Yeah I knew the volt ohm meter part. It was the "precision" part that threw me. I didn't know if he was talking about a specific, expensive kind or just any old VOM I could get at like AutoZone or Advance.

 

Hey 00AccordLX5spd, it could be possible that the particular CEL's that you have are a product of some upstream problem. With a bad IAC, my car was confused whether it is at operating temp or not. I believe that the car uses different ign & timing maps depending on engine sensor input(ie. temp, rpm, oxygen), so running on the highway at 70, with the help of air passing over the radiator could trick the vehicle into thinking that the car wasn't at operating temp, causing 02 sensor, crank position sensors to out of an excepted range. How does your temperature gauge read? Normal(good old honda, just below halfway mark on the temp gauge) or is it eradict? I have even seen 02 and crank sensors bark, over bad gas before. Are you in cold weather that uses a winter blend of fuel? Good luck man.

 

Thanks zex.
Operating temp stays constant - right below the halfway mark.
The RPM's jump around even at idle, I just used the example of being on the highway cruising at 70 to try to better explain the way the engine felt.
Speedometer seems normal too. No jumping around there either.
The only thing that is erratic on any of the gauges is the RPM.
I never use winter blend fuel either.
I don't even know if they sell the stuff here in Mississippi. Right now it is 90 outside and the humidity feels like you are in a steam room.Even in the dead ofwinter time it can get up to about 75 or 80 on any given day (then be 30 the next day)even in January!
The RPM's have been pulling this crap for quite a while now (like 2 or 3 years.) It just didn't happen as frequently as it does now and the check engine light didn't come on till about 6 months or so ago. My wife drives the car and she hardly ever mentions it to meeither so the only time I notice is when I am driving.
I really think it has something to do with the spark plugs/wires not being changed in a LONG time. I am going to check all I can this weekend & let you guys know what I come up with. I am leaving it at the shop on Monday to have the tbelt, water pump, & sealschanged. I plan on doing the plugs & wires myself though. I don't want to have to pay for something I can do!
Thanks to all! ANY suggestions are still welcome as I am going to attempt a diagnosis this weekend!

 

Changed the spark plugs last weekend. Then put the car in for t-belt, water pump, drive belts, & oil seals. Got the car back on Friday. This morning I reset the ECU. CEL only went off for about 1 or 2 second then came right back on[:@]. Drove around today and the rpm fluctuations are still there (although not quite as bad as before.) Today it only happened one time, and the rpms only jumped around for about 30 seconds, then everything was back to normal. When I changed the plugs,all the wires looked great.After inspecting the wires I even cranked the car up inthe dark to check for any arcing - none.All the plugs that I took out were clean as a whistle too. The gaps were a bit toowide on the old ones, but other than that I didn't see a single thing wrongwith the old ones. So I guess I wasn't too surprised when the rpm fluctuations were still there.
I think I am going to look for a VOMso I can check the ignition coil.
I also may look for an external tach I can hook up to check the IAC.

 

Since your problem is intermittent, the coil could check good. WhenI said precision, I meant a decent quality instrument capable of resolving +/- 1Kohms. Most any of the digital VOM's, even the inexpensive ones will do this. Make sure you have the specs for your vehicle. If measurements are marginal, i.e resistance near lower end of expected range, the coil may be bad. My understanding is the range of spec resistances is related to temperature, not expected variability of the coil.

On a no-start 90EX, I measured the coil resistance near the lower end of the spec range, and thought it was probably OK. After replacing the ignitor w/ no change, I finally checked coil again w/ a better VOM, and got resistance below the spec lower limit. New coil and I was running again.

good luck

 

Thanks Texas...do you think I could get a decent VOM at an AutoZone, Advance, or O'reilley? I haven't gone to look for one yet.
Also...does anybody have any experience with the CKP sensor? I was reading my Haynes which says: "The crank angle sensor (CKP) determines the timing for the fuel injection and ignition on each cylinder. It also detects engine RPM."
I know I need a VOM to check that too. Heck...pretty much everything I have researched that looks like could be causing this problem requires a VOM to check! So I know I really need one. I'm gonna try to get by AZ and look for one tomorrow.

 

You can buy inexpensive digital models for <$20 from Walmart, AZ, etc that should be fine.

The CKP sensor is another coil loop where a voltage is induced by a magnet. You measure the coil resistance to check them. They don't often go bad, so unless you have a CKP fault code, this is probably not your problem.

good luck

 

code P O725 on the 95 acc v6 has to do with the coil input to the tcm,,,
i have seen it a few times turned out to be a bad coil,, But you need to DIAGNOSE it first .

here is what you do,, as adviced you need a voltmeter,, First off chk, to make sure that the connection at the coil is nice , clean and tight,
If it is ,, disconnect the A ( 26) connector at the tcm,, turn the key on, chk for voltage between A5 ( positive Blue wire ) and A 13 ( negative brown/black wire ) , If there is battery voltage , make sure that the connector is clean and tight when it plugs into the tcm ,there is a long shot that it could also be a bad tcm but i would be surprised if it turns out to be it .
,If no battery voltage ,, there is a short or open in the blue wire from tcm to coil,, ,,then you need to do is a continuity test on the blue wire from tcm to coil..,
Do the test, but i am willing to bet that it turns out to be a bad coil , or poor connection at coil,,

 

Will do. Thanks desert!

 

OK...so I'm a moron.
I have a few questions:
1) deserthonda, are you talking about doing a test of the ignition coil? Here is a picture from my manual:


[IMG]local://upfiles/7626/8552C12669A74FAA904A2EB31F78B4CC.gif[/IMG]

Or are you talking about an Ignition Control Module Test? Picture below

[IMG]local://upfiles/7626/CEFA14602B944ADD88B6FF4B31D87A9E.gif[/IMG]

2) One of the most important questions. The VOM has a red wire and a black wire with probes on the end. Which color wire do I plug in where?
For example: in picture #1, my Haynes says to "touch the probes to primary terminals(A and C) of the coil, measure the primary resistance and compare your reading to chapter specifications" Which probe (black or red)do I touch in which terminals?

I'm sorry if I am slow with this. I just want to do it right and I am not sure exactly how.

Oh yeah I almost forgot. The connections on both sides of the coil (like in picture #1) were very tight. I couldn't even get the4-p connectorloose, but I knew I wouldn't really know what to do if I did get it loose, so I wanted to ask you guys how to use this VOM before I started sticking probes in it.