Well, as long as we are wipping the dead horse, I believe the most likely bad thing to happen when measuring ANY circuit with a meter is to fat finger a probe and short something (not that I have ever done that-right!). And to Jima's point, you should nver (and I hate that word) measure resistance while the circuit in question is powered from elsewhwere. First, the measurement is not likely to be correct since the "extra" voltage will cover up what jim described. And, you are more likely to introduce a voltage or load somewhere it is not supposed to be. So resitance checks for dead circuits and voltage tests for live circuits.
AND, as jim described, a scope is still a damned valuable test instrument when analyzing electronic control circuits. For automotive purposes, pretty good ones are available for less than $1000. The only problem versus code scanning is the one I mentioned earlier, which is shorting a circuit under test. I have found that "Vampire test clips" and pins used the same way is the most effective and safest way to get to the circuit under test. To get an ides of some things you can find with a scope (even if you don't buy their scope), see picoscope.com > automotive > library. I have NO affiliation and do not even use their scope, but they have great info.

 

Hi Guys,
Thanks for all your help. Depending on weather will be getting started on some of your ideas. I did disconnect the air temp sensor just for grins and car went into "restricted performance" mode but seems to have cured the lurching and misfires. Rough idle still.
I don't know yet if the air temp sensor is the problem but will test it this evening. Since disconnecting that sensor improved performance, I hope that is the problem but am concerned the restricted performance mode may be masking another problem.
Will keep you updated depending on the weather.

 

I must apologize if I'm unclear, but I was referring to the IAT as a thermistor and not O2 sensor which actually produce electricity as it gets warmer and you wouldn't use an ohm meter to check for voltage anyway. One also wouldn't test for continuity when there's voltage going through anyway.
However I'm against using any kind of a vampire clip to pierce any wiring leading back to an ECU, this could potentially corrode and give false reading back to the ECU.
When the CEL lights up the system goes to base, such as base timing, base fuel delivery etc and this could, as Ross mentioned could hide some performance issues. It is best to reset the CEL and see if you're getting the same codes the second time around.

Alan.

 

Hey Jim,

Just jacked the car up to get to the O2 sensors and could not get my hand nor tolls near them, it is so tight. Anyone know the trick to accessing them?

Thanks,
Ken

 

Finally some warm weather. I found a good tip on the forum here and switched the connectors above the tranny which go to the O2 sensors. Code 1646 did not appear so am ruling out O2 sensors.
BUT, several new codes appeared,
P0303
P0313
P300
P0102
P1326
P1637
P1316
Checked plugs on cylinder 3(both sides) and did not seem fouled. Still running rough especially when cold.
I will switch coils and see if that changes the cylinder misfire number. Aoto Zone guys says to smoke check vacuum system with so many codes.
Any other ideas?
Cheers,
Ken

 

Ken:
With all of your various codes, I suggest you need to really diagnose the problem rather than going on a parts changing mission. That said, your MAF code suggests you should clean the MAF sensor.
Other than that, I suggest you either buy or borrow a scanner that can chart the o2 sensors, the temp sensors and so on. And a scope wouldn't be bad, either. If you aren't interested in that, this might be a case where you should have someone scan it for you.

 

Yep, that's actually what I meant but didn't explain too well. No need to mess around removing sensors when you can just switch the plugs around.

You did switch the sensors back over once you determined you had no P1646, yes? They can't stay permanently crossed.

Jim

 

Hi Jim,

I was planning to but wanted to drive a bit and rescan. Thanks for reminding though.
Cheers
Ken

 

Hey Everyone,
I want to give a great round of appaluse to those who have been so diligently trying to assist me.
Went out tonight and did the propane test for vacuum leaks but could not get the engine to rev even sticking the propane into the air intake. Then listened and taped a hose from the valve cover which may have had a small leak
Though I cleaned before with injector cleaner, I took the MAS off and throughly soaked and cleaned in alcohol as someone here suggested.
WaaLaa!! My kitty screams again!
Again, just an old fart who has been hit by the Great Reccession and could not afford what I used to.
Thanks so much, I am deeply grateful!

 

Glad you got it sorted, Ken! Happy motoring