Start Up RPMs

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landtoy80

landtoy80

Joined
Mar 13, 2003
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Location
North Front Range, CO
My start up rpm's use to be at 1500 rpms or less.
In the last year it worked its way up to 1900 to 2000 rpms.
I don't reguard it as a problem but what would cause it to change?
 
Check your IAC. Just pull it and take a gander. The plunger in mine was heavily covered with carbon. It cleans up easy with mineral spirits; just be gentle. Should take you about 15 minutes total.
 
Isn't this also a result of a dirty throttle body?

I have startup RPm's of about 1900 as well, was planning on removing the throttle body and cleaning it well (per you description in another thread, Scamper) to remedy the problem. Am I correct in my assumption that this will work?
 
I cleaned mine when I had checked the valves.
It was very dirty. After it was cleaned up the start up and idle was the same as before I cleaned it.
At that time my start up idle was in the 1200 to 1500 range.

Its the EGR that gets the intake chamber carboned up. The port from the EGR is where it gets plugged.
I don't see how a plugged EGR port could affect the start up idle.

There are small ports in the butterfly that get plugged. I think they could change the idle.
 
It's really easy to clean those small ports out with the TB removed. Not sure how it can be done without removal since you can't really see them. But the IAC is so much easier to check and clean that I'd do that first. If that doesn't help, them maybe do a TB cleaning.
 
My main fuel relay was stuck open. I changed it and now my start-up idle is about 1200.
 
Wow, your's useto run up to 1500 rpms at startup? Mine has never done that, about 1200 is the top it ever gets for a second or two then down to 800 rpms where it's rock solid no matter if warm or cold or what. My a/c doesn't work so I haven't tried it with that to see what it bumps it up to.
 
Cleaning the throttle body, including those tiny EGR ports, dropped mine from 16-8000 down to 1100rpm, but it has gradually crept up again to 14-1500rpm and now it has started roaring again just when it catches.
 
This deal seems to be the common for you high idle guys.. clean TB, lowers idle some initially, then increases back up again. Makes me wonder if cleaning your TB may be more of a low idle problem resolution than high idle. Obviously there's some change in the flow from cleaning it, then the ECU adjusts and you end up back where you started.

What say ye?

:beer:
Rookie2
 
Hmmm, this discussion had me checking my start up RPM this morning. It's reading ~500 rpm. I wonder if the tach is off? I'll hook up a tach/dwell meter tonight to cross check it, assuming I can figure out where I should hook up the leads.... ;)
 
Hellooooo,


It's beginning to look alot like Fall.........:D


A bit colder in the mornings?


Do not forget to take that variable into consideration before you pop the hood to fix something that is not broken.....yet..:rolleyes:
 
I had no change after cleaning out the entire intake, but I was not able to pull the IAC valve due to a buggered bolt head.

This morning initial idle climbed to 1750RPM, and immediately dropped down to 1450RPM. I wish I could limit that initial jump to 1500RPM. Someday I'll see if I can get the IAC valve out for inspection.
 
This all sounds familiar. I was at 1600 - 1750 at cold startup idle for 2+ minutes, and now I am at 800 - 900 for 15 seconds and then 600 from then on. This is what I did and the results:

Cleaned throttle body and inadvertently removed the IAC and TPS without marking where the TPS was set.

When I reassembled, I pulled the EFI relay instead of the EFI fuse (and I thought that was sufficient) and at that time I noticed no change.

I fawked around with the TPS trying to get it back to the correct position. No change in idle, but some change in shifting.

Then I decided to O-Ring the IAC so I double o-ringed it and it immediatly dropped right down to 700-800 at cold startup and ran perfect at 600... but my shift points were still off (note: I still hadn't pulled the EFI fuse)

Then ... I decided that the shift points were still not perfect so I moved the TPS a couple of mm in one direction and finally had a lightbulb moment to pull the EFI fuse.. resetting the EFI system. This cause my running idle to lower to 200 - 300 rpms and made me think that maybe I fixed the high idle problem before I o-ringed it. Unfortunately, its impossible to say.

I removed 1 o-ring and pulled the fuse again. This time it runs just under 600 rpms in drive with no A/C. Startup is barely up to 800 when cold. I suspect I could just remove the o-ring and pull the fuse again and it would run perfect... but I'm sick of messing with it for now.

I hope this is useful.

Chris
 
Chris, So did you ever move the TPS back?

I get about a 1300-1400 when starting...hot or cold outside, then after a minute or two it's down to 1000. After driving it a bit, it idles around 700-800.
 
Safado,

I have moved it several times. I think I have it real close now. I believe that in my case the TPS has more to do with the funky 1st to 2nd stalled shifting/high rev than the startup idle. But since I was thoroughly unscientific about my procedures, it is impossible to say what actually made the big difference (aside from the o-rings).

C.
 
chris did you clean or adjust the IAC? If not, it sounds like the thing you did different from the rest of us is add an o-ring to the IAC and adjust the TPS.
 
Semlin,

I did not adjust the IAC (unless emasculating those three little screws on the inside is an adjustment). The big differences came when I o-ringed the IAC and when I pulled the EFI fuse.

FWIW, pulling the EFI relay seems to do exactly--let me be clear-- NOTHING!


C.
 
O- rings

On my Son's 95 we used two o-rings.
I had the link to the procedure... but can't locate @ this time
 
I pulled and cleaned my throttle body, and replaced my nasty throttle cable.
I didn't mess with the electronics at all.
My engine ran much smoother and the stumble I had was gone.... but

my startup idle used to be low, not sure exactly, but I think about 1200-1500.
now startup idle is 1800 RPM and stays there for maybe 60 sec.

cleaning my throttle body seems to have created a hi startup idle problem for me :rolleyes:

haven't pulled the EFI fuse (been months since I've done this) maybe I should try this?
 
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