Engine Codes

JDMax · Jun 9, 2004

I had a check engine light come on and had the codes read off the car. According to the guy who pulled the codes it had something to do with number 4 and 8 cylinders missing or not firing.

I can tell a noticable loss of power when I drive but the engine isn't running rough at either idle or open throttle. Anybody else run into problems with 4 and 8 cylinders not working right?

I'm trying to get a headstart on what the problems might be before I take it in to Ford.

Car is a 98 GT with about 64K miles on it. The mechanic who pulled the codes thought it might be a fuel filter. Any other suggestions?

The codes that were pulled were P0304 and P0308

Go HoTO! · Jun 9, 2004

Fuel filter is a good start especially with your miles and if it is original. Replace it...it's cheap. Then run some injector cleaner!!! See how that works. Another reason for a miss fire is a lean condition. The hotter weather lately could have put you over the edge with that. Do you have an after-market MAF? If so, put the stock one back on UNLESS you have it dyno tuned for it. I would feel confident that this will adress your issues. Avoid driving the car as you will ruin the cats for starters.

shaddixstang · Jun 9, 2004

Had the same problem before. Changed spark plugs and wires and that fixed it. May not be that easy though

JDMax · Jun 9, 2004

P0304 and P0308

Because I have two cylinders opposite of each other misfiring could it be a coil pack that is going bad and throwing things off?

JDMax · Jun 10, 2004

OK, just got a fuel filter. Now does anybody know where it is on the car and what I need to do to replace it?

Figure I will try replacing things in this order.

1) Fuel filter
2) Plug wires
3) Plugs
4) Coil Pack
5) ???

JDMax · Jun 13, 2004

Fuel Filter didn't fix the problem so on to the spark plugs.

I am in the process of changing out the plugs now and when I took the plugs out the original ones were gapped at .065. Is this correct? I thought the gap should be .054

Could this difference in gap sized have been causing me any issues with power?

jstreet0204 · Jun 13, 2004

JDMax said:
Fuel Filter didn't fix the problem so on to the spark plugs.

I am in the process of changing out the plugs now and when I took the plugs out the original ones were gapped at .065. Is this correct? I thought the gap should be .054

Could this difference in gap sized have been causing me any issues with power?

After you change the plugs, swap the coil packs and see if the codes changes to different cylinders. If it does you know its the coil pack. If it doesn't My next guess would be the crank position sensor.

JDMax · Jun 14, 2004

Finally got the check engine light problem cleared up. Changed the plugs and number 4 was covered in fuel. After the replacements the engine stopped throwing error codes. I have reset the computer just to be on the safe side.

The new problem is that at WOT the car starts surging around 3000-3500 and continues. Not violent surges you can just feel the engine surging every 3-4 seconds apart. Drives fine at low speed and idles correctly.

Could this issue have anything to do with the new plug gaps versus where the old gaps were at? Where are some good places to start looking.

I have searched both here and Corral but most of the surging questions are at idle and low rpms.

Go HoTO! · Jun 14, 2004

Go over to modulardepot.com and see if someone can help there.

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