Idle Problems - LT1 w/New 24X system - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
LinkBack Thread Tools
post #1 of 15 (permalink) Old 04-20-2014, 06:01 PM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
Idle Problems - LT1 w/New 24X system

I recently upgraded to the 24X LS1 Ignition system due to an Opti issue. I will say that my engine idled like a champ on the stock opti setup but at high rpm the opti just came apart internally. Anyway I have a fresh built 383 LT1 engine. Fairly aggressive cam, CNC ported factory heads intake so and so forth. Anyway Like I said the engine idled awsome with the opti but since I've upgraded to the 24X system I'm having all kinds of idle issues to make it simple here is a list:

Terrible cold idle won't run unless I keep foot on the throttle
Very erratic idle once warmed up. Seems to idle fine one minute than it keep wanting to cut out the next minute.
As time goes on the idle seems to be getting progressively worse.
When warm the idle some time won't hold and I keep my foot on the throttle and then all of a sudden the RPMs just shoot up for some unknown reason.

I just got an HP Tuners Suite and been trying to see if I can locate a problem. I'm not super versed in tuning but I know some basics functions.

From what I can see Bank 1 LTFT are pegged out. I'm not sure if its rich or lean new to HP Tuners Dash Board but the meter read full to the top and indicates 25.0. Bank 2 LTFT seem to be right in the middle.

Anyway I'm not sure if I have a mechanical issue (nothing mechanical has been changed) or if I have a tuning issue???

Any help??
tes96ta is offline  
Sponsored Links
Advertisement
 
post #2 of 15 (permalink) Old 04-22-2014, 09:31 PM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
This idle issue is driving me nuts. Today while trying again to get it to idle (with negative results) I noticed something odd. When I had the engine off and the ignition on I was looking at the HP Tuners Dash board and Chart. With the engine off and ignition on I noticed that the Bank 1 LTFT was pegged out to 25%. When I touched the throttle just enough to open the blade to 2% the LTFT reading went right to 0. Then when I let off the throttle and it went back to 0% the LTFT jumped back up to 25%. Is this normal???
tes96ta is offline  
post #3 of 15 (permalink) Old 04-23-2014, 12:20 AM
Regular Member
 
MYLTWON's Avatar
 
Join Date: Dec 2009
Location: OH-IO
Posts: 730
 
What is the 02 voltage doing? Is the other bank looking normal? Sounds like the split blms might be do to the big cam, funny that this developed after the conversion. Usually the split blm problem is more noticeable on the lt computer. I assume you had a tune done on the replacement pcm.


Quote:
Originally Posted by CKJ View Post
Hi-performance is so outdated.. everybody's doing it to where its not even cool anymore. I'm going for Prius MPG on a LTx
94 z28. Forged 383 12:1, Trickflow 205cc heads ported by TEA, LE 242/248, Viperized T56, Carbon Fiber Driveshaft, Moser 9'' with strange center section, 4.11 gear, Full UMI suspension, everything from the k-member to the sway bar links, 150 shot of N20, and lots of other crap
MYLTWON is offline  
Sponsored Links
Advertisement
 
post #4 of 15 (permalink) Old 04-23-2014, 07:27 AM
Global Moderator
 
cocobolo95's Avatar
 
Join Date: Sep 2008
Location: Fruitland Park,Florida
Posts: 12,918
 
Check for vacuum and exhaust leaks. Check out your tps and see if there's a glitch in how the reading is between totally closed and fully open.

Dampen spark plug wires and run engine at night. Look for spark leakage.

And as myltwon asked, did you tune the ls pcm?
cocobolo95 is offline  
post #5 of 15 (permalink) Old 04-23-2014, 08:40 AM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
The base tune was completed by PCMforLess.com. They did the tune for the engine when it had the distributor and it was right on the money. But since I went with the 24x the idle has been a mess.
tes96ta is offline  
post #6 of 15 (permalink) Old 04-23-2014, 08:43 AM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
Quote:
Originally Posted by MYLTWON View Post
What is the 02 voltage doing? Is the other bank looking normal? Sounds like the split blms might be do to the big cam, funny that this developed after the conversion. Usually the split blm problem is more noticeable on the lt computer. I assume you had a tune done on the replacement pcm.
The voltages on the O2's seem very low to me at idle they seem to hover under 300mV mostly in the 200 range. If I goose the throttle they do go up but at idle they are bottomed out. Bank 2 LTFT seem at little high as well but not pegged out like Bank 1.
tes96ta is offline  
post #7 of 15 (permalink) Old 04-23-2014, 09:44 AM
Regular Member
 
steveo's Avatar
 
Join Date: Feb 2008
Location: Vancouver Isl., BC
Posts: 5,011
 
so you have a very lean idle, then. is it idling in closed loop? 'cause it doesn't sound like it's trimming
steveo is offline  
post #8 of 15 (permalink) Old 04-23-2014, 11:09 AM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
Quote:
Originally Posted by steveo View Post
so you have a very lean idle, then. is it idling in closed loop? 'cause it doesn't sound like it's trimming
You ask an interesting question. Because when it's cold it won't idle at all but once it's warmed up it gets a little better but not much. During this idle issue it sets a MAP code. As soon as I clear the code the engine stalls out.
tes96ta is offline  
post #9 of 15 (permalink) Old 04-23-2014, 11:39 AM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
I also wanted to add that I took all of Bank 1 (Driverside) sparkplugs out. Cyl. 1 & 3 were light tan-ish white, while Cyl. 5 & 7 were blank and very sooty. I'm all over the place with this thing.
tes96ta is offline  
post #10 of 15 (permalink) Old 04-24-2014, 01:51 PM
Regular Member
 
MYLTWON's Avatar
 
Join Date: Dec 2009
Location: OH-IO
Posts: 730
 
How big is the cam and what type of vacuum are you pulling?


Quote:
Originally Posted by CKJ View Post
Hi-performance is so outdated.. everybody's doing it to where its not even cool anymore. I'm going for Prius MPG on a LTx
94 z28. Forged 383 12:1, Trickflow 205cc heads ported by TEA, LE 242/248, Viperized T56, Carbon Fiber Driveshaft, Moser 9'' with strange center section, 4.11 gear, Full UMI suspension, everything from the k-member to the sway bar links, 150 shot of N20, and lots of other crap
MYLTWON is offline  
post #11 of 15 (permalink) Old 04-24-2014, 03:49 PM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
Quote:
Originally Posted by MYLTWON View Post
How big is the cam and what type of vacuum are you pulling?
Cam Specs: Intake / Exhaust
Valve Lift .604 / .577
Duration @ .050" 238.1 / 242.9
Adv. Duration 271.7 / 274.2
Lobe Separation 108.0*

Vacuum @ idle approx. 850 rpm 8"-10"


I've checked all over for vacuum leaks and I can't find any.
tes96ta is offline  
post #12 of 15 (permalink) Old 05-09-2014, 11:14 PM
Regular Member
 
Join Date: Feb 2014
Location: Agawam MA
Posts: 18
 
Di d u wire the injectors and coils differently? The lt1 and the ls with the 411 PCM use a different firing order I was able to start my car off a stock 02 ls1 calibration and idle fine with a heavily modified lt1. open up ur program and look at the injector bank assignment and post ur order I can check it tomorrow when I get to my shop. I'm on a different computer now. Are you on the hp tuners forum ??? Lots of help there if u read thru all the posts
Mechanic A is offline  
post #13 of 15 (permalink) Old 05-11-2014, 08:43 AM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
Quote:
Originally Posted by Mechanic A View Post
Di d u wire the injectors and coils differently? The lt1 and the ls with the 411 PCM use a different firing order I was able to start my car off a stock 02 ls1 calibration and idle fine with a heavily modified lt1. open up ur program and look at the injector bank assignment and post ur order I can check it tomorrow when I get to my shop. I'm on a different computer now. Are you on the hp tuners forum ??? Lots of help there if u read thru all the posts

I wired up the injectors and coils per the instructions from EFI Connection. I double checked them and I have them wired just as the instruction describe. I am on HP Tuners site it just seems like there isn't a lot of support for the LT1/24x stuff. Its not nearly as popular as the LS stuff. Where do I find the inj. bank assignment in the HP program?
tes96ta is offline  
post #14 of 15 (permalink) Old 05-11-2014, 11:52 AM
Regular Member
 
Join Date: Feb 2014
Location: Agawam MA
Posts: 18
 
It's under engine >fuel>General and then top row of middle column and it should read top to bottom 01101001. Meaning injector a -0 b -1 c-1 and so on. And yes very little support for the lt on hp but there are a few guy who have done the swap and seem very smart but help on that sit is kind of hard to come by. If u figure out how to post logs and tunes the help will come if you are patient And I did find u on there and respond Also under the injector table the is the injector flow rate which needs to be set to ur injector size check that and see if it's the same value all the way across This shouldn't cause ur problems but .....does need to be changed. I am a novice when it comes to tuning but I will try to help. If you post your tune on hp I can compare it to mine
Mechanic A is offline  
post #15 of 15 (permalink) Old 05-11-2014, 08:09 PM Thread Starter
Regular Member
 
Join Date: Sep 2007
Location: Maryland
Posts: 119
 
Quote:
Originally Posted by Mechanic A View Post
It's under engine >fuel>General and then top row of middle column and it should read top to bottom 01101001. Meaning injector a -0 b -1 c-1 and so on. And yes very little support for the lt on hp but there are a few guy who have done the swap and seem very smart but help on that sit is kind of hard to come by. If u figure out how to post logs and tunes the help will come if you are patient And I did find u on there and respond Also under the injector table the is the injector flow rate which needs to be set to ur injector size check that and see if it's the same value all the way across This shouldn't cause ur problems but .....does need to be changed. I am a novice when it comes to tuning but I will try to help. If you post your tune on hp I can compare it to mine
I checked the injector settings and they are correct. I really hope to get this stuff figured out. I really want to learn how to tune it just seems complicated and I dont want to screw anything up.
tes96ta is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome