1FZFE Slight Miss at Idle

[PapaJoe]

As a follow-up to this: I changed out the small vac hoses and the miss disappeared. No check engine light. Several of the vac hoses broke apart when I pried them with a pick so there was likely a leak.
Anyway, looks like a vac leak was causing #6 to miss.

 

[rannon]

I don’t know. Maybe all 1FZFEs do this? It’s not terrible, but you feel the hiccup in driver seat.

Precisely - I have this symptom and I feel it in the driver's seat. Full HG service less than 200 miles ago. So strange. Solution?

 

[Indiana80]

Precisely - I have this symptom and I feel it in the driver's seat. Full HG service less than 200 miles ago. So strange. Solution?

I’ve had 2 highly regarded 1FZ mechanics tell me that some just idle like that. One called it a “burble” at idle. In my case, I had a new short block with cleaned up head installed. The shop that did the original work sucked. Valves weren’t properly adjusted and had a vac leak at intake gasket. 2nd shop remedied and made a huge difference. I’ve done a lot of little follow up work on it- new MAF, all new vac lines, new EGR Valve, new fuel pump, and every sensor I replaced except the knock sensors. Someone told me knock sensors either work or they don’t. Injectors were refurbed by Witchhunter- maybe I should have replaced them, as some have said. End story, I have a near perfect idle at ~650RPMs with the very occasional “burble”. It’s almost non-existent with a tank full of ethanol-free fuel, and more noticeable with ethanol-blended fuel. If it helps anyone, with an ultra gauge and pure “gas” I see ~+3 for long term fuel trim and -3 for short term fuel trim. With ethanol gas my long term fuel trim hits +10 and it idles a little rougher. I spent a long time time chasing the “burble”. Embrace it, it probably will always be there to some degree.

 

[rannon]

Wow, new short block even? That is basically a brand new engine (jealous), and still the burble? Great term for it btw, it's a burble alright.

I can only imagine how frustrated you must have been after dealing with that first shop given the depth of work to be done.

Well thanks for weighing in and sharing those details. I suppose embracing it to some degree is a good way to go. I'll do all the normal box checks like wires, o2, rotor, cap and such and embrace it after that.

 

[Indiana80]

Wow, new short block even? That is basically a brand new engine (jealous), and still the burble? Great term for it btw, it's a burble alright.

I can only imagine how frustrated you must have been after dealing with that first shop given the depth of work to be done.

Well thanks for weighing in and sharing those details. I suppose embracing it to some degree is a good way to go. I'll do all the normal box checks like wires, o2, rotor, cap and such and embrace it after that.

As long as it runs down the road well, not burning copious amounts of oil, and not losing coolant, don’t sweat it. An ultra gauge tool is helpful in monitoring temps and watching fuel trims.

 

[Indiana80]

As long as it runs down the road well, not burning copious amounts of oil, and not losing coolant, don’t sweat it. An ultra gauge tool is helpful in monitoring temps and watching fuel trims.

 

[Indiana80]

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My buddy bought a new Bronco when they first came out. He had to wait to take delivery, based on discount he arranged with dealer- allowed them to keep his truck for others to test drive for a few months since they were scarce at the time. I couldn’t resist this picture. The 80 is the gold standard of SUVs.

 

[rannon]

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Cheers to that. Thanks again.

 

[Indiana80]

My buddy bought a new Bronco when they first came out. He had to wait to take delivery, based on discount he arranged with dealer- allowed them to keep his truck for others to test drive for a few months since they were scarce at the time. I couldn’t resist this picture. The 80 is the gold standard of SUVs.

And in case you’re getting any wild ideas, I put a new main engine wire harness and known good ECU in it. Also replaced all the engine ground wires, swapped in new military grade battery cables (super nice MUD member sells them), and replaced the oil dipstick tube with NOS- the old one was seeping and I figured maybe a vac leak. No change in burble. With a vacuum gauge, mine indicates no unmetered air getting in. Biggest improvement came from non-ethanol gas. Someday I might throw some new OEM injectors in, or not. Or, if market comes back to COVID levels, I may list on Bring-A-Trailer. It’s a super clean, dry, no rust on body or frame, southern truck. In the mean time, I’m just going to drive it and smile- but only in the summer and fall- I’m in Indiana.

 

[rannon]

And in case you’re getting any wild ideas, I put a new main engine wire harness and known good ECU in it. Also replaced all the engine ground wires, swapped in new military grade battery cables (super nice MUD member sells them), and replaced the oil dipstick tube with NOS- the old one was seeping and I figured maybe a vac leak. No change in burble. With a vacuum gauge, mine indicates no unmetered air getting in. Biggest improvement came from non-ethanol gas. Someday I might throw some new OEM injectors in, or not. Or, if market comes back to COVID levels, I may list on Bring-A-Trailer. It’s a super clean, dry, no rust on body or frame, southern truck. In the mean time, I’m just going to drive it and smile- but only in the summer and fall- I’m in Indiana.

Holy crap! Well that settles that! It actually puts my mind at ease to be honest - drive and smile and move on with it. THANK YOU!

 

[thelal]

...

I clear my settings regularly, especially before a long trip (3+ hours). Because I DD my truck, it learns the setting based on in-city traffic and slower speeds. When I hit the highway, it continues o fuel it based on those levels and I get horrible mileage. I can see a 1-2 MPG increase when I do this.

interesting on the improvement on MPG