JFROG

ok did search already. reading code 45. rough and erratic idle and stumbles at times and dies. will try new o2 sensor. what else should i look for?

phess11

Carb ever been rebuilt?

JFROG

its a few years old. never been rebuilt. was thinking about doing that today. ive seen usually the plunger is the first thing to go bad and dirty real easy.

JFROG

will rebuild. set timing at 6 still runs like crap. what should i really look for. does anyone have a pic of the plugs i probably need to seal? should i change out tps? m/c working fine. right now will not tolerate IAB past 2 1/2 turns out.

phess11

pics in this thread...

https://www.thirdgen.org/forums/tech...ht=epoxy+plugs

phess11

TPS discussion here.

https://www.thirdgen.org/forums/carb...light=tps+test

Damon

When the mixture control solenoid stops working (or is unplugged) a computer controlled QJet will default to running full-rich, and very badly, similar to what you describe.

You should hear definite "clicking" from the carb for about 30 seconds or so when you turn it to the key-on position. No clickie, no workie.

Not a "fix" but something to keep in mind. Nothing worse that chasing your tail for weeks just to find out the big blue 2-wire MC solenoid connector on the top of the carb is unpluuged and causing all your problems.

JFROG

its plugged and it clicks, engine was just rebuilt so wondering if carb is dirty?? also wondering about timing. set at 6 with timing light and 4wire est unplugged. idle screw all the way in and idles bout 550 like crap. engine stock except for mild lunati cam bm-II

JFROG

carb looks good inside. gaskets were in good shape. looks like a reman. unit. with the different screws and the plugs look to not have been leaking. bowl had fuel when carb opened. i even checked the distributer to make sure rotor was at 1 position at tdc. i dont know what else to check??? maybe wires cap rotor??? how many ohms do wires need to have ??

Damon

550 RPM idle with a "BM-II" cam? As in "Bracket Master" cam? What kinda specs are we talking on that cam? Up to about 220* @ .050 a computer controlled carb setup will usually work OK. Beyond that, it gets dicey. 550 RPM idle with just about any non-stock cam is likely to be very rough. 800-900 RPMs probably going to work a lot better with any type of performance cam.

Also, I'd look at a little more advance in the ignition with any non-stock cam. Even stock-cammed motors can typically take about 4* over stock ignition setting without problems.

Saying all this, I feel almost certain I'm still not getting at the root cause of the problem here. Any more information you might be able to give about the combo might help me clue in on something.

JFROG

it is the 00016 218 .050. just checked a couple of plug wires. reading about 8500 - 10000 ohms (total wire) actually the 10000 was on a short wire.) cant remember parameters will search maybe try cap and rotor. they are the cheaper looking one.

JFROG

thinking weak spark = rich at o2 sensor?

naf

iTrader: (7)

Have you connected a dwell meter to it yet? Only way to really tell everything is working correctly.

When it's running full-rich, opening IAB should help it run better and idle higher. Pull the connector off the TPS to put it in full-rich mode and see if there's a change. Plug every vaccuum port to verify there are no leaks.

If you've got it open already you can do a quick check of the TPS to make sure its resistance varies linearly as the plunger's pushed in. Won't guarantee it's good but erratic readings will tell you if it's bad.

JFROG

changed cap rotor, o2 sensor. still runs the same rough at idle and can hear missing at 2200rpm. when running at about 2k rpm for about 40 sec. chk eng light will come on and read code 45 (rich). I did check dwell. and was i think about 35-40. (can't remember but know it was in range when i checked). i cant think of anything else to check. ???? wish i had another carb to hook up and compare and rule out that.

JFROG

also pulled code 41 this time. does any one know what it means?

naf

iTrader: (7)

When you check dwell make sure that the reading is ranging +/- 5 degrees or so-needle bouncing back and forth even without change in throttle. This shows that the O2 sensor is adjusting the MCS settings. The dwell rate is determined by the TPS and MAP readings and the ecm will re-write these points based on O2 readings (at least when everything is working correctly). If the dwell meter is steady and changes with throttle position, the ecm is using it's "last known good" but isn't modifying its table with new values, meaning O2 is not reading or carb adjustments are too far off for the O2 sensor to get into it's narrow band. If the dwell is steady, rich and doesn't change with throttle position, the carb is stuck in warm-up mode.

JFROG

will recheck that, I think it was doing that. am going to pull carb off again and go ahead and put some epoxy over the plugs just to be sure.

JFROG

oh yeah i am using the wire connector by the blower motor. just making sure i'm ok.

naf

iTrader: (7)

Wire connector by blower motor is correct.

JFROG

well sealed plugs with epoxy. still rough idle. cuts off or almost when put into gear. can get to idle in drive at >600rpm ok. but when put back in park will go up to about 900 for about 15sec. then will even out at about 1100rpm, also if i run engine about 2000rpm for 10 sec idle will stay up a bit and might come down if throttle is blipped. sounds like a miss but has new cap rotor wires and ac delco plugs. timing set about 10deg i am debating on just getting a new carb??? was running better before rebuild. was just smoking (valve seals)

JFROG

also i can fully close the iab (clockwise) with no change will begin to stumble at about 3 turns out. the o-rings are intact and not bad. could it be m/c solenoid? clicks and can feel it moving

Damon

If it clicks and you can feel it moving, it's probably OK. Only other test is an Ohm test between the 2 terminals of the MC solenoid plug. Should come in around 20 Ohms. Below 10 or above 30 it's shot, even if it clicks.

naf

iTrader: (7)

Dwell ranging like it's supposed too? Probably not if the IAB can go all the way in. Have you plugged every vaccuum port to verify there are no leaks?

JFROG

dwell at 30 (6cyl) hits up to 50 when warmed up. can back out iab and slowly bring down to about 35 (stumbling) then if i give it throttle it will shoot up to 50 and stall. am going back to double check vac leaks just need to run to get a can of carb cleaner. also checked ohms at m/c solenoid connection on carb. read 0 ohms. another parts carb read the same. should that have been around 20 ohms?

naf

iTrader: (7)

Have you checked plunger travel of the M/C? You can use a secondary rod placed in the vent hole and you should be able to push it down and feel the plunger move against the spring. Travel should be about 1/8 inch.

Dwell at 50 means it's trying to lean the mixture, probably why engine runs with IAB in (also leans).

Have your idle mixture screws been exposed?

Damon

I've checked a million of them. It's definitely supposed to be ~20 ohms between the 2 poles on the big blue MC solenoid terminals (unplugged from the rest of the wiring harness, obviously). In fact, that's GM spec, which is where I learned it.

JFROG

i do get travel i guess approx 1/8 inch. actually used the straw from the carb cleaner spray can. im going crazy with this carb. i dont have cash to fork out for new one but my dad did give me a holley 600cfm and a vacuum dist. i do want to keep the ccc might look into cost of new m/c tps and get another rebuild kit. oh yeah the mix screws are sealed. tried to drill them out already

naf

iTrader: (7)

Damon didn't point it out but if you're reading 0 ohms across the M/C contacts it indicates a short in the coil. If it were shorted, classical laws would not allow it to click and it should be blowing the fuse. If you got this reading on two units I would suspect either instrument or operator error (sorry).

A bad M/C would cause your problems, just double check it before replacing (or pull one out of another carb that you know is good...how much is a new one anyway?). Check your fuse, too.

JFROG

new one is about $126.00, then would still need to buy the kit and tps . looks like ill be going with the holley 600 . I used a crafstman multimeter and "zeroed" the ohms setting, not sure whats going on but i can assure you it does click, although the clicking does sound different when i put the jumper wire in the aldl port to check codes. btw where do i hook pcv and brake booster on carb with 1 big port in the rear?

five7kid

iTrader: (14)

www.partsamerica.com Search for p/n FS2701. $59.99. Kit, p/n CK1042, $24.99. Adjustment tool kit, p/n CST28N, $9.59.

Much cheaper than a mechanical carb and distributor. And intake manifold.

JFROG

actually my dad gave me the carb, dist, and adapter. just need to know where to hook the pcv and brake booster

naf

iTrader: (7)

If you go with the holley hang on to your ccc-qjet stuff. You may want to go back to it, especially if you wind up not getting 20-23 mpg.

Damon

Yeah, about $60 for a replacement MC solenoid at your local parts store. Most of the ones in junkyard carbs are in good shape, though. It's just an electro-magnet. The only moving part is the plunger which is separate from the solenoid itself and gets moved up and down by the magnetic field of the solenoid acting on it's steel shaft.

naf

iTrader: (7)

If I was 17 (again) and my dad gave me a holley and dist I would probably want to hook it up and experiment, too. Can't hurt, might be some fun and I would run it for a while until I had the funds to fix the q-jet right. Post a photo of the carb and I can show you where to hook everything.

Let us know what kind of mileage you get with the holley, I bet it probably wouldn't take long to make up the cost of q-jet repairs with the extra fuel costs.

If you had to swap intakes it would be a different story though, hate scraping old gasket material off, especially after 20 years.

JFROG

if i was 17 again i could just buy a new one, since i wouldn't have any bills and kids. might just break down and get out the visa i have aside for emergencies dont want to but guess better to maintain my sanity. just want to make sure thats the problem. (the carb)

JFROG

ok now just noticed m/c soleniod will click only when aldl ports 5&6 jumped to read codes also the egr solenoid (2wires and vacumm) also click real fast. never seen that thing do that. will not click when ignition is turned on (not started) but now notice that the m/c solenoid is constantly clicking while engine running? hard to hear at times. is this computer error?

JFROG

ok double checked. now clicks with ignition on. dwell meter was still hooked up and no power.

Damon

The MC solenoid should be clicking any time the engine is running or the key is turned on (although it will turn off after a minute or so if it doesn't see the engine has been started). That's a good thing- means it's working.

Not sure about the EGR solenoid. It might click when you jumper the ALDL into diagnostic mode. When running it's what the computer uses it to send vacuum to the EGR valve and it does work on a "duty cycle" principle (open time vs. closed time) similar to the MC solenoid so I imagine it could make clicking sounds.

naf

iTrader: (7)

Alright let's answer a few questions:

1) dwell meter is connected at diagnostic lead, right? You should be able to start and run the engine with it connected here and not interfere with the cycling of the m/c. ohm reading was taken with m/c connector off?
2) was cam changed with the rebuild? or did the carb run fine with this cam before?
3) did turning the IAB affect dwell? did needle on dwell meter wave back and forth a few degrees indicating closed loop?
4) did you verify no vaccuum leaks by plugging every port at the carb with a plastic cap? best way, really imo. i like to leave them capped until I have the carb adjustments right then reconnect one at a time to make sure.
5) you said idle mixture screws were not exposed? this carb may need mixture screw adjustment to bring it into adjustment with the cam change...

Sorry about the "17" thing, got you confused with another poster...if you find you need a new m/c I can send you a known good used one. Just pm me your address.

JFROG

rebuilt again (put in new float and re checked all measurements) idle rough when cold little better when warm. did not die when put in gear this time. noted when cold black smoke then when warm no more. once again ports plugged. idle changes when vacuum port open, m/c disconnected, tps disconnected, but no change when map sensor disconnected. vacuum or connector. if i remember correctly shouldn't there have been a change? no code has been thrown (except after disconnecting it) could this be the culprit? also should there have been a change in dwell when disconnected?

naf

iTrader: (7)

Disconnecting the MAP sensor will only cause a change when the system is in closed loop. You'll know you're in true closed loop when the dwell reading changes with IAB adjustment (and the needle bounces back and forth slightly +/- 5 degrees or so). A bad MAP should throw a code.

JFROG

Ok got a digital multimeter M/C solenoid reads 22.8 ohms. TPS sensor is 0.5 -idle and 4.0 at wot. spark plugs are black. all 8 of them. cleaned with wire brush. will these readings make the car run like crap? with all the carbon on the plugs im wondering about the coil???? (has new wires cap and rotor)

naf

iTrader: (7)

Those readings are fine. You are running rich for some reason. When you turned the IAB out you were leaning the mixture but you likely ran out of range on the IAB adjustment. When you checked the plugs both banks were the same? Choke blade is at 90 degrees straight up, right? Check your idle mixture screws and see how many turns out they are, between 3 and 7 turns out should be good.

If you're getting mis-fire the ccc-qjet would respond to the extra O2 in the exhaust by richening the mixture and dwell would drop. You said your dwell ranges from 50 degrees to 35 degrees and changes as IAB is turned out, right? It appears your system is attempting to compensate for a rich mixture. Providing it's going into true closed loop (dwell meter needle bouncing). You haven't yet made me feel confident about that.

Verify closed loop operation.
Check choke.
Check idle mixture screws.

JFROG

all plugs were the same. choke blade is up 90degrees (except when cold), opened up the mixture screws,cleaned out and backed out 6 turns, still no response with iab. not sure about closed loop verification. when the engine is cold dwell sits at 30 then when warmed up will jump up to about 50 and thats when i can get the dwell to come down for a few seconds then works its way back up to 50 this same process will continue until i almost back out iab screw completely then the dwell seems like it wants to come down but runs really bad. eventually the engine will die and wont start unless i have part throttle and will die if idles. once the engine cools down it will start but the whole process above is repeated. checked the coil resistance and got 0 at bat and tach, but infinite at high tension terminal - bat and tach terminals. manual says to replace only if all are infinite, would like to double check with new coil or switch one out first.
also would clogged cat cause this? not glowing but did have bad valve seals before rebuild.

naf

iTrader: (7)

Try it again with idle mixture screws three turns out and IAB three turns out.

You never told me if this problem started with the cam swap?

See attached for coil troubleshooting procedures, but doubt that's your problem.

JFROG

yeah thought i had mentioned the cam swap earlier, posted the specs above. it ran fine before the rebuild ( other than bad valve seals and he found a broken vacuum hose). will try the settings (got to go fill gas can first). thats the test i did to the coil. have a few old manuals at the house.

JFROG

sorry naf that was damon that responded about the cam. its a lunati bracketmaster II 00016 -- 218 - .050. bought from advanced auto parts. just wanted somthing above stock but not radical,

JFROG

ok tried everything, 3turns 4turns, 5turns,adjusting the iab and so on the dwell did the same thing.could never get the dwell to come downby adjusting any screw. i did notice if it stalls when i restart it the dwell will sit at 30 then go right back to 50, when it does stall it will spit gas up not just the vapor but actual drops of gas. dont know what else to try or look for?????? all internal measurements are at spec. although i did notice that when i looked at a carb at the store the inlet was to the side this one is out the front but the rest looks the same. ?

phess11

Sure sounds like maybe too much fuel pressure, or float seat, or float level. Do you have a mechanical fuel pump? When you rebuild the carb did you replace the float seat? Did you check that there was no junk in the seat hole. Sounds a little like you are pumping too much gas into the carb, and flooding the fuel bowl. just a thought.

naf

iTrader: (7)

Qjets with inlets to the front were used on 2nd gens (and other models of course). I'm not going to say that they were never used on 3rd gens but I've not seen one. So it could have been a swap or it could be original but if it worked correctly before the rebuild it should work now.

When you first start the engine the dwell should hit 30 degrees until it sees a good temp reading from the CTS. It will then go to its "last known good" setting for that particular TPS and MAP readings. It will not begin to re-write these settings until the O2 sensor begins to provide input. Two things need to happen for this: O2 sensor temp high enough and O2 readings within the narrow band that the sensor can respond to. Only then will the motor be in true closed loop and the ecm will begin re-writing the dwell cycle blocks with new settings. That's when you'll see the dwell needle waving back and forth about +/- 5 degrees at idle.

One basic thing that comes to mind is ignition advance. Have you verified that you're getting around 20 degrees at idle (with EST reconnected)? Sometimes the module wires can get crossed and your timing will do funky things.

If the rich problem started with the cam change and adjusting idle mixture screws from 3 to 7 turns out didn't make a difference, I'd go back and look at the things you worked on during the change-distributor/timing gears/rocker