Microtech Area is for discussing Microtech systems

Low end matrix adjustment question

Old 06-15-18, 05:51 PM
Rotary Enthusiast
Thread Starter
Join Date: Aug 2008
Location: Portsmouth UK
Posts: 1,101
Received 13 Likes on 13 Posts
Low end matrix adjustment question

I have been working through a few little map issues at and around idle having finally sorted my TPS issue out. and I have one remaining gripe I want to try and sort out.
Just need a little pointer.
So when I drive the car during warmup when I come off the throttle or pull up to a stop the engine rpm drops right down and almost stalls. sometimes it will completely stall. It is only during warmup and fine when hot. AFR during warmup is pretty stable and constant around 12.5.
I think the issue is it starts cold with the rpm a little lower and in the 18HG 500rpm cell. then when it is about 3/4 warm it moves into the 1000rpm 18HG cell. see table below.

The red boxed cell is where my hot idle ends up. I now have this down at 0.86 in fact and idle is nice around 12.8-13AFR.
Anyway.. I think the issue during warmup is when you come off the throtte the rpm dips back into the idle 18hg cell and looks like it goes a little bit lean.. starts getting into the 13's and touching 14.. at which point the motor will stall. I cannot get it to idle any sense that lean so no real surprise. After my last drive I decided to try and richen up the 18HG idle cell a bit. So have put this up to 1.00 currently. it definitely seems to have helped and does not go near 14's but still stumbles a bit in the 13's as you come off throttle.
So my first question is how much richer would you expect to normally see this 18Hg idle cell to get a smooth run and no stumbling about coming off throttle?
Also if I am bringing this up to say 1.10 or maybe richer would I be correct in thinking I need to bring up the cells to the left of idle and idle 18Hg up also to give my graph a little upward tail at the end? So using these purely as an example if idle 18 HG is 1.10, should I make idle 24hg 1.15? In turn what do I do about the 30Hg line where that is much lower values? or do I need to tail this up a bit from the 1500rpm line so I can get a smooth upward trend through that bottom corner of the table and idle 30hg ends up say 1.20?

Thanks in advance for any info.
Leeroy_25 is offline  
Related Topics
Thread Starter
Last Post
04-22-11 05:35 AM
3rd Generation Specific (1993-2002)
06-02-03 12:24 AM
1st Generation Specific (1979-1985)
05-20-03 03:03 AM
05-12-03 03:00 PM
06-15-02 12:04 AM

Thread Tools
Search this Thread
Quick Reply: Low end matrix adjustment question

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: