Misfire when engine is warm

[niter3]

Seems I'm having some issues with a bit of misfiring when my engine warms up during idle. I was having previous issues with a loss of power when giving it some gas the car would misfire and have no power. Well I've swapped out the spark plugs and it has pretty much cured 90% of the problem except for the warm engine misfire during idle.

I was wondering what could cause the car to misfire this way? The wires are probably about 2 years old but to my looking, they look pretty descent.

Thanks,

niter3

[Jeff P]

I'd test the resistance of the plug wires and see if any vary a little too much.  Also check the injectors, preferably when they're hot.  They should be around 12 ohms each.  I take it you made sure your plugs are gapped to .045?

Edit:  Spelling correction.

[niter3]

Yes I made sure they are all gapped properly. How do you check the risistance of your plug wires and the injectors?

[Jeff P]

A loose plug boot can cause a misfire, as can a cut in a wire (but you already checked yours).

To measure resistance....Use an ohmmeter (or multimeter) with one lead going to each end of a plug wire to measure the Ohms (a.k.a. resistance).  Don't do them all at once or they could get out of order As for the injectors, you'll need to do a few things to get to them.  Remove the hose going from the airbox to the throttlebody.  Disconnect the IAC, TPS, vacuum line assembly, and cables from the throttlebody.  Disconnect the hose from the back of the plenum and remove the L-shaped pipe.  Then remove the EGR valve, unbolt the throttlebody from the plenum (you can leave the coolant lines attached), unbolt the bracket from the back of the plenum, unbolt and remove the plenum, and disconnect the connectors from the injectors.  Honestly it's been a couple years since I've done it, so you may need to disconnect the fuel lines from the fuel rail and maybe remove the rail also.  You'll see once you get in there.  You also might be able to leave the EGR valve attached to the plenum.  Once you can access the injectors, use your ohmmeter/multimeter to measure the resistance between the two pins on each.  As mentioned before, about 12 Ohms apiece.  It sounds more difficult than it is, believe me Though sometimes the plenum is stuck on there pretty well.

[niter3]

I'm not going to say for sure, but I have a strong feeling it's not related to the fuel injectors. I mentioned before that my car was running rough so I swapped the spark plugs which resolved 90% of the issues. I'm only finding my car running rough when the car warms up and basically only during idle and anything under 2rpms. Once I get over 2rpms, it usually goes away. Resistance makes sense to me, but how it ties into the fact that I have to wait for the car to warm up first doesn't it. Also, before swapping the plugs out it never had this type of problem. It was a problem trying to accelerate faster when I was already driving. The car had no power and just misfired. Well this issue is fixed, but the new issue is here.

What's the chances of the new plugs having resistance problems? However, I do believe it could have something to do with the wires? I purchased these high performance wires approximately 2 years ago. How often do you usually have to swap out wires?

Thanks,

Mike

[Jeff P]

Wires are usually good for a few years (depending on driving frequency, conditions, etc.).  New plugs shouldn't ever have a resistance problem.

[Mr Goodwrench]

I think its 12ohms per foot of wire like everyone said
but plug wires can go faster than u think.  ive seen wires a year old needing to be replaced (poor wires((cheap ones)) an no silicone grease on the to keep moisture out
its tha funky green crap that slows the flow of power

Mr Goodwrench

[niter3]

Well I did purchase these wires off ebay for only 50$ shipped and all. What I don't understand is this happened after I changed the plugs. I'm guessing I may of aggrevated the wires by moving around during the spark plug change??? Well I guess the next step is to swap the wires out.

Also, before I forget, these issues seem to arise after driving for 30 minutes or so on the highway. I travel to and from work on the highway which is 30 minutes each way.

niter3

[Mr Goodwrench]

Also check your coil towers for junk on them.  a brass wire brush works well.  make shure to lube everything well..

Mr Goodwrench