Popping noise from engine bay during start up, free rev, light roll on throttle

[Sportsguy83]

Originally Posted by sierra

I was always taught to not idle a cold engine but drive it straight away and gently until the temp is up to normal. Also that it takes up to 30mins to get everything up to normal operating temperature.

Everything I have read about it confirms that to idle a cold engine for any time not only wastes fuel but causes harm and i've just done some more googling to double check.
Basically, a cold running engine is bad news and you need to get up to temp as quickly as possible but on minimal load. To let it idle keeps it cold longer with the rich mixture causing wear to the cylinder walls.

Great info, I learn something new everyday! Thanks!

[driftartist]

what about when the car goes into closed loop and the o2 sensors are warmed up the fuel trim changes according....sure driving at minimal load will make the car heat up faster but i dont think idling the car at startup will damage anything as the pgfi will create the best fuel trim to prevent damage. the 02 sensors generally heat up on 60-90 seconds and then trim goes to closed loop.

[sierra]

Originally Posted by driftartist

what about when the car goes into closed loop and the o2 sensors are warmed up the fuel trim changes according....sure driving at minimal load will make the car heat up faster but i dont think idling the car at startup will damage anything as the pgfi will create the best fuel trim to prevent damage. the 02 sensors generally heat up on 60-90 seconds and then trim goes to closed loop.

Let's say it isn't detrimental to let it idle cold. What's the point in letting it idle anyway? 30 sec at idle seems to be the time to get everything circulated and ready to go. Gentle driving at low rpm with minimal load, then increasing as the temp rises, makes sense and is widely accepted to prevent wear.
I can understand the thought that letting it idle to warm it up is the right thing to do.
Across the road from a business I had was workshop that rebuilt a customers engine and they were very good at what they did. The customer left the car there for over a year in storage while he went overseas. Every morning they started it up and drove it across the road, leaving it idling while they sorted the other cars out, brought it back across and turned it off. Same at the close.
When the owner came back to pick up his car he brought it back and complained the engine was knackered and they had done a crap job.
They argued it was knackered from all the cold start idling and he shouldn't have left it there. I have no idea how that one got resolved.

Apparently it can also plug the cat because it's cold and stays cold at idle, so it can't burn off the carbon as it normally would.

[frsvr4]

Originally Posted by blu_

OT but letting your car "warm up" at idle does more harm than good on modern engines.

Please elaborate. There's clearly a threshold where letting it idle to warm up goes from beneficial to useless and then another threshold from useless to harmful. Is the first threshold 20 seconds? 1 minute? Your blanket statement is insufficiently vague.

Originally Posted by sierra

I was always taught to not idle a cold engine but drive it straight away and gently until the temp is up to normal. Also that it takes up to 30mins to get everything up to normal operating temperature.

Everything I have read about it confirms that to idle a cold engine for any time not only wastes fuel but causes harm and i've just done some more googling to double check.
Basically, a cold running engine is bad news and you need to get up to temp as quickly as possible but on minimal load. To let it idle keeps it cold longer with the rich mixture causing wear to the cylinder walls.

1) you're claiming that modern engines run so excessively rich @ idle that fuel washes past the cylinder rings (which causes tons of ring & wall wear and engine bearing wear as fuel is a horrible lubricant). What's your A:F at start-up?

2) the alleged excessively rich start-up condition goes away when you go into gear at low rpm? Are you saying the ECU realizes you're in gear and adjusts the A:F? Otherwise you're just getting more revolutions (even if it's less time) with an excessively rich A:F. Not to mention the oil pressure...

3) have you ever seen an accurate oil pressure gauge on an ice cold engine? You can drive the car as gently as physically possible and still see 100+ psi @ 2000 to 2500 rpm's. What's the oil pressure relief valve on these cars set to?

tldr - support your blanket statements, gentlemen.

[sierra]

Originally Posted by AdamVR4

Your blanket statement is insufficiently vague.

I wish you had asked me to be more vague too.

It's just an opinion at the end of the day and you could be correct.

[blu_]

Originally Posted by AdamVR4

Your blanket statement is insufficiently vague.

Wait, you want me to be more vague?

[Margovincent_22x]

Have the same problem and I had it checked and will wait for results tomorrow.

[YodrOne]

I recently came across the same problem as the OP. My car is used in a very similar fashion (lot's of HPDE and as a daily driver). The symptoms and sounds according to the video are also exactly the same and it's been getting worse over the last month or so. Time for a dealer visit.

I'll update once everything's settled. Btw, only mods on my car are RCE springs, Hawk DTC-60 pads/fluid and I run Yoko AD08 tires for track on some cheap tirerack 17's. Mechanically and otherwise bone stock.

[Dezoris]

Originally Posted by YodrOne

I recently came across the same problem as the OP. My car is used in a very similar fashion (lot's of HPDE and as a daily driver). The symptoms and sounds according to the video are also exactly the same and it's been getting worse over the last month or so. Time for a dealer visit.

I'll update once everything's settled. Btw, only mods on my car are RCE springs, Hawk DTC-60 pads/fluid and I run Yoko AD08 tires for track on some cheap tirerack 17's. Mechanically and otherwise bone stock.

If it pops contantly on stabs of throttle at idle after warm its probably DI seals. Post up video if possible.

[YodrOne]

Originally Posted by Dezoris

If it pops contantly on stabs of throttle at idle after warm its probably DI seals. Post up video if possible.

Sorry, no time to do a video right now but it's definitely the DI seals. Took it to the dealer and that's what they came up with. Seals are on back order. Hopefully that's the extent of it.


My car only has 16k miles on it. Gonna suck if I have to have this done at that interval.

[CBR600RR]

How loud is this "Firecracker" sound anyways? what does it sound like while driving?

does it occur during the middle acceleration? or just when going from off throttle to on throttle?

[Astroboy]

Originally Posted by Sargy

Hasnt happened to me for a month now
But the 4-5 months before I heard a pop every once in a while, twice backfiring (sounded awesome!)

But seeing all of this, I'm slightly concerned. Havent had any of this activity while driving though.

Did your car start running like shit when you had this? What are the symptoms, just popping sounds? Any while driving?
I experience a pop like sound, along with a slight shake to my car with it, right when I turn it on. It only happens when I turn the wheel completely to the right. Like literally, right when it starts up, you hear just one pop like sound. My engine also use to rattle when the symptom occurred but soon stopped after I added motor mounts. So Idk what it could be. Car runs fine no idle dips or anything

Originally Posted by Mark Slide Squad

I just had the same exact issue with my car a couple weeks back. Starting popping and misfiring, and the noise was coming from the intake manifold area. It happened when you would first start it up, and also when you had a lot of load on it at low RPM. Took it to the dealer and they had the car for about a week. They had to get a master toyota tech flown in to really figure it out, since the regular guys at the dealer found nothing wrong. The master tech checked fuel pressure, compression, leak-down, plugs, MAFS, and a bunch of other things and found nothing. Then he ran the car only using the multiport injection and the car ran fine. Then he ran it only using the direct injection, and it was misfiring/popping. They traced it down to a bad isolator on one of the direct injectors. It was actually just straight up MISSING! It was there before, so something happened, perhaps related to heat. I think eventually the injector isolator cracked and broke apart and created a vacuum leak. At any rate, it took them several days to get a new isolator as it was on back order. They replaced it, and the car runs like a champ now. I'm pretty sure it's the same problem you have, and I have heard of a few other people now on here having the same issue.

[Astroboy]

Originally Posted by YodrOne

I recently came across the same problem as the OP. My car is used in a very similar fashion (lot's of HPDE and as a daily driver). The symptoms and sounds according to the video are also exactly the same and it's been getting worse over the last month or so. Time for a dealer visit.

I'll update once everything's settled. Btw, only mods on my car are RCE springs, Hawk DTC-60 pads/fluid and I run Yoko AD08 tires for track on some cheap tirerack 17's. Mechanically and otherwise bone stock.

Did your car run like shit while driving? Seriously how loud is this pop or popping? Any changes in the rpms?

[Astroboy]

Originally Posted by Margovincent_22x

Have the same problem and I had it checked and will wait for results tomorrow.

What were the results?