Microtech Area is for discussing Microtech systems

Microtech LT12 install runs rough

Old 09-21-08, 06:28 PM
  #1  
Rotary Enthusiast
10 Year Member
Thread Starter
iTrader: (1)
 
cbrock's Avatar
 
Join Date: Aug 2001
Location: MI 48111
Posts: 982
Likes: 0
Received 0 Likes on 0 Posts
LT12 install runs rough

finally got my LT12 installed in my 88. I got the TPS reading 0 on screen, its hard for me to see the light on the ECU due to the install location. It fires up, but sounds and runs rough. My fuel pressure is a little low, but not horrible.

My question is on the timing. The motor has never been opened or touched except for installing the 3574. I just wired everything up and fired it up with the above results.

Do I have to mess with the timing now that I have the microtech? Or do I have a stuck seal from sitting for 2 years? Or both
cbrock is offline  
Old 09-22-08, 01:40 AM
  #2  
Gen 2 Raced Hard NA 13B
5 Year Member
 
Join Date: Apr 2006
Location: Canada
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Engine Problem (Check)

If you run in a range of 36 to 45 PSI on fuel pressure you would only notice a small air fuel ratio change(1 to 1.5 points in most set ups).So do not worry about low fuel pressure to much. But you will most likely have a gummed up fuel filter and stale gas. Change out both. Timing on a rotary can be off by 10 to 15 d egress and still start up and run quite well. Us a timing light check at idle and rev to 3500 to 4500 to see if it has full advance. Total advance 26 degrees max have it full at 3500 RPM. Check plugs or better yet put in a new set. Side seals or apex seals will not stick from sitting for two year. The only problem with a rotary sitting would be moister in the rotor chambers causing rust. This would o cure with a motor exposed to damp conditions only and for long periods. I would say go through and look at your AFR at each RPM from idle to max under load. If it is hunting at idle look to adding fuel. If it has a low low lump cam sound to it your rich at idle and remove fuel. NA rotaries like 12.8 to 13 -1 AFR. Light loads stay at 14 to 1 and WOT 13 to 13.4 works fine.

Happy tuning.
SCCA RX7 RACER
SCCA RX7 RACER is offline  
Old 09-22-08, 07:34 AM
  #3  
Rotary Freak
iTrader: (8)
 
rx72c's Avatar
 
Join Date: Jun 2003
Location: Australia
Posts: 2,608
Likes: 0
Received 0 Likes on 0 Posts
show us your current map.
And ill tell you were to go from their.
rx72c is offline  
Old 09-22-08, 12:03 PM
  #4  
Rotary Enthusiast
10 Year Member
Thread Starter
iTrader: (1)
 
cbrock's Avatar
 
Join Date: Aug 2001
Location: MI 48111
Posts: 982
Likes: 0
Received 0 Likes on 0 Posts
I'll check the timing once I get it warmed up and idling good. It has only a minute or so of run time. It did improve greatly once I got the fuel pressure up. There was maybe 2-3 gallons of old gas that had stabel in it, unknown moisture content and 10 gallons of fresh.

So if the CAS has never been touched then it "should" be fine where it's at?
cbrock is offline  
Old 09-22-08, 05:50 PM
  #5  
Rotary Freak
iTrader: (8)
 
rx72c's Avatar
 
Join Date: Jun 2003
Location: Australia
Posts: 2,608
Likes: 0
Received 0 Likes on 0 Posts
yep. i wouldnt touch it just yet.

i believe the problem is in your fuel/map.
rx72c is offline  
Old 09-24-08, 07:51 AM
  #6  
Rotary Enthusiast
10 Year Member
Thread Starter
iTrader: (1)
 
cbrock's Avatar
 
Join Date: Aug 2001
Location: MI 48111
Posts: 982
Likes: 0
Received 0 Likes on 0 Posts
Last night I fired it up again. This time I got the wide band hooked up right and was getting some readings. While it's running for the first 30-45 seconds it has a missing, rough running sound, then as the temp starts coming up a little bit it really smooths out and will idle and rev up smooth.

I was seeing AFR of 10:1 and when it was idling I was around 12.5-13. The idle is set a little bit high at 900 and I'm pulling 18-19" vac. My chevelle would do that when it was lean, but the 7 smells a bit rich so I suppose it could go the other way too.
cbrock is offline  
Old 09-24-08, 10:23 AM
  #7  
Rotary Enthusiast
10 Year Member
Thread Starter
iTrader: (1)
 
cbrock's Avatar
 
Join Date: Aug 2001
Location: MI 48111
Posts: 982
Likes: 0
Received 0 Likes on 0 Posts
that's 10:1 cold start having to keep my foot with it then 12.5-13 once it would idle.
cbrock is offline  
Old 09-24-08, 05:36 PM
  #8  
Rotary Freak
iTrader: (8)
 
rx72c's Avatar
 
Join Date: Jun 2003
Location: Australia
Posts: 2,608
Likes: 0
Received 0 Likes on 0 Posts
Like i said. In your tune.
Your cold start is off.
And 900rpm isnt a high idle?
rx72c is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
bb6guy
Old School and Other Rotary
10
10-01-18 08:07 AM
trickster
2nd Generation Specific (1986-1992)
20
03-29-18 02:05 PM
bb6guy
3rd Generation Specific (1993-2002)
3
08-12-15 03:29 PM
gabescanlon
Interior / Exterior / Audio
1
08-11-15 05:59 PM


Thread Tools
Search this Thread
Quick Reply: Microtech LT12 install runs rough


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:
Description:
Your question will be posted in: