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Discussion Starter #1
Hello fellow Alfa Owners! This is my first post here.
I just recently picked up a pretty nice 91 Spider. I've been driving her daily, so I've named her Daly Dryver.
Anyway, I replaced the thermostat o-ring last week, and after I buttoned her up, I went to take a drive and she protested!
She starts easily, purrs like a kitten at idle, but when the accelerator is depressed, she surges and will not speed up past 1500 RPM. It manifests as an engine oscillation frequency of 1 second, or about 60 surges a minute. The engine surge RPM change is about 700.
It doesn't matter how far the throttle is open - part way or all the way. She sounds different at the different throttle openings, due to the size of the opening. The oscillation frequency remains the same. The RPM change remains the same. She does this with the air cleaner duct in or out. I've looked for something obvious that I might have inadvertently disconnected, but have found nothing. While I had her down, I did take the air filter housing off because it needed repair. I did some cleaning while I was down there.
I thought it might have been the gas filter, but I changed that out, and no change.
The OBD (On Board Diagnostic) shows no faults. Code 4444
I've got the CarDisc DVD and and haven't found anything on it.
The ride is stock, no alterations.
Somebody help me here, please.
Usually I am the guy people ask for help on cars, but this one has me bewildered....just like a woman!:hammer:
 

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But Mad North-Northwest
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Most likely you've introduced an air leak somewhere. Check for any disconnected hoses, or tears in the big rubber hose across the engine.
 

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I did take the air filter housing off because it needed repair.
Did you plug the MAF back in when you re installed the air filter housing?

Good luck,

Vin
 

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Discussion Starter #4
Hi, Guys.
I checked and rechecked the only two sensors in the area for the system, took it all apart, put it all back together, and now She works!
I have no idea what was jacked, but we're back on the road.
Thank you for the advice.

David
 

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Discussion Starter #5
Hello All,
The two sensors that I unplugged and re-plugged are the "engine coolant temperature sensor" and the "air flow meter" which also contains the "intaken air temperature sensor" within the same plug connector. I didn't see anything wrong with either.
I will note, that I investigated under the distributor cap and plug wires as well, but saw nothing there.
The ignition wasn't missing out, so I didn't think I would find anything there anyway.
I can't say that I am providing any real value here, but I am happy that we're back on the road!

I will tell you, while I had the air filter out, I found that I needed a new element. I ordered a K&N element for $64 dollars, US, and thought I was getting reamed. When I got the element, I found that it is a LIFETIME filter element, very well made, cotton, not paper, washable, with steel screen on either side, reversible, intended to last the life of the car.......
I'd say it's worth the extra money.

David
 

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Discussion Starter #6
Hello All,
The two sensors that I unplugged and re-plugged are the "engine coolant temperature sensor" and the "air flow meter" which also contains the "intaken air temperature sensor" within the same plug connector. I didn't see anything wrong with either.
I will note, that I investigated under the distributor cap and plug wires as well, but saw nothing there.
The ignition wasn't missing out, so I didn't think I would find anything there anyway.
I can't say that I am providing any real value here, but I am happy that we're back on the road!

I will tell you, while I had the air filter out, I found that I needed a new element. I ordered a K&N element for $64 dollars, US, and thought I was getting reamed. When I got the element, I found that it is a LIFETIME filter element, very well made, cotton, not paper, washable, with steel screen on either side, reversible, intended to last the life of the car.......
I'd say it's worth the extra money.

David
 

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But Mad North-Northwest
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Check that the AFM plug pins are okay and that it's seated properly. I've heard of the pins getting pressed into the connector so they don't make contact properly.
 

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Discussion Starter #8
Tom, I looked pretty closely at those connections, especially the AFM connector, and I honestly could see no fault with it. They are clean, undamaged, good continuity. I'm still baffled. It is a mystery. Daly runs great now. She loves me again!
Now that I have the CarDisc DVD, I'll be able to find test parameters for the different sensors...........................if I live long enough. I must say, I can find stuff a lot quicker in the "Old fashioned "slow, obsolete, hard copy media" than the "superior digital format"! I'm just an Old School kind of guy.

David
 

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Discussion Starter #9
Greetings, Gents and Ladies,
I felt I should update my issue of my surging problem. The problem arose two more times since I last posted.
Turns out that the cause of the problem was totally disassociated with what I was dinking around with to start with.
It was another case of something else jacking after you fix something totally unrelated to it.
This happens to folks that work on cars a lot. Pure coincidence, but causes severe head scratching.
I traced it to a defective secondary fuel pump. The high pressure unit located under the passenger side of the car. The unit had NO pressure but the primary pump in the tank gave enough pressure to start and/or limp home.
I'm surprised, really, that no one else had experienced this behavior with their cars.
It was an easy fix. So, I'm looking at this new pump trying to figure out which lead goes where, and notice that the terminals are different sized. The guys that put these cars together are amazing!

David
 

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Unless I'm mistaken, failure of the the high pressure fuel pump (or it's control system), characteristically results in a "no start" situation on FI Alfas.
 

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Discussion Starter #11
Hello Steve,

You may be correct that the characteristic behavior of the fuel injected S4 Alfas is a "no start" condition. It could be that I just got lucky on this one.
The last time it failed I was 6 miles from the house and I was able to drive home. I could get her up to about 45 MPH. She would always start, like nothing was wrong, but would surge when the throttle was opened. The failure has been intermittent. I've had intermittent problems on other cars (unAlfas) where the fuel pump (electric) was going bad.
During operation, I could detect the pump relays operating. I tested the pump terminals for power, and the relays are working properly. The pump ran when wired directly to power. When it ran though, it didn't act as if it was loaded, like it was making pressure.
I put a pressure gauge on the pump and pressure was zero.
Since I've changed the pump, I've noticed an increase in power. She runs better.
Perhaps other owners can weigh in on this. I have not found any reference of a "limp home" feature of the system in the Shop Manual. Like I said, I might have just been lucky.
I'm 100% confident that the fuel pump was the culprit. Once I got the old pump out and started messing around with it, it is definitely faulty.

Thank you for your input.

David
 
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