My tach seems to ratchet up and plateau some through the RPM's when I slowly rev the engine in park. What could make it do this? Also, I have replaced the pickup coil in the distributor and this had no effect. Isn't that where the tach signal originates? Thanks guys.

 

Have you replaced your wires with Solid core wires?I put a set of solid core wires on my car and it did exactly what your saying.The wires create a magnetic field by the firewall that screws with the tach signal at the distributor.

 

Ahhh...It very well could be those Accel 300+ Race wires under the hood. Hell, come to think of it that may have something to do with my slightly rough idle too because I don't remember when that started but it could have been after the new wires this past summer. Think I should get rid of those wires and put some Delcos back in? Or maybe MSD, Moroso or Holley or whatever? Thanks for the help. I'm not much of an electrician.

 

BTT

 

Had same problem, I just moved the wires as far away from each other as I could, espeically from all the ignition control wires and it fixed the problem. Then again I have a stock coil, sounds like you may not.

 

I have the Accel GM coil, but it didn't seem to make a bit of difference when I put it on. Thanks for the suggestion about getting the wires away from the ignition control wires, I'll try that and see if it helps. If not, perhaps it's time to go back to Delco parts.

 

do you pick up any ignition noise on your radio?


ODB

 

Hey ODB! No, I don't, that's why I didn't think the wires could be a problem. Can they still cause electrical gremlins without some RFI? Thanks.

 

make sure all your wires are on tight, one a mine came loose once, tach jumped around....

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1986 Trans Am
305 TPI
"If it's not one thing, it's another!"
http://www2.hanover.edu/hierlmeier

 

The accel wires are suppresion so i'd doubt they are the culprit unless they're routed differently. I would say its the tach or wiring to it (grounds). If it runs fine the pickup isn't the prob. The signal comes from the - coil wire in the dual pack connector... I'd say it's the tach itself.

 

The accel wires are suppresion so i'd doubt they are the culprit (RMI/EMI wise) unless they're routed differently. I would say its the tach or wiring to it (grounds). The signal comes from the - coil wire in the dual pack connector... Check your wires anyway, pesonally I think the accel wires are the shi//iest wires made (from experience: boots pulling off, mis-fires, high resistances when bending them (after 3 months of use)) If new wires don't solve the prob and you say you changed the pickup, maybe the module is wounded. If everything checks out I would say the tach is bad. The tach output is totally independent and its mal-operation will not effect anything. Try hooking up a under hood test tach. If the readings are screwy than the module is bad.