86 Spider Quadrifoglio - Alfa Romeo Bulletin Board & Forums

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Old 06-25-2011, 07:51 AM
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86 Spider Quadrifoglio

I have noticed a problem with my Alfa. It only seems to happen when the engine gets hot, around 175 which is its normal running temperature. It sounds like the car is not getting either enough gas or air when I accelerate. There is also some slight jerking when going from a stand still into first and an even less but constant jerking when I am cruising at a constant speed. When this happens, the engine has a rather throaty sound during the acceleration in the 1st and 2nd gear until it gets past 2500 rpms. I have made sure that the air intake hose is tight, but have noticed some slight cracking. I am thinking about replacing that, but I am not sure where to go to get the part. My concern is that something else besides the air intake hose is causing the problem. Again, this only seems to happen with the engine is hot and when I accelerate. Any help I can get would be greatly appreciated.
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Old 06-25-2011, 08:29 AM
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My guess is that when you accelerate the engine torque reaction causes it to rock on the engine mounts pulling on the air duct and possibly opening up those cracks. The resulant 'false air' (unmetered by the Air Flow Meter) messes up with the computer's calculations for fuel injection.

Might also be a good idea to check the engine mounts. As they age & sag they let the engine rock too far and can also allow the fan to strike the shroud (ruining both) and even to bounce up & dent the hood!
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Mebane, North Carolina

L-jetronic Spider diagnosis (1982-1989)
L-jetronic V-6 diagnosis
OK injectors - fuel injector cleaning
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Old 06-29-2011, 03:17 PM
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I sealed the crack but the problem is still occurring. I noticed today that when this going on, the rpms flux between 1000 and 800 rpms. Now I don't know if its the air flow meter or something else. Any ideas would be great.

-Nate
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Old 06-29-2011, 05:24 PM
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I hate to keep mentioning this, but I just completed a rather extensive rework on the plenum side of the engine on my 88 Quad. I replaced the injectors with rebuilts with new hoses, replaced the plenum couplers, and about every hose that was on that side of the engine. One hose I repladed was dated 3 of 87. Obviously, when these cars get 20 + years on them, a lot of rubber hoses carbonize into the flexibility of hard plastic. It might be time for you to consider doing a similiar replacement of your fuel injection and vacumn hoses. I have always had a rather variable idle on this car since I aquired it last July. But now it idles like my 2010 Frontier. It is immencely more pleasureable to drive and I feel more confident about taking it out on a road trip. I am of the opinion that 20 years is about the limit on the life of rubber hoses and such.

Robert In Memphis, TN
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