fj62 fuel pulsation damper (idle stutter) (2 Viewers)

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Other things to check is adjusting the throttle
position sensor and making sure you have good fuel pressure. I’m chasing the same thing as well as a slow start when the motor is cold.
CLEANING the throttle makes a huge difference too. I wrote about this in a thread a while ago where I cleaned mine good and proper, including the idle and vacuum passageways, the end of the ICS "plunger" and the idle control screw (sent that with some other bits through my ultrasonic). Replaced the screw with a new O-ring and a dab of blue threadlocker on the screw so it stays in adjustment when set. Did this off the truck, so you wanna make sure you have a new throttle body gasket. Used almost an entire can of B12 Chemtool but I got a LOT of carbon and sludge buildup out of mine. When I reinstalled it I was able to turn the screw in WAY farther than it had been previously to get the idle back down to 700 RPM.

I would honestly do this before messing with the fuel pressure regulator. Even if one DOES end up needing a regulator, the throttle body is already cleaned and some preventative maintenance is done.

@blainehale tell me more about this vapor hone cabinet.....
 
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CLEANING the throttle makes a huge difference too. I wrote about this in a thread a while ago where I cleaned mine good and proper, including the idle and vacuum passageways, the end of the ICS "plunger" and the idle control screw (sent that with some other bits through my ultrasonic). Replaced the screw with a new O-ring and a dab of blue threadlocker on the screw so it stays in adjustment when set. Did this off the truck, so you wanna make sure you have a new throttle body gasket. Used almost an entire can of B12 Chemtool but I got a LOT of carbon and sludge buildup out of mine. When I reinstalled it I was able to turn the screw in WAY farther than it had been previously to get the idle back down to 700 RPM.

I would honestly do this before messing with the fuel pressure regulator. Even if one DOES end up needing a regulator, the throttle body is already cleaned and some preventative maintenance is done.

@blainehale tell me more about this vapor hone cabinet.....

Sounds like that's going to be my next logical step after this thermostat housing rebuild. for sure.

I've had this cabinet for about 4 years. I restore old motorcycles for fun so it's been invaluable to me. One of my best shop investments besides the compressor that runs it. Weekend Warrior - Vapor Blasting Equipment for Sale- Vapor Honing Technologies - http://vaporhoningtechnologies.com/weekend-warrior/
 
Sounds like that's going to be my next logical step after this thermostat housing rebuild. for sure.

I've had this cabinet for about 4 years. I restore old motorcycles for fun so it's been invaluable to me. One of my best shop investments besides the compressor that runs it. Weekend Warrior - Vapor Blasting Equipment for Sale- Vapor Honing Technologies - http://vaporhoningtechnologies.com/weekend-warrior/
So is it literally just water vapor blasting and a clean water rinse type deal? I take it you have to dry the parts fast enough to prevent corrosion?
 
So is it literally just water vapor blasting and a clean water rinse type deal? I take it you have to dry the parts fast enough to prevent corrosion?

It uses water as transportation for the media so it's a lot less abrasive than dry media. You can blast plastic and soft metals with no issues. I use silica as my media. Still need a hefty air compressor to run it, though. Yeah, ideally you want to dry things but I'm not sure water would corrode anything unless left for a very long time. If you're blasting things and worrying about them rusting after, you should probably be replating those things anyway or they'll rust from the moisture in the air or rain, regardless of how you blast them.
 
I guess I can just do some spade terminals until I can find the correct connectors. If anyone has any ideas of where I can source the stock connectors, though, I'd be pretty happy!
 
I found the plug for the cold start timer switch and water temp sensor (grey and green.) Still need that weird one for the water temp SWITCH.

The price is pretty ridiculous. I could get a whole bunch of these for that price but I didn't know the exact fit. Noted for future me! Amazon

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I guess I can just do some spade terminals until I can find the correct connectors. If anyone has any ideas of where I can source the stock connectors, though, I'd be pretty happy!
I had (broke it gotta order a new one) the "prison shank" from Wit's End, which is awesome for pulling connectors apart for repairs. I had the exact issue with the connector of the 4WD indicator switch on my tcase this summer, so pulled the teminals out, slipped the rubber seal up over the wires, soldered the wire leads back in place on the terminals (would've preferred to have new terminals to crimp and solder, but I made it work) and reinstalled. As a strain relief to prevent it from happening again, I added a 2" long bit of adhesive lined shrink wrap around the soldered point on the terminal, which I was still able to slide the connector's rubber seal back down over to retain the weather seal of the rebuilt connector. Now I've got a good Toyota sealed connector, and strain relief provided by the shrink wrap.
 
Unfortunately rebuilding the thermostat housing with all new sensors and wires did not resolve the idle stutter. All is not lost, though. My temp gauge on the dash finally reads accurately and my heater has never worked so dang well and so quickly. I'm still glad I did that much-needed maintenance.
Onward to the fuel and air system. I'll start with air, since that's easy to trace. I know it's running very rich so maybe it's starved for air. Next will be cooling the throttle body and cleaning that. Any other thoughts?
 
Have you checked your fuel pressure?
Checked out EGR system?
TPS set properly?
Examine rubber intake boots for cracks/leaks?
Set valves?
Checked for vacuum leaks?
...just throwing out some ideas.
 
Hi, If your still running smog ,I’d check it ALL carefully . I bet the problem is there. Any old sensors that are not broke I’d save off of the thermostat. Mike
 
Hi, If your still running smog ,I’d check it ALL carefully . I bet the problem is there. Any old sensors that are not broke I’d save off of the thermostat. Mike
I removed all that last year.

Have you checked your fuel pressure?
Checked out EGR system?
TPS set properly?
Examine rubber intake boots for cracks/leaks?
Set valves?
Checked for vacuum leaks?
...just throwing out some ideas.
All things I need to go over this week. I've been slowly replacing all the vacuum lines. With the issue only occurring at idle and only when the truck is warmed up, would that point to one thing over another?
 
I removed all that last year.


All things I need to go over this week. I've been slowly replacing all the vacuum lines. With the issue only occurring at idle and only when the truck is warmed up, would that point to one thing over another?
Sounds like you've been through the coolant temp situation. A vacuum leak has a much more profound impact at idle (during high engine vacuum operation) than when into the throttle. The engine also runs richer when cold which could help compensate for a vacuum leak. I would concentrate on vacuum leaks and look good at the intake boots. The air flow meter is on the airbox, so any leaks on those are unmetered air throwing things off. They get old, hard and brittle, and your engine mounts get soft and mushy from leaks.. combine the two and your engine moves more than it should with a less pliable intake hose. Very common..
 
Sounds like you've been through the coolant temp situation. A vacuum leak has a much more profound impact at idle (during high engine vacuum operation) than when into the throttle. The engine also runs richer when cold which could help compensate for a vacuum leak. I would concentrate on vacuum leaks and look good at the intake boots. The air flow meter is on the airbox, so any leaks on those are unmetered air throwing things off. They get old, hard and brittle, and your engine mounts get soft and mushy from leaks.. combine the two and your engine moves more than it should with a less pliable intake hose. Very common..
Something just clicked in my head, thanks to you. I replaced the spark plugs last year and had to do some intake moving to get good access. I noticed the stumble issue increased after that. I think we may have a lead here, finally!
 
I was wondering if this could be my issue? I swear it got like this after my recent waterpump change out. Would it at least make a code if failing or failed?
While this may not apply in your situation, I had a stumble idle when the engine was warm caused by a bad temp sensor on the water housing. Engine was Hot, ECU thought it was cold
 
Well, back at it again. Decided to try a crude vacuum leak test. The ol' mineral oil vape. Try not to laugh at my airbox seal off cap :) It's only under a few PSI and I wanted to remove the filter housing from the loop as it just pours vapor out of the front air intake. Long story short...I couldn't find a single vacuum leak. I unplugged a few lines around the system and could see vapor coming out, just to insure it was working. I guess all the vacuum hoses I replaced over the past year are working great.
Any more ideas what it could be? I'm getting close to just taking it to a shop or having the injectors cleaned/replaced. Going to double down on vacuum testing and try butane or carb cleaner when the engine cools down.

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Question: Would it be possible that the ECU is still acting like it has all the smog gear attached? I removed that stuff over a year ago now.
 
Question: Would it be possible that the ECU is still acting like it has all the smog gear attached? I removed that stuff over a year ago now.
I don’t think it’s that smart. As long as everything was blocked off properly (ie no big air leaks) I don’t think it’d matter.

Looking at the diagnostic codes the only thing emissions related thing that goes through the ECU are the oxygen sensors.
 
Went at it with some carb/brake cleaner to see if I could find a leak that way. Zero change in idle aside from the normal surging when it's warmed up. So I think I all but have the vacuum leak out of the question here, at this point.
 
Reviving thread. Any luck with resolving this?

My rpm fluctuates when warm (550-750) at times, only in idle. Slightly rough. No codes Getting better though, truck sat for a few with prior owner. A Mechanic Changed filter (reportedly) & fuel pump tank redo prior to running. I changed Plugs, rotor, cap, checked timing, new TPS cleaned throttle body, ISC plunger, compression warm 153-160 (roughish idle when warm but ALL new plugs are sooty). Ran fuel injector cleaner.

Will test pressure in a few days (im thinking it’s rich with a faulty FPR, exhaust smell no smoke but exhaust has buildup) as truck has 206K and I don’t know if mechanic measured. No fuel smell elsewhere. No codes so I’m not testing water temp sensor (fat hands) or o2. Both look decent. Could not find vacuum leak with cleaner. AFM test out but did not test air temp.

Also - I have seen videos of air leaks at the top of the AFM where there is factory applied sealant. Don’t know if that affects.
 
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