Camry idle stumbles when starting

[ajkalian]

I've got a 2000 Camry 6cyl and noticed that when I started it up in the morning the idle speeds up as it should in a cold engine, then slows down and almost stalls out. But applying a bit of pressure on the accelerator gets me out of the driveway and down the street. After that it idles fine around 1200-1300 then when it warms up, falls back to 700-750. It doesn't seem to affect anything else, just a bit annoying.

So a couple of days ago I did an oil change and as part of it, I usually remove the air filter and blow it out with compressed air, and then vacuum out the debris that gathers in the box the air filter fits in. When I removed the air filter I noticed that one corner of the gasket that surrounds the air filter was all bent out of shape and crimped pretty badly. I guess I got a temporary case of the Dumb Ass when I put it in and wasn't paying attention. I tried putting the gasket back in place, but it was too mangled to stay where it was supposed to. So I epoxied it to the air filter, waited for it to set, and then carefully put it back in the box.

I usually get Fram filters, and I thought they had a solid flange around the air filter. But this time around I decided to try something different, so I got a Purolator air filter. It was black, and had the gasket.

Note to self, get a Fram orange single piece next time and avoid these problems.

So I'm at WalMart and decide to look at air filters, and guess what. The Fram's are now black, and exactly like the Purolator ones and they have the gasket that goes around the filter. There were some single piece orange ones there, but the ones for the Camry were all black with the gaskets. Did I miss something. Did Purolator buy out Fram? Or did WalMart substitute Purolator air filters for Fram filters.

Anyway, when I started up the car after the air filter gasket Monkey Drill, it fired right up, ramped up the idle, as it should and now everything is right with the universe.

So, be careful when you put in the air filter with a gasket around the outside. Be sure that it seats properly. Seems that a tight seal is pretty important for proper engine operation. Who knew.


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[fenixus]

that's interesting... I once had a problem with detached air filter gasket too, I actually improperly installed it in the box so the gasket got caught by box cover when I was closing clamps. it haven't caused any adverse effects on wife's 5s-fe though ... was running like that for 6 months or so...

I usually used FRAM air filters or sometimes Purolator and I have to admit that I haven't seen the orange gasket FRAM since a long time.... both look same nowadays (same shitty gasket design, easy to get detached).

[Jason.MZW20]

Yeah, the MAF is sensitive to pressure changes in the air stream. The 1MZs with AFR sensors will adjust very quickly. I would've loved to see your fuel trim data for something like that. I'm at +72% with a bad MAF. The AFR sensors ramp up the injectors really quickly, so my engine never stalled, but it did have a lumpy idle.

[ajkalian]

Originally Posted by Jason.MZW20

Yeah, the MAF is sensitive to pressure changes in the air stream. The 1MZs with AFR sensors will adjust very quickly. I would've loved to see your fuel trim data for something like that. I'm at +72% with a bad MAF. The AFR sensors ramp up the injectors really quickly, so my engine never stalled, but it did have a lumpy idle.

I'm not sure if this shows anything, since both times the car isn't running, It was scanned after driving around town. Maybe parked for 10 minutes each time. The top one is from the 2/13 when the gasket was foobar, and the bottom one was from today 2/23 after I repaired the gasket.






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[fenixus]

MAF detected exactly same air flow in both screen shots. also the second screen shot shows too cold coolant temperature and engine is still in Open Loop mode and ECU was ignoring the AFR sensors (no readings on them as well).

I see that first pic shows Open Loop as well, but in fact ECU was in a closed loop already (80C coolant right before thermostat opens) and AFR readings are there.

i'd say it doesn't prove anything, sorry.

[ajkalian]

Originally Posted by fenixus

MAF detected exactly same air flow in both screen shots. also the second screen shot shows too cold coolant temperature and engine is still in Open Loop mode and ECU was ignoring the AFR sensors (no readings on them as well).

I see that first pic shows Open Loop as well, but in fact ECU was in a closed loop already (80C coolant right before thermostat opens) and AFR readings are there.

i'd say it doesn't prove anything, sorry.

Yea, I didn't think it would be of any value. No matter, the stalling got fixed when I fixed the gasket.

Of course I could fold back the gasket, then go for a drive, warm it up, and then take another scan. Come back home, fix the gasket again, then go for another trip and another scan and compare the results. But somebody will have to pay me some money to do all of that.


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[fenixus]

LOL

i'm not paying

[Jason.MZW20]

That's the standard MAF voltage at IGN ON. Mine also reads 0.24gm/s.

Also, the CA spec ECUs are only in open loop at this time. Once the engine is started, it's immediately in closed loop.

If you change the throttle position at IGN ON, you'll see the fuel trim maps for the TPS %. My idle has always suffered with +14% or more LTFTs with a slow MAF, now idle is at +72% with a bad MAF (completely maxed).



This is with the engine running, of course. But, IGN ON would show the same thing just without RPM or airflow data.

1.89gm/s is way too low. 3.3-4.7gm/s is considered normal for idle. It was a junkyard MAF with unknown mileage.

[fenixus]

good eye! I actually missed the fact that RPM was saying 0rpm so engine was not running

so with shut off engine, MAF is not really detecting anything useful, because there is no air flow per se ...

man, you need a new MAF ... +74% total FT !!??

Originally Posted by Jason.MZW20

That's the standard MAF voltage at IGN ON. Mine also reads 0.24gm/s.

Also, the CA spec ECUs are only in open loop at this time. Once the engine is started, it's immediately in closed loop.

If you change the throttle position at IGN ON, you'll see the fuel trim maps for the TPS %. My idle has always suffered with +14% or more LTFTs with a slow MAF, now idle is at +72% with a bad MAF (completely maxed).



This is with the engine running, of course. But, IGN ON would show the same thing just without RPM or airflow data.

1.89gm/s is way too low. 3.3-4.7gm/s is considered normal for idle. It was a junkyard MAF with unknown mileage.

[Jason.MZW20]

Yeah, I know. Because the closed loop system is maxed, ever since I found out (P0171 reported), I haven't driven the car.

Now you see how important the MAF readings are as they control the primary injection pulsewidths. It's likely the injection pulsewidths are below 1.0ms before correction. At 0.9ms using a 2.9ms normal injection pulse as a reference, the difference is still only 69%. Could be somewhere between 0.7ms (76%) and 0.8ms (72.4%).

If you notice, bank 2 is still reading lean. 0.695V * 5 = 3.475V, which is slightly lean even though the system is maxed.

[fenixus]

yes, you are correct, I see what you mean now. so basically that junk yard MAF was garbage? 1.89g/s is way below normal (mine reads like 3.4g/s at idle IIRC).

brand new OEM one from online dealer is around $170 (at least for my chassis code), maybe it's time to get one of those?

Originally Posted by Jason.MZW20

Yeah, I know. Because the closed loop system is maxed, ever since I found out (P0171 reported), I haven't driven the car.

Now you see how important the MAF readings are as they control the primary injection pulsewidths. It's likely the injection pulsewidths are below 1.0ms before correction. At 0.9ms using a 2.9ms normal injection pulse as a reference, the difference is still only 69%. Could be somewhere between 0.7ms (76%) and 0.8ms (72.4%).

If you notice, bank 2 is still reading lean. 0.695V * 5 = 3.475V, which is slightly lean even though the system is maxed.

[Jason.MZW20]

Originally Posted by fenixus

yes, you are correct, I see what you mean now. so basically that junk yard MAF was garbage? 1.89g/s is way below normal (mine reads like 3.4g/s at idle IIRC).

brand new OEM one from online dealer is around $170 (at least for my chassis code), maybe it's time to get one of those?

Yeah, I'm going to get a new MAF since it includes the gasket. I'm tired of making gaskets with black RTV. Even when my MAF was reading around 3.2gm/s, my fuel trims were still positive, so my engine is healthy. I could tell my MAF had issues since it would read 3.2gm/s for a few seconds then slowly drop as I continued to idle. Eventually, it'd settle to around 2.2-2.5gm/s and the fuel trims were completely screwed at +35%.

[ajkalian]

Originally Posted by Jason.MZW20

Yeah, I'm going to get a new MAF since it includes the gasket. I'm tired of making gaskets with black RTV. Even when my MAF was reading around 3.2gm/s, my fuel trims were still positive, so my engine is healthy. I could tell my MAF had issues since it would read 3.2gm/s for a few seconds then slowly drop as I continued to idle. Eventually, it'd settle to around 2.2-2.5gm/s and the fuel trims were completely screwed at +35%.

Ya know it's funny you mentioned the gasket on the MAF. I replaced my MAF several years ago. Toyota wanted like $170 and I got it at Autozone for $85 IIRC. Anyway it didn't come with a gasket, so I re-used my old one.

But I figured I'd get one from the dealer. So off I go, but when I get to the dealers parts counter the guy says that the part number I gave him 22204-20010 doesn't show a gasket. Well I explain to him that it does come with a gasket because I have one. So he calls over the Manager of the parts department. Mr. KnowItAll agrees with the parts guy, and says that he has never seen a gasket for the MAF. So I look at both of them with my best "you people are so full of shit" look, and the Manager says, "can you show me?" Sure I say, no problem, as I pull a 10mm wrench out of my pocket, since I was planning on replacing it in the parking lot.

We go out to the car, and I took the MAF off and sure enough there was the gasket. Mr. KnowItAll was speechless and just mumbled something like "well you learn something new every day." I just nodded in agreement, put the MAF back in, along with the old gasket and to this day the original one is still in there.

So what's the deal with this gasket. Does it cause cancer in rats, and the EPA has banned it?

I feel so special that I have an original one.


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[Jason.MZW20]

I have no idea what Toyota was thinking. In the service manual, it says to replace the gasket. Yet, you go to the parts counter and try to get a gasket and they say, well, one isn't shown. So, you can't get one separately. I guess Toyota changed face and just decided that it'd be okay to reuse the old gasket. And it does need a gasket otherwise, unfiltered air is drawn in from the MAF mounting area.

But what about when you need a new gasket after the old one hardens up? It just doesn't make sense. The newer MAFs use an o-ring, so they're completely different than these ones.

[ajkalian]

Originally Posted by Jason.MZW20

I have no idea what Toyota was thinking. In the service manual, it says to replace the gasket. Yet, you go to the parts counter and try to get a gasket and they say, well, one isn't shown. So, you can't get one separately. I guess Toyota changed face and just decided that it'd be okay to reuse the old gasket. And it does need a gasket otherwise, unfiltered air is drawn in from the MAF mounting area.

But what about when you need a new gasket after the old one hardens up? It just doesn't make sense. The newer MAFs use an o-ring, so they're completely different than these ones.

Here, take this with you to the parts counter, and holding it in one hand, and pointing with the other, say with a scowl on your face...Hey LeRoy, WTF is this ???






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