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Discussion Starter · #1 ·
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?
 

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2007 Pilot EXL, 2012 Civic LX, 2007 VTX1300C
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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
 

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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.
 

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Discussion Starter · #6 ·
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?
 

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Discussion Starter · #7 ·
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.
 

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Discussion Starter · #8 ·
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?
 

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Discussion Starter · #10 ·

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2007 Pilot EXL, 2012 Civic LX, 2007 VTX1300C
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misfires can be fun to track down. sometimes starting with swapping coils from cylinders that aren't getting a misfire code can be a quick easy place to start. swapping fuel injectors is NOT as easy. IF you've gotten as far as to attempting injector swapping you might as well have a shop test and service them all. I would save this step for last after verifying the idle air control is working normally, there are no vacuum leaks or exhaust leaks, and you have good compression and cylinders hold adequate pressure on leak down test
 

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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.
 

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Discussion Starter · #15 ·
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.
 

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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.
 

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Since your only issues are misfires, I'm going to rule out air, or gas. They usually are accompanied with associated codes. Same with EGR. I'm thinking electrical. You have ruled out timing belt, and sensors would pick up on that. The misfires are both heads, and so it isn't associated with one head. I'm not thinking it is internal engine issues.
Another easy thing to check is Serpentine belt, especially if it was making noise prior. It could be dragging. I don't think it is valve lash since they don't fail together like that. You would have had issues with a single maybe 2 cylinders.
Have you checked your fluids? Transmission will be hard to check since it has to be done at operating temperature, but check your engine oil and see if it is low. Do not add transmission fluid since it will show low cold.
I'm thinking wiring issues.
 

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You can check the battery cables for resistance and voltage drop as well. With the DMM attached to the positive cable, attach the other lead to the end of the positive cable. The cable to the starter is fine as it is starting the car, and won't effect the car once started, so check the cable leading into the fuse box. You have to put it under load, so have someone crank the engine and check that there is little to no voltage loss. You will see the voltage spike if it is losing voltage. If you see no voltage loss, check the cable to the alternator. Same test. Same results, check the ground cable. Go to setting resistance, and do the same with the ground wire from the battery to the chassis. You should see very little resistance. If it spikes you found your wire. Your battery could be bad too. Even though it is new, doesn't mean it is good. Especially if you went with a bad brand, or they sold you an old/used battery. I go with Walmarts Everstart Maxx. Works great 5 year warranty. Check the case of the battery. Do the same test with the DMM one lead on the positive, and start touching the case of the battery with the other lead. If the case is dirty you can get voltage drop through the case. Corrosion on the terminals can also cause voltage drop. You want to keep these things clean so the power can flow through the system and not into the air.
 

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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.
always startat the cheap endwhen problem solving. Plugs. Without a spark nothing happens. I’ve gotten into the habit of one plug at a time, check clean regap replace, the restart the engine. Minimizes the places you have to look in case things don’t start..
 
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