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Discussion Starter #1
Here's the problem. Took the car out to a little winter carnival with my kid. It ran great as it has since I acquired it a few months ago. It was windy and raining off and on. I parked the car, and we went to the fair for a little over 2 hours. I came back and the car was running like crap.
The symptoms include: A really rough idle. The car almost dies at times, but never actually dies. It is a real dog at low speeds and during acceleration. When I accelerate I hear a rapid clicking noise that seems to be coming from the driver's side of the engine compartment. When I remove the oil cap or the dipstick, the car dies as if from too much air. I actually removed the oil cap while idling a week ago and although the car ran a little rough it still idled. Not the case anymore.

I spent some time farting around with it during my kid's nap. I found a small leak in a couple of hoses and replaced them all. I read on the BB that the oil vapor separator may be the culprit, so I pulled that out and cleaned it and made sure all the hoses were on there tight. The problem is better, but still not running correctly. Now it still runs like a dog at low speeds, but at times it runs fine. I will accelerate and can feel the car alternating from a poor running state to normal. Any ideas? I am new to this and am currently lost as to what my next step may be.
 

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When I remove the oil cap or the dipstick, the car dies as if from too much air.
I agree that an intake air leak is your likely problem. Check the large ducts running across the top of the engine. The 'accordian' section of the rubbery duct can develop cracks & leaks that come & go.

In addition to cleaning out the oil vapor separator, check the small hose that goes from the bottom of the separator down and across to the base of the dip stick tube. That can get clogged with crud, too.

While you are checking things under the hood, clean & tighten all the grounds.

Also, check the harness connectors at the AFM & TPS.

A whole page about the L-jet system is in the link in my signature.

One other thought - since you mentioned rain - did the distributor get wet? Are the spark plug wires old?
 

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Discussion Starter #3
Just put the kid down for nap and went out to the garage. It looks like #4 cylinder is not firing. I checked the plug and it was wet. I see a spark on the lead and can hear it arcing when I hold the lead just above the plug. The plug wires may be old. I am not sure, but they don't look that bad. The distributor may have gotten wet, but that is probably a long shot. The large hoses across the top are snug and secure and in really good shape. I am not sure why I have spark but no ignition in the #4 cylinder. I will check the little hose going from the separator to the dip stick.
 

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I've had similar - a seemingly 'dead' cylinder that I eventually traced to a loose/leaky vacuum hose. My assumption is that where the faulty hose attaches to the intake must affect one cylinder more than the others.

Keep searching for an air leak (aka false air as all air entering the engine must pass through the AFM otherwise it is not measured - i.e. 'false air'). Here's a thread where I describe my search for air leaks and used an idea suggested by a fellow BB member to track down a particularly sneaky air leak. Embarrassing Confession
 

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Not clear to me about where you saw the spark, was it just at the end of the wire or at the plug itself? Could just be a bad plug; although it does sound like an air leak, it doesn't take much of one to really screw things up.
 

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Discussion Starter #6
I got some time tonight to mess with it some more. After sitting all day and being completely cold I started it. It actually ran great. I pulled the dipstick and no stall. Same with the oil cap. I pulled the #4 plug wire and heard a slight decrease in RPM's. It seemed great. I had blown through a piece of tubing into the dipstick housing and thought that perhaps I had blown some crap out of the tube or something. My kid was ready to go to bed so I ran inside for about 10 minutes and left the car idling to warm up. When I came back it ran like crud again. The heat is obviously affecting the problem. I have encountered problems like this with Vespas and it was almost always electrical. So, I put some new plug wires in and nothing changed. Still running crappy. I have searched high and low for a leak and can't find a thing.
Not really sure what to do now.
 

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Discussion Starter #7
The saga continues........I couldn't sleep because I was thinking so much about what could be wrong with the car. So, I drove to Autozone and got a set of new plugs. I did this because previously I had switched the plugs from #3 and #4 and this caused #3 to be the bad cylinder. So, I figured it was the plug. However, when I changed only the "bad" plug out of #3 it was still not firing. So, I put in a fresh set of 4 to see what would happen and the car is at least driveable. About the same as before. But, when I pull any of the plugs I hardly notice a change in the way it runs. Still dies when the dipstick or oil cap are removed. Could this be caused by something internally in the motor? I do have some oil seeping from the oil cap as well as some around the headers. I am just thinking that the motor is getting a little tired and needs to be partially rebuilt. What do you all think? I am still pretty new to Alfas, and car maintenance in general. This is the first multiple cylinder 4 stroke I have ever touched. I have restored Vespas for about 11 years though, and that is helping me through this adventure.
 

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A few weeks ago my car was running poorly, I heard clicking sounds as if they were coming from the water pump. I drove to work about 30 miles then on the way back the car lost power and stalled ( I was able to pull up to the breakdown lane) car would not restart was towed home. The next morning the cr RESTARTED and was driven inside my garage. when I inspected the cap and rotor the rotor arm was completely burned off to the stud!!!

So check your cap and rotor.

question for the forum - How in the heck was I able to restart the car and drive it inside the garage with a burned out rotor? ir seemed to run fine.

what caused the totor to burn like that, moisture from the rain?
 

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I've accidentaly left the wiring plug off the AFM after other maintenance and had the car run real bad...as you would expect. It would run, but want to stall at every stop sign and miss under acceleration.

Check that wiring connection...good luck!
 

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Check all the stuff in the L-jet diagnosis page (link below).

Test the AAV - it is supposed to be open when the engine is cold (to allow air past the throttle for 'fast idle') and then close as it warms up.
I agree, I had problems with mine last year, went thru the diagnostics and now the car runs great. All vacumn hoses looked good...but they leaked.
Also, do a complete tune-up, new wires, plugs, check timing. I've replaced spark plugs and had new ones fail on me many times in the past few decades! :)
 

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Discussion Starter #12
Thanks for all the info guys. The L-jet page is great. I am a teacher and you guys just gave me a lot of things to keep my free time occupied. Can't wait to dive in there!

I drove it to work today and it ran fairly well. Low RPMs are still a little rough. It takes a bit for the RPM's to get up there.

Any good source for how to do a "complete tune up?" I have never done one on any car, ever. Scooters don't really need tune ups. No distributor, one cylinder, etc. I am sure I can do it if I have a good guide.
 

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Any good source for how to do a "complete tune up?"

I am sure I can do it if I have a good guide.
For our L-jet cars, a 'good tune-up' would mean checking all the items in the L-jet page and installing a new cap/rotor/wires/spark plugs and possibly a new oxygen sensor. Set the ignition timing per the L-jet article's instructions - the computer takes over from there.

The computer needs a valid signal from the 02 sensor to adjust the fuel mixture. An O2 sensor typically lasts 30,000 to 60,000 miles. If/when it fails the computer defaults to a slightly richer than ideal mixture. The car will run but not as well (efficiently) as with a functioning O2 sensor. And a rich mixture is not good for the catalytic converter.
 

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Discussion Starter #14
I originally had trouble getting the car to pass the Arizona emissions test when I first purchased it. I replaced the O2 sensor then. This was in the summer, so I think I am good as far as that goes. I ordered a set of hoses and plan to dig into the car on my Xmas holiday. I will let you all know how it goes. Should I just get the plugs, plug wires, rotor, and cap from IAP? Do you have any recommendations for me as to what brand to buy, etc.
 

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Our Spider seems to like the Lodge spark plugs the best. Others will likely have different favorites. Lodge spark plugs are available at IAP (& other suppliers) along with cap & rotor. Go to the 'anything about Alfa Romeos' section for the suppliers thread for a list of A-R part suppliers.

I bought a set of spark plug wires from Advance Auto Parts (chain auto parts store). They list two sets - one (the higher priced) includes the resistor ends, another (lower priced) does not. Their price was a lot less than the sets from IAP (& others).

Be sure you get cap & rotor from the same manufacture. It is possible for parts from different sources to not be combatible.

For the ultimate in Spider vacuum hoses click here.
 

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For our L-jet cars, a 'good tune-up' would mean checking all the items in the L-jet page and installing a new cap/rotor/wires/spark plugs and possibly a new oxygen sensor.
I should add that new air & fuel filters would be part of a good 'tune-up'.

Also checking valve clearances, cam timing and timing chain tension. (Thus a new cam cover gasket is advised, too.) Adjusting valve clearances is a bit more work as it involves moving the camshaft aside to R/R a shim under the valve 'bucket'. But certainly checking valve clearances should be part of your routine maintenance.
 

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Interesting, my Spider has/had the same problem. #4 would stop firing after the engine warmed up. Just curious, have you checked compression? It's about 7 to 10 PSI lower than the other cylinders on mine, dunno if this is related to the no-fire problem or not. The car had fresh Bosch plugs when I got it, I've also cleaned the rotor and cap (just got a new cap which I'll install soon) though they looked good, checked/set ignition timing, replaced plug wires, but the problem persisted. It too was getting a spark, and fuel. But, as I've been doing wiring work and a few other (probably unrelated) things, the few short times I've run the car #4 has not failed. I've let it warm up pretty good too.....I'm pretty sure whoever worked on the car previously had the coil wired backwards though, which would reduce spark voltage. Perhaps that was my problem.

I found a few small air leaks and fixed them....still not 100% sure I got everything, so I'll probably order new hoses soon.
 

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Eric ...

This is somewhat unrelated but your comment that the O2 sensor is only good for 30K - 60K miles peaked my interest. I have a 90's graduate with approx. 95K miles. Since I bought the car I have been getting intermitment ECU air leak codes (the CE light comes on ... I goose the gas ... and it goes out ... etc.) I have replaced most of the hoses and have smoke tested the car. NO AIR LEAK. I put a DVM on the O2 sensor and it appears to be regulating the voltage as designed.

Question ... Other than a DVM is there another way I can check to see if it is working?
 

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Once warmed up if the O2 sensor shows a voltage signal that varies a bit but averages about .4-.5V at idle and about .9V at 2,000 - 3,000 rpms it is likely working OK. Note the signal must vary: .2, .6, .3, .5, .7, .4, etc - not a steady reading.

If it gives a steady signal (or no reading), it is likely not working.

I'm not sure but it is possible the O2 sensor in your model might be longer lasting. It should have the built-in heater to get up to working temp sooner and maybe that helps them last longer, too.

Anyway for the $30-$50 cost of a new O2 sensor it seems worth making it a part of routine maintenance/replacement. A faulty O2 sensor will both waste fuel and could pollute the catalytic converter.
 

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Discussion Starter #20
So, I guess I pushed it too far. The car died on me tonight. I cranked and cranked it and nothing. When it died it just lost power and the motor wound down. I put gas in it hoping that was the problem. Nope! I don't know what it is.....any ideas based on my previous posts? I am hoping it isn't the fuel pumps or a compression related issue because I don't know if I can fix those problems. Any help would be appreciated.
 
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