car runs terrible on start up, then clears up. help!
#1
TECH Fanatic
Thread Starter
iTrader: (4)
Join Date: Jul 2003
Location: Orange Park/ Jacksonville, FL
Posts: 1,075
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I installed my LT's and ORY in April, and my car ran great! a few weeks later I descreened my MAF
(cause everyone I know without a screen has no problems). It ran bad for 2 days, then cleared up and ran great until last month. When I start it up, it idles ok at first, then gets worse for a minute or 2, then, like someone snaps their fingers, the car runs great. if I try to drive it before it clears up, it will missfire badly (i have the random missfire code). heres what I've tried so far:
putting the screen back in
changed my o2's
new fuel filter
cleaned tb (especially the IAC)
the problem went away after all of that, but only for 2 weeks, and now its back
PLEASE HELP!!!!!
![Bang Head](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_banghead.gif)
putting the screen back in
changed my o2's
new fuel filter
cleaned tb (especially the IAC)
the problem went away after all of that, but only for 2 weeks, and now its back
PLEASE HELP!!!!!
Last edited by JBIRD02; 09-16-2004 at 09:15 PM.
#2
TECH Fanatic
Thread Starter
iTrader: (4)
Join Date: Jul 2003
Location: Orange Park/ Jacksonville, FL
Posts: 1,075
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I just asked my friend about the problem, and he said to start the car, then unhook the MAF sensor, so I did, and no change, it ran like it always does. He said it shouldve made the car run really shitty, if not, I need to replace my MAF, is this true???
#4
TECH Senior Member
iTrader: (4)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Wrencher is correct about plugs and wires. are you setting any codes? SES light on?
Also, your friend is partially right about unplugging the MAF making your car run like ****. Try warming the car up fully before unplugging the MAF. That way the car is running in "closed loop" mode, where it is reading data from your o2 and maf sensors, and not just working off VE tables.
Also, your friend is partially right about unplugging the MAF making your car run like ****. Try warming the car up fully before unplugging the MAF. That way the car is running in "closed loop" mode, where it is reading data from your o2 and maf sensors, and not just working off VE tables.
#5
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,604
Likes: 0
Received 6 Likes
on
6 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech20year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I think once it gets hot enough for closed loop the
trims are making the mixture all better, but it's
whacked by nature.
Try cleaning your MAF, the K&N may have spooged
up the sense wires?
trims are making the mixture all better, but it's
whacked by nature.
Try cleaning your MAF, the K&N may have spooged
up the sense wires?
#6
TECH Fanatic
Thread Starter
iTrader: (4)
Join Date: Jul 2003
Location: Orange Park/ Jacksonville, FL
Posts: 1,075
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
thanks guys, this problem comes and goes, making me think its a sensor problem, but I checked my plugs and wires (which are brand new) and everything's still tight. I shouldve clarified that my missfire is only if i drive it right after startup, once the A.I.R. turns off and goes into closed loop, it runs perfectly (no missfires at any rpm, even during WOT). jimmyblue, I will try cleaning the MAF, what do I use??
p.s. it was idling at 1500 the other day, could it be a bad IAC??
p.s. it was idling at 1500 the other day, could it be a bad IAC??
#7
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,604
Likes: 0
Received 6 Likes
on
6 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech20year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
High idle can be a vacuum leak too, which would further
aggravate lean conditions.
Use something like CRC QD contact cleaner that you can
get at home depot, or something else that claims to be
plastic-safe and leave no residue.
aggravate lean conditions.
Use something like CRC QD contact cleaner that you can
get at home depot, or something else that claims to be
plastic-safe and leave no residue.
Trending Topics
#8
TECH Fanatic
Thread Starter
iTrader: (4)
Join Date: Jul 2003
Location: Orange Park/ Jacksonville, FL
Posts: 1,075
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
actually, its really rich on startup. I know by the smell and my A/F gauge is maxed out to the rich side. It then starts to lean itself out to the stoich range (this is when it runs bad), then closed loop takes over and the lights bounce back and forth like they should and it runs fine. i'll get some of that cleaner though and try to clean the MAF.
Thanks!
Thanks!
Last edited by JBIRD02; 09-17-2004 at 05:21 PM.
#10
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by JBIRD02
Someone told me today, it could be a bad IAT or IAC, would either of these cause this problem? anyone have one of these go bad??
#11
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I have similar issues since cam/ headers / injector swap.
Sometimes at idle it will jump up to 1200 rpm and hang there and then settle back down after a bit.
Runs like a bag on startup sometimes until it gets warm.
Sometimes at idle it will jump up to 1200 rpm and hang there and then settle back down after a bit.
Runs like a bag on startup sometimes until it gets warm.
#12
TECH Fanatic
Thread Starter
iTrader: (4)
Join Date: Jul 2003
Location: Orange Park/ Jacksonville, FL
Posts: 1,075
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
thanks guys, the only code thrown is for the AIR not being hooked up. As of right now, the problem cleared itself up and is running fine, but I'm sure it will come back soon, this is the 3rd time. If anyone else wants to add their $.02, I would appreciate it!
#13
TECH Enthusiast
Join Date: Apr 2004
Location: Chandler, Arizona
Posts: 749
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
My idle was going all over the place until I took out the IAC valve and cleaned it up. It was coverd with gunk and the valve seat in the throttle body was also very dirty.