Odd Cold Start Issue

jabraham2005 · Jul 6, 2022

pkrface said:
No VCM and 30K on timing belt. The valve adjustment crossed my mind, but why would it act differently the longer it sits cold? For the record this issue is consistent regardless of cold or warm temps. Same issue at 0F or 90F.

I’m guessing this would be a valve adjustment issue. I had the issue with my 2005 Honda Odyssey with about 180k. My thoughts are it’s never had a valve adjustment and with that amount of miles, 192k, it’s probably needed that’s why you’re getting multiple misfire code P0300. Mine would do the same thing at cold start up but once it warmed up it was totally fine it was much worse in the winter time that it was in summer. You have to remember the valve lash clearance is different when cold then it is when it’s warm so you could have exhaust valves that are way to tight when cold thus causing multiple misfire code. When you do a cold start up next time try keeping the engine at about 2000 RPMs for about a min or so after you start it and see if misfire code comes up. When I had that issue that’s what I would do to keep the computer from setting a check engine light until i finally did the valve adjustment and that solved my issue.

pkrface · Jul 6, 2022

Thanks guys, a good fuel injector cleaning will be the next step. Haven’t been using cheap gas, but have only owed the car for 3.5 years and 35K miles. No issues the first 3 years.

pkrface · Jul 6, 2022

jabraham2005 said:
I’m guessing this would be a valve adjustment issue. I had the issue with my 2005 Honda Odyssey with about 180k. My thoughts are it’s never had a valve adjustment and with that amount of miles, 192k, it’s probably needed that’s why you’re getting multiple misfire code P0300. Mine would do the same thing at cold start up but once it warmed up it was totally fine it was much worse in the winter time that it was in summer. You have to remember the valve lash clearance is different when cold then it is when it’s warm so you could have exhaust valves that are way to tight when cold thus causing multiple misfire code. When you do a cold start up next time try keeping the engine at about 2000 RPMs for about a min or so after you start it and see if misfire code comes up. When I had that issue that’s what I would do to keep the computer from setting a check engine light until i finally did the valve adjustment and that solved my issue.

I understand the cold to warm lash issue, but a little throttle applied right at start up and it clears up in 2 seconds. No joke, that quick. If I don’t apply a little throttle it will sit there and stumble/miss until it trips the CEL, but hit the throttle once right away and the miss is gone and it won’t trip the CEL. Happens so fast there isn’t time for it to warm up.

Oldgringo65 · Jul 6, 2022

pkrface said:
The 3.7 is pretty much the same as the 3.5. Just tweaked a bit to run higher compression to turn out 300 hp when the Ody was at 244 hp. This is the kind of thinking I’m looking for though. The problem has been slightly improved since the PCV valve change and the throttle body cleaning. By my logic that may indicate a poor performing injector or two? Cleaning the throttle body should have improved the air flow, correct? So an injector not spraying a perfectly fine mist, but not too far off or spec, might cause the problem right at start up and clear up quickly because added throttle increases the air flow plus heat builds pretty quick. That’s my best working theory at the moment, but still having trouble rectifying the 24 hours cold vs 48+ hours cold. What if the injectors were leaking down very slowly and had no pressure at start up? The faulty injector when it leaks down would develop a small air pocket, so turning the key and waiting for pressure to build before turning over would be of no use because the air pocket can’t escape fast enough just because fuel pressure was applied, but the injector had yet to be fired? So if instead of P0300 multiple misfires I could determine which injectors were the culprit I could change just the offenders. Thoughts?

Exactly my thoughts. I just rebuilt the top end of my J35A7 thanks to, believe it or not, a serpentine belt shredding and worked its way behind the crank pulley and into the timing belt. A lot of new parts and still had misfires on 1 and 5. Replaced those two new fuel injectors with two old ones and it purs like a kitten. The Foxwell nt510e really helped. Replacing the fuel injectors isn't a hard task. Take pictures as you remove the intake manifold. Saves guesswork.

pkrface · Jul 7, 2022

Oldgringo65 said:
Exactly my thoughts. I just rebuilt the top end of my J35A7 thanks to, believe it or not, a serpentine belt shredding and worked its way behind the crank pulley and into the timing belt. A lot of new parts and still had misfires on 1 and 5. Replaced those two new fuel injectors with two old ones and it purs like a kitten. The Foxwell nt510e really helped. Replacing the fuel injectors isn't a hard task. Take pictures as you remove the intake manifold. Saves guesswork.

Yeah I'm not intimidated on the fuel injector replacement. Just trying to make sure I only go in once. Interestingly the other day when I started it after it sat for 3 days I waited for a few seconds and it threw a P0304 code, so I have one suspect now identified. Between it running rougher than a single misfire and the P0300 code I'm convinced there are at least two.

DIY Fan · Jul 7, 2022

Carbon deposits on pistons? Maybe soak the pistons with Seafoam?

pkrface · Jul 7, 2022

DIY Fan said:
Carbon deposits on pistons? Maybe soak the pistons with Seafoam?

Why would that cause a varying symptom that changes depending on how long between starts? Again, not saying it's impossible, but the logic isn't there for that one unless you know something I don't.

WiiMaster · Jul 7, 2022

I think for something like Seafoam, it's easy enough to do that there's not much use in trying to find the logic in it, might as well just do it.

jabraham2005 · Jul 7, 2022

pkrface said:
I understand the cold to warm lash issue, but a little throttle applied right at start up and it clears up in 2 seconds. No joke, that quick. If I don’t apply a little throttle it will sit there and stumble/miss until it trips the CEL, but hit the throttle once right away and the miss is gone and it won’t trip the CEL. Happens so fast there isn’t time for it to warm up.

It doesn’t clear it up it just keeps it from throwing any misfire codes because you’re running the engine at a little bit higher rpm than just idle. You have to keep your foot on the throttle at about 1500 to 2000 RPMs for about a minute or so. Just basing a lot of information on past experience with this particular engine. If the valves are to tight it can cause a misfire, kind of like if you had bent valves they would not seat properly and would cause a misfire.

pkrface · Jul 7, 2022

jabraham2005 said:
It doesn’t clear it up it just keeps it from throwing any misfire codes because you’re running the engine at a little bit higher rpm than just idle. You have to keep your foot on the throttle at about 1500 to 2000 RPMs for about a minute or so. Just basing a lot of information on past experience with this particular engine. If the valves are to tight it can cause a misfire, kind of like if you had bent valves they would not seat properly and would cause a misfire.

Ok, that makes sense. No/low compression due to valves not seating well at least sounds plausible. Still not sure why it would act differently when it sits for 48+ hours vs 24. At 72 hours it‘s pretty much as bad as it’s going to get. Also getting white smoke at the same time, but not if started every day. Still leaning toward a fuel injector issue.

DIY Fan · Jul 7, 2022

I do not know anything but I am good at guessing. I only threw out several guesses on the off chance that one or more of them might be correct. Its possible your engine has more than one issue which is making it difficult to troubleshoot. Maybe a slight valve issue, a moderate amount of carbon buildup, a slightly leaking injector, full moon cycle? Honestly, I hope you get it fixed and good luck. We have 5 cars and when something goes wrong I usually try the cheap/easy fixes first.

pkrface · Jul 7, 2022

DIY Fan said:
I do not know anything but I am good at guessing. I only threw out several guesses on the off chance that one or more of them might be correct. Its possible your engine has more than one issue which is making it difficult to troubleshoot. Maybe a slight valve issue, a moderate amount of carbon buildup, a slightly leaking injector, full moon cycle? Honestly, I hope you get it fixed and good luck. We have 5 cars and when something goes wrong I usually try the cheap/easy fixes first.

I do the same thing, guess. Just looking to take the lowest cost, most educated guess possible first.

DIY Fan · Jul 16, 2022

Did you ever get this fixed?

pkrface · Jul 16, 2022

Not yet. Planning on getting a good fuel rail/injector cleaning done and see if that clears it up, but other priorities have crept up and it may be a few weeks at least. It's been an ongoing and progressing issue for pushing a year now, but the car typically only gets driven 1-2X a week for less than 20 miles which makes it less pressing to solve. The plan is to replace the car this fall, but I sell my own stuff and like to present even high mile cars as needing nothing currently with maintenance up to date so that it should be able to be driven confidently for 6-12 months for little to no expense other than gas and oil changes.

pkrface · Jul 28, 2022

Update. My low fuel light came on and it tripped an idea. I dumped a full can of SeaFoam into what I would estimate was around 4 gallons of fuel then drove about 20 miles. Let it sit for 48 hours then started it up. It was noticeably better, almost completely normal. I think I'm going to dump another can in to what I would now estimate is 2.5 gallons remaining in the tank. It will get driven a few short trips through the weekend, then will sit for Monday-Thursday at a minimum and we'll see what that does.

pkrface · Jul 30, 2022

Another update. Let the car sit 48 hours again and the start up this morning again was nearly normal. Slight miss right as the engine caught, but gone almost instantly. Most people wouldn't pick up on it. Let it idle without touching the accelerator for a few seconds then dropped it into reverse and pulled out. In the recent past this would have resulted in a continued miss and would have triggered the CEL. The fuel light typically comes on with approximately 4 gallons left in the tank judged by the fact that the tank is listed at 21 gallon capacity and if I fill up as soon as the light comes on I'll get 17 gallons in the tank, so the initial can of SeaFoam went into 4 gallons. Seafoam advises 1 oz of product per gallon of gas, so I put in approximately 4X that. Drove several short trips that equaled 20 miles to get the result I got this morning. I had a 20 mile round trip this morning and wanted to try adding another can of SeaFoam before that trip, so I did. Car will now sit at least 5 days, so I'll report again in about a week, but the issue seems 95% cured already.

pkrface · Aug 5, 2022

Another update. After sitting 5 days I was back to the same level of problem I had. Started really rough, missing, etc., but by giving it a little gas cleared up pretty quickly and didn't throw a CEL. I'm sure it would have if just left to idle. Hope to leave it sit for 48 hours and see if that improvement is still intact and if so will deem it a dirty injector issue and spring for a fuel rail cleaning in the near future, though may be a bit as it gets driven so little it won't be a top priority.

DIY Fan · Aug 25, 2022

On another misfire thread John Clark just said... "replace upstream and downstream O2 sensors".

Head Replacement

So, here we go! Currently sitting at this point. The plan is to document putting the pieces back together, I'll try to take a few photos here and there too. My head is ready, just have to go pick it up, along with the gasket set and new head bolts. I have a bunch of stuff to do first though...

www.odyclub.com

Odd Cold Start Issue

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DIY Fan

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DIY Fan

Head Replacement

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