StuartUNC

So i've been reading a lot of post lately and been searching for common problems and sollutions to fix it. Yet again, another person has an idle issue with the 3.0.

Anyway, it's been a very specific problem. Basically from cold start it will rpm to 1500 (I live in colorado), then after the temperature kicks up it drops to 800. Normal.

If... I put a load on the engine, it will randomly kick up to 1500 again. On occasion, it will randomly drop to 800.

However!!! if i turn the truck off, then turn it back on, it goes back to 800 rpm.

Whats going on?

I have done all of the following and checked the list 3X!!!

Cleaned throttle, swapped throttle, purchased new throttle, swapped TPS sensor, adjusted TPS sensor, purchased new sensor, replaced every vacuum line, and yes, checked them 3 times. No codes are present with the engine. MAF is good, O2 is good, it's all good! And yes I did mess with the throttle screw to adjust, but after you screw it all the way, yada yada everyone on the forum with idle issues does that first. Anyway lol. Any ideas? Air flow meter? Knock sensor? My guess is it has something to do with cold start injector system, but what do i know? Lol.

Thanks for reading.

thook

Do you mean "after" you put a load on it? For example, let's say you're in traffic, you're at a light, light turns green, you go, at the next light you've stopped and come to an idle, and it hangs out at 1500rpm. Something like that? Does it seem to be associated at all with whether or not your applying the brakes? Or, does the idle also jump/drop when you're in Park with no brakes applied?

It's possible it could just be the throttle cable sticking. You say when you shut it off and then start it again the idle will go to normal. Do you use any throttle when you're starting the engine?

scope103

There's an "idle-up" for the power steering pump and for the air conditioner. If either of those is not working correctly, it could randomly "idle up." To eliminate that, find the two pair of vacuum lines and connect the pairs together. If no change, put them back.

jbtvt

Could well be a vacuum issue or a VSV, do you have AC? I'd also be looking at the AFM, may be sticking.

StuartUNC

Thanks for the input. I don't believe its the vacuum line that connects to the brakes. The vacuum line that initiates brake power if the engine cuts out. I believe thats what you were refering to?

Anyway, yes the load does not matter if it's me just pushing the gas pedal for a few minutes, or if i haul ass to a stop light, it just does it... 95% of the time. Seldom do i get a 800 and it's random. Sometimes it'll do it if i'm just sitting at a stop light for a small amount of time. Freaks me out cause the whole engine changes lol.

When I say all, all vacuum lines have been done... except the ac. I will try that tomorrow, as i'm in the middle of doing my timing belt. I ditched the AC a long time ago, but i never thought about the vacuum lines it uses. I'm thinking i'll just pull it anyway since 1. it sucks the engine too much and 2. it is just dead weight on my pickup.

While i'm doing the timing belt, i suppose i should mess around a little bit with the intake. Maybe i'm missing a vacuum line undernieth. That thing is such a pain and there are so many lines that run under that thing. I thought I got them all.

I still have a weird hunch it's my cold start sensor. I feel that for some reason it's just having a hard time recognizing that the engine is up to temp and it can't stop the fuel from spraying. When I get my camera I can post some pics of what i'm doing. I'll show you guys how extensive I was with the vacuum lines. Honestly i did pretty much everything (including the powersteering) vacuum lines. They're all matching according to the manuals I have.

Oh random btw, but while i was messing with my truck, i unplugged the cold start injector, even though it could be dirty, it did not drop down to 800. I could feel it ticking which indicated it was still spraying extra fuel in the truck.

OH! and another thing... This have been going on and on and on for almost a year now. I didn't notice it till i swapped out the dlx cluster for the sr5 lol. Yes that was wired correctly btw. Anyhoo, I still get about 23 HW and 15 in town even with this idle issue. So I doubt that it's spraying when i'm actually driving the truck.

Anyway thanks again guys. Appreciate it.