Electrically problems???

[Steve Brown]

I just recently purchased a 91 Spider and have a couple of problems.
The speedo rests at 10 mph not zero. It seems like it is reasonably accurate above 10 mph. Minor issue but it would be nice to correct.
The tach doesn't appear to be accurate. It seems to read on the low side. At 70 mph, in 5th gear it reads below 2k rpms and I haven't gotten it to read above 3k
A few days ago the tach won't register above 1100-1200 rpm and the engine began reving up on it's own, pulsing for a 30-60 seconds and then it would stop. It did this a number of times both under power and at stop lights
Could these related issues? Any ideas.
Thanks
Steve

[DaveC]

No idea about the tach. However, the speedo is correct. Alfa, for some reason, put the speedo arm stop pins at 10 mph as well as the Tach at 500 rpm.

Dave

[John M]

Hey Steve:

Welcome to the Alfabb and congrats on the new car. Check out this thread to fix your tachometer:

How to fix your slow reading speedometer or tachometer on 91-94 Spiders


Should get 1000rpms for every 22.14 mph in 5th gear.

Dave addressed the speedo peg.

As for your racing idle, I would check a few things.

1. the throttle position sensor to make sure its returning to its closed position when not depressing the gas pedal. It clicks when it hits its closed position so check it with the motor off. And the next time it does this racing, see if it can be corrected by turning the bell crank clockwise to close the TPS. Adjust the throttle linkage/cable as necessary.
2. Check all the air hoses running between the AFM and the intake for leaks, cracks, etc. Also check all the vacuum hoses running from the intake manifold to the vapor recover switch and the fuel pressure regulator.
3. Check all the electrical connections to the various sensors and AFM.
Disconnect them, fill them with dielectric grease, and reconnect them.

Finally, is your check engine light on when its doing this. If she cannot be fixed by turning the TPS to closed position, then let the car go on doing it without depressing the gas until you get a check engine light on. This will give you a code and perhaps a good direction to go with the inspections.

Best Regards,
John M

[Steve Brown]

Thanks John and Dave,
The check engine light is on periodically but proceeded the surging.
What is the AFM and are things you are recommending possible fixes for the faulty Tach readings?
Steve

[Gubi]

Quote:

Originally Posted by Steve Brown Thanks John and Dave, The check engine light is on periodically but proceeded the surging. What is the AFM and are things you are recommending possible fixes for the faulty Tach readings? Steve

[Gubi]

Heh, if I'd been thinking straight at work today, I would've just done a search. It's amazing how going home clears your head. John M already wrote out the procedure in a different post...I'll go ahead and shamelessly pillage his hard work here:

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You will need to pull the code from the ECU and reply back. Here is how you pull the code. It is flashed through the check engine light through a series of long and short flashes. Here is how to pull the code:

1. Turn the ignition key to the "on position" so that all the lights light up on the dash. Do not start the engine nor have it running.
2. Remove the access panel from your carpeted rear deck behind the passenger seat.
3. Locate the ECU button. There is a button on the outside of the steel box that the ECU sits in. The button faces the passenger side "b" pillar, the passenger side rear speaker, and seat belt retractor. Note that you will have to reach around to the outside of the steel box that the ECU sits in so have long flexible fingers or skinny ones that can fit between the carpeted deck and the top of the steel box.
4. Depress and hold the ECU button for 5 secs.
5. Release the button once the check engine light goes off.
6. The Check Engine light will flash the code.
7. Once the code is flashed (and it will repeat) you can simply turn the ignition key to the off position.

Here is how to read the code:
The check engine light flashes the code by long and short flashes.

1. The check engine light does a long flash followed by a long delay to say "here comes the code"
2. Then the individual numbers will be flashed by short flashes with a long delay between each seperate number.
3. The error code is a 4 digit code beginning in the number 1.
4. Code repeats over and over.
Here is an example:

F=Long flash
f=short flash
D=long delay
d=short delay

Error code 1234 1234

F........D.......f..D........f..d..f..D.......f..d ..f..d..f..D..........f..d..f..d..f..d..f..D...... .......F........D.......f..D........f..d..f..D.... ...f..d..f..d..f..D..........f..d..f..d..f..d..f.. D.............

So this would be read: Code 1234 Code 1234
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I'll add the following: you most likely have multiple codes stored...one for every time the light has come on. These may be the same code over and over again or they may vary. It's a good idea to go through them all and then clear the computer.

After each code flashes, you hold down the button for a couple of seconds and then release it...it will then start flashing the next code. Once you have gone through all the codes, the computer will flash 4-4-4-4. At this point you can clear the codes by holding down the button for a full ten seconds (make sure you wrote down all the other numbers first). It may take a while to get through all the codes, so be patient.

Post the codes you get here and it may give us some idea of what the problem is.

[John M]

Gubi.....that has to be the best post I have ever read.

Hey Steve:

The AFM (air flow meter) is the black/silver sensor that resides on top of the air filter housing. Its in the front driver's side of the engine compartment and has a big rubber intake hose that runs from it to another hard intake hose that goes to the intake.

Yes on the tach stuff. Mine did the same thing...as many do...and was reading low. Follow that link to the previous post where I outlined a couple of possible fixes.

And as Gubi suggested.....get those codes off the ECM located behind the passenger seat and below the carpeted deck.

You'll be up and running in no time.

Best Regards,
John M

[Steve Brown]

Thanks for the input. I will get the codes this weekend.
Have a great weekend.
Steve

[Steve Brown]

Gubi,
The only code I found was 1214. And that code continues to be stored as I rechecked the codes this morning after clearing them yesterday.
Hope this helps.
Thanks
Steve

[John M]

Hey Steve:

Its your engine temp sensor. Described perfectly in the trouble shooting manual. Eratic op when cold....normal when warmed up. I have attached a PDF file for you. Check sensor and harness and replace as necessary.

Best Regards,
John M

[Steve Brown]

Does the engine temp sensor provide input to the temp gauge? The temp guage appears to work fine. In town it runs half mark over 175 and on the highway right at 175
Could the engine temp sensor be causing the pulsing of the engine? This happens when the engine is warmed up, not cold.

Thanks
Steve

[DaveC]

John M is talking about the engine management temp sensor. There is a seperate sender for the gauge.

I wonder if their is a fight between the O2 sensor and the Temp. sensor. Temp sensor stuck in cold position, richening mixture. O2 sensor reads rich mixture, leans out mixture. (Pulse, pulse, pulse!!??)

Dave

[John M]

Hey Steve:

I am not exactly sure where that particular sensor is located. Its on the intake side of the motor...bolted into the intake and near the fuel rail and injectors. I believe its under the plastic intake tube. Should be two sensors there. The one towards the front of the engine is for your gauge. And next one going towards the back of the motor should be the one in question. 1214 indicates a reading from this sensor that is out of range. So start by checking to see if the sensor is securely connected to the harness. That may be all it is. If she is connected good and still creating this problem, get an ohm meter and follow the instructions within the PDF file above. Let us know how its coming.

Best Regards,
John M

[Steve Brown]

Thanks John,
I will check this out tonight. Not sure where to find an ohm meter, but will look around.
Steve

[Gubi]

If you're planning on keeping the Alfa, definitely spend the money and buy a good quality digital volt/ohmmeter (VOM). Don't buy a cheap one...you want one that's high impedance to prevent possibly frying circuitry. It's one of the most useful tools you can have. Also, if you haven't already done so, buy the Cardisc manuals for the car. It's the only thing more useful than this site for Alfa information.

Like John said, the sensor you're looking for is on the intake side between the two middle injectors. Can't remember if it's above or below and I'm not in a position to check (I'm in Canada right now, eh?) but it's pretty obvious...a little round plug thingy screwed into the engine with a single spade connector and wire coming off of it. You need to disconnect the black intake hoses between the air flow meter and the throttle body to really get to it effectively. I always unplug the spade connector when I check sensors so that the ECU module doesn't see any voltage from your test meter...probably not an issue if you buy a good VOM, but I'm a "suspenders and belt" type of guy.

Let us know what you find out.