my car is running really rich (10.8 mpg when driven lightly and carbon coming out of the exhaust) and i was wondering if i could adjust the "primary enrichment" on the carburator (from a tech article on here) to run leaner to save on gas and to make it run better. if i could do that would it solve my problem? if anyone else has a better idea that would work please let me know. thanks.

 

If this is the computer-controlled Q-Jet, then adjusting on things is a BIG MISTAKE. They don't just up and get out of adjustment all by themselves; which means that adjusting on them simply throws the carb even further out of whack.

First thing to do would be to fix the leaking plugs on the underside of the fuel bowl, underneath the primary jets. Those ALWAYS develop leaks, and when they do, they in effect expose the fuel bowl (raw gasoline) to intake manifold vacuum, which sucks in as much gasoline as will fit through the leak.

Pop the carb off, remove the throttle plate, wire-brush and sand all the old built-up gasoline crud off of them, flush them with lacquer thinner until they're sterile, and coat them with JB Weld. Then put the carb back on and see what it's like. You might be amazed.

 

so you could not use the carb to compensate for the car running rich for reasons unrelated to the carb?

 

IF AND ONLY IF there are other factors, besides a broken carb.

Q-Jets are designed in such a way that virtually ANY OTHER FACTOR that occurs, will cause the carb to feed too little gas. It's an EMISSIONS design. If you put too much cam in, it'll run lean. If you put headers on and don't recalibrate the carb, it'll run lean. And so on.

For all practical purposes, there are NO "OTHER FACTORS" that will make a Q-Jet run rich, at least on the primary side.

Conclusion: your problem isn't "other factors". It's a broken carb. Fix the carb before you go dinking with adjustments that (a) won't fix the problem and (b) you won't be able to put back right whenever you DO fix the problem.

 

if i put the carb on that i would like to put on (holley 650 double pumper) it probably wouldnt give me much better gas milage (maybe a couple mpgs) then where i am at now would it? (this is on a 305)

 

Probably not.

You'd also have to buy a distributor; the computer controls that too, and it's an all-or-nothing proposition.

A tube of JB Weld is alot cheaper than a distributor.

 

I'm assuming there is no "check engine" light lit up? An O2 sensor would be my first thought, if the check engine light is on.

 

check engine light is on. i cannot get codes off of the computer by either a obd1 code reader or jumping the two terminals on the plug for the computer. in a previous thread somebody told me that my computer may not be working at all and that if the computer is not working that the light will be on as a "failsafe". the fuse for the computer is also not blown. help is greatly appreciated, b/c i am ready to sell it if i cant get better then 10.8 mpg. another thing worth mentioning is that the pollution control gear has been removed by the previous owner, and he also likely messed up other stuff as well.

 

ok, fair enough.
If your computer is pooched, then your probably not getting the O2 signal processed, and the carb probably isn't adjusting itself, nor the timing.

I'm not sure what you mean by pollution control gear... air pump? egr? Cat? O2 sensor? what?

Might want to fix or replace the computer, chances are the carb will start working better. If the wiring is beyond repair, you've gotta get that carb you want, along with a distributor, and perhaps a means of locking your torque convertor, if applicable.

 

the smog pump, egr, and cat have all been removed. could my car run with a dead computer??? i dont think that any of the wire near the computer was messed with at all by the previous owner, but would a computer just randomly die after 90,000 miles?

 

It'll run with a hosed computer, but not very well. There wont be any mixture control or ignition advance at the dist., which will make the car run like crap.

 

that would explain why i am running really rich. if there is no mixture control am i like running at WOT the whole time?

 

i already checked ebay, and there wasnt a computer for a 1987 camaro w/ carbed 305. is there anywhere else i could check? how much would this be expected to cost? is there a way that i can for sure tell if my computer is bad?

 

I thought you've already determined that your computer is bad?

Junkyards would have been my first thought.
I'd check and double check, then go ahead and triple check the wiring. Look for shorts and opens, etc etc. Trace the wiring from the ALDL connector back and see if anything is funky.

It won't run like you're at WOT all the time, I think it runs in open loop all the time, ie cold start mode. With no ignition advance though.

If it was me, i'd just toss all computer related stuff, computers, and troubleshooting wiring scares the bejesus out of me.

How about you go ahead and put your car info in your sidebar eh? Like what transmission you have?

 

i have a 700r4. i am relatively sure it is bad but i will check it again.

 

What you need is the troubleshooting procedure for the ecm. I don't have a copy here but I'll look around when I get the chance. First thing to check though is operation of the mixture control solenoid. If it's clicking when the engine is running (or ignition on) then the ecm is attempting to control the mixture and may be fine.

You should be able to use a computer from pretty much any year LG4 (or L69 for that matter) the sensors/connections are the same AFAIK. Should be able to pick one up pretty cheap at a JY. I suspect, however, that if yours is not working there is something that has been disconnected or "dinked" with.

There are a few things, outside of the carb, that could cause it to run rich (although probably not as far out of whack as the mileage you're reporting indicates). Among them (for general info):

A failed TPS will normally send an erroneous WOT reading to the ecm commanding full rich.

A broken/loose connection to the CTS (fairly common with age on these) will fail to send a warm signal to ECM keeping engine in warm-up mode.

A bad O2 sensor will normally fail to a lean reading causing a richer mixture.

And my favorite, a vaccuum leak can cause a lean condition in the driver's side cylinder bank where the O2 sensor is. The ecm compensates but causes a rich condition on the opposite bank.

In the end, though, Sofakingdom is correct and "dinking" with the carb will not "fix" any of the above.

 

there is no clicking whatsoever near the carb when i start the car or turn the key to accessory. what is the CTS? a vacuum leak is a possibility, where would it likely occur? if my computer is not working, then a faulty o2 sensor would not be one of the causes, correct?

 

Your ecm does not appear to be working so none of the "general information" things I mentioned are likely to be primary causes. The M/C solenoid is immediately below the two wire connector on top of the carb and will click only with the ignition in "Run". If the engine isn't started for 30 seconds or so after the key is turned to run it will stop clicking.

Most likely the previous owner did indeed "dink" with something. I'd first check the power wire from the battery to the ecm. There should be a dedicated power wire for the ecm with a pull apart connector coming from the positive terminal of the battery. Check for this and confirm that the ecm under the pass dash has 12 volt power.

 

the plugs seem untampered with, and the two wires that the haynes manual said that [we think] were constant on were reading .6 volts. that doesnt seem right. i dont know where the fuses are located for those wires, the fuses are supposed to be inline. i must be doing something wrong.

 

Did you means to say that at the moment there's no CC carb to be had on Ebay, not that '87s didn't come with CC carbs?

 

Look at the positive lead off of the battery. There should be a smaller wire split off from it and running along the inner fender toward the pass side firewall. You should see a pull apart connector maybe a foot along that wire from the battery. This is the always-on power lead to the ecm. There is either an in-line fuse or, more likely, a fusible link in this lead. Verify that it's there, getting power through the connector and power from this lead is at the ecm.

 

i meant that at the moment on ebay there was no computer for a 1987 camaro that came with a carburated 305.

 

there were only two wires coming off of the battery, one to the starter and one to the alternator. im not exactly sure where the ecm gets power from. also while i was looking at my fuse pannel i saw two plugs that were not plugged into anything and i saw no where to plug them into. im not sure what this would be.

another note is that while i was checking for the power to the ecm at the ecm, i unplugged the ecm plug and started it and my car ran fine and my check engine light remained on as usual. i appreciate the help and i really need to get this figured out.

 

in addition to that, does the tps go into the computer?

 

Sounds like your ECM doesn't have power.

You need to find that pigtail, and hook it to the batt.

It should come out of the ECM harness, which is the big fat one that comes up from behind and under the blower motor on the pass side. Look for a single orange or red wire hanging out of it. That wire needs battery power. You gotta find it, and hook it up. Sounds like that's Step 1 of fixing what ills your car.

This is why "adjusting" on the carb is a bad idea. There's NO HOPE of getting it to work right by doing that if the whole control system isn't even powered on. That's about like trying to adjust the hue and tint controls on your TV to get a better picture, when it's not even plugged into the wall.

Yes of course the TPS goes to the computer. The computer uses the TPS to tell where your foot is, so that it can control the fuel mixture and ignition timing accordingly.

 

i might need to clarify a little bit, sorry. the plugs that were not connected to anything were by my fuse pannel under my drivers side. i have no idea what they may have been plugged into, whatever it was, if anything, is not there now. all of the wires near the ecm are plugged into the ecm and the power wires to the ecm read .6 volts on the volt meter. i am unsure what that means in my situation. i will continue to check for other wires, but i have to go to work now.

 

The ones by the fuse panel probably don't have anything to do with the issue at hand. Don't pay any attention to those just yet. Next time you get the chance, check the big harness up by the right strut tower for the ECM's power wire, like I described. Once you get that located and hooked back up, then it might start being possible to get your car running right.

 

Disconnect the battery and see if you still get 0.6v, if the meter still reads some millivolts it's probably trying to autorange.
Without a schematic I can guess based on my car:
That inline fuse by the battery powers multiple circuits. If you have a fuel pump relay, there should be an orange wire connected to it, follow it, there should a point in the harness where it's soldered to a few other orange wires, the ECM is powered by one of these. It's probably cut somewhere on the passenger side before it goes into the cab.

Of course the fuel pump circuit may have also been rewired.

 

i tested the wires that plug directly into the ecm and multiple wires had ~12v. i have no idea why they read .6v last time i must have done something wrong. the other wires appeared intact. now that i know that my ecm was getting power, can i make the assumption that the computer is dead? would it be worth it to get it checked or should i just find a new one? what kind of price range can i be expecting? i will also search on this.

i also wanted to add again that i have driven this car with the computer unplugged and set in the back seat for a day or two now and it runs as normally as it ever has.

 

No you can't assume that.

You still don't know that the ECM is getting power.

Have you located its power feed, out there at the battery, yet?

Most likely, the reason it runs the same with the ECM disconnected as connected, is because the ECM is getting no power. See my sig.

 

i found an orange wire that we tracked back to the ecm bundle, that wire connected up to a black/pink wire that plugged into the ecm. the orange wire and the black/pink wire that it was connected to had ~12v. according to my haynes manual the ecm power wire is black/pink. i really appreciate your help.

 

im going to post up some wiring & diagnostic diagrams, i hope they are the right ones.

 

the other 2.
you may need to save all them to your computer & open them with windows picture & fax viewer to zoom in to read them.

 

are there any pictures on how to do this jb weld thing on the trot plates? sorry im a visual guy. my car runs rich too but i know the ecm and mcs are fine.

 

See attached for jb weld thing:

http://www.carcraft.com/howto/57178/

Thanks DENN_SHAH for the troubleshooting stuff. I knew I'd seen it before but couldn't find it. Now I've got it saved in my "car stuff" folder. I was away for work over the weekend but looks like you've got what you need to get started.