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- #81
1997 1FZ Hiccupy idle and running rich
- Thread starter TX FJ80
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- 1997 rough idle
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Well you don't have a vacuum leak. Cross that off.
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- #83
One other piece of information that I might have omitted - it takes longer than expected to catch when cranking.
I took her out for an “Italian tune-up” today and when I went to start it after getting really warm - it seemed to take a couple extra revolutions to fire.
I took her out for an “Italian tune-up” today and when I went to start it after getting really warm - it seemed to take a couple extra revolutions to fire.
I've seen that be the fuel pump relay. I'll check tomorrow, but I'm sure I have a set of stock injectors laying around. If you want, fill out the paperwork and send me the shipping label and form and I'll sent out my set in place of yours and you won't have the truck down during the service.
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- #85
That’s really nice of you! I’m game.
Speaking of, I found another note in the PO’s paperwork suggesting a “Landtank MAF” - I read up on it. Could the improved sensor and airflow help with a less than smooth idle?
Also, I haven’t verified fuel pressure yet. Should I just to be safe?
Another thing i noticed today - the idle is smoother in drive with the brake applied (like at a stop light) and as soon as it goes in Park is when I can feel the odd hiccup here and there vibrate through my seat and steering wheel.
Other things I’m pondering, would love some feedback:
IAC lazy/gummed up/otherwise underperforming?
Dirty throttle body?
Fuel pressure regulator?
it could have one of my MAFs, take a pic of what you have.
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- #87
It doesn’t. It has the old stock style housing and MAF - I know because I swapped in a known good one from an LX450.
It was on a list of things he wanted to upgrade/change.
you should check the wiring to the connector as it could be still configured for my MAF.
Is that she said? Asking for a friendThat's interesting. I thought I retired in 2016.
I think some FZJ80s just have a slightly bumpy idle. Newer vehicles make it difficult to assess the 25 year-old beauties that are discussed here. I’ve got a 97 LX450. I’ve installed a new OEM block, head rebuilt (all valves within spec), injectors refurbed by witchhunter, no vacuum leaks. All new bits around the engine- including new engine harness. Still a very, very slight bumpiness in the seat at idle. Very hard to tell unless your OCD is turned on. Only thing I haven’t touched is fuel pump or fuel pump relay. I had one of the most highly regarded 80s mechanics tell me that some 1FZs just idle that way- even after replacing everything. If it’s running well aside from the ever-so-slightly bumpy idle, I’d just drive it.
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- #92
I hear you on all of that! Part of my obsessive hunt for this is to make sure I do not have some lurking problem that I am choosing to ignore...the other part is a little hyperfocus/OCD, and now a little sunk-cost fallacy - I can't let all this hard work go to waste!
If I work my way through all of the major systems, inspecting, cleaning, replacing the worn bits, catch-up any deferred maintenance, etc. and I still have a lumpy idle, well then I can look at my baselining as an investment into more trouble-free miles and peace of mind that is "just the way she is" and start enjoying her! I have had lots of quirky cars over the years - it just takes time to get there.
I fondly remember my 1994 LC has having a very smooth idle...but come to think of it, my other car at the time was a W123 diesel Mercedes, so that might have affected my judgment. I guess I never thought of that angle.
The vehicle that preceded the current LC was a very low-mileage vault like XC90, and the other cars I have now are my wife's NX300h and my city car - a VW e-Golf. I suspect my seat time in brand-new and electric vehicles is heightening my senses subconsciously.
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- #93
1 success, 1 partial victory, and 1 fail today.
I was able to successfully R&R the spark plugs - not great, not terrible shape. I numbered them and kept them - can post a pic tomorrow.
I failed at getting the all of the parts out of the way to do the spark plugs fast enough for the truck to stay warmed up for the compression check. It was my very first time taking that much apart on a 1FZ, and I wanted to go slowly as to not cause more harm than good - plus, my back was killing me leaning over the fender.
Even though I failed at getting the conditions correct for a compression check, I was able to get a fairly even compression reading for all 6 cylinders.
Throttle plate open, cranking for 5 revolutions:
- #1 - 160
- #2 - 155-160 (in between)
- #3 - 160-165
- #4 - 160
- #5 - 155-160
- #6 - 160
The bottom end is all stock with 250,95X on the clock, head/disty all new 60K miles ago. When the OE head gasket gave up, PO had it fixed right.
I plan on taking the upper intake off to do the injector-out cleaning and redoing all of the vacuum lines under there and some other stuff, so will check the valve adjustments then - when it is easier to access.
Relief is the right word - I didn't think it was possible this was due to internals, but sure is nice to have the data in front of me confirming all is well inside from a compression standpoint.
I am running out of usual suspects!
- Compression - good
- Timing - good
- Air - pulls hard vacuum and holds it - should be good, right?
- Spark - seems to be good, cap/rotor/plugs all new - wires seem fine
- Fuel - SUSPECT - need to test fuel pressure, FPR, fuel pump relay/circuit - have read about this causing low/shaky idling elsewhere
I am trying to think of anything else out of ordinary it could be.
- Electrical/magnetic interference?
- Wonky crankshaft position sensor/wiring?
- Very early stages of HB failure?
- Weak relay/relays?
- Timing one tooth off?
- Main engine wire harness failure?
- ECM slightly malfunctioning?
As Indiana80 said above - and I heard from others as well - some 1FZs just idle this way. That very well might be my final answer.
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- #94
One last observation/question.
I forgot to mention that I went ahead and installed the HuddExpo "test" kit in order to eliminate the vacuum spaghetti under the intake and/or uncommanded EGR opening as my root cause.
When installed the kit I noticed the EGR sensor was almost caked in black soot/carbon build-up.
Besides disassembly and cleaning, is there any way to break-up/clean what I imagine to be an intake that's caked in carbon? I was not planning on running my EGR for much longer, is there any downside to leaving it as-is?
Does the 1FZ handle the ol' water torture/Seafoam being sucked directly into the manifold trick well? I know it was a surefire way to revive an old Volvo redblock from carbon build-up and sitting, but my experience is application specific.
I forgot to mention that I went ahead and installed the HuddExpo "test" kit in order to eliminate the vacuum spaghetti under the intake and/or uncommanded EGR opening as my root cause.
When installed the kit I noticed the EGR sensor was almost caked in black soot/carbon build-up.
Besides disassembly and cleaning, is there any way to break-up/clean what I imagine to be an intake that's caked in carbon? I was not planning on running my EGR for much longer, is there any downside to leaving it as-is?
Does the 1FZ handle the ol' water torture/Seafoam being sucked directly into the manifold trick well? I know it was a surefire way to revive an old Volvo redblock from carbon build-up and sitting, but my experience is application specific.
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- #95
Thanks! I will get a pic tomorrow.
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- #96
Looks like a stock pin-out situation.
I am occupied this coming weekend, but will pull the TB within the next two weeks, clean it all up, including the IAC/ports, reinstall, and reassess.
I believe it to be isolated to IAC or fuel pressure when hot - also not ruling injector leakage, as you have suggested.
I have a 1fz-f carb'd cruiser and was fighting this exact issue.
Mine was the fuel filter, once replaced smoothed everything out.
Mine was the fuel filter, once replaced smoothed everything out.
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- #98
Mine was done 60K miles ago, but probably not a bad idea. I really should get some fuel pressure readings anyhow.
Also, the throttle body butterfly looked carboned up and the IAC has never been off the TB from what I can tell, so I am going to remove the whole assembly, partially disassemble, clean, etc.
i also have a 1fz that idles a bit rough. i'm comparing it to inline six bmw motors from the same era or newer. idling in D at a stop light i swear i can fill a slight miss through my butt, but not always, and the idle on my ultragauge reads between 600-650 rpm. i could just be looking for a problem where one doesn't exist.
i'm wondering what you are seeing for STFT, LTFT, and O2 voltages, and any other pertinent info from the Ultragauge (MAF?). as i saw you asking about, my TPS values range from 10-75I'm looking for numbers i can compare against, as i can't quite wrap my head around what I'm seeing for those at various conditions; cold engine and hot engine.
FWIW, my around town fuel mileage is about 10mpg on my ultragauge, which i've done a basic calibration for my 285 tires. i only get a 1/4mi before i hit a traffic light on my 5mi commute, so i'm always accelerating a big truck from a dead stop. front O2 sensor is new, rear i can't get off. most of the vacuum hoses are crusty and on the list to replace, as is the dist cap, plugs, wires, fuel filter, pcv and hoses, intake hose. none of those are obviously bad but i don't have records of their last replacement. i have most of those parts already, just haven't found the time. my plan is to pull the upper intake and send my injectors out at the same time, while i'm doing the filter, vacuum hoses, and tb coolant hose. i do have a vacuum test gauge so i'll duplicate what you did. and fuel pressure if i can find a good way to tap in.
i'm wondering what you are seeing for STFT, LTFT, and O2 voltages, and any other pertinent info from the Ultragauge (MAF?). as i saw you asking about, my TPS values range from 10-75I'm looking for numbers i can compare against, as i can't quite wrap my head around what I'm seeing for those at various conditions; cold engine and hot engine.
FWIW, my around town fuel mileage is about 10mpg on my ultragauge, which i've done a basic calibration for my 285 tires. i only get a 1/4mi before i hit a traffic light on my 5mi commute, so i'm always accelerating a big truck from a dead stop. front O2 sensor is new, rear i can't get off. most of the vacuum hoses are crusty and on the list to replace, as is the dist cap, plugs, wires, fuel filter, pcv and hoses, intake hose. none of those are obviously bad but i don't have records of their last replacement. i have most of those parts already, just haven't found the time. my plan is to pull the upper intake and send my injectors out at the same time, while i'm doing the filter, vacuum hoses, and tb coolant hose. i do have a vacuum test gauge so i'll duplicate what you did. and fuel pressure if i can find a good way to tap in.
