[ccbcc]

This happened after the spouse returned from grocery shopping with a mixed highway + local driving: the car struggled to start, and after it started, it stalled immediately. There was some notable vibration from the engine bay before it stalled. For the first 2 tries, it left a strong gasoline odor. After a 3rd start, I pumped gas for a min or so and the car got into the normal working state. Once in this state, everything worked fine and I drove the car on the road without issue. It even stopped at STOP signs and traffic lights without stalling or abnormal vibration.


[Update 1]: After turning on/off a few times, the symptom is now repeatable: if right foot rests on brake, the car cranks strong but it won’t start; if/when cranking the car and at the same time pumping gas (ie right foot not on brake pedal), the car can start -- is the foot not on brake a sign that something went bad? Once started and pumped gas for a few seconds, the car drives just fine – it doesn’t stall in subsequent stops at STOP signs or at red lights.

[Update 2]: When the hard-to-start-then-stall occurred, there was no CEL or any warning light on the instrument panel initially. After many on/off tries, now the engine light and VTM-4 light are on.

Vehicle repair history: it’s a 2004 EX-L, 4WD with 203K miles:
- Starter and alternator are still original
- spark plugs were replaced with NGK at 152K miles in 2017
- EGR valve was replaced in 2017 at 155K miles
- timing belt and water pump n all belts are replaced at 157K miles in 2017
- diff fluid changed in 2019 at 172K
- 2 O2 sensors (the ‘04 EXL only has 2 O2 sensors) were replaced in 2018 at 164K miles
- valve adjustment done & PCV replaced in 2021 at 189K mile
- The battery was replaced in Nov, 2022 and is practically new

I searched and the past working fixes include: valve adjustment; fixing timing belt jump one tooth. Neither seems the cause of the problem I am experience.

Where do I look next?

 

[ccbcc]

Find out what CEL code(s) you have. Could be IACV (idle air control valve), check and clean with throttle body cleaners.

Codes are P0300, P0301, P0304, P0305, basically misfires in many cyls.

I tested a few more times today and the symptoms are now consistent: after overnight, the car cold started at 1st crank; drove a mile or two without stalling at STOP or traffic light. It couldn't start warm or struggled to start and stalled immediately unless pumping gas. If I was able to switch gear to R or D and after the car moved, the engine would not stall.

The most recent repair that may relate to the problem was in Aug'2022, when the leaky exhaust flex pipe was cut and a metal piece was soldered onto it. In the last 2 weeks, there have been noise at 40+ mph which seemed coming from that region and it's plausible that vibration has put the O2 sensor in a mal/bad state. If yes, how to diagnose a bad or non-working O2 sensor?

 

[ccbcc]

yeah there's a reason why the Honda FSM has a section for testing fuel pressure. or you could just replace the pump assembly. have you had the injectors serviced? over time with high mileage the injectors will flow less and have poor spray patterns

Appreciate the suggestion.

The fact that the car, once I am able to put it in R or D without stalling, drives normally, seems to rule out the fuel pump.

The current symptom is that code start is OK; warm start struggled and stalled immediately.

 

[ccbcc]

Were the EGR passageways cleaned when the EGR valve was replaced?
Was the replacement EGR valve OEM?

Also what is the behavior if you attempt to crank with your foot on neither pedal? Make sure it’s in park, parking brake set, with both feet off the pedals when you try this.

EGR valve was replaced and the passages cleaned in 2017, about 50K miles back. I don't recall where I bought EGR, probably from RockAuto, so chances are that it's not OEM.

I tried to start the car without stepping on any pedal, and when gear at both P and Neutral, the car can start (when engine is lukewarm), but it only lasted a few seconds before it stalled, unless I pump gas. Are we onto something here?

 

[ccbcc]

Find out what CEL code(s) you have. Could be IACV (idle air control valve), check and clean with throttle body cleaners.

Ah, checked the log: the throttle body was cleaned back in mid 2020.

 

[ccbcc]

Possible areas to explore:

• fuel line leak
• fuel pump
• bad fuel (have you filled up somewhere different lately, i.e., not top tier?) TOP TIER™ Gasoline Brands
• what shape is your key in (immobilizer chip issue) Aw, nuts. Cranks but doesn't turn over.
• main relay solder
• brake switch

Thank you for a list! This will keep me busy for a while.

The gas in tank is fresh -- it was pumped at Costco last Friday Jan 13.

 

[ccbcc]

What battery terminal connections do you have? Original or aftermarket?

Original. Never changed battery terminals.

 

[ccbcc]

Time to pull the spark plugs and inspect both plugs and coils. Reverify the plugs are correct type, condition and gap. Any signs of burning, arcing or damage to coils? Replace as necessary. Not a fan of rockauto or non OEM ignition components.

If Cats are original, surprised they aren’t coding as failed. A short time after my EGR fell on its face, mine went out.

Will pull the plugs and examine coils tomorrow.

Between plugs/coils, iac, and fuel injectors, what is the best sequence to tackle the problem? I hate to replace parts while not knowing the exact cause.

 

[ccbcc]

Make sure they are tight. Check all of your ground cables and make sure they are all secured. Look for corrosion, cuts, kinks, etc... If they all look good next is to check they are good.
Do you have a DMM? You can check for voltage drop. Place one lead on the positive terminal, and get a voltage check before starting. Once you have the battery voltage start checking all of the ground locations for voltage. It should stay the same. This includes checking ground on the vehicles body, the engine, or anywhere else you see metal. If that is all good. Have someone crank the car and check voltage while cranking. It can drop a little, but you don't want it to drop bellow about 10 volts.

I am with you about the reasoning that the problem is unlikely an individual cyl (thus less likely a plug or coil problem). IAC valve is plausible as it affects all cyls, so are wire connections or the healthiness of the battery, or fuel line problem.

A few thoughts wrt battery, cable and wire connection:
1) the battery was bought in Costco. It's their Interstate line and the last one I bought lasted 6 years. It was installed by me and the connections look good to me. The terminals are clean.
2) The ground cable connecting to a place underneath the starter is rusty and should be replaced any way.

There is one missing link: the car can start immediately when cold, but it struggles to start and then stall when it's warm. A wire connection problem cannot explain why the engine temperature plays a role here.

 

[ccbcc]

and

Yes, misfires at cyl 1 4 5 6 are reported consistently and repeatable.

easy, when the vehicle is cold it's going into higher idle full rich mode to help warm up the engine faster. with engine warm its going to go into its default low idle mode with normal semi-lean fuel mixture. still putting money on the IACV.
electrical problems would show up during other operating conditions

Alright, the plan of attack:
1. Take the IAC valve off the throttle body and do a thorough cleaning. If needed, replace it with a new one, but i will do a cleaning first. It's never done and it's due regardless.
2. Pull plugs from cyl 4 5 6 and 1 and do a visual inspection of plugs and coils first and take from there.

The piloteer community is amazing and I'd like to thank everyone in this thread for your suggestions and camaraderie!

 

[ccbcc]

Well, IAC malfunctioning is a hypothesis, not a fact yet. I don't have an explanation why cyl#1 4 5 6 misfired, but not 2 and 3.

I pulled out the coils and plugs for cyl#4 5 6 and the #4 is soaked with oil while #5 and #6 are bone dry! Seems that I have leaky valve gasket!

In mid 2021, I was adjusting valve lash and replaced only the front valve cover with (1/2 of) the felpro set; the back bank was very much pliable and I decided to not change it. That was only 14K miles ago!

Damn Felpro! For all fellow piloteers: if you adjust valve lash, do yourself a favor and get the OEM valve cover gasket!

Anything else to fix when oil getting into the plug well? and how to clean up the oil in the #4 well?

 

[ccbcc]

you replaced the valve cover outermost gasket but did you do the press fit tube seals at the same time?
if not, don't blame felpro. I went with a beck/arnley kit and no leaks anywhere. just clean the oil out of the tube before reinstalling the plug.
also those covers require a special torque sequence to properly seal it down.
everything in the factory service manual

Did I press fit tube seals? yes, I used a large socket and gently pressed it. I did get 14K miles since the valve adjustment. Could my craftsmanship be improved? Probably. After all, it was the first and probably last time I do a valve lash adjustment.

Anyhow, I made some progress today and replaced the #4 tube seal with a Honda OEM one today. The old seal was ripped in the middle. No wonder oil leaked. I managed to remove the front cover for cyl#4 5 6 without removing the intake manifold because there is plenty of space to move the cover out once the 5x 10mm bolts are removed. This probably saved me a good 2-3 hours.


" just clean the oil out of the tube before reinstalling the plug." --> I used a piece of paper towel to clean up the oil. There must be still oil left in the plug well since the engine bay had a puff of smoke shortly after the car started & warmed up. Smoke did not re-occur though, so I am reasonably sure that left-over oil is burnt up.

Good news: the CEL disappeared, and the car is drivable.
Bad news: the car was still shaky after a warm start, as if it will stall. This is observed after idle relearning (I disconnected the battery when replacing the tube seal).

Another sign that something is not working as expected: when gear is at "P" and after a warm start without pumping gas, RPM jumps to ~1500 momentarily and then it settles at ~700-800. What gives the momentary RPM surge?

P.S. 1. the attached pic is the old #4 tube seal after the cover is removed.
2. a 10mm socket was dropped in the car and nowhere to be found. A cost that was not budgeted.

 

[ccbcc]

Howdy,
I just had a similar issue with my wife's 2004 Pilot. It was very intermittent, but long story short, I believe you need to replace the main relay, under the dash, near the steering column. I spent the extra and bought the Honda, O.E. part.
I also remember, when the green security light would light up, it would start up normally. If it didn't light up, it would crank, but not start. At one point, the vehicle would crank and not start.
I would tap the relay; the light would then come on and I then knew it was going to start.

Good luck, I hope this helps,
K-Lap

P.S.
You mentioned at one point, when it was acting up, you could smell fuel, so that eliminates the fuel pump and other fuel delivery items...

In my case I never experienced the green security key not showing up. Thanks for your input though.

 

[ccbcc]

The surge is Idle Air Control Valve. The shaking is likely related. Remove the Throttle body and clean it really well. Do not move the Butterfly Valve. I would say clean it without removing the Throttle Body, but I bet the gasket is bad. Replace with a new one, and make sure to get the old off. Do not scratch the aluminum surface. You can use a plastic razer blade sold at Walmart. Make sure to dry it before re-installing it. If you don't the liquid-carbon created from cleaning will dry and cause the butterfly valve to stick, or could settle at the bottom of the butterfly valve and cause it to restrict airflow.
Razer blades

I am tackling IAC valve. I got to the point where throttle body is detached and I cleaned it thoroughly.

I am stuck at removing the second Philip screw that fastens the IAC to the throttle body. It's rusted and the screw head is stripped. I cut a deep groove with a hacksaw and hoped I could use a flat screwdriver to loosen it, but it doesn't budge so far.

 

[ccbcc]

If you have a quality vice grip, you can get on the screw head from the side and twist it off. If you made a good cut on the screw head you can also use plyers or something similar on the flathead to help twist the screwdriver giving you more leverage.

Yeah, after cutting a deep groove, and used the flat head screwdriver, it didn't budge: the screw is rusted and it's really tight, even after I soaked it w/ WD-40 overnight. It's probably not a good idea to continue in this route as there were shredded metal pieces from twisting. If the metal on the screw head is broken into pieces, it will be really a long day.

I tried a vise grip today and no success yet. The screw head is round and the grip is not firm enough to break it loose. Also there is not enough space to find a good angle to grip. I will give a few more tries, and if I cannot break it loose, I will take it to a shop.

 

[ccbcc]

Do you own an impact driver with a flathead bit?

impact driver, yes. Flathead bit, no. I didn't know that I can use a flathead bit with impact.

 

[ccbcc]

@royalbiggster I really appreciate your tips. With the flathead bit + impact driver, I managed to break it loose and the IAC valve was taken off the throttle body. I replaced it with Standard Motor AC229 -- it's sold by Amazon and made in USA, and I hope that it works as well as the OEM one.

In addition to this, I checked coils and spark plugs for all 6 cylinders: #1 and #4 are soaked with oil. I replaced the #4 cyl plug seal a couple of days ago and today did #1. The end result is that the car does not stall any more, and the check engine light disappeared after driving for about 30 mins. That is good.

What's annoying is that at warm idle, it still has noticeable vibrations from the engine bay. Note that all these are after performing the idle learning procedure. It seems that there is something extra/else that is not working properly, or will vibrations disappear after driving it for some time? The car drives fine without vibration at both local and highway speed.

I will leave the lesson here again: do NOT use FelPro kit if you do valve adjustment. Both #1 and #4 plug well seal looked as it they were "torn" in the middle and both resulted oil leak. The fact it worked for about 2 years and 14K miles and the tears being in the center indicate the quality issue, instead of the workmanship. See the attached photo where you can see the tear for cyl#1.

 

[ccbcc]

@undivide I also put oil on the seals before I installed them into the cover.

@royalbiggster By the time I read your instructions, everything is put together. I will remember the tips if I get to the seals and covers next time.

About the car: I am almost back to square one: fixing two plug seal leaks is good; installing a new IAC perhaps helps a tiny bit.

After driving a couple local shopping trips, all symptoms returned: CEL is back along with VTM-4 light; warm starts stall the engine; the crank is strong, so most likely not an ignition circuit or battery problem. Once the car is in "R" or "D" for a few seconds, it won't stall and it drives OK.

Latest codes:
-- P030{1, 2, 4, 5, 6}: all cyls misfire except #3.
-- P0300: Random misfire detected
-- P1399: misfire in any cylinder
-- P0113: intake Air Temperature Sensor 1 Circuit High Input;

At this point, my bet is not in air, fuel, or ignition/plugs, but something "global" that affects all cylinders -- timing.

Incidentally, there is a thread with awfully similar symptoms and it was that timing belt jumped one tooth:
2004 stalling when warm

The last timing belt change was in 2017 at 158K miles, about 46K miles ago. Given that it worked for over 5.5 years, is there any possibility that the timing belt tooth jumped one? Could it be that the tensioner is on its way out? How to inspect if the time belt has jumped?

 

[ccbcc]

Where is the gasoline odor coming from? I asked before, but maybe you didn't read it.

When I said gasoline smell, it could be the smell of burning oil before tube seals are replaced. I don't smell gasoline any more.

There is some odor (a tad stronger than normal) in the exhaust pipe, a sign that the exhaust valves may not be closing as tightly as they should.

@ckeator I read your thread and the damaged seals look exactly what I saw in cyl#1 and cyl#4. They looked as if they were cut by a sharp knife: the rubber is still very much soft and pliable, but there is a cut/tear in the inner ring.

There is no noticeable loss of oil yet as I have refrained from driving it after the problem surfaced. The #1 and #4 plugs were soaked with oil before seals were replaced. There would have been oil loss for sure if the seals are not fixed.

I doubt that valve lash is the cause: it was adjusted in the summer of 2021, and the symptom started all of sudden about 10 days ago. More importantly, engine stalling only happened when warm start. After the car moves (either Reverse or Driving) even for a short distance, the car will not stall and the vibration is minimal at STOP or traffic light. It seems the load -- engine engaging with transmission plays a role here.

The current hypothesis: the tensioner of the timing belt started to act up and the belt may have jumped a tooth or two; with load, it may have forced the belt to behave differently from the state at start time. The symptom returns if the engine stops and starts again. This piloteer had fixed the problem which is almost identical to what I am experiencing: 2004 stalling when warm . What do you all think?

Another hypothesis: could timing belt off a tooth have accelerated the deterioration of the plug tube seal?

 

[ccbcc]

@royalbiggster with the 2 pics, it makes perfect sense, and indeed I am to blame instead of FelPro. Just make sure I understand correctly: is the bottom picture after pushing the seal along the wall and is the top the wrong installation? I will take a second look and get to it.

Yes, I performed the idle re-learning procedure.

The air intake temp sensor: the code started new yesterday. One twist was that, when re-assembling the engine cover and intake manifold, I forgot to connect the sensor wire. Hopefully it will go away, if not, replacement is simple.