2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
Sponsored by:

No power at full throttle

Thread Tools
 
Search this Thread
 
Old 07-09-23, 05:19 PM
  #1  
Junior Member
Thread Starter
 
indebt4fc's Avatar
 
Join Date: May 2023
Location: Canada
Posts: 10
Received 0 Likes on 0 Posts
No power at full throttle

At full throttle in gear my s4 88 rx7 has little power till 4000 then it struggle rev to any higher, but at quarter throttle it smoothly revs till redline and in neutral or with clutch in it revs instantly to redline
Old 07-09-23, 09:25 PM
  #2  
Rotary Freak
 
WondrousBread's Avatar
 
Join Date: Jul 2016
Location: Beeton, Ontario
Posts: 1,648
Received 479 Likes on 332 Posts
The hiccup at 4000rpm is the notorious "3800rpm hesitation". Do some searching and you'll see how common it is.

Normally it's caused by bad grounds, but you mention being down on power across the board. This implies to me that you are probably running lean, which compounds with the lean spike at 3800rpm when the secondary injectors come online.

I would start by checking for vacuum leaks, as that is the most likely cause. Checking and cleaning all the grounds also wouldn't hurt.

One last thing to mention is that these cars (NA anyways) don't really make much power until 4000rpm anyways. It shouldn't be "slow" below 4000, but it doesn't have the same torque as other cars do. 4000-7000 is where the fun happens in Rx7s.
Old 07-12-23, 09:50 PM
  #3  
Junior Member
Thread Starter
 
indebt4fc's Avatar
 
Join Date: May 2023
Location: Canada
Posts: 10
Received 0 Likes on 0 Posts
I checked and cleaned my grounds, I also added an extra ground from the engine to the the firewall, I started to test sensors and started with my throttle position sensor, at full open between a and b i get 1.97k ohms, at closed I get 1.6k ohms, between b and c i get 1.97k ohms.
About 900 ohms from a c. I'm gonna test my secondary injectors tomorrow and my afm
Old 07-13-23, 10:52 AM
  #4  
Junior Member
 
wilfff's Avatar
 
Join Date: Mar 2018
Location: Long Beach
Posts: 36
Received 10 Likes on 8 Posts
Your TPS readings look off. You should be seeing 5k ohms at some points. See below from fsm.
Kind of goes inline with the running lean WondrousBread is saying. At full open you should be at 5k, but you're only seeing 1.9k. So your ECU isn't giving correct fuel amount at fuel open.

EDIT: Also " ...but at quarter throttle it smoothly revs till redline..." , at quarter throttle it is possible your TPS just so happens to be near the expected ohm value and can climb revs as a result. If that makes sense.


Last edited by wilfff; 07-13-23 at 11:01 AM.
Old 07-13-23, 07:31 PM
  #5  
Full Member

 
Malic's Avatar
 
Join Date: Jun 2021
Location: Minnesota
Posts: 124
Received 21 Likes on 19 Posts
Is timing confirmed?
Old 07-19-23, 02:39 PM
  #6  
Junior Member

 
SeamusCoker's Avatar
 
Join Date: Oct 2015
Location: USA
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
Did you figure out the problem?
Old 07-20-23, 02:30 PM
  #7  
Junior Member
 
mho2023's Avatar
 
Join Date: Jul 2023
Location: IOWA
Posts: 18
Received 0 Likes on 0 Posts
Let me know the issue if you've found it please!
Old 07-20-23, 10:11 PM
  #8  
Junior Member
Thread Starter
 
indebt4fc's Avatar
 
Join Date: May 2023
Location: Canada
Posts: 10
Received 0 Likes on 0 Posts
So I believe it was a vacuum leak near the 5th 6th port actuators, I can't confirm cause I blew my pilot bearing and can't recreate the issue till I get that fixed, But that seemed to have solved the bad idle with tps
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
antiSUV
3rd Generation Specific (1993-2002)
10
11-27-11 10:40 AM
NBR Systems
2nd Generation Specific (1986-1992)
8
03-15-10 09:37 PM
Houstonderk
Haltech Forum
1
07-18-07 12:19 PM
Mankdrake 2661
2nd Generation Specific (1986-1992)
10
07-20-05 11:29 PM
Swolbynos
2nd Generation Specific (1986-1992)
7
11-23-04 09:20 PM



Quick Reply: No power at full throttle



All times are GMT -5. The time now is 04:11 PM.