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I've been checking here since April 2015, found lots of good solutions, etc. I've done the basic tune up stuff plus o2 sensor, new TPS, new EGR solenoid, new distributor, fan pulley bracket, ball joints, CV axles. I'm about to tackle valve cover gaskets, new injectors. Truck has driven pretty well, but I've always had the 300-500 rpm idle, up down up down. I took EGR valve off for 1st time, cleaned out the bottom tube with carb cleaner, pipe cleaner. And sure enough I'm idling at 800 no sweat, been about a week. Initially this threw code 41 -- TPS. As it happens, to compensate for bad idle, I've had TPS adjusted incorrectly (no code). I adjusted TPS and all is fine. Anyway, this info may be buried in another thread, but I thought I'd share this quick "tip". Truck has 242,000 miles.
Last edited by toiyodah4WD; 10-01-2016 at 02:51 PM.
Reason: add photo
I seem to be stuck at a high idle (1000rpm) after cleaning out my entire intake manifold. I can get it to go down after adjusting the idle screw but it always seems to bump back up.Think this could be egr related too? Neglected to clean it out when I had the whole intake off lol
I even put thread tape around the o ring. Maybe Is should try some more.
You may be having a TPS issue. The "air intake system" has been decarbonized and this is going to kick your idle up When truck is idling at operating temp, loosen tps and and incrementally adjust, you may find a sweet spot where idle kicks down. ldle will obviously go up too depending on position.
The EGR valve tube to clean is the thin silver horizontal tube in picture. It can only help overall.
You may be having a TPS issue. The "air intake system" has been decarbonized and this is going to kick your idle up When truck is idling at operating temp, loosen tps and and incrementally adjust, you may find a sweet spot where idle kicks down. ldle will obviously go up too depending on position.
The EGR valve tube to clean is the thin silver horizontal tube in picture. It can only help overall.
In a span of 20 minutes I did what's in my original post. Erratic low idling before. Smooth idle around 800 after (I did have to adjust TPS). No other factors at all are in play. Follow where that thin tube goes --- into the EGR Vacuum modulator.
I am having the 300-500 random idle issue too, 50% of the time I stop at a light or stop sign and pop it out of gear. I wonder if this is my problem...
What do you mean by "pop it out of gear"? I always take it out of gear when I stop. I do not keep it in gear with foot on clutch. Or do you mean shifter slips out of 1st unintentionally when you start from dead stop, if so, you need a new shifter bushing.
Pop is out of gear is a bad choice of words. Nothing is wrong with my manual tranny. I simply mean when I take it out of gear when I arrive at a light/stop sign. When I am sitting in neutral after the engine is warmed up. Yes of course my foot is off the clutch pedal.
I mean when I have been driving (engine warm) and come to a stop light or a stop, and take the truck out of gear (as anyone normally would). It is during this idle where my normal 850rpm idle becomes a 350-500rpm bouncing idle for 15 seconds, almost like a major vacuum leak.
Does this seem like the EGR system?
Last edited by 89fourrunner; 10-11-2016 at 04:56 AM.
It's an easy enough thing to do, so I'd try it. That thin tube was at least 50% choked off, and it goes to EGR "vacuum modulator" so in laymen's terms it makes sense to me that it would help. I should say last year I happened to get a new Denso EGR vacuum modulator, I think I was searching for a solution to maybe vacuum issues. Not sure if this makes my "fix" more effective.
I have solved the issue, but I am not 100% sure what solved it. I replaced a ton of vacuum lines, although it all looked okay. I sprayed carb cleaner through the hard lines associated with the egr vacuum modulator. I also carb cleaned its filter and inside the housing. I sprayed carb cleaner through each access port of the egr valve itself without removing it, and finally I found that the vacuum line from the BVSV to the throttle body was disconnected, so I inspected the line and reconnected it. That was most likely the issue if I had to guess.
The idle issue is gone.
Between this fix and the recent tune up I did this thing is running great at 363,000 miles. Knock on wood!
Last edited by 89fourrunner; 10-12-2016 at 04:33 AM.
10-01-2016, 02:32 PM
