Random Misfire Diagnosis- 2000 Honda Prelude SH

[h22rider]

Hello gearheads,

I come to you all in hopes we can pinpoint what is causing my CEL: P0301, P0303, P1399 which translates to cylinder 1, cylinder 3, random misfire codes.

Car: 2000 Honda Prelude SH
Mileage: 143,000 miles

What has been done so far within past 5k miles:

NGK (6441-4PK) Iridium IX Spark Plugs
NGK (8019) HE65 Premium Spark Plug Wire Set
NGK 24286 Oxygen Sensor - NGK/NTK
NGK 24285 Oxygen Sensor - NGK/NTK
MagnaFlow 22644 Direct Fit Catalytic Converter


Symptoms:
The CEL came on, changed the cap and rotor because when I inspected the contact points looked a little burnt. CEL went away but after ~200 miles, the CEL came back on. I do not feel any misfires at idle or while driving. The car idles at 700 RPM and does not feel weak/bogging/sputtering when accelerating. One symptom I do experience is on a cold start, the car cranks about 2-4 times more before firing. Once warmed and starting the car, it fires right up without any sort of hesitation.

I went to autozone and bought a cheap set of NGK V-Power Copper plugs just to rule out faulty plugs and when I swapped them in, there was definitely bogging/sputtering during acceleration. I put the Iridium plugs back in and the sputtering went away as well as the CEL is gone however I have a feeling it will come back on within 200 miles. I managed to get a snapshot of the Iridium spark plugs when I switched them out with the V-Power, from top to bottom cylinder 1-4 respectively:




Possibilities:
1. EGR valve and intake manifold ports clogged
2. Ignition Coil
3. Distributor Ignition Control Module
4. Fuel Injectors

My question is this:
Can a clogged EGR/Intake manifold port cause misfires? My father and a good friend who knows a thing or 2 about preludes thinks it's the distributor. Another friend of mine who works on preludes says that if I haven't cleaned the intake manifold ports and EGR, he would start there. What do you guys think? I'm pretty handy but before I start dumping a small fortune diagnosing this and tearing apart my car I would like to get some feedback. Thank you for any help!

 

[Nukeman7]

I can almost guarantee you that it is one or two bad coils. I chased the exact same codes and symptoms on a 2003 Odyssey and a 2001 Accord. The Honda on-board diagnosis system is not very accurate in identifying the specific cylinder with the bad coil(s). I had two bad coils on the Odyssey and had codes showing misfires on 5 different cylinders. On the Accord, it showed random misfires on all four cylinders when only one coil was bad. I think it uses a signal from the knock sensor and crank position sensor to approximate the cylinder when a misfire is detected. However, you can get a full set of Chinese made coils on Amazon or eBay less than the cost of 2 Honda OEM coils from the dealer.

 

[h22rider]

Just a heads up, the 5th prelude w/ h22a4 has an external coil.

 

[mk378]

Plug 1 seems a lot blacker than the others I would concentrate on that cylinder. Compression test? Clogged EGR should not cause misfiring.

 

[3800Series]

Maybe a healthy dose of a PEA cleaner?

I'm dealing with a similar problem on one of my cars (different make) but I suspect mine is ignition coil related. Cars not throwing a CEL code but it felt different and finally I got tired of wondering.

Cars throwing miss fire alerts on cylinders 1-4 but 5 and 6 are perfectly fine (waste spark ignition system).

 

[Jim_Truett]

When was the last time the valve lash was inspected and adjusted? Why did it need a new converter with only 143k miles?

 

[h22rider]

I got a new exhaust system, invidia q300 and while I was down there swapped out the cat. I had to change the clutch and needed to take off the header and downpipe together since the bolts were so rusted on the header to downpipe and cat, so the exhaust is new from the cat back. The valves hasn't been adjusted since I purchased the vehicle last year.

 

[Dan55]

Valve adjustment, coil.

 

[PeterPolyol]

Big vote for Ignition coil/disty. Changing plugs (and type of plug) seemed to expose it big time. The ignitor inside of the disty tends to get roasted over time and it's performance degrades until it fails; a common issue with integrated coil-ignitor-distributor units.

EDIT: OP mentioned his coil is external but the ignition control module (ignitor) is still in the disty.

 

[h22rider]

Ok so you think it's the ICM or ignition coil? Either way, I have already placed an order for a new OEM ignition coil since I got it at a fair price. Do you suggest I get an entirely new distributor as well since the ICM is inside the distributor?

 

[PeterPolyol]

Sorry I mindlessly typed "Ignition coil/disty" as those were the two relevant options from your list but yes I mean the ignitor or ICM. They're basically a 4-pin HEI module with a unique shape and serviceable in these distys. If you're really good at this stuff and like extra work, the other option is an upgrade (to a generic 4 pin HEI or even a nice quality transistor)and relocate to a cooler location to avoid problems in the future. Of course getting 140-something-thousand miles out of each one ($40ish dollar part), why bother? Coil's likely still good but a nice new one can't hurt.

 

[h22rider]

I'm going to order a spare ICM, they are pretty cheap on ebay. Is there any possibility that the misfires could also be caused by a faulty crankshaft position sensor as well? I'll start with the basics and get the coil, ICM but just wondering the symptoms to be expected as well. Thanks to all who have helped me with this!

 

[Jim_Truett]

I would check the valve lash before throwing parts at it. A tight exhaust valve that expands and doesn't fully seal when hot can first show as a misfire.

 

[LSX454R]

On Honda engines, typically in my experience your dealing with an ignition issue. Have RARELY seen injectors go bad. EGR shouldn't cause that, even if it was an egr issue you would most likely have an egr performance code. The overwhelming consensus here is ign./coil.

 

[mightymousetech]

Originally Posted By: LSX454R
On Honda engines, typically in my experience your dealing with an ignition issue. Have RARELY seen injectors go bad. EGR shouldn't cause that, even if it was an egr issue you would most likely have an egr performance code. The overwhelming consensus here is ign./coil.


Agree with the injector issue, very rare, but this is a 17 year old car now. Absolutely check the EGR, plugged/partially plugged EGR ports are often the cause of misfires. I see it often. The fact that it takes so long for the code to return also points to a plugged EGR system. You will only get the code with the EGR valve full open, when the vehicle is fully warmed up and cruising at a steady speed on the highway.

Unfortunately, cleaning the ports is a bit of a PITA on these motors. Have to drill a hole in the port plugs, use a small slide hammer to pull out the plugs, then get new plugs from the dealer.

http://www.preludepower.com/forums/showthread.php?t=275440

 

[h22rider]

hey mightymouse, happy 4th of july man. thanks for your response and the link. ive done a port cleaning before on my previous 5th gen, i remember vividly lots of cursing and time consuming. this time around i bought an entirely new lower manifold and will be tapping with 1/4 NPT hex socket plugs for easier cleaning in the future. so, i guess on my to do list will be:

1. port cleaning
2. new ingnition coil
3. new distributor
4. eventually a valve adjustment

hopefully this will solve the issues im having. at the current moment, there is no CEL, no idling issues, no hesitation or sputtering. it still takes 2-4 cranks on a cold start but will fire up.

 

[amusing]

H22rider, On review of your plan for cleaning intake egr ports
I recall my process on 99 base H22A4 to remove the Honda caps was tap a nail into
center and wiggle to the sides and tilt up they popped out each and every one it was so easy
I did not remove the fuel rail and a slide hammer was not needed.
Honda caps for about 50 cents each at the dealer Last year.

 

[andyd]

My only experience with Hondas is replacing the #4 exhaust valves. I would do a compression check, just because, then I would check the lash, way overdue @ 143K. I really liked the 16 valve twin cam engine.