'82 Spider - car can't get above idle. Nearing my diagnostic wits end. - Alfa Romeo Bulletin Board & Forums
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post #1 of 33 (permalink) Old 06-01-2019, 10:39 AM Thread Starter
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'82 Spider - car can't get above idle. Nearing my diagnostic wits end.

Hi All,

I've been trying to resuscitate this Spider for the past few weekends. It's a 1982 with L-jet. I took a weekend trip in the car, and on the morning of the second day, the car started to bog down badly a couple minutes after starting off. It wouldn't rev above ~1500 rpm. The car would just cut out. It will rev up on a cold start, but after 2 minutes, the car resumes its behavior. It ended up on a tow truck home.

I started down the L-jet diagnostic path, and am now a bit stymied. Here's what's all been checked:

We measured fuel pressure at the rail - 36 psi with regulator disconnected, less with it connected - exactly within spec.
Chased potential vacuum leaks and checked hoses.
Went through the grounds - cleaned, checked, and sandpapered all of them.
Replaced injector seals - even replaced the injectors while in there.
Opened up the AFM, checked and tested it. Traces looked good. Ran the car with it disconnected. No fix.
Checked & replaced spark plugs
Disconnected the exhaust at the manifold and ran the car to see if the cat was plugged. Same issue with open exhaust.


The car will still rev up for the first minute or two until she warms up. Then no go. This seems like a good clue - but I haven't been able to figure out what to do with it. Any idea where to head from here?

Thanks guys!
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post #2 of 33 (permalink) Old 06-01-2019, 10:53 AM
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You said the car say for a while. I would start with checking the fuel pump and see if it's clogged. Check the gas tank for any rust that may be contributing to a clogged fuel pump.
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post #3 of 33 (permalink) Old 06-01-2019, 11:42 AM
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fuel filter could be bad......easy and cheap to replace and worth doing even if it is not the problem!

if problem occurs only when engine starts to warm up, I'd be looking at the cold start side of things

for instance, does the cold start injector (CSI) stop spraying when it starts warming up?
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Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #4 of 33 (permalink) Old 06-01-2019, 11:43 AM Thread Starter
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It's getting full fuel pressure at the fuel rail - I'm hoping that rules out issues with fuel delivery Could a pump or filter cause this issue but still read full pressure?

Last edited by caliautobahn; 06-01-2019 at 12:17 PM.
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post #5 of 33 (permalink) Old 06-01-2019, 01:30 PM
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Quote:
Originally Posted by spiderserie4 View Post
If problem occurs only when engine starts to warm up, I'd be looking at the cold start side of things

for instance, does the cold start injector (CSI) stop spraying when it starts warming up?
I agree, also check the Aux Air Valve.

I am personally a fan of pulling the dipstick out far enough to break the seal, and checking for a 300RPM drop in idle speed (for a warm engine). If the RPM drops, the integrity of your vacuum system is good.
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-Kevin
1988 Spider Veloce (with lots of 3D printed parts)
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post #6 of 33 (permalink) Old 06-01-2019, 01:58 PM
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I'm leaning toward the AAV or a vacuum leak too. The dipstick trick works well and I have found a stethoscope finds vacuum leaks pretty readily.
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post #7 of 33 (permalink) Old 06-01-2019, 01:58 PM
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Check ohms at the coolant temperature sender.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #8 of 33 (permalink) Old 06-01-2019, 03:23 PM
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The AAV admits a small amount of air relative to the throttle and it is unlikely to be the culprit. If the cold start injector was spraying continuously then it would make the engine die at low rpm but would run better at large throttle openings. I would suspect the fuel filter or fuel pump first. What happens to the fuel pressure when you rev the engine?

If fuel pressure holds up then the ignition system could be the problem. Both the ignition module and the coil can fail as they heat up.

Ed Prytherch
79 Spider
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76 Suzuki GT500
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A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #9 of 33 (permalink) Old 06-01-2019, 07:44 PM
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Be 150% certain the main air duct across the top of the engine had no leaks. Splits in the accordian section will open up randomly and cause grief. All air entering the engine must pass through the AFM (air flow meter) for the computer to know how much fuel to inject.

- - Eric
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post #10 of 33 (permalink) Old 06-02-2019, 02:38 PM Thread Starter
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Ok, interesting development. Hooked up the fuel pressure tester and a vacuum gauge to the car. It'll run 36 PSI without dropping (with the vacuum for the fuel pressure regulator removed). Even when revved. It pulls about 10 inches of vacuum at idle.

BUT! When testing the cold revs to about 3000-4000 rpm cold, waiting for the point where the engine would die with heat - it rattled from the cats and then blew out a bunch of gold-metallic flecks, and a couple chunks of catalyst.

I could swear a couple weekends ago it was still bogging with the exhaust manifold dropped/open. Next step is to drop the exhaust manifold and run it open - I think.
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post #11 of 33 (permalink) Old 06-02-2019, 02:42 PM
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Quote:
Originally Posted by caliautobahn View Post
It's getting full fuel pressure at the fuel rail - I'm hoping that rules out issues with fuel delivery Could a pump or filter cause this issue but still read full pressure?
Pressure is not the same as volume

The older I get.. the faster I was....
Tom
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post #12 of 33 (permalink) Old 06-02-2019, 02:53 PM
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Yikes. Cat converters don't melt on their own: that's caused by rich running. My guess is that that's a symptom, not a cause. Something is likely causing very rich running and that's why it won't rev and it melted your cat.

Did you check the coolant temperature sensor resistance yet? If that goes bad it'll run really rich. Should be 2000-3000 Ohms at room temperature, 250-400 with a hot engine. Instructions here:

https://www.hpsimotorsports.com/l-jetronic--spider-

Also check your vacuum line to the fuel pressure regulator for any traces of fuel. If the FPR diaphragm fails it'll dump raw fuel right into the engine through that line.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #13 of 33 (permalink) Old 06-02-2019, 03:27 PM Thread Starter
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CTS tested - in spec - just shy of 2000 ohms at 85 degrees.

FPR line doesn't seem to be ingesting fuel - no smell right after running.
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post #14 of 33 (permalink) Old 06-02-2019, 03:31 PM Thread Starter
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Plugs look fine - just to the lighter side of milk chocolate. Thinking since the cat is dead anyways and it's the only wonky thing I've found - might cut a scallop out of the exhaust right before the cat and see if that opens her up.
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post #15 of 33 (permalink) Old 06-02-2019, 04:30 PM
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Your cat was probably just old; they do this eventually. I had one do this but not as bad as yours- it was an 83 BMW 4cyl. It just bogged and lacked any power for a while. You need a new downpipe/cat. I found one for about $200 on Ebay in '15, but they are way more expensive now. You can always take it to a muffler shop and have them weld in a new cat for you, generic.

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