'88 Pioneer high Rev when cranking?

[Classy Comanche]

So I've noticed very uncommonly my truck will high Rev for about 2 or 3 seconds when I crank it. Runs good, performs good and drives good. Just a bit stumped on why it's doing it. It did it today leaving work. Is their anything in particular I need to have looked at? Or is the flap in the throttle body sticking occasionally? Or is it something along the lines of the computer in the engine having no memory and starting over with idle control and fuel mixture? I don't know if you guys have had this happen or if it's a major thing really. Thank you!

[cruiser54]

so, after it starts it goes to a higher idle than normal for a few seconds before it settles down? 

[Classy Comanche]

Yeah. Does it every once and when while. It's very uncommon but Does it moreso when it's cold outside. Just sort of odd to me

[cruiser54]

Your odd is my normal. 

[Classy Comanche]

Ohh hm. Well it could be the flap in the throttle body sticking open or coated in carbon [I am not a mechanic I'm just taking a very educated guess] or I have been talking to the mechanic working on mine and he said it could be the computer having no memory of the last start up making it do a whole new fuel mix/ fuel output and throttle control. Nice to know I'm not the only one seeing this going on. Sounds harmless but I figured I'd ask just to make sure

[cruiser54]

Clean your throttle body and don't believe the mechanic. http://cruiser54.com/?p=60

[Classy Comanche]

Okay ill look into that. I'll have him clean it and take a peek at it 

[cruiser54]

why not do it yourself?

[Classy Comanche]

I'm nervous about taking things apart art doing things as such. Afraid I'll break somthing or mess it up. The guy that's working on my truck is a member on here and does absolutely fantastic and I trust him greatly. I know they aren't difficult motors to work on. It's just I trust a mechanic moreso than me trying and breaking somthing by sheer accident 

[cruiser54]

Okay. Makes sense.

[Classy Comanche]

Yeah his truck is a inline 4 and he works on mine by having me bring it by the shop. He's refreshed so much on it including my what was cooling nightmare, very cool dude and can't thank him enough for helping me and continuing to do so, same for you fellas!

[jpnjake]

I’d clean your idle air control valve on the side of your throttle body, it’s to torks screws and you just use like wd40 or carburetor cleaner and a cloth and get it to move in and out freely 

[Classy Comanche]

Oh okay! I'll definitely take a look at that. I'll look at my vacuum lines as well. May be a dumb question which isn't related to this but when I hit the brake, I hear hissing. I have a small vacuum leak somewhere. But what I'm asking is is that vacuum leak linked to that high crank? It only hisses if I press the brake. I read up that vacuum leaks cause high idles since the engine is getting more O2 than it needs before the O2 sensor tells it to quiet down. I think what I'm trying to ask is the brake vacuum line connected to the vacuum line in the engine. Probably a dumb question I know but I didn't know if my vacuum lines dealing with my brakes are linked to the vacuum lines in my engine like the vacuum line harness

[cruiser54]

It absolutely is connected to the intake manifold from the booster. 

I'm not sure I would be blaming the occasional high idle on the booster just yet. 

[Classy Comanche]

That makes sense. It'd more than likely be the master cylinder, vacuum hose or the O2 sensor? which I luckily will be having pit on along with new air filter, plugs, cable plugs....etc. Small odd and end stuff

[Classy Comanche]

So I'm coming back to this thread. Cruiser you said your Comanche high revs when you crank it right? Now Mines doing it every start. I had the butterfly valve in my throttle body cleaned along with a new air filter, plugs, plug wires and distributor cap. Is this high rev detrimental? That's the key thing I'm wanting to know. I do plan to have my sensors replaced too. IAC being one. But here's a video I attached so everyone can compare on how mine cranks to yours. The air restrictor was also taken off so it could improve breathing. 

[howeitsdone]

Sounds very healthy to me

[Classy Comanche]

Oh wow really? Its always had lower tone start previously. Does yours do this? Because this is definitely new territory for me. I know the renix motors are notorious for doing this but I didn't know that sounded healthy? She definitely has more pep in her step when taking off. That's for sure with the tune up I had done today. 

[howeitsdone]

Lol mine sounds like it wants to punch me in the face, but those are my demons.

 

Your truck sounds happy. Almost every car starts with high RPMs and levels out. Especially longer on a cold start. Gets it warm. If it started high and then stayed there permanently or just about stalls and fluctuates then there is an issue, but your truck levels out and idles normal.

[Ωhm]

28 minutes ago, Classy Comanche said:

The air restrictor was also taken off so it could improve breathing.

 

What is this air restrictor? Air Box w/filter????

[Classy Comanche]

Oh well that I didn't know! I guess that tune up really got my engine back to what it was supposed to be! As for the "air restrictor" os what I called it. It's like a....a small hose. It was near my air filter box. I'll show a quick photo and attach it. But yeah I every since I bought the truck it had a lower almost small sputtering idle to it. The plugs that were taken out looked rough and my plug cables and distributor was covered in a decent amount of coolant from previous bottle splits and explosions. Truck runs great and has a higher noticeable idle as well which I expected from new plugs and all. 

[Ωhm]

Air restrictor OFF maybe that what I hear on your CRANK/START video. Suggest one more @cruiser54 test:  RENIX THROTTLE BODY BUTTERFLY ADJUSTMENT

Still as mentions above (@howeitsdone), sounds healthy, sounds like a RENIX.

[Classy Comanche]

Most definitely! That's definitely on my list next to do next. I'm 100% looking into that guide. The mechanic I go to knows all of cruisers guides and I've been talking to him and you guys and he said he will do that next time I go up there. The butterfly valve is sqeaky shiny clean, idles so smooth and noticed it has about a 0.5 of a second faster start. Glad the this sounds healthy. Guess I was so used to it sounding "sick and tired" that I've never heard one do this before. Like I said I'm just worried I'd start it one morning it high rev then- BANG, then engine blows for a sudden high rev 

[cruiser54]

The poor thing just needed a tune-up!!

[Classy Comanche]

Big time. Definitely runs soooooo much better. Glad this start up isn't a bad thing. But I can tell a huge difference. Before I bought it the truck was only ran once a week. And before that the truck sat for 2 years without running and before that! Was driven once a week to the drugstore or grocery store by my great grandparents. It had maintenance done. Just needed it again badly after settling for 2+ years under a shelter. If it weren't for me pestering my grandfather to sell it to me to save it it'd be rotting away today- actually it would be crushed. 9 months after a I bought it a huge Oak tree fell on the shelter and pancaked it.