Hey guys, LG4. New E4ME CC Qjet. TPS showing .61 (tad high, no biggy).
Warmed the car up into closed loop. No SES light.
Dwell in drive around 500rpm showed almost perfect at 34-28, it bounced back and forth. I got in the car, put it in neutral, revved it up real quick, then back into drive and checked again. Dwell reads 45. Tryed revving it again, same thing 45. I tryed adjusting the idle mixture screws, no change. and the idle air bleed, no change what so ever. I have my dwell meters positive on the green connector back near the blower, and the negative on the batterys negative. Any ideas why it jumped when i revved it? and why wont it change?

Also, the car has a bog issue the second you give it gas. My AF gauge shows the car going very lean then it starts picking up, and things return to a tad rich and the car runs good. I replaced my carb to manifold gasket hoping that was the issue, and it did help the bogging slightly, but not fixed.

Any ideas guys? Thanks!

 

If you still have your smog pump, make sure the diverter valve isn't broken and sending air to your manifolds all the time, confusing your oxygen sensor. Happened to me and took weeks to figure out why sometimes the dwell would act normal and sometimes it would be fixed dwell. It should always jump when you rev, but it should be returning to where it was.

New-ish oxygen sensor? And if you have headers I've heard it recommended to switch to a heated one.

That bogging sounds like you need to tighten the spring for the secondary air flap.

 

Smog pump has been removed. whats the diverter valve look like? and where is it located to make sure i've removed it. Also, i do have headers, they are shortys though. And the AF gauge i have seems to operate fine in idle for about 2 mins as long as i take it for a drive before i test. Also i dont think it's a secondarys issue, because it bogs, has power, then looses some power around 3k rpm, then runs great 3.5k and up. I would think secondaries would only cause one bog (second you hit the gas).

Thanks!

 

This forum won't stop crashing.

The diverter is an ugly lump of hose connections, vac diaphrams, and solenoids. Next to the alt. If you have headers and they're not smog tube ones, it's irrelevant.

I'm not sure where the cutoff line for how far away from the heads your oxygen sensor needs to be before you need a heated one. Probably see if it dwells right immediately after driving but goes weird after a couple minutes of idle, then it would be a little too far. I upgraded mine before noticing it was the valve, so I don't know how much it changed things with my headers, about $70 after buying good wire and weatherproof crimp joints.

 

nope, i removed that diverter valve. The o2 sensor is pretty close to the exhaust ports. They're 2460HKR's. I'd have to guess maybe 15"?

Any other ideas guys?

 

Is your O2 sensor heated?

If it isn't heated sitting in neutral is hardly enough to keep it hot.

Hold the RPM's at 2k-2.5k for about a minute or so before setting the dwell so the oxygen sensor gets hot enough to take control. It won't take it long to cool so you may have to heat it up again if you loose control again.

 

I have done that as well. Even took it out, beat it around for a few minutes, pulled into my drive, put it in drive and checked really really quickly. Same thing, around 45 dwell and wont change. anymore ideas guys?

 

Ok guys, big post coming up, lots of pictures and a video. Hopefully someone can help me out :x

This is a general shot of the engine bay, car has a new 1984 CC QJet carb, smog pump delete, 2460HKR shorty headers, new non-heated o2 sensor.



This is where i have my positive lead of my dwell meter hooked to.
The negative side is to the batterys negative.


General shot of the front of the carb.


This picture is of the driver side of the carb, that adjustment screw at the bottom below the TPS connector is a idle mixture screw, correct? Theres another one in the same spot on the front passenger side of the carb.


General shot of the passenger side of the carb.

 

Shot of the back of the carb, on my origonal carb there wasnt a vacuum port on the top, so i capped this one off, thats what i should have done, correct?


This is a shot of a hose that i could remove thats behind the motor (was for smog pump) is this an issue leaving it?


Some connectors left from the smog pump, again, shouldnt be an issue right?


The screw on the top there is the idle air bleed adjustment screw correct?


Picture of the dwell meter



Note: the dwell stays the same whether the motors in closed loop, or open. Also the bog issue seems to occur in both modes as well.

Last but not least, a quick video of the issue, as you can see the O2 sensor is heated and working, notice the bog when going WOT and the AF gauge dipping into the lean area before spiking back up. When i first get out of the car, i left it in park on accident, so i got back in and put it in drive. Same dwell. Can anyone shine some light on this issue? ><

http://www.youtube.com/watch?v=I68Mm3HkF7s

Thanks!

 

You've got the dwell hooked up right. Are you reading the 6 or 8 scale? Supposed to read the 6 for some reason.

Is the coolant temp sensor new, or just looks new? My 85 phonebook-sized manual says if the dwell is fixed anywhere between ten and fifty, it's oxygen sensor or coolant temp sensor. But I see the needle bouncing around like it's not fixed, it's just in the wrong place.

Doesn't necessarily need to be in drive, you just don't want it to be at a much different idle rpm if it's in neutral/park.

You should be checking with the air cleaner on, changes it by about five on mine.

Have you tried sticking a towel over the air intake and seeing if leaning the mixture that way changes things?

Yes that's a mixture screw. Should be bottomed then backed out about 3 1/2. Same with the air bleed.

I can't tell a thing from that video though.

Seriously, this forum's server has major issues.

 

No, i haven't tried a towel over the intake yet. What should happen to the dwell? It should decrease correct?
The dwell never seems to change, yes i replaced the thermostat coolant sensor recently. and removed the EFE from the housing. This issue wasnt present until this new carb was put on. So far it looks like junk to, now it has a new issue, it's binding in the linkage at 3/4 throttle, i found the spot where it's binding though, ill try to fix that tomorrow.

If anyone else has any idea's or can help out, please let me know :x

 

Just to be safe: Pull the connector off the CTS and short it out. This will tell the ECM that it's fully warm and take the CTS out of the equation. Check the CTS pigtail too. They get abused from the AIR plumbing that run's over them and the wires can lose continuity creating an open circuit = ECM thinks the engine is cold.

You're probably fine without a heated O2 although one may speed up cold weather closed loop.

If no help (and most likely problem):

Set your idle mixture screws two turns out, IAB 2 turns out. With the engine warmed up turn your IAB out 1/2 turn at a time giving it a minute or so to see if the dwell responds. Go out to about 7 then start over with the idle mixture screws half a turn farther out until the dwell starts to respond. Don't go past seven turns out on either. Make sure the idle mixture screws are kept the same number of turns out.

You may want to plug EVERY vacuum port on the carb and manifold to rule out vac leaks when doing this. Just keep the VAC sensor (hard plastic line to rear port of carb) plugged in- the ECM needs this. After getting good dwell you can plug them in one at a time. If one is leaking the dwell reading will show it.

You'll know you're in the ball park when the dwell begins varying at idle and responds to choking the airhorn (with a rag) by trying to lean the mixture-higher dwell readings. Remember that dwell is a measurement of the amount of time the needles are down in the jets (restricting fuel flow) expressed as a percentage.

Post back your results.

 

I'll do that tomorrow naf and post the results, atm i put the old carb back on to confirm it was indeed a problem with the new carb. Old carb runs fine, so it's an issue with the new one. I will put the new one back on and give it another shot, thanks!

 

It's most likely that the new carb is just not within the narrow adjustment window for the motor. When the ECM doesn't see readings (remember it's a narrow band) that it can adjust to, it won't go into closed loop. Do the idle mixture screw/IAB trial til you get there. Let me know how it goes.