Choke tuning....

[garion]

Hi all.. I've been enjoying this wonderful AZ weather, driving the Spider when I get a chance. But I've been running into a 'nuisance' problem. The choke. Carb is a DFEV.

This morning, I'd say somewhere in the 60's.. I get the car, hit the gas once, turn the key. Fires right up, 1500 rpm or so... I leave it there for a minute, tap the gas, and idle comes down to 800 or so.. Perfect. This is what I expect...

I then start driving it, and after it gets fully warmed up, it now idles at lights at 11-1200.. Higher than I would expect..

Drove the car into work, parked it, left work about 5 hours later... Go to start the car, hit the gas once, turn the key... turns over, but won't catch.. It needed some feathering of the gas to get started, and then when it did, it idles around 500, way to low... Once I warm her up a bit, returns to the 1200 rpm idle...

I've checked the choke pull off, it looks to be oriented right. Choke does open up.

Any thoughts?

[majicwrench]

Carbed cars have sooo many things that can go wrong and cause such issues. What year??

[bradartigue]

Inspect but do not adjust, especially if it was working correctly and now isn't. The conditions you describe sound like you started either leaking through something or you have a dirty idle jet. I don't know your car, but you could have a vacuum-operated distributor, a brake booster, a fast idle device, or two or three ports capped. Inspect these. The brake booster you can test by simply disconnecting it from the manifold and covering the port (makes stopping a little more difficult is all). The other ports you can simply cap off to test. Since the problem is in the idle circuit you can also simply remove both idle jets from the outside and blast them and their orifice out with carburetor cleaner.

Running fast, then slow, then fast, is almost always an air leak, but worth inspecting the whole thing.

[garion]

Thanks guys. I'll take a look. Its a 79, with a DFEV. I bought the car last Feb, only got it drivable (safely) recently (steering, suspension, brakes). In that time, I've swapped heads from a 1.8 (MOAR POWER! I know,only a little, but hey). All ports on the carb are plugged, except the one above the idle mixture, which goes to my vacuum advance (brand new). I have not taken the carb apart at all, so its quite possible that something is clogged up. The connected on the brake booster seems sketchy, but I don't hear anything, and the brakes are fine.

Anyways, I'll check it out this weekend in detail, and post here.

[garion]

Ok, so I checked for vacuum leaks, and couldn't find any. I was spraying carb cleaning in the areas that might be leaking (brake booster, my plugged ports, etc..)... As suggested, I took my idle jets outs, and sprayed carb cleaner in the hole, and cleaned off the jets...

And then my ignition died, no spark at all from the coil. So now I'm diagnosing that. It took me two hours to get to that conclusion, after all, all i did was clean out those jets, no even on the same side of the car as the ignition.

*sigh* Fiat gods strike again.

[bradartigue]

Ok, so I checked for vacuum leaks, and couldn't find any. I was spraying carb cleaning in the areas that might be leaking (brake booster, my plugged ports, etc..)... As suggested, I took my idle jets outs, and sprayed carb cleaner in the hole, and cleaned off the jets...

And then my ignition died, no spark at all from the coil. So now I'm diagnosing that. It took me two hours to get to that conclusion, after all, all i did was clean out those jets, no even on the same side of the car as the ignition.

*sigh* Fiat gods strike again.

Is your distributor loose, did it move? If your distributor started moving while driving then your RPMs would go up (if it was advancing, which is what they usually do when loose)...would have caused all the problems you're describing.

[garion]

No, the distributor is not loose. Checked that last night. Right now, I'm not getting anything out of the coil.. I put a timing light on the wire from the coil to the dist, and got nothing. Thats as far as I got diagnosing.. I plan on doing some more tonight after work.. Its either the coil, control module, pickup, or wiring..

[bradartigue]

No, the distributor is not loose. Checked that last night. Right now, I'm not getting anything out of the coil.. I put a timing light on the wire from the coil to the dist, and got nothing. Thats as far as I got diagnosing.. I plan on doing some more tonight after work.. Its either the coil, control module, pickup, or wiring..

Or fouled plugs. You won't get a reading at the wire if the plugs are fouled beyond use. Test the coil at the coil.

[garion]

Coil tested. 1.5 ohms between the primary terminals and 10k ohms from terminal to the secondary (I forget the actual number, but it was at least 10k). I have 12v to the + side of the coil with the key on.

It looks like I have a bad/loose connector on the pickup, so I've ordered a new pickup, and for giggles, a new control module.

At one point, I got the car started, saw the timing light flashing, and then the engine cut out. No flashes when attempting to start it. So I don't believe it to be fouled plugs, since it ran.

[bradartigue]

Coil tested. 1.5 ohms between the primary terminals and 10k ohms from terminal to the secondary (I forget the actual number, but it was at least 10k). I have 12v to the + side of the coil with the key on.

It looks like I have a bad/loose connector on the pickup, so I've ordered a new pickup, and for giggles, a new control module.

At one point, I got the car started, saw the timing light flashing, and then the engine cut out. No flashes when attempting to start it. So I don't believe it to be fouled plugs, since it ran.

Does the same thing with bad/fouled plugs. Easy enough to check them before you install the new unit.

[majicwrench]

I disagree. Current still flowing thru coil wire w fouled plugs, will trigger timing light just fine.

[garion]

Just replaced the control module and pickup. While I was there, I cleaned up all the contacts, some of which had some corrosion. The pickup/control module connector was definitely suspect...

Got it all back together, and she started right up. I also re-measured the coil, and the primary is at 1.1ohms and the secondary at 10.9k ohms. From what i can tell, the primary is out of spec, and the secondary is just within, according to this, on page 55-20: http://www.njfiats.org/joomla/images/st ... trical.pdf... Would it be worth picking up a new coil?

Now back to my choke/start issue.. When we last left our hero, we had just sprayed the idle jets clean, and double checked our vacuum.. As I mention, she started right up, idled at 1100-1200 or so, and then rose a bit to 1500. Then when I tapped the gas, she went to 500 or so rpm. After that, I called it a night. I'll see what happens this weekend.

[bradartigue]

I disagree. Current still flowing thru coil wire w fouled plugs, will trigger timing light just fine.

I disagreed too until about 4 months ago. I found on this 79 we've been steadily (and miserably) working on - it is a problematic car - that the fouled plugs made everything in the ignition mess up. Same exact symptoms as are described here. It is an easy enough thing to check. It has made me wonder if the problem isn't a very weak system to begin with, and the plugs being enough to tip it over the edge.

[garion]

Reviving my old thread... When we last left, I had fixed my ignition, and was working on the choke...

Since then, I discovered that I had my two idle jets swapped.. This greatly improved the running. It was running ok before, but now... Smooth..

I then hooked my fuel return line back up.. This caused another fuel leak, which was also repaired.. This fixed my "takes some cranking after the car sits a few days" problem...

So back to the choke... I figured out that I was adjusting the choke incorrectly.. I was adjusting by having the car cold, hitting the gas to enable the choke, and the adjusting the choke to be nearly fully closed... This is *close* to the actual procedure.. You're supposed to do all of that, but hold the throttle at 1/3 open, and then adjust to almost fully closed...

Now I start up immediately, and idles somewhere around 2k... After 10-20 seconds or so, I blip the gas, and idle settles down to 1100... As she warms up, idle eventually settles at 800-900 rpm. Success!

But with a warm start, say sitting 15-20 minutes, I need to hit the gas to get her to start again...

I'm getting close!