Cant get smooth idle!!!
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New Member
Joined: Jul 2018
Posts: 4
Cant get smooth idle!!!
I have a 2004 S10 with a 4-3 Vortec, has a rough idle and throws an engine code for random misfire. I have already replaced all the plugs and correctly Gap them, brand new wires, brand new cap and rotor, brand new coil pack, brand new ignition control module, and a new mass air flow sensor
it seems to have maybe got a little bit better but still has a very rough idle and hesitation on initial throttle response. Can anyone give me another direction to go from here? I'm sick of throwing money at this thing already!
it seems to have maybe got a little bit better but still has a very rough idle and hesitation on initial throttle response. Can anyone give me another direction to go from here? I'm sick of throwing money at this thing already!
Moderator
Joined: Apr 2013
Posts: 878
From: NY
I would start with a fuel pressure test. A little bit of diagnostic work will save you a ton of money from throwing parts at it
follow the instructions in this thread and see what you find.
Fuel pressure testing
follow the instructions in this thread and see what you find.
Fuel pressure testing
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
Which misfire codes?
Any other codes? Any pending codes?
Any other things done recently like clean MAF, clean EGR valve, clean throttle body, compression test, any other parts replaced?
What lead you to replace the parts in your first post?
George
Any other codes? Any pending codes?
Any other things done recently like clean MAF, clean EGR valve, clean throttle body, compression test, any other parts replaced?
What lead you to replace the parts in your first post?
George
Thread Starter
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New Member
Joined: Jul 2018
Posts: 4
Re 04 s10
It originally threw a code for mass air flow sensor and random misfire, before replacing all the parts I listed in my first post, I replaced the mass airflow sensor. The stutter and the rough idle seems take it a tiny bit better with everything I do. But nonetheless, it is still bad! As soon as it gets above around 2500 RPMs it runs fairly smooth, I know it's something simple like a sensor or a leak of some type! Just can't Pin It Down! I've dealt with quite a few fuel issues over time and it just doesn't feel like that... None the less I will of course get some fuel pressure readings ASAP. Does anybody know anything about this EGR valve? The rough idle and hesitation is just so unique... It seems like it should be an easy fix! I just can't find that right sensor! LOL
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
Rough idle has a long and impressive list of possible causes so it can be frustrating to solve so be patient but you can figure it out. You have already addressed the ICM thru plugs so that rules out almost all ignition related causes (except the ICM drive signal and all connectors and wiring) so let’s start elsewhere.
lets start with low cost things that you can do yourself:
Do the fuel pressure tests in the sticky
replace your fuel filter
test/replace your PCV valve
vacuum leaks. Check the vacuum lines, test idle vacuum if you have a gauge. Has the lower intake manifold gasket job been done yet?
clean the throttle body/plate
what is your idle speed on a scanner
clean the EGR valve
clean the IAC valve
if these don’t solve your problem, I will ask you to post some live scanner data readings.
George
lets start with low cost things that you can do yourself:
Do the fuel pressure tests in the sticky
replace your fuel filter
test/replace your PCV valve
vacuum leaks. Check the vacuum lines, test idle vacuum if you have a gauge. Has the lower intake manifold gasket job been done yet?
clean the throttle body/plate
what is your idle speed on a scanner
clean the EGR valve
clean the IAC valve
if these don’t solve your problem, I will ask you to post some live scanner data readings.
George
Starting Member
Joined: Aug 2015
Posts: 216
From: Mt Vernon/Fort Hunt, Virginia
It originally threw a code for mass air flow sensor and random misfire, before replacing all the parts I listed in my first post, I replaced the mass airflow sensor. The stutter and the rough idle seems take it a tiny bit better with everything I do. But nonetheless, it is still bad! As soon as it gets above around 2500 RPMs it runs fairly smooth, I know it's something simple like a sensor or a leak of some type! Just can't Pin It Down! I've dealt with quite a few fuel issues over time and it just doesn't feel like that... None the less I will of course get some fuel pressure readings ASAP. Does anybody know anything about this EGR valve? The rough idle and hesitation is just so unique... It seems like it should be an easy fix! I just can't find that right sensor! LOL
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