Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

VERY lean on acceleration

Thread Tools
 
Search this Thread
 
Old 12-19-2019, 12:36 PM
  #1  
yardpro
Rennlist Member
Thread Starter
 
yardpro's Avatar
 
Join Date: Dec 2010
Location: Morehead City NC
Posts: 1,951
Likes: 0
Received 18 Likes on 16 Posts
Default VERY lean on acceleration

SO i have a wideband 02 and an AFR gauge.
its mounted in a separate bung on the drivers side in my X pipe (has two bungs)

When i punch it my AFR jumps up to 17-18 for a few seconds then drops back down to 13ish. when it drops back down the power comes on like a light switch.

I also have a surging idle (will sometimes stall).

i have wd40'd the IAC, with no change.

I am thinking that the issue now is the MAF. this sound about right?
.
Old 12-19-2019, 09:28 PM
  #2  
Speedtoys
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 13,582
Received 1,034 Likes on 623 Posts
Default

When was the last full and complete intake refresh?
Old 12-20-2019, 02:13 AM
  #3  
The Forgotten On
Rennlist Member
 
The Forgotten On's Avatar
 
Join Date: May 2012
Location: Thousand Oaks California
Posts: 4,966
Received 316 Likes on 263 Posts
Default

Sounds like ruptured IAC hoses under the intake. I had similar symptoms driving my 89 and I was greeted with ruptured hoses after replacing the maf and 02 sensor.

Get a can of ether and start spraying around the intake to find the leak. If the idle rises, there is your problem.

You'll need to take the intake off to fix most of them so plan on doing a top end refresh or at least hoses and gaskets at minimum.

Old 12-20-2019, 06:58 AM
  #4  
yardpro
Rennlist Member
Thread Starter
 
yardpro's Avatar
 
Join Date: Dec 2010
Location: Morehead City NC
Posts: 1,951
Likes: 0
Received 18 Likes on 16 Posts
Default

Originally Posted by Speedtoys
When was the last full and complete intake refresh?
last full intake was 8-10 years. a few years before I bought it.

also I forgot to add I have a very rich idle.....
Old 12-20-2019, 10:48 PM
  #5  
Speedtoys
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 13,582
Received 1,034 Likes on 623 Posts
Default

Originally Posted by yardpro
last full intake was 8-10 years. a few years before I bought it.

also I forgot to add I have a very rich idle.....

Ya..its time for a pull apart. You've got multiple issues that all lead to leaks.
Old 12-20-2019, 10:56 PM
  #6  
Speedtoys
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 13,582
Received 1,034 Likes on 623 Posts
Default

https://rennlist.com/forums/928-foru...-for-sale.html

Hit up home depot, buy these, identify the leak.

Last edited by Speedtoys; 12-21-2019 at 07:28 PM.
Old 12-21-2019, 09:58 AM
  #7  
yardpro
Rennlist Member
Thread Starter
 
yardpro's Avatar
 
Join Date: Dec 2010
Location: Morehead City NC
Posts: 1,951
Likes: 0
Received 18 Likes on 16 Posts
Default

Originally Posted by Speedtoys
https://rennlist.com/forums/928-foru...-for-sale.html

Hit up home depot, buy these, identify the leak.6.5.0
I already made one of those for my kids BMW to do a diy smoke test. Looks like I’ll be breaking it out on mine...

Thx
The following users liked this post:
Speedtoys (12-21-2019)
Old 12-22-2019, 10:27 PM
  #8  
yardpro
Rennlist Member
Thread Starter
 
yardpro's Avatar
 
Join Date: Dec 2010
Location: Morehead City NC
Posts: 1,951
Likes: 0
Received 18 Likes on 16 Posts
Default

So here's a question.

Idle does not fluctuate until car is warmed up.
Won't a vac leak show even when cold.



Quick Reply: VERY lean on acceleration



All times are GMT -3. The time now is 10:28 AM.