mmm what next??

[stillwell]

Ok guys rough idle back.took throttle body off tonite cleaned it really good disconect'd batt,ran some sea foam in it,turn'd on a/c drove 15 miles sevice engine light flickering off/on.way back start'd to clear up and in town ran like new!great fix'd it shut it off start'd it rough idle again but not bad just not smooth??where and what next?:bang head::bang head:

[MT-2500]

Make model year and engine and mileage?

If check engine light has been on or is on check for codes past and present and post back code no.

Tell us the hole service history of what you have done or not done or any recent work done on it.

How are you disconnecting battery and why?
Which post are you unpluging first and hooking back up last?

[stillwell]

02 trail blazer,4+4,I unplugg'd batt because i reed some where that it as to relearn itself???i just took off pos cable for a few min.had 2 code readers come up same no plugg'd in don't get it.

[stillwell]

146,000 4.2 vortec

[stillwell]

146,000 4.2 vortec also put a fuel pump in 4 months ago had rust lines and leaking fuel.ran fine till last week.put in a new cam position acuator.ran great for a few hrs then boom back to same shit.

[maxwedge]

Your code memory was lost when the battery was disconnected you need a scan now to see what is present, does it misfire at idle or just idle too low, from here it is hard to tell what is happening here.

[stillwell]

ya it shakes it idle.idles at 900

[MT-2500]

Unkooking battery pos is very dangerous to your computers.
Could blow or spike them.
Never unplug it to clear codes or reset computter.
Use a scanner for that.
If you need to unkook battery always unhook neg first and hook it back up last.

If the replaced fuel pump was a junk airtex or aftermarket you need to run a pressure check on it.
They have a high fail rate and low pressure .

As Maxwedge said we need to know if idle slow or engine miss.
And you need to get it on a scanner and check codes and post back code no.
Any cylinder miss firing when bad idle?

A blinking service engine light is a engine miss fire.
Has it ever been tuned up with AC Delco plugs?

[stillwell]

tomarrow running a snap on scanner.drove it tonite seems to be rough and then runs like new comes in and out?let off gas at cruz speed and smooths right out gas it ,rough again just jumps in and out?is the fuel filter out side of tank?being i repace pump had a rust hole in steele line rust particles could have made there way for blockage?i'll let u know in the a.m.Hey just want to say thanks for all ur help guys it's my sis's and she's begging me to fix it day by day!it takes time.as i was reading about "relearn itself" i drove with a/c on and 15 mile later in town ran perfect.shut it off start'd it and rough?almost as it is surging.then bam perfect? chevy!Glad my restore'd 79 Trans am has none of this shit.

[MT-2500]

Let us know what he canner shows.
If any codes post back code no.
If you are still getting flashing or blinking check engine light it has a miss fire.
Good scanner will show missfires and what cylinder and how many missfires.
What brand fuel pump did you install?
The scanner will show readings that pont to low fuel pressure but best to drive it with a fuel pressure gauge on it to check for proper fuel pressure and always recheck fuel filter.
Another good tool is a engine vacumn gauge.
Also when running rough or missing is to check for wich cylinders are missing.

Let us know how it goes.

[stillwell]

i don't remember what brand she got.check engine light flashs and after 10 min it stay;s lit.what would cause 2 scan tools to read the same not hook'd up???i'll post codes if i get them today around 2 this afternoon.again thanks

[MT-2500]

N0 power on pin 16 of diagnostic connector.

Start checking fuse for power both side.

[MT-2500]

Check the Cigar fuse no 13 underhood fuse box.
It powers pin 16.

On the fuel pump if it was a Airtex or aftermarket pump you are in for problems.
Always use Delphi OEM type fuel pumps.
Airtex have a high fail rate and pressure problems.

[stillwell]

Waiting to get in for the scan!old guy at the shop i'll check that fuse thanks i'll get back asap ...my money must not be green enough

[stillwell]

OK!!!code po303#3 mis fire,code u1064 code u1152.coil 70 bucks also had an cam acuater siliniod witch i replaced all ready.