Stumbling/Stalling during Idle

[Mattglas]

what did the smoke smell like? How much resistance was their when you first pushed down on the air plate? Pushing down that far would dumped fuel into the hot heads and any valve that was open. It could have just been fuel boiling off. or oil residue in the intake from crankcase venting. worst case would be coolant vapor steaming off. It just depends on what smell like as to what it might be.

It didn't really smell like anything and the plate had pressure everytime I pushed on it. It probably was fuel boiling off.

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[DMC5180]

It didnt really stutter, though the movement did get faster towards the end of it's travel.

I also noticed the mine seemingly has a bigger gap than yours. I included a picture just for comparison

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I should have mentioned that I have Dave's Idle ECU. that's why mine Closed all the way before popping open.

[lazabby]

Sweet, once I get this issue fixed I'll pm you about buying one.


In other news, while testing I noticed that when the cooling fans came on the car would suddenly start to idle hunt. Once the fans stopped the idle hunting stopped. Possible ground issue?

My car is hunting with the AC on. Might be a similar issue as yours. I have new plugs, new fuel injectors, new CO2 sensor. I may need to tweak the idle with the dwell meter.

[David T]

My car is hunting with the AC on. Might be a similar issue as yours. I have new plugs, new fuel injectors, new CO2 sensor. I may need to tweak the idle with the dwell meter.

You cannot "fix" the idle by adjusting things. If the idle is hunting a lot (some is normal) it is because of some imbalance among the 6 cylinders. As it comes around to the weaker one the motor slows down and then speeds up as it fires on the next, more powerful one. Something is different among the cylinders, a spark plug gap, a valve adjustment, a bad ignition wire, something that makes one or more cylinders less efficient. Just because you have new parts does not mean they are all the same. Especially the fuel injectors.

[Mattglas]

Today I was thinking about Bitsyncmaster's post on how sudden problems could be the result of the fuel pump. So, I decided to check it out. Which was a good idea, judging by all the rotten plastic clogging it.

20170801_223920.jpg20170801_223915.jpg20170801_230333.jpg20170801_223941.jpg

I'm not really sure how any of it got there. The first thing I did when I purchased my car was clean the fuel tank.

[Jonathan]

Today I was thinking about Bitsyncmaster's post on how sudden problems could be the result of the fuel pump. So, I decided to check it out. Which was a good idea, judging by all the rotten plastic clogging it.

20170801_223920.jpg20170801_223915.jpg20170801_230333.jpg20170801_223941.jpg

I'm not really sure how any of it got there. The first thing I did when I purchased my car was clean the fuel tank.

And did you get your car fairly recently?

If you put that new fuel pump/sender combo into a clean tank, that debris would need to have either been part of something else already in the system or introduced through one of the openings.

New material can obviously come into the fuel system by way of filling up at the gas station. Not likely that it's in the gas you're buying, but maybe down through the fuel filler cap. Some piece of plastic that was being used to cover things being painted perhaps?

Existing material might be part of the inside of some hose that's deteriorating. Or plastic wrap not realized was still on a new part like the fuel pump/sender combo unit or even the fuel sender hole filler cap (the one not used anymore with the combo set-up). I've seen packaging mistakenly left in systems in industrial environments so it could happen with our cars too.

Another possibility might be the fuel filler neck when you did your cleaning was hiding a mess of spider webs or other bug or critter debris. If that wasn't noticed and then everything got buttoned back up and the tank filled with fresh gas, it could have flushed it all in there. Same too with the smaller lines for the roll over valve (although less likely as they're pretty small and don't have any "flow" through them).

Based on the volume of comments I see or hear from people with fuel tank contamination, I'd guess it was an old hose disintegrating that left you with this mess. I've not seen my own evidence of that first hand, so take it with a grain of salt, but it does get mentioned frequently.

[Mattglas]

And did you get your car fairly recently?

If you put that new fuel pump/sender combo into a clean tank, that debris would need to have either been part of something else already in the system or introduced through one of the openings.

New material can obviously come into the fuel system by way of filling up at the gas station. Not likely that it's in the gas you're buying, but maybe down through the fuel filler cap. Some piece of plastic that was being used to cover things being painted perhaps?

Existing material might be part of the inside of some hose that's deteriorating. Or plastic wrap not realized was still on a new part like the fuel pump/sender combo unit or even the fuel sender hole filler cap (the one not used anymore with the combo set-up). I've seen packaging mistakenly left in systems in industrial environments so it could happen with our cars too.

Another possibility might be the fuel filler neck when you did your cleaning was hiding a mess of spider webs or other bug or critter debris. If that wasn't noticed and then everything got buttoned back up and the tank filled with fresh gas, it could have flushed it all in there. Same too with the smaller lines for the roll over valve (although less likely as they're pretty small and don't have any "flow" through them).

Based on the volume of comments I see or hear from people with fuel tank contamination, I'd guess it was an old hose disintegrating that left you with this mess. I've not seen my own evidence of that first hand, so take it with a grain of salt, but it does get mentioned frequently.

I think the debris must have come from the fuel filler tube. I couldn't find anything else that could have caused it.

[Mattglas]

I did some fuel injector testing in order to rule them out as a problem. I'm not really sure what to make of my findings, the amount of fuel in each container varied on every test I did.
I pushed the plunger down fully for 1 min and checked if each container reached the 6oz mark. Some times they did and sometimes they didn't. Could this be a problem with the fuel distributor? I changed the injectors around and still got the same results.

First test:
20170808_221928.jpg

Third Test:
20170808_232156.jpg

[Bitsyncmaster]

I did some fuel injector testing in order to rule them out as a problem. I'm not really sure what to make of my findings, the amount of fuel in each container varied on every test I did.
I pushed the plunger down fully for 1 min and checked if each container reached the 6oz mark. Some times they did and sometimes they didn't. Could this be a problem with the fuel distributor? I changed the injectors around and still got the same results.

First test:
20170808_221928.jpg

Third Test:
20170808_232156.jpg

Try running the test pushing the air plate about half way down. I had one cars test really have a problem pressed fully.

[Mattglas]

Try running the test pushing the air plate about half way down. I had one cars test really have a problem pressed fully.

I redid the test pushing halfway down and found that the inconsistency goes away. However, they are not exactly even. Some have a just a bit more gas in them.

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