General Rotary Tech Support Use this forum for tech questions not specific to a certain model year

Low compression on fresh rebuild

Old 05-28-19, 03:06 AM
  #1  
sim
Currently building my rx7
Thread Starter
 
sim's Avatar
 
Join Date: Mar 2006
Location: england (leicestershire)
Posts: 72
Received 1 Like on 1 Post
Low compression on fresh rebuild

Hi guys,
having starting issues. I know this could be a number of things and Iíve tried most I also keep fouling plugs.

i know I have low compression 65psi front back and across all faces
Iíve read I should expect low compression on a rebuilt motor, the motor is a full Bridgeport with one piece goopy seals and solid corner seals. And a second hand set of housings.
Now I did get the motor starting regular and quite well on the standard injectors but Iíve recently upgraded them to 4x1000cc grams and now the issue has worsened.

Ive had it running a few times and when itís running itís sound.
Do you think I should strip the motor or work with it for a bit longer, Iím slowly learning about the ecu and building my confidence but Iím going through plugs like mad and itís becoming quite frustrating at times.

i cant even take it for a spin as I have no tax, insurance or mot.

sim is offline  
Old 05-28-19, 03:48 AM
  #2  
Junior Member
 
Join Date: Jan 2018
Location: Norway
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Why don't fit the oem injectors so you can start it and let i idle for some time so you get the compression up?
Maluch is offline  
Old 05-28-19, 05:03 AM
  #3  
sim
Currently building my rx7
Thread Starter
 
sim's Avatar
 
Join Date: Mar 2006
Location: england (leicestershire)
Posts: 72
Received 1 Like on 1 Post
Originally Posted by Maluch View Post
Why don't fit the oem injectors so you can start it and let i idle for some time so you get the compression up?
Iíve had it idling for some time now and Iíve changed the map so Iíd still have work to do on the map if I was to refit the old injectors.
sim is offline  
Old 05-28-19, 12:51 PM
  #4  
32psi+
iTrader: (42)
 
Copeland's Avatar
 
Join Date: Sep 2006
Location: Raleigh, NC
Posts: 1,264
Received 15 Likes on 15 Posts
Originally Posted by sim View Post
I’ve had it idling for some time now and I’ve changed the map so I’d still have work to do on the map if I was to refit the old injectors.
I suggest saving a copy of your map before doing any modifications so that you don't lock yourself out in a situation like this. So save one now as some *NAMEOFMAP*_original.map kind of file and just save another copy to some other name going forward. I have probably 300+ revisions of my own tune so I can go back and check what has changed or copy previous values I have used to experiment.

It sounds like you need to have the car tuned but the motor doesn't sound very healthy either with only 65psi compression (which may or may not go up if car is ran some). You're fighting two things at once and neither is helping you. Solve one or the other and it will be a lot easier.

What ECU are you using?

Last edited by Copeland; 05-28-19 at 12:56 PM.
Copeland is offline  
Old 05-28-19, 01:17 PM
  #5  
sim
Currently building my rx7
Thread Starter
 
sim's Avatar
 
Join Date: Mar 2006
Location: england (leicestershire)
Posts: 72
Received 1 Like on 1 Post
Originally Posted by Copeland View Post
I suggest saving a copy of your map before doing any modifications so that you don't lock yourself out in a situation like this. So save one now as some *NAMEOFMAP*_original.map kind of file and just save another copy to some other name going forward. I have probably 300+ revisions of my own tune so I can go back and check what has changed or copy previous values I have used to experiment.

It sounds like you need to have the car tuned but the motor doesn't sound very healthy either with only 65psi compression (which may or may not go up if car is ran some). You're fighting two things at once and neither is helping you. Solve one or the other and it will be a lot easier.

What ECU are you using?
Iím using microtech lt10s with x4 box and four trailing coils.
this is why Iím in two mind if I should pull the motor anyway. When I had it running and starting on the 550s I was happy and had no reason to question the engine at that time.
I did save a map but for some reason when I reloaded it it was not the map I saved so I ended up loosing both.
sim is offline  
Old 05-28-19, 01:20 PM
  #6  
sim
Currently building my rx7
Thread Starter
 
sim's Avatar
 
Join Date: Mar 2006
Location: england (leicestershire)
Posts: 72
Received 1 Like on 1 Post
The default map I start with is the one silverrotor posted as a stock Tll base map plus -51 in the mixtrm.
sim is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Scrappy_Brap
General Rotary Tech Support
20
01-23-16 10:13 AM
sideways-FC
2nd Generation Specific (1986-1992)
7
12-13-13 07:11 AM
Mx6-Rx7 Addict
2nd Generation Specific (1986-1992)
3
11-14-06 01:21 AM
Russ-R
2nd Generation Specific (1986-1992)
5
06-04-06 07:54 PM
fc3sxtasy87
2nd Generation Specific (1986-1992)
4
09-06-05 08:38 PM


Thread Tools
Search this Thread
Quick Reply: Low compression on fresh rebuild


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: