LOL there weren't too many of them. It still does not run as good as I'd like, but it will hold me over until I have the time to do another TPI conversion. At least the system is adjusting as it should.

 

The silly little assumptions we make. All this time I thought you knew about the diagnostic connector. . .

Of course, using a scanner on the ALDL would have eliminated that problem as well.

 

Oh yeah I definitely did not know there was a dwell connector. All the posts I was reading about people reading dwell, talked about back probing the MCS. It was always a huge pain to run the engine w/ wires forced into the MCS connector. Hell I can run my dwell meter in the cabin if I want to now!

I have intentionally steered clear of CCC cars in the past, so I had never worked on one of these before. This car was a V6 to V8 engine swap I did over a couple weekends, so I didn't have time to set anything up except throw a CCC setup on there. It started out as a free car, so I didn't pay too much attention to anything other than functionality under the hood. Surprisingly the Varajet setup used 90% of the same wires as the CCC V8, just w/ different length wires. Some of the underhood harness is still V6 stuff (including the dwell connector) and some I had to merge w/ junkyard V8 stuff. It all works surprisingly, now w/ no check engine lights. But yeah, between all the different colored splice connectors under there, I had no idea what that extra loose connector was. I thought something was missing there. It is a marvel that this car runs at all. It's a super lame roller 305 long block that I built from parts of several different engines, with a shift kitted 700R4 that lays down rubber shifting even though the car is so damn slow.

But thanks to you guys it is running cleaner than it was before. I still think it is hiccupy when it isn't warmed up yet (although I am expecting EFI type performance so maybe I am not being fair to carbs in general), but fully warmed up it runs as good as a slapped together low compression 305 can run.

For you guys w/ well tuned CCC setups, if you get into the gas heavy (primaries only, not flooring it, just to pull out into traffic) and the car has only been running for a few minutes in cold weather, is performance flawless, or does it pop and hesitate at all? I have the choke taking 4 minutes to pull off, so there is definitely enough choke on time. I can start it and drive around like grandma immediately w/ no warmup no problem, but pulling out into traffic I'm still cautious.

 

If you have an open element air cleaner, your partially warmed symptoms sound typical. The factory dual snorkel with operating thermovac system will eliminate pretty much all of that.

I also don't have an EFE valve, which helps the way it runs when partially warmed. I just grit my way through it, which is typically 2-3 minutes into running at below freezing outside temps. An extra little pump on the accelerator when it "bogs" (letting off the throttle before getting on it again) typically gets it to recover. Perhaps not as user-friendly as EFI, but certainly tolerable considering the performance/cost ratio for other situations (fully warmed up, at the track, etc.).

 

So now the explanation, given that we've got the original problem figured out......

By the way, I ain't no electrical engineer, so no guarantees I'm explaing this correctly, but probably pretty close.

I'll use the distributor analogy again for starters: You can read dwell 2 ways- hooked up in parallel with the negative side of the coil and a ground OR across the coil's + and - posts. They will read reversed if you do it by probing across the coil posts becuase the voltage potential between your dwell meter will be HOT when the points are CLOSED (voltage flowing through the coil). If you do it the other way (the right way) by probing between the - coil post and a ground it will be HOT when the points are OPEN (the negative side of the coil will be hot becuase it's got no ground to flow to except through the probes of your dwell meter).

Now, it won't be a perfect inverse number hooked up one way or the other becuase doing it the wrong/backwards way leaves the load (the ignition coil or the MC solenoid, which are both electromagnets, by the way) between you dwell meter's probes. And that load (a SEMI-conductor: an inductor, actually) throws just a bit of a wrinkle in things vs. hooking it up the right way, in parallel with the ground path (NOT a semi-conductor, just a pure, plain conductor). So what you get is not just a reversed reading, but a reverse reading with a bit on an error or an "offset" thrown into it.

Obviously, something very similar to that is happening when you hook up your dwell meter across the MC solenoid wires (like attaching to the + and - terminals of a coil, gives reversed reading plus some error thrown in). Hook it up using the proper dwell connector and I'm almost sure you're then running in parallel with the ground side of the circuit, giving proper readings.

I'm kicking myself that I didn't figure this out previously. I've done the checking on cars using the proper connector but when I went to do my bench testing I did it the backwards way across the MC solenoid terminals, giving me reversed readings just like you were seeing. I just didn't put 2 and 2 together very quickly. I'm embarassed that I didn't figure this out about 10 posts ago- it was staring me right in the face the whole time!

So, last up on the adenda.... you are still needing to set the IAB and Idle Mixture screws pretty lean to get reasonable dwell readings, eh? 6 turns out on the IAB and 3 on the mixture screws is still a damned lean setting considering that 4 and 4 is usually about right on most motors. So I'm back to STILL not being able to explain that one, other than the "every engine is different" BS answer I posted above. It may in fact be that, or it might be something you can actually figure out (like my original thought about a flaky evap system bleeding vapor purge when it shouldn't).

 

Gas heavy, no primaries, still cold. No hiccups or hesitation for me. I've removed the EFE and am using an open element (firebird with otherwise stock LG4). Cold temps here last week in the 30's.

Another potential indicator that you're running leaner than you should be.

 

Evap has been ruled out. The system is still requiring a mixture so lean that the car does not run right. If I trust the dwell readings, the whole primary side is too lean, from tip in to heavy part throttle. When the car is 100% hot it is barely rich enough to drive "okay", but I am terrified trying to cross traffic when it's not 100% warmed up because it is so lean. I have a lot of choke on-time so the choke can't help out any more. So I have made zero progress since almost 2 years ago w/ this setup. The dwell flip flop was interesting and it's good to know the ECU is okay, but that's about all I can confirm w/ this setup.

I am using a stock intake w/ thermostatic air door and manifold heat snorkel!!! I am not using an open element air cleaner and I don't have any of the factory stuff disabled. There is no reason why this thing should be unhappy.

If I richen the IAB to where dwell is very unhappy the car runs better but then starts throwing rich check engine lights.

I don't think there is any hope for this thing!!! So shooting for 50% dwell w/ the system reading backwards was still getting my IAB and idle screws to about the same super lean point.

Oh well, I tried. With the amount of time I have wasted on this system I could have done many, many hours worth of more productive things. I'd throw my favorite Edelbrock 600 on here but I don't think the cat would be too happy with an aftermarket richer carb.

 

what kind of dwell meter are you using? that's probably not the problem but would be curious how my old Actron would read on your car.

maybe we could compare these stock cars. might see why one is running so lean and the other so rich.

 

I actually checked against another new Actron that I borrowed from my brother, and the readings are the same. It's not the meter.

 

Just rechecked mine this weekend and found it was between 20 and 24. I couldn't get it back in line with the IAB unless I turned it almost all the way in. Started over with 4 1/2 out on the mixture needles and 4 turns out on the IAB. I adjusted each mixture a little at time and wound up with 5 turns out and didn't move the IAB much at all to get 30degrees on my Actron meter. Runs good now and is consistently varying between 28 and 32.

 

Silver 87: That's a little rich on the IAB. I'd check for a vacuum leak somewhere. A good idea is to cap every vacuum line on the manifold and carb (except the VAC sensor line at rear of carb) then see if the dwell settings change. If they do, reconnect each line one at a time til you find the offender.

 

I thought I wanted 4 out on the IAB? I thought the target dwell I'm aiming for is 30 on a 60 degree scale which would be 50%? How is what I got now too rich? I just checked for vacuum leaks just now and didn't see anything. I am still learning this crazy CCC system. Before I did the adjustments this weekend, the car had a hesitation or hiccup on partial throttle from a dead stop. Now it's gone and running real strong unlike before.

 

I apologize. When I first read your post I thought for some crazy reason you didn't turn the IAB out much from seated, not from 4 turns out. Appears you're gravy and I'm just confused.

Glad you got it running in the sweet spot.

 

It does seem to be running good now, but it did something weird last night. I had parked the car last night and went out about 2 or 3 hours later and hit the starter and it fired, but didn't stay running. I pushed the gas pedal down and released to set the choke and tried it again, but didn't want to start. It acted like I flooded it and had to hold it to the floor and clear it out. Neighbors must have loved that at 10:30 at night. Drove it today and made a few stops and everything went good today. The weather had changed dramatically here in a few hours time that it was parked. Went from warm and dry to cold and foggy. I'm wondering if the ECM starts from it's last known good closed loop settings and stays that way until the O2 sensor warms up and goes back into closed loop?

 

From what I've been able to determine, what I've read and little tests I've done, the ECM has three modes.

1) Cold start mode where it's not adjusting the mixture.

2) Coolant Temp Sensor (CTS) warms up but O2 sensor is not hot enough to provide data. ECM uses last known good data for TPS and VAC sensors to adjust mixture.

3) Fully warm. ECM uses last known good data for TPS and VAC and re-writes blocks based on O2 sensor input.

I'm not as certain as I once was how much role the TPS has in timing advance vs. the direct tach read to ECM. Again some of what I've read is generic to computer controlled carbs and may not apply to specific models. Certainly open for discussion.

Wouldn't worry too much about the no start if it remains a random event. Going cool/humid after running can make much of the intake tract a condensation trap. It was unlikely ecm related.

 

Reading this thread has convinced me of one thing. It's time to buy a dwell meter and take that next step to insanity.

 

After getting the dwell adjusted the car runs great warmed up and the check engine light never came back on. This is after probably 100+ key on/off cycles. I still could not get the car to run right when it had been warmed up for 5 minutes, choke was just about off, but the engine wasn't fully warm yet. A stock engine should not need more choke on time than the book called out (3.5 minutes or so). With the dwell set properly, the choke on time set properly, and the stock heated air cleaner assembly instact, there isn't anything else that was left to adjust. The ECU controls cold enrichment but with a stock engine that should not have needed any additional fuel. But it is neither here nor there at this point.

In a few more weeks, the 305 engine and CCC system are coming out of the car and getting replaced with my hot roller 327 from my 2nd gen, with the TPI based stealth ram and painless harness. Thank God. If anyone needs some good CCC carbs I will list them in the for sale section within the next few weeks. I acquired several of them when I thought the carb was the problem. At least 2 of them are rebuilt and calibrated.

Thanks guys for your help. W/ your assistance on the dwell I at least got the closed loop state to run more or less correctly. But as for cold start and warmup, forget it.