Won't go over 3K rpm in park

Jerry473

Original poster
Member
Aug 2, 2015
6
After a coil (2) went on my 4.2l i6 the truck won't rev over 3k. No problem driving though, cleaned throttle body ( a few times) pulled fuses to reset also. Since then changed both O2 sensors. Now runs bad a while then good back and forth 3-4 days then switches back. What have I missed? If it was a filter wouldn't it run bad all the time? Also changed alternator about 2 years ago. By the way 200k on the vehicle and transmission rebuilt by some one else 1.5 years ago
 

Sparky

Member
Dec 4, 2011
12,927
I didn't think the computer lets it rev over 3k while in park.
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
Sparky is correct. Stock there is a limiter when in park.
 

Jerry473

Original poster
Member
Aug 2, 2015
6
Ok I have heard that before, honestly thought that it used to, but anyway thoughts on the other issues?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
As per http://www.obd-codes.com/p0171

A code P0171 may mean that one or more of the following has happened: The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There could be a vacuum leak downstream of the MAF sensor Possible cracked vacuum line/connect. Failed or faulty oxygen sensor (bank 1, sensor 1) Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!) Exhaust leak between engine and first oxygen sensor

Read more at: http://www.obd-codes.com/p0171
Copyright OBD-Codes.com
 

littleblazer

Member
Jul 6, 2014
9,265
Mine will run up to around 3300 rpms... Limiter is about 3K if that's what you mean...
 

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