Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

How quickly does the PCM adjust after rocker install?

Old Apr 23, 2007 | 01:47 AM
  #1  
67Goat's Avatar
Thread Starter
Senior Member
Posts like a 4 Banger
 
Joined: Jun 2006
Posts: 113
Likes: 0
From: Chicago, IL
67Goat is on a distinguished road
Default How quickly does the PCM adjust after rocker install?

So I'll be updating another post detailing my 1.95 rocker install. In the meantime, I was wondering how long it takes the PCM to adjust to the change? Driving home after the install, the car really felt sluggish from idle to about 4500 RPM. One time when I gunned it, I could see black smoke in the headlights of the car behind me. The car felt like it needed some motivation.
Reply
Old Apr 23, 2007 | 02:11 AM
  #2  
McGrath's Avatar
Senior Member
Certified GM nut
 
Joined: May 2005
Posts: 2,155
Likes: 0
From: Wickliffe, Ohio
McGrath is on a distinguished road
Default

I've heard about 100miles for the pcm to adjust to new mods. Just drive like you normaly do and in due time all your power will be waiting for you

Ed
Reply
Old Apr 23, 2007 | 02:27 AM
  #3  
big_news_1's Avatar
Senior Member
True Car Nut
 
Joined: Jun 2004
Posts: 3,459
Likes: 1
From: Glendale, AZ
big_news_1 is on a distinguished road
Default

1.95 rockers are a pretty sizeable change. Give the car a few days and a range of driving conditions. If possible, get some scan data to see how the PCM is reacting to the changes.
Reply
Old Apr 23, 2007 | 06:44 AM
  #4  
BillBoost37's Avatar
DINOSAURUS BOOSTUS

Expert Gearhead
 
Joined: Mar 2005
Posts: 41,391
Likes: 30
From: Enfield, CT
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

Did you happen to look at fuel trims, O2'* or KR after you made the change? These may have been indicators as to what was happening.

1.95'*....that required a spring and retainer change correct?
Reply
Old Apr 23, 2007 | 07:46 AM
  #5  
willwren's Avatar
Junior Member
Posts like a Ricer Type-R
 
Joined: Aug 2002
Posts: 11
Likes: 13
willwren is on a distinguished road
Default

OBD1 will take about 100 miles for 1.8'*, OBD2 a bit less. I'd give the 1.95'* about that amount of time on OBD2, but like the other Bill said, watch that scantool while it comes to you. You can actually watch it learn.
Reply
Old Apr 23, 2007 | 09:56 AM
  #6  
TommyGloves's Avatar
Senior Member
Posts like a Turbo
 
Joined: Jul 2005
Posts: 239
Likes: 1
From: Palatine, IL
TommyGloves is on a distinguished road
Default

You could also disconnect the battery for 10 minutes to let the PCM reset. This might be a good option to let fuel trims, etc start from zero. No need to overcome the current adjustments.
Reply
Old Apr 23, 2007 | 10:00 AM
  #7  
BillBoost37's Avatar
DINOSAURUS BOOSTUS

Expert Gearhead
 
Joined: Mar 2005
Posts: 41,391
Likes: 30
From: Enfield, CT
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

Probably the best way to go Tom..
Reply
Old Apr 23, 2007 | 10:28 AM
  #8  
67Goat's Avatar
Thread Starter
Senior Member
Posts like a 4 Banger
 
Joined: Jun 2006
Posts: 113
Likes: 0
From: Chicago, IL
67Goat is on a distinguished road
Default

Great - Thanks all for the feedback. I did have the battery disconnected for two days while I was working on it, so it probably is starting from scratch. I might re-scan in a couple days to see how it is going. I was just getting worried because I heard usually it would learn after about 30 minutes of normal driving and it was using quite a bit more fuel than normal. I swapped the PCM to ZZP'* a few days ago and it seemed to run fine then, so pretty sure that is not it.
Reply
Old Apr 23, 2007 | 11:17 AM
  #9  
agrazela's Avatar
Senior Member
Posts like a Corvette
 
Joined: Jan 2007
Posts: 1,451
Likes: 0
From: San Diego, CA
agrazela is on a distinguished road
Default

Originally Posted by 67Goat
Great - Thanks all for the feedback. I did have the battery disconnected for two days while I was working on it, so it probably is starting from scratch. I might re-scan in a couple days to see how it is going. I was just getting worried because I heard usually it would learn after about 30 minutes of normal driving and it was using quite a bit more fuel than normal. I swapped the PCM to ZZP'* a few days ago and it seemed to run fine then, so pretty sure that is not it.
1.95 rockers is a big change, and bigger changes do require longer fuel trim learn times.

You'll be bouncing alternately between overly lean / overly rich for awhile, so drive like a grandma for at least a few days to a week. ONLY AFTER a couple hundred miles and some definite improvements in the way the car runs should you even consider gunning it.

Do you have a scantool? If not, beg, borrow, or buy one, 'cause without it you'll be blind. As others have said, scan for KR and LTFT and STFT and O2. Also scan rpm, TP%, MAP, MAF, IAT and IPW.

Silly question perhaps, but did you tell zzp about your 1.95 rockers when you ordered the PCM? (In other words, is that PCM tuned to the rockers?)
Reply
Old Apr 23, 2007 | 11:25 AM
  #10  
firebuick's Avatar
Senior Member
Posts like a Camaro
 
Joined: Oct 2006
Posts: 987
Likes: 0
From: montreal canada NEBF07 ONBF07
firebuick is on a distinguished road
Default

what are we looking for when you say to check MAP MAF and IPW can i check these whit my aeroforce i know i have maf sensor and map frequency but dont know what is the normal reading .i do know about KR and IAT thank you
Reply

Thread Tools
Search this Thread

All times are GMT -4. The time now is 06:39 AM.