1997 1FZ Hiccupy idle and running rich (1 Viewer)

[TX FJ80]

There is a way to "turn off" the EGR via a test plug. Read up on this thread. I have done this for the last 10k with no issues.

Have you checked your emissions setup like this? MPGs good?

I checked my EGR function tonight - applying vacuum kills the engine like the FSM says it should. It didn't seem to respond to applying and positive pressure, so that's good.

One of the modulator tests - air flow through Port Q test below and above 2500 RPMs seemed to pass fine.

However, I was unable to get any vacuum between the modulator and the EGR when the engine was hot, at any RPM. I might have c*cked that last test up, so I will try again tomorrow in the daylight.

Unless I decide to go down the EGR delete path, it looks like I need to re-check the vacuum system - not for leaks but for commanding the wrong airflows through the VCV or a dead VSV.

I have learned more than I never wanted to know about emissions controls...

 

[mudgudgeon]

I have learned more than I never wanted to know about emissions controls...

lol

The joys of owning an old cruiser! Is amazing what you learn

 

[landtank]

lol

The joys of owning an old cruiser! Is amazing what you learn

and half the lessons are how to disable, remove or avoid the problem.

 

[logicbyondreaso]

Have you checked your emissions setup like this? MPGs good?

I checked my EGR function tonight - applying vacuum kills the engine like the FSM says it should. It didn't seem to respond to applying and positive pressure, so that's good.

One of the modulator tests - air flow through Port Q test below and above 2500 RPMs seemed to pass fine.

However, I was unable to get any vacuum between the modulator and the EGR when the engine was hot, at any RPM. I might have c*cked that last test up, so I will try again tomorrow in the daylight.

Unless I decide to go down the EGR delete path, it looks like I need to re-check the vacuum system - not for leaks but for commanding the wrong airflows through the VCV or a dead VSV.

I have learned more than I never wanted to know about emissions controls...

My truck runs very well. I did re-do all of my vacuum lines during baselining like you are doing now. During that phase I found my VSV was faulty causing a P0401 code. Once replaced with new, the code cleared. I drove it around for a few thousand miles to verify it was fixed and then installed the HuddExpo "test" kit. I installed the kit to keep the intake cleaner and reduce heat near the harness even though I insulated it.
All of the above was done before I made any modifications such as the LandTank MAF kit and supercharger. I wanted the truck to run as designed before adding any components.

After inspection, the harness was wrapped in fiberglass heat tape and then with thermaflect tape.

 

[TX FJ80]

I wanted the truck to run as designed before adding any components.

After inspection, the harness was wrapped in fiberglass heat tape and then with thermaflect tape.

View attachment 2566380 View attachment 2566382

I am headed down your same path then. I ordered the HuddExpo kit, but I am going to get every single thing functioning as designed first, then start making mods.

Can't build a solid house on a shaky foundation, or some cheesy platitude like that.

Question: If I suspect the modulator works, but is not getting the right inputs at the right time, does that point to VSV?

 

[TX FJ80]

During that phase I found my VSV was faulty causing a P0401 code. Once replaced with new, the code cleared.

I wish I could get all of that from under the manifold and redo it without taking the top of the intake off, but here we are. I saw a video of a guy fishing it out of there, but I am less than 6 months out from shoulder surgery, so there's no way I can contort myself into a space like that at the moment.

 

[TX FJ80]

If you haven’t replaced the O2 sensors I’d do that. I’ve been using the Denso parts for this for a while.

Ding ding ding!

After getting the Ultragauge setup I have only driven it 2-3 times, but not a single value was really off the charts, I had decided to just keep going with baselining and replacing things as I got to them, since a little hiccup in the idle was the only real symptom.

While driving around with my spouse yesterday the UG wouldn't shut up. Turns out it picked up a pending trouble code - P0136 - but it never got set after another 2 drive cycles and it never pended again either.

FSM says that's 100% positive for either 1) the O2 sensor itself, or 2) the wiring to/from the sensor. Not saying I don't have other issues, but doing the pair of O2s seems to be the next best item to tackle.

New Denso sensors en route - already picked up 6 new nuts for the O2 sensors and two OE Toyota gaskets in my last TPD order.

 

[3lgaucho]

I read into the thread a bit but didn’t see if you’ve already checked your o2 sensor voltages/ fuel trims with an obd2 diagnostic. I had similar symptoms and both o2 sensors were barely showing any voltage with the engine fully warm

 

[TX FJ80]

I read into the thread a bit but didn’t see if you’ve already checked your o2 sensor voltages/ fuel trims with an obd2 diagnostic. I had similar symptoms and both o2 sensors were barely showing any voltage with the engine fully warm

Some other life stuff has kinda gotten in the way but I will be back to this soon.

In short, yes. I got an Ultragauge and noticed I was getting very inconsistent voltages from the rear sensor and the front sensor seems a bit lazy. I’m sure once that is corrected and I disconnect the battery for a bit and it relearns all will be well.

 

[TX FJ80]

Well…I have finally made it back around to this problem. I had a little side quest with a leaking rear heater and a dead battery/grounding issue.

I spent a little time this afternoon changing some additional small vacuum lines and checking the static timing.

I read the static time as 3° BTDC, so I bumped it to about 8° based on the previous advice of the commenters on this thread. Immediately the idle did seem to increase a little.

I drove her around a little and everything seemed fine, but when I parked, the shaky idle returned - possibly even worse than before. The longer this goes on, the more I am sensitive to it.

Still smells rich to me, as well. It makes it a huge disincentive to drive, as it is parked tailpipe to garage, and it makes our garage smell like a pit lane for hours.

I am running an Ultragauge and all values look relatively normal. O2 voltages and both STFT and LTFT have been ~3 and not diverging.

No codes pending and/or set and so no CEL. I’m at my wit’s end.

I have replaced:

• Brake booster hose and check valve
• PCV and 2nd Breather hose
• ALL the vacuum lines not hidden beneath the manifold
• Charcoal canister and plumbing
• Distributor cap and rotor
• Fusible link
• Battery
• Both O2 sensors
• Sure there are other things, just not recalling at the moment

I have swapped and/or checked:

• Known good MAF
• Known good air hose from maf to TB
• Harmonic balancer in decent shape
• Coolant reagent headgasket test passed - no reaction - several times

Am I fighting a losing battle here? I feel like a chud that just fired the parts cannon and ended up in the same place as he started.

The only relatively simple things left that i can think of are plugs and wires. They were new 60,000 miles ago.

What else?

Honestly, this has been so miserable I’m aiming to get this problem sorted out and find a low-mileage, late 100-series. I’m tired of p!$$ing into the wind.

 

[ppc]

Have you done a compression test, check valve clearances?

 

[TX FJ80]

Have you done a compression test, check valve clearances?

I have done neither. I know I probably need to do both, but I’m not up for the valve clearance/adjustment from a difficulty/frustration angle, and I haven’t done a compression check out of fear that this engine is toast. I bought it with a little bit of rough idle - I’m only scared of it because I might learn I have bought this problem.

I’m going to do new plugs and wires and do the compression check when I’m in there.

There’s a good shop locally I want to do the valve clearance adjustment, but they are about 25 miles away and he’s backed up anyhow. I might take it over the Christmas break, depending on the compression check.

 

[ppc]

Just checking the valve clearances is is not that hard or time consuming once the valve cover is removed. Just make sure you record what the measurements are. It will give you piece of mind. The difficulty will come when you actually need to make an adjustment.

 

[cruiserdan]

Have you checked the manifold vacuum? Depending on altitude you should have 14 to 17 inches of vacuum and it should be stable. If it is low or fluctuating that's a problem

 

[TX FJ80]

Have you checked the manifold vacuum? Depending on altitude you should have 14 to 17 inches of vacuum and it should be stable. If it is low or fluctuating that's a problem

I feel dumb for answering honestly…nope.

Argh! Where is the best place to hookup a vacuum gauge? I don’t want to “unplug” something and induce a leak elsewhere. I could always just tee-in.

The other thing I’m going to attempt in the next 2 days is remove and clean the throttle body, including removing/checking/cleaning IAC and TPS.

I’m about 650 ft above sea level, so nothing extreme.

I would feel bad about the attempts I have made to resolve this so far, but the bits I replaced were showing age or were already failing, so only steps forward, but not quite there.

 

[landtank]

at this point I'd have the injectors serviced if they haven't been done.

 

[TX FJ80]

at this point I'd have the injectors serviced if they haven't been done.

Thanks for the idea.

I have a receipt for that from 10 years and 60K miles ago. Not sure if that matters now or not.

Who does that kind of thing and what should I expect to pay? I see these are g-d awful expensive to buy new, if they are even available.

 

[landtank]

I've used WitchHunter Performance - Injector Cleaning & Flow Testing Services - https://www.witchhunter.com/ and there are others. I'm thinking you might have a leaky injector.

 

[logicbyondreaso]

I’ve used both WitchHunter and Mr. Injector.
Mr. Injector was much faster turnaround and excellent communication.

 

[TX FJ80]

I've used WitchHunter Performance - Injector Cleaning & Flow Testing Services - https://www.witchhunter.com/ and there are others. I'm thinking you might have a leaky injector.

I found the PO’s receipt from Witchhunter - these injectors were cleaned and flow tested 10/27/2010.

The last evidence of the wire set being replaced is at 190K in November 2010.

Plugs were done at 239K in December 2017.

Has anyone had any luck with rebuilt injectors? I really don’t want to tear it down and leave it, even for a week or so, while I wait to get my injectors back.

Also, I found notes from the PO in the receipts and in the FSM that he had been chasing a rough idle for a while as well. Oy vey.