More gremlins !.... Need help PLEASE!

[Daryl]

And the hits just keep coming!....

1. Tach is all over the place! I started noticing that the needle is registering inaccurately. Seems ok at rest/idle but is random otherwise; and
2. When slowing to a stop the rpm’s don’t dump down very quickly to idle even when I put it in neutral. They kind of stay revved up for a bit. Could this be the IAC? (Hope so because I have a replacement ordered already)
Or, could it be a throttle body issue; ECU?; or ???

 

[ttocs]

what throttle body is on the car?

 

[Daryl]

what throttle body is on the car?

BBK 75mm

 

[Daryl]

BBK 75mm

I do have some of the forward tubing and air filter elements off right now while I wrestle with remedying that concoction!

 

[evilcw311]

Iac is a huge culprit of this but so is a vacuum leak. Easiest way to check for a vacuum leak is a smoke test.


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[Daryl]

Iac is a huge culprit of this but so is a vacuum leak. Easiest way to check for a vacuum leak is a smoke test.


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Heard of it. Never done it. How do you do a smoke test?

 

[evilcw311]

Heard of it. Never done it. How do you do a smoke test?

Buy a cigar and smoke it. [emoji38]

You pull a vacuum line, brake booster is good to use. Then blow smoke through it. Watch for smoke to escape anywhere. Hence, smoke test.


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[Daryl]

I can do that! Haven’t had a stogie in a while.

 

[evilcw311]

I can do that! Haven’t had a stogie in a while.

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[Chip66]

And the hits just keep coming!....

1. Tach is all over the place! I started noticing that the needle is registering inaccurately. Seems ok at rest/idle but is random otherwise; and

I'd say this is the ignition pickup which is where the signal from the tach originates.

Engine RPM is never all over the place. It revs up and coasts down.

 

[Daryl]

Sounds very possible, Chip. Where is the ignition pickup located?

 

[Chip66]

In the distributor. You have to remove the distributor and dismantle it to replace the pickup. This will require removing two roll pins and pressing the gear off and on. Just make sure you don't put the gear on 180 degrees off.

It is possible to do this fix without even getting out a timing light. Make sure you keep track of where the rotor is pointed exactly before you pull the distributor. The distributor also has a small indent on the bottom that will be lined up if the timing has never been adjusted.

Or you can simply buy a replacement distributor.

I'd definitely do this before the IAC. The IAC won't make the tach erratic. The pick-up will.

 

[Daryl]

In the distributor. You have to remove the distributor and dismantle it to replace the pickup. This will require removing two roll pins and pressing the gear off and on. Just make sure you don't put the gear on 180 degrees off.

It is possible to do this fix without even getting out a timing light. Make sure you keep track of where the rotor is pointed exactly before you pull the distributor. The distributor also has a small indent on the bottom that will be lined up if the timing has never been adjusted.

Or you can simply buy a replacement distributor.

I'd definitely do this before the IAC. The IAC won't make the tach erratic. The pick-up will.

It’s a brand new distributor, but I haven’t driven it yet. I noticed the erratic tach prior.