Hello all,
I am at wits end. My daily driver just started misfiring.
I changed the spark plugs , wires , cap and rotor about a year ago. They all are still in good condition and working order. I have checked fuel pressure and compression… all within manual spec.
i wrongly deduced a fuel injector problem and have changed them as well. The codes I received prior are as follows: P1399, P0300, P0303 and P0304.
i pulled the plug wires off individually and the engine stumbled on cylinders 1, 2 and 3…… there was no stumble on 4. Although I was still receiving spark from the #4 plug wire to the plug. I have swapped plugs and wires - no change.
Can anyone assist me on what to look for next ?
Bad coil ? IGN control module ? Or “CYP” sensor ?
No vacuum leaks noted either.
I greatly appreciate any help or direction.
Thanks in advance
Honda guy - misfiring in Mississippi

 

Since cylinders 1, 2, and 3 stumbled when you pulled them, the ICM and coil and distributor are likely good. You can take a look at the post in the distributor cap for the #4 cylinder to see if there is any buildup just to be thorough.

Did #4 stumble doing the power balance test before you replaced the injectors?

Each injector has 2 wires where the injector gets constant power on one wire and the PCM grounds the second wire momentarily to open the fuel injector. The constant power wire will be the same color on each injector and I think they are all red or red with a blk/wht stripe. If you have a test light hooked to ground, does the #4 power wire have 12V with the key in the II position?

Do you have a compression tester or a leakdown tester?

 

Hi “PAhonda”
Nice to hear from you again. I still haven’t properly addressed my intermittent temp gauge problem but hope so soon.
Unfortunately this misfire condition popped up on me a few days ago. I sincerely appreciate your guidance.

I will do as you suggest and re-examine the distributor cap paying close attention to the # 4 post.

Yes, #4 cylinder did stumble doing the “balance check” BEFORE I replaced the injectors. I replaced all the injectors just for the sake of being in that area.

I’m going to locate a test light and and check for power as you suggest at the injector connector … although I checked the injectors earlier by placing a long punch against the injector and to my ear. A audible clicking noise was detected.

No…. I do not have a leak down tester .. only a compression gauge … do you suspect a defective valve ????

Again , I’m grateful for your guidance.

Thank you !

 

I don't know what the problem is, just trying to eliminate items. It does sound like #4 is having a problem, so a compression test may narrow down what is happening.

If #4 did stumble during your first misfire test, then consider reinstalling one of the original fuel injectors. You could have a bad one out of the box or a bad used injector. Better yet, swap #4 injector with #1 and see if #1 fails the power balance test.

 

Well Sir,

I got it fixed. I will never ever trust aftermarket parts again. I started back to square one by pulling the plug wires individually. When I did , I noticed spark emanating from the side of the plug at the manufactures seam arcing towards the valve cover.

I checked the other 3 wires the same way. 3 of the 4 wires displayed the same defective results. I should have caught this anomaly in the beginning - my mistake. I had assumed the wires were in good order since they were less 18 months old. I won’t make that mistake again.

I purchased a new wire set and replaced them all. In addition I purchased platinum NGK plugs and changed them to.
Final result - no misfire and running great. Although , I did waste money on the fuel injectors , I would like to think my fuel mileage would slightly increase due to changing wires ,plugs and injectors.

Valuable lesson learned today. I hope it help someone else as well.

Now to tackle the intermittent temp gauge …..

 

Glad you figured it out. I'd say stick with the OEM or NGK spark plug wires. The OEM seem to last forever.

 

Never again aftermarket parts - Never ……

 

I've heard that old OEM plug wires are better than new aftermarket. My 2000 has the original wires and I checked them. Still exceed original electrical specifications. 195k miles.

Some aftermarket parts are fine, depends on what the part is.

 

As soon as I’m able , I’m going back to OEM plug wires , funny thing, though, when I originally missed diagnosed the problem, I replaced the fuel injectors. Of course, with aftermarket parts, and they seem to be acting funny. My car is harder to start. I think I’ll go back in with the non-defective OEM injectors.