1997 FZJ80 - stock
250K total miles
60K miles ago - HG, new head, new everything "upper engine" besides intake/TB
Hiccupy idle and running rich. I describe it as hiccupy because it isn't stumbling, low, high, or even shaking the truck. You can only really feel it in your seat, and it's not 100% consistent.
I have owned the truck less than 96 hours, driven it about 150 miles, and had the first cold start in freezing weather, which has revealed *some* sort of small problem/problems.
I owned a very abused 1994 LC before that I rescued, drove for about a year, lost a place to park it, and sold it on.
I did NOT get a PPI, as I have previous experience with the 1FZ, the previous owner was meticulous, and kept great records and spared no expense on the truck. HG was previously done and there is paperwork to substantiate the work and PO's care over the last 10 years. I also did an exhaust gas test on the radiator, checked all fluids for signs of contamination, etc. - nothing out of order or out of place. As far as drivability...it is absolutely excellent,
EDIT: I also just noticed I have gas cap woosh. F.
My thoughts for potential cause thus far -
What else? Where to start?
I am very used to working on pure mechanical engine systems (diesel Mercedes, aircooled VWs, SBC) and also modern CANBUS systems - this combo of simple electro-mechanical/vacuum system without plug-n-play modular diagnostics is not easily understood by me.
Even though I have been thumbing through the FSM, I cannot figure out where to start.
Please help me with a starting point.
250K total miles
60K miles ago - HG, new head, new everything "upper engine" besides intake/TB
Hiccupy idle and running rich. I describe it as hiccupy because it isn't stumbling, low, high, or even shaking the truck. You can only really feel it in your seat, and it's not 100% consistent.
I have owned the truck less than 96 hours, driven it about 150 miles, and had the first cold start in freezing weather, which has revealed *some* sort of small problem/problems.
I owned a very abused 1994 LC before that I rescued, drove for about a year, lost a place to park it, and sold it on.
I did NOT get a PPI, as I have previous experience with the 1FZ, the previous owner was meticulous, and kept great records and spared no expense on the truck. HG was previously done and there is paperwork to substantiate the work and PO's care over the last 10 years. I also did an exhaust gas test on the radiator, checked all fluids for signs of contamination, etc. - nothing out of order or out of place. As far as drivability...it is absolutely excellent,
EDIT: I also just noticed I have gas cap woosh. F.
My thoughts for potential cause thus far -
- Small unmetered air leak in/around air hose from filter to TB (OEM air hose form 2017 - clamps look original though)
- Something to do with the gas cap woosh.
- Lazy O2 sensors (I believe original)
- Ignition timing, cracked plug, failing plug wire(s) - (everything was brand new OEM in 2010, plugs were changed 2017+)
- Vacuum leak (some hoses look new, some look OE)
- Sticky/lazy injector
- Fuel pressure fluctuations (no evidence of a fuel pump failing or being replaced, fuel filter done in 2010, 60K miles ago)
What else? Where to start?
I am very used to working on pure mechanical engine systems (diesel Mercedes, aircooled VWs, SBC) and also modern CANBUS systems - this combo of simple electro-mechanical/vacuum system without plug-n-play modular diagnostics is not easily understood by me.
Even though I have been thumbing through the FSM, I cannot figure out where to start.
Please help me with a starting point.