91 Toyota Camry: Where do I make connections to test engine rpm?

I have a 91 Camry LE. I am trying to diagnose a possible problem cylinder by grounding out spark plug wires one at a time. Here are my questions about this procedure:

  1. Where do I connect my Sears auto tester (which measures engine rpm)? It is a basic tester which has two leads for this purpose

  1. How do I ground out each plug wire so I do not cause damage to me or the sensitive distributor components?

Your thoughts on this would be appreciated.

Al Kondo

Reply to
Al Kondo
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A couple questions need to be asked before we can answer yours.

#1. Are these leads labeled in any fashion? If they are, what are those labels? If it's a basic tester, I would assume it would only have 1 lead or

3 leads if you're talking about power and ground.

#2. What or who told you you need to ground out plug wires? What are you trying to accomplish by grounding them out?

-Bruce

Reply to
Bruce Chang

If this an an old Sears tach, dwell., rpm tester.Do not hook it up to a plug wire. If you are tring to see if you are getting spark to a plug, hook a timing light to the wire. If you are tring to find a dead cylinder, pull the plugs one at a time and look. The plug in the malfunctioning cylinder wll look different. What are you trying to do anyway ?

Reply to
TOLYN9

This is in reply to the earlier postings about my problem. I figured out how to use the tach tester to determine the rpm's on my engine. With respect to why I need to ground out the spark plug wires.... The reason I thought that I would need to do this is because I read a posting that if I pulled the wires without doing this I could damage the distributor. I am trying to determine which cylinder is affected by disabling it by pulling the spark plug wire. I hope to determine the "bad" cylinder by observing which one has the least drop in engine rpm's when the plug wire is removed. With this said... Does it make sense to ground out the spark plug wire?

Thanks, Al Kondo

Reply to
Al Kondo

Yes it does.

An easy method taught for distributorless ignition (works on distributor types also) is to install a 3" length of 3/16" vacuum hose* between the sparklug terminal and the plug wire terminal, then with the engine running, use a 12 volt test lamp connected to ground to short out each cylinder momentarily, record any resulting RPM drop. Make sure you disable any automatic idle speed controls that may be present to avoid the PCM effecting the outcome of the test, disconnecting the O2 sensor may also be recommended as it too can cause the PCM to compensate. (sometimes it matters, sometimes it doesn't)

  • vacuum hose will conduct the HV secondary quite nicely.
Reply to
Neil Nelson

In a recent posting by Neil in this thread, he suggested that I use a hose to connect the spark plug and plug wire. He further suggested that I could ground the connection with a test light to ground out the spark plug. I have a problem with this procedure in my Camry because is has a deep recessed spark plug and the plug wire ends in a 5 - 6" plastic connector. In other words, it would be very difficult to connect the plug to plug wire with a hose as you suggested. Is there another way of doing this procedure? Could I just ground the plug wire to some point on the engine?

Al Kondo

Reply to
Al Kondo

If you insist on doing this, you need a tach with an 'inductive pickup' lead. This goes around a spark plug wire and senses the current going through the wire by it's change in the electric field rather than needing metal to metal contact.

What's the problem you're try>In a recent posting by Neil in this thread, he suggested that I use a

Reply to
Bob Hetzel

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