hotcam pcm tune? - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

Welcome to LS1LT1.com/LS3forums.com - please click here to register...

LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
Presented by:

New User? Register
LS1 Forums Register Photo Gallery Tech/FAQ Members List Calendar Auto Loans Search Today's Posts Mark Forums Read Auto EscrowInsurance
Premium Membership Videos Perf Tools Mobile/iPhone Link to Us! Social Groups Follow LS1LT1 on Twitter


Go Back   LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums > Engine Tech > LT1 | LT4 | L99 Engine Tech

LS1LT1.com is the premier Pontiac Forum on the internet. Registered Users do not see the above ads.
Reply
 
Share LinkBack Thread Tools
Old 02-16-2012, 08:09 PM   #1
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default hotcam pcm tune?

i have a hotcam in my lt1 and now the engine runs REALLY rich, so bad that it fouls the plugs after driving a while. i chased this issue as if it were another problem for a long time. i am pretty sure that it just needs a tune, but i was told that the hotcam would be drivable but need a tune only to take advantage of it. i invested in tunercats system but i just want to be sure that this is the only issue and that im not overlooking some other possible problem. has anyone else had experience with this?
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Old 02-16-2012, 09:15 PM   #2
Less than 8 cylinder Moderator
 
GTP231's Avatar
 
Join Date: Aug 2005
Location: Dover DE aka Slower Lower
Posts: 4,975
My Facebook
GTP231 Tradesman Level Tech I
Default

What supporting mods do you have? How old are all the tune up parts and are you certain the cam install was done properly?
__________________
Mr. Black Angus
01 PT Cruiser (beater for now)
03 GTP Stock I swear
13.464 @ 103.51 mph spinning a lil Totaled 9/25/2010
LSx> L67> Cross Fire> LTx
Quote:
Originally Posted by Grims View Post
God said, let there be light, and the optispark was born...and he saw that it was bad.
Quote:
Originally Posted by sweetbmxrider View Post
Lt1's suck.
GTP231 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 09:17 PM   #3
Less than 8 cylinder Moderator
 
GTP231's Avatar
 
Join Date: Aug 2005
Location: Dover DE aka Slower Lower
Posts: 4,975
My Facebook
GTP231 Tradesman Level Tech I
Default

Moved to a better section for the topic
__________________
Mr. Black Angus
01 PT Cruiser (beater for now)
03 GTP Stock I swear
13.464 @ 103.51 mph spinning a lil Totaled 9/25/2010
LSx> L67> Cross Fire> LTx
Quote:
Originally Posted by Grims View Post
God said, let there be light, and the optispark was born...and he saw that it was bad.
Quote:
Originally Posted by sweetbmxrider View Post
Lt1's suck.
GTP231 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 09:30 PM   #4
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default

lt4 hotcam stock bottomend ported heads 3.73 grs locker, automatic, cai, mid headers. new everything. engine rebuilt. flat tops. cam timing marks aligned but no further "degreeing". have replaced plugs, wires and o2 sensors
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 09:42 PM   #5
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default

Quote:
Originally Posted by GTP231 View Post
What supporting mods do you have? How old are all the tune up parts and are you certain the cam install was done properly?
hotcam, stock bottom end rebuilt, flat tops, ported heads mid headers cai 3.73 grs n locker, 3' borla catback. replaced plugs, wires and 02 sensors again. cam timing marks aligned but no further "degreeing"
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 10:14 PM   #6
Less than 8 cylinder Moderator
 
GTP231's Avatar
 
Join Date: Aug 2005
Location: Dover DE aka Slower Lower
Posts: 4,975
My Facebook
GTP231 Tradesman Level Tech I
Default

The ported heads can cause further tune requirements but not that much. Have you checked the ect reading with a scan tool?
Any exhaust leaks?
__________________
Mr. Black Angus
01 PT Cruiser (beater for now)
03 GTP Stock I swear
13.464 @ 103.51 mph spinning a lil Totaled 9/25/2010
LSx> L67> Cross Fire> LTx
Quote:
Originally Posted by Grims View Post
God said, let there be light, and the optispark was born...and he saw that it was bad.
Quote:
Originally Posted by sweetbmxrider View Post
Lt1's suck.

Last edited by GTP231; 02-16-2012 at 10:17 PM.
GTP231 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 10:40 PM   #7
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default

coolant temp reads fine, exhaust is good. i even redid the intake gaskets just to be sure.it runs on all 8 but really rich, stumbles at low end but opens up nice after 2500rpms. enough to spin second gear in the automatic without pwr braking it. took the car to a good diagnostic tech (repair shop, not performance) couldnt find problem. but we tricked the MAP sensor by attaching it to a vacuum pump and pumped it up to 20in. and the car ran beautiful. the cam is only producing 11-12in. vacuum

Last edited by SS95; 02-16-2012 at 10:43 PM.
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 11:30 PM   #8
Regular Member
 
Viper's Avatar
 
Join Date: Jul 2010
Location: New Mexico
Posts: 1,051
Viper Apprentice Level Tech I
Default

Hotcam should pull more vacume than that at idle. If not tuned the idle could be low timing or fuel trim not right at speed for that cam. Make sure the new o2's are working correctly. Get it tuned.
__________________
93 Z28 T-tops T56 6spd 3.23 Gears,
Mostly Stock.

Last edited by Viper; 02-18-2012 at 01:34 AM.
Viper is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-16-2012, 11:45 PM   #9
95Z
Admin
 
Join Date: Mar 2008
Location: MD
Posts: 8,045
95Z Apprentice Level Tech III
Default

If its an auto the stock rpm of 550 rpm at idle might just be too low for it, but if that were the only issue it would clear up the second you hit the gas. As long as the car is 94+ it should run acceptable without a tune except at idle.

I'm assuming the car is a 95 from your name? If its a 93 (speed density) it would definitely be the tune.

Another thing I would check (or double check) is the valve adjustment. If its off (too tight) it will throw your vac readings off at idle too.

You didn't make any injector changes did you? Make sure the regulator has the vac line hooked up too.
__________________


Yep its slow.

Making the world a warmer place one gallon at a time.
95Z is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-17-2012, 09:48 AM   #10
Regular Member
 
Join Date: Mar 2008
Location: Atlanta, GA
Posts: 1,210
bobdec Apprentice Level Tech II
Default

My hot cam tune idles at 700 in drive RPM in the very low 40's Kpa (12-13 in Hg) vacuum. Idle speed and Kpa was improved by tuning closed TPS timing, idle underspeed/overspeed timing and setting idle RPM, all done after TPS voltage adjustments. It ran a little rich at low end that I corrected with individual cylinder trim multipliers. However it never ran rich enough to cause problems at any RPM range. You vacuum is a little low, but not bad for no idle tuning. To foul plugs and/or O2's you have something wrong. High fuel pressure, are injectors stock, are the O2's Bosch ? Are your O2's reading rich (BLM's or trims) on the scanner and pulling fuel to no avail, or are they reading lean and adding fuel that may be causing the problem. Exhaust leaks will false cause lean readings.
__________________
I'm Bob.. 1994 Z28, A4, Stall, CAI, Cam, RR's, 342 rear, LT's , CatBack, Tuned

Last edited by bobdec; 02-17-2012 at 09:52 AM.
bobdec is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-17-2012, 05:28 PM   #11
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default

Quote:
Originally Posted by 95Z View Post
If its an auto the stock rpm of 550 rpm at idle might just be too low for it, but if that were the only issue it would clear up the second you hit the gas. As long as the car is 94+ it should run acceptable without a tune except at idle.

I'm assuming the car is a 95 from your name? If its a 93 (speed density) it would definitely be the tune.

Another thing I would check (or double check) is the valve adjustment. If its off (too tight) it will throw your vac readings off at idle too.

You didn't make any injector changes did you? Make sure the regulator has the vac line hooked up too.
its a 95, stock injectors adjustable fuel pressure reg. set at 43-44 psi. i have new rockers coming in the mail so i ll be sure too adjust them properly. so being that its a 95, your saying that it should run good enough for daily driving and that if it doesnt then theres a problem other than the tune?
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-17-2012, 05:45 PM   #12
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default

Quote:
Originally Posted by bobdec View Post
My hot cam tune idles at 700 in drive RPM in the very low 40's Kpa (12-13 in Hg) vacuum. Idle speed and Kpa was improved by tuning closed TPS timing, idle underspeed/overspeed timing and setting idle RPM, all done after TPS voltage adjustments. It ran a little rich at low end that I corrected with individual cylinder trim multipliers. However it never ran rich enough to cause problems at any RPM range. You vacuum is a little low, but not bad for no idle tuning. To foul plugs and/or O2's you have something wrong. High fuel pressure, are injectors stock, are the O2's Bosch ? Are your O2's reading rich (BLM's or trims) on the scanner and pulling fuel to no avail, or are they reading lean and adding fuel that may be causing the problem. Exhaust leaks will false cause lean readings.
scanner showed really low millivolts (rich) at o2 sensors ( they were reading and adjusting but could not get it above 400 millvolts) im gonna adjust the valves when i get the rockers, fuel psi and check for exhaust leaks, after that its just getting tuned. the way it acted when i tricked the map (ran incredible) tells me that the map thinks im on the gas when at idle so the pcm might be fighting itself
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-17-2012, 09:33 PM   #13
Regular Member
 
Join Date: Mar 2008
Location: Atlanta, GA
Posts: 1,210
bobdec Apprentice Level Tech II
Default

You said "scanner showed really low millivolts (rich) at o2 sensors ( they were reading and adjusting but could not get it above 400 millvolts" . That's lean and they will add fuel, 450Mv average is close to normal, as they cycle between 100-900 Mv. Under 450 average is lean. So your PCM is adding fuel. Not sure about the MAP, the PCM seeing false high vacuum (low Kpa) at low RPM could see that as deceleration and start pulling fuel, just a thought. Sure wish you had TTS DataMaster, it's free for 20 logs, helps tremendously in problems like this. Also freescan is free. By the way your FP is a little higher than normal, it's usually high 30's at idle and goes up +5 lbs when vacuum is removed from the regulator. Doesn't seem off enough to cause your problems.
__________________
I'm Bob.. 1994 Z28, A4, Stall, CAI, Cam, RR's, 342 rear, LT's , CatBack, Tuned

Last edited by bobdec; 02-17-2012 at 09:37 PM.
bobdec is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-17-2012, 09:35 PM   #14
Less than 8 cylinder Moderator
 
GTP231's Avatar
 
Join Date: Aug 2005
Location: Dover DE aka Slower Lower
Posts: 4,975
My Facebook
GTP231 Tradesman Level Tech I
Default

Below 500 millivolts pcm is adding fuel since its seeing a lean condition. Try adjusting the rockers before the new ones arrive just to be sure that is or isn't your problem. What was the O2 reading when you tricked the MAP?
__________________
Mr. Black Angus
01 PT Cruiser (beater for now)
03 GTP Stock I swear
13.464 @ 103.51 mph spinning a lil Totaled 9/25/2010
LSx> L67> Cross Fire> LTx
Quote:
Originally Posted by Grims View Post
God said, let there be light, and the optispark was born...and he saw that it was bad.
Quote:
Originally Posted by sweetbmxrider View Post
Lt1's suck.

Last edited by GTP231; 02-17-2012 at 09:37 PM.
GTP231 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 02-17-2012, 10:41 PM   #15
Regular Member
 
Join Date: Feb 2012
Location: S.Jersey
Posts: 12
SS95 user's tech expertise is unknown at this point
Default

Quote:
Originally Posted by GTP231 View Post
Below 500 millivolts pcm is adding fuel since its seeing a lean condition. Try adjusting the rockers before the new ones arrive just to be sure that is or isn't your problem. What was the O2 reading when you tricked the MAP?
i must have been wrong about the milivolts i posted if 400 is lean, its been a while since i had it on a live data scanner, i just remember that it was definately about 2-300 millivolts too rich and its obvious from the smell and black smoke when i rev it. so first thing first, adjust the valves, check/repair exhaust leaks. so giving the parts and head work with stock injectors, were should i set the fuel psi at idle/open throttle. when i attached the map to a vacuum pump up to 20in it had no hesitation and throttle response 100% better (in park quick hit on the pedal) i didnt check the scanner like that, i was too excited about how good it was running.
SS95 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not 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


» Recommended
Find technical articles on a Chevy Corvette, including tips and tricks on a Chevy Camaro and expert advice for Pontiac Firebird, along with reviews on the Cadillac CTS.
» Auto Insurance
» Sponsors
Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 04:38 PM.



Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.5.2
Copyright © 2005 - 2011 by LS1LT1.com

Our Friends:


Illegal Street Racing | Super Cars | LT1 Tech Articles