[jbes3]

I was driving like a madman today, and noticed my car was misfiiring like crazy at 5K? I was wondering what the resistance should be on the plug wires? Also, how can I check the coil packs? Is there anything else (other than spark plugs and wires), that I can replace or check? Thanks!

PS-Misfiring will cause the check engine light to come on, right?

 

[99BlackVenom]

I had a similar problem a few months back. The codes said #3 and #5 misfiring. We checked the plugs (had around 32k miles) and they looked normal. Replaced the coil packs on 3 and 5 and misfire was still there.

We "fixed" it by unconnecting the battery cable causing the computer to reset. We think the computer was getting a false input from an ABS sensor. You may want to try that first before spending money on coil packs.

 

[Chris98vobra]

If you have an Ohm meter you can measure the coil packs. Should read 12K-13K between both banks on each pack. This COULD be the problem. You don't say if you checked your plugs. That is a good chance. Wires will measure different based on make and length. I think stock Ford wires are around 2K or so a foot. Just measure all of them and look for inconsistencies. A bd one will show really high or open. Yes, if a misfire is bad enough you will set a MIL.

jbes3 - he has 2 big coil packs that drive his ignition, you have 8 individual ones. They act a bit different when giving problems. ABS signals causing a misfire??

Chris

 

[Chris Doss]

Hey Chris (would like to pick your brain a sec)

Could you elaborate a bit on testing the coil packs. I'm just curious sine once it gets warmer I start back up on tuning the car myself (Tweecer). I want to ensure my ignition and fuel systems are up to par before I do (I have made some minor changes already to timing and the MAF transfer function). I plan to replace the fuel filter and with over 40k miles on the coil packs I want to be sure they are working OK. In addition the new FRPP wire I have are of questionable qulity and although they are newer (<5k miles) I want to ensure they are firing OK.

Do I start the car, pull the spark wire from the coil pack, and then use the ohm meter to test the coil pack inidvidual port and then the wire? If so, I see you indicated I should see between 12-13k for the coil pack port, how about the spark wire (is that the 2k you menthioned?) Thanks Chris (cool name btw)


Could Jbes problem be spark blowout? What kind of plugs are you using jbes, what gap?

 

[Chris98vobra]

Hi Chris,

Don't start the car. Looking at the front of the car, pull wires from the far left pair (front and back wire) then measure. Mine read 13K. Then move over to the right pair, then to the other coil pack the same way. Very easy. As for wires, just pull off each and measure the resistance. The resistance will be a multiple of the length. So if one is 1 foot and reads 2K, then a 1.5 foot one would read 3K. If you see one at 100K it is obviously bad.

Chris

 

[Chris98vobra]

Duplicate

 

[jbes3]

I haven't checked anything yet. Up here in lovely Minot, ND, it is a bit chilly outside. I am waiting til Monday to take it to our Hobby Shop and check it out. I just wanted some numbers of what I SHOULD be reading.

What plugs would you guys recommend? GAP?

Chris Doss--I have a TwEEcer RT in my 93. The datalogging is AWESOME! I am still learning all about it. Do you know if I can switch it to my Cobra, and just change the computer(From the 93 to 98) program?


Thanks for the help.

 

[Chris Yates]

Is the misfire during WOT or all the time?

 

[jbes3]

WOT

 

[Chris Yates]

You need to buy/borrow an obd-ii tester and grab some data. A flaky IMRC controller will give the impression you have a misfire. This is because the timing will jump from 18ish to 27ish over and over, that's felt as a hesitation/misfire. This is a very common failure on the 96-98 cars. Logging your timing will help figure this out.

Thanks,

 

[agit8or]

Is this common for it to intermittantly do this? I am wondering if this is my problem. It doesn't feel like a missfire, but like a BUNCH of timing is pulled for a second or two.

 

[Chris Yates]

Yes, it's a pretty common failure as the IMRC controller ages.

Thanks,

 

[vheflin]

The resistance for the plug wires should be less than 7000 ohms per foot according to the chiltons manual.

 

[c5eater]

IMRC controller? what's the fix?

 

[Chris Yates]

Remove and replace the actuator (under the intake). You first want to verify that if the problem by data logging the timing and IMRC circuit.