trouble revving over 4,000rpm - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 6 (permalink) Old 04-16-2014, 05:40 PM Thread Starter
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trouble revving over 4,000rpm

89 Alfa Spider Ljetronic having trouble revving over 4,000 rpms when driving...bogs as well between first and second....any idea where to look?....also, oil pressure gauge reads low on idle but normalizes when driving...should I be concerned about oil pressure sensor or gauge or am I looking at a bad oil pump?
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post #2 of 6 (permalink) Old 04-18-2014, 05:32 AM
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It is 'normal' for the oil pressure gauge to read low with warm oil at idle. If you connect a mechanical gauge it'd read a more reasonable pressure under those condition - don't worry about it.

As for the revving, first check the tach. They are also known to not be very accurate. If it is really the engine that won't rev to redline then start by going through the L-jet Diagnosis page. Check especially for intake air or vacuum leaks. L-jet is very intolerant of 'false air' (the L stands for Luft - German for air).

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post #3 of 6 (permalink) Old 04-18-2014, 05:52 AM
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Most likely its a air leak around the rubber crossover tube that occurs when the engine torque leans the motor to the passenger side.

Tubes get hard with age, and the passenger side motor mount sags with time and use. You should replace both, but as a test wrap both ends of the tube with duct tape which will temporarily stop the leaks.

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post #4 of 6 (permalink) Old 04-18-2014, 07:42 AM Thread Starter
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I had covered all of the leaks mentioned in the diagnosis.I think I am having issues with the AAV valve.I am trying to get to work properly when engine is cold..completely bogged out when cold.also negative on the battery is loose and I am about to fix that as well
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post #5 of 6 (permalink) Old 04-18-2014, 08:27 AM
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The AAV provides air to bypass the throttle plate - the intent is to increase the cold idle. I don't think a faulty AAV would cause the symptoms you describe.

Definately fix the battery cables (clean & secure all of them while you are at it).

As Richard advises, engine torque can open up a small split in the air duct that crosses over the engine. This messes up the Air Flow Meter's calculations for fuel. It does not take a large leak to mess up the L-jet system.

L-jet is a system - all the bits have to work for it to work right. Go through all the checks in the L-jet diagnosis page to get it working properly.

- - Eric
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post #6 of 6 (permalink) Old 04-18-2014, 08:29 AM
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Quote:
Originally Posted by ghnl View Post
As for the revving, first check the tach. They are also known to not be very accurate.
This. For an '89 Spider, if the tach has never been adjusted I can almost guarantee it's reading low.

Tom

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1974 GTV
1991 Spider
Former: 1987 Milano Gold
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