tune up tach meter wandering - long post

Keep it on topic, it will make it easier to find what you need.
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gandyrail
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Your car is a: 1981 2000

tune up tach meter wandering - long post

Post by gandyrail »

What is making my autometer tach jump around from 640RPM to 760RPM no matter what plug wire I am hooked to.
I have a 81 FI 2000 with about 100K miles; I got this project in August last year, it was not running well. I had issues until I cut out the bad cat, duh :roll: . I have replaced: exhaust cambox gasket, TBelt, waterpump, thermostat, all hoses in engine compartment, engine breather hose, the short 90D hose by oil filter, cleaned all the crap out of slobber chamber, ugg; installed a new vapor canister, cleaned all grounds, new plugs, wires, rotor, fuel filter, air filter, new tps, new ignition control module, resealed dizzy, replaced the pickup and then melted the wire on hot exhaust (oops); so running the old one; (no cracks in wires, the white wire is stiff w scuffs so will replace again soon) Have 37 psi fuel pressure after the pump. Havn't checked vac pressure or addressed the injectors. Cleaned the AuxAirReg, but I suspect it. :?:
I can't idle until the car warms up. Car starts nice, idles about 760RPM when warmed up; 780 by dash tach-- but my tune up tack is without steady reading longer than a second thats not right it reads good on other cars--
My AFM is spotless inside, the adjustment plug was removed .. I get a noticeable increase in idle speed by turning the screw about a 1/4 turn clockwise, so I turned it to the fastest idle and left it there. I have new Oring on idle adjustment. Wont change the O2 senser until I get running good .. I think I'm close
Any thoughts about next step would be appreciated.. I am thinking injector seals is the issue?
76was124
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Your car is a: 1981 Spider 2000
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Re: tune up tach meter wandering - long post

Post by 76was124 »

gandyrail wrote:What is making my autometer tach jump around from 640RPM to 760RPM no matter what plug wire I am hooked to.
Are you saying it continuously bounces or it ocassionaly jumps? If ocassionaly jumps does the idle change or do you hear a missing?

Regarding the bad idle at cold, the first thing I would check is AAV. Search the forum for ways to test / adjust the opening/ closing. You could pinch the hose closed to see if idle drops further when cold, or put a by-pass hose around it as a test and see if it idles well until warm-up. Did you check the temp sensor readings on the coolant T at the intake?
Current 81 Spider 2000
Previous 76 Spider
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RRoller123
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Re: tune up tach meter wandering - long post

Post by RRoller123 »

+1 on the AAV.
'80 FI Spider 2000
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GeorgeT
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Re: tune up tach meter wandering - long post

Post by GeorgeT »

Check the pickup wires under the distributor plate for fraying. Frayed wires are a common problem that could cause the tach issue you have.
gandyrail
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Re: tune up tach meter wandering - long post

Post by gandyrail »

Thanks for reading my ramble guys
wanders continously no noticable miss
pulled 2 and 3 plug and looked good but only got 50 mile on them
wires under dizzy good
coolent sensor at tee checks out, both at tee and at ecu
HAve to go to work now anther day for a buck
Play a bit tonight
76was124
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Re: tune up tach meter wandering - long post

Post by 76was124 »

Did you properly gap the pickup sensor in the distributor when you changed it?
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gandyrail
Posts: 47
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Re: tune up tach meter wandering - long post

Post by gandyrail »

yep used a sliver cut off a box that I micro-measured having correct thickness.
I had issue for a while the magnet was not marked and I put it in upside down - that don't work well.
I will check gap again in case it moved, if it did it might be to tight. It's probably OK don't know why it would change unless I did not get screws tight :roll:
I noticed some fuel damp spots on the tops of a couple of injector hose connections ... So going to fuel rail with new hose and O-rings Its on the to do list anyway and it cant hurt.
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