Technical => Engine Tech => Topic started by: SlaughterDog on February 13, 2012, 04:21:23 PM
Title: What's normal RPM for a 5.0 cold startup?
Post by: SlaughterDog on February 13, 2012, 04:21:23 PM
Every time I start my engine cold, it starts right up but idles revs to 2000 for several seconds, sometimes it'll jump up to 3k for a second, before idling down to 1k. Is that normal, and if not, what should I look at to fix it?
Title: What's normal RPM for a 5.0 cold startup?
Post by: mcb82gt on February 13, 2012, 06:25:39 PM
Mine usually goes up to about 1500-1800 and settles down after about 15/20 seconds.
Title: What's normal RPM for a 5.0 cold startup?
Post by: EricCoolCats on February 13, 2012, 07:27:17 PM
What year 5.0 are we talking here?
I believe specs are in the 750-800 rpm range...
Title: What's normal RPM for a 5.0 cold startup?
Post by: daminc on February 13, 2012, 07:51:53 PM
my book says 600 for an 87.... Just timed my car and set the rpm Saturday .... mine starts at about 1100, and drops to 600ish
Title: What's normal RPM for a 5.0 cold startup?
Post by: SlaughterDog on February 13, 2012, 09:00:46 PM
It's an 87. 2k just sounds way too high.
Title: What's normal RPM for a 5.0 cold startup?
Post by: V8Demon on February 13, 2012, 09:30:21 PM
Mine'll go to 1200 or so for a bit, then down to the 800 I have it set at....
Title: What's normal RPM for a 5.0 cold startup?
Post by: Haystack on February 13, 2012, 10:44:12 PM
800rpm out of gear, 600 rpm in gear. If your idle is set higher then a 600rpm minimum, it will cause it to hunt trying to minimize rpm's.
Title: What's normal RPM for a 5.0 cold startup?
Post by: daminc on February 14, 2012, 07:29:39 AM
Yes, I should have mentioned 600 in gear
Title: What's normal RPM for a 5.0 cold startup?
Post by: V8Demon on February 14, 2012, 07:38:46 AM
Mine runes at about 800 in gear as well. A little bit less. With the cam I have I'm sure that @ 600 it wouldn't idle very well. If you set the base idle properly, this is a non-issue.
http://sbftech.com/index.php/topic,1031.0.html
Quote
1. Clean TB with carb cleaner and nylon brush (toothbrush size). Engine off, fully open TB blade and spray/brush TB until all gunk and oil residue is cleaned.
2. Allow to dry, or close TB blade and start engine until it clears all carb cleaner fumes/liquid.
3. Let engine idle...if it doesn't, increase idle speed via TB stop screw until engine stays idling on its own.
4. Disconnect IAC valve, if engine dies repeat 3 with IAC disconnected.
5. Set idle speed to the lowest setting possible between 600-800 rpms with IAC disconnected. It is key to use the lowest possible to prevent idle surge, rolling, etc once the IAC is connected as follows.
6. Turn engine off, and reconnect IAC
7. With Ign On Eng Off, check TPS voltage output....if it's between .7vdc - 1.0vdc, it's OK. This voltage check should be done between the Green and Black wires at the TPS side connector as shown in the pic below....(-) terminal of the DVOM on the Black wire and (+) terminal on the Green wire.
8. Disconnect battery (-) for 3-5 minutes.
9. Reconnect battery, start engine, allow it to idle for 2-4 minutes to confirm setup,
10. If idle speed falls too low or stalls, increase idle speed via the TB set screw a little at a time.
11. Turn engine off for 20 seconds, re-start engine and repeat 9 - 11 if required.
12. Reconfirm TPS output is within the .7vdc - 1.0vdc range.......you're done!...
FYI..no need to reset ECM KAM (reset computer) b/c the TPS minimum value used for idle control, is automatically reset by the EEC-IV every time the ign is cycled on-off for 20 seconds-on, and as explained in the next post
13. Allow a 10-20 minute "relearning" period under normal driving conditions (drive cycle).....now you're done.
Title: What's normal RPM for a 5.0 cold startup?
Post by: daminc on February 14, 2012, 07:45:37 AM
mine actually idles closer to 700 out of gear.... it won't go below a certain rpm.... I still have to check for codes after doing the timing and idle. I had a couple pop up before when I checked.. I'll clear them and do a idle re-check later in the week, and repost my results.
Title: What's normal RPM for a 5.0 cold startup?
Post by: 50tbrd88 on February 14, 2012, 11:00:53 AM
On cold startup mine will be around 1000-1200 rpms for a few seconds but then will idle at about 700-750.