's butt.

Only engine I ever had that is smoother is a Mopar 440.

Now it is time to attend to the other two leaks- both power steering hoses, and the A.C. compressor.

Thank You So Very Much,

Seth

 

This is somewhat late now that you've seemed to have it worked out, but I noticed you said that you have a Bosch O2 sensor. Coming from personal experience, I would change it out with an AC Delco O2 sensor. I was trying to find the reason why my own car was idling so rough and couldn't find a solution. One day I just got the urge to change out my fairly used (15000 miles or so) Bosch sensor with an AC Delco sensor, just to see if it would affect anything. The car idled a lot smoother with the AC part than the Bosch, and I started getting more miles to the gallon than I did previously with the Bosch part.

I found a thread on these boards a while back that examined how the Bosch sensor makes the car run richer than it should, even when the car is working perfectly. That's when I decided to never run Bosch product in my car again.

 

Thank You.

I think I'll try just that. Still have the factory unit.
As I got the Bosch from Strauss Stores, I can possibly get my money back if this holds true.

Who knows if I am running within N.Y. specs. My nose is good, but not as precise as an emissions sniffer.

Seth

 

i was just wondering about this all, but do you have an electronic quadrajet? because i do, and its not running all too great, and if ours are the same, this could become very handy in the future.

 

Yes, I have the computer-controlled Rochester Quadrajet.

From what I see, a properly-tuned Rochester [computerized or stand-alone], can be considered a top-performing carb. Great idle, improved gas milage over other designs, and suprising durability [mine was 22-years-old before anyone touched it].

Just ask for advice, and we will help.

Seth

 

To the Jersey Shore and back. Knock on wood, the car performed flawlessly and odorlessly.
The new chip is nice, but I am not crazy about lock-up. It is not as consistant as before. As long as this early 700-R-4 does not suffer from lack of oil circulation, I really do not care. What do you know about this aspect of the early 700-R-4's?

Gas mileage:
The traffic ranged from stop & go to 80 M.P.H.

Near the Outer Bridge Crossing, there was a 5 mile backup, because a 1956 Buick was lying dead in one of two lanes.

I have one third of a tank left and am down several ounces of R-12. But we did not suffer in the heat, as the engine always remained between 160* and 180*.

BTW: The new chip does not cycle the mixture solenoid until the engine is running. No more clicking for the 1st minute the ignition is on, but engine has not yet been cranked.

Seth

 

Computer threw a Code 13 tonight. Lasted less than a minute. Must be that new Bosch O2 sensor that you have said is possible crap.

Does this sound about right?

Time to reinstall the factory sensor. If the code does not repeat, I will insist on a refund, if I can find the receipt.



Seth

 

I've never had problems with the Bosch sensors but I'd swap it out anyway if you already have one to put in.

Code 13, possible TPS sticking/bad O2, maybe the computer's seeing O2 and MAP changes at the same throttle position?

Good news otherwise.

Mike

 

I'll get a tube of electrically-conductive anti-seize lube, before installing the GM sensor.

I forgot to say that the computer threw the code while idling, not driving.

Seth

 

I think that the sensors come with anti-sieze already.

 

My o.e.m. sensor is old and used. There is nothing on the threads.
But,

Seth

 

it really shouldn't as the juice will current will travel out the negative and then into the positive. current can't flow unless there is both a - and +. for your ECU to fry you would need to have it in the path of the current which it wouldn't be.

 

Time to follow suggestion, and install original O2 sensor.
The trouble light came on after re-starting a recently-shut motor [about 5 minutes off]. Light extinguished in about one minute.

Same situation later in evening.

This is what happened once last week, as you see in an earlier posting in this thread.

Also, I found an unused Bosch O2 sensor for a little 4-banger Audi. Are these things compatible with our cars? I have not as yet even compared threaded-end sizes. I ask, because this thing has not only the single black sensor wire, but also a pair of white wires for a heater [ I gather that this is what these are for ]. If the O2 sensor heats faster, it will produce a voltage sooner, and force the computer into closed-loop. If the heater remains on [or can it burn out when wired without a timer ?????? ], the sensor should remain hot enough during idle, to maintain closed-loop. Opened-loop uses more gas, which is so expensive.

P.S.: Except for some pinging [need pricier gas], the new chip is working out just fine. Old was nice, but I did stupidly cook it.

P.S. P.S.: I will repeat what I asked earlier today: Why are my pipes still sooty? Exhaust is odor-free, so emissions are possibly within New York State limits. Is there so much dirt in the engine or pipes?

Seth

 

I run a heated O2, mainly because it's placed farther from the head in the y-pipe. I've read and been told that the heated O2 will last longer and will be fine without a timer. Got about two years on mine now.

A GM part number for the three wire O2 is 25176708. If you can get a part number for the audi sensor you may be able to cross reference, but it's probably compatible.

You may be able to cure the pinging by backing off base timing, but I wouldn't go past 0 degrees.

May take a while for all the soot to clear your pipes and cat. Give it a month or so then see. As long as you're not staining the pavement behind you. Your well plugs could be leaking down overnight causing it to run rich for the first few seconds (didn't you epoxy them?).

Code 13 right?

 

Thanks once again.

Yes to the Code 13.

And I used no epoxy in the rebuild.

Seth

 

If your fuel wells are leaking out overnight you'll have a hard start first thing (starter motor running til fuel bowls fill) then an initially rich condition that clears in a few seconds. After it sets for a few days you can manually pump your booster to see if the bowls are empty. I suspect, however, that after some miles your soot should clear.

On your 13, maybe hook the meter to the TPS and make sure the voltage change is somewhat linear throughout its range? Try the heated O2 and it may clear up as well.