Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

There she blows (928 S4 '89 manual running rich)

 
Old 05-19-2014, 07:39 PM
  #31  
JakeS2
User
Thread Starter
 
JakeS2's Avatar
 
Join Date: Jul 2007
Location: Finland, Europe
Posts: 397
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks dr bob. I'll check that. I don't have a mityvac but I have (11 pcs of) Irimo ZH405 vacuum pumps. Maybe I can use one for testing
JakeS2 is offline  
Old 05-22-2014, 05:41 PM
  #32  
JakeS2
User
Thread Starter
 
JakeS2's Avatar
 
Join Date: Jul 2007
Location: Finland, Europe
Posts: 397
Likes: 0
Received 0 Likes on 0 Posts
Default

While waiting for other parts to arrive I decided I'll do additinoal tests with vacuum leaks. And guess what, found some. The oil breather pipes that run from pass. side valve cover to intake leaked! Not much but just enough I suppose.
JakeS2 is offline  
Old 06-13-2016, 06:22 PM
  #33  
JakeS2
User
Thread Starter
 
JakeS2's Avatar
 
Join Date: Jul 2007
Location: Finland, Europe
Posts: 397
Likes: 0
Received 0 Likes on 0 Posts
Default

Ok, this is closing post for this oooold thread.

Running rich original problem: injectors were totally shot! All 8 of them leaked(!) and two leaked really bad. All of them were clogged also and two of them were really clogged.

So, what happened? We pulled intake for ICV change and managed to get some sand into the engine (yes, proper cleaning next time) - so, engine apart.

Engine out and took heads off - and then I took a long breath. Head gasket on both sides had failed on two cylinders (yes, matching to the clogged ones) and if we would have continued to run on that year - engine would have gone boom!

So, little summary...
- cylinders were ok, no scratches
- new rod bearings
- all new seals
- machined heads
- valves where worked to match factory values
- S3 cams
- new ICV
- new this and that
- new coils

All by myself! I have never ever re-built an engine from scratch on my own, so the Porsche 32V V8 is the correct setup for the first time - after this nothing feels like a 'big job'.

...and now getting a techedge + LSU4.9 to monitor running.
JakeS2 is offline  
Old 06-13-2016, 11:29 PM
  #34  
M. Requin
Addict
Rennlist Member
 
M. Requin's Avatar
 
Join Date: Mar 2007
Location: Central Virginia
Posts: 3,415
Likes: 0
Received 4 Likes on 4 Posts
Default

Thanks for the history, the details, and the great followup- great job!
M. Requin is offline  
Old 08-02-2016, 12:56 AM
  #35  
JakeS2
User
Thread Starter
 
JakeS2's Avatar
 
Join Date: Jul 2007
Location: Finland, Europe
Posts: 397
Likes: 0
Received 0 Likes on 0 Posts
Default There she blows (928 S4 '89 manual running rich) [SOLVED]

Let's put closure to this thread.

So, although the engine was rebuilt, it did not fix the strange running rich problem. So, back to debugging table:
- o2 sensor : changed, no effect
- another coil changed (as it was almost dead!) - some improvement but immediately when engine got warm - it went rich (AFR +10).
- re-re-re-re-recheck regulators and dampers - BINGO! When engine was just shut down, taking vacuum line from regulator caused a fuel leak. Decided to change 'em all.

So, we're now at 14.7 idle AFR, on WOT it goes to 12-ish (we have maps from 0 to rev.max on 4. gear), on normal acceleration it's at 13-14.

Thanks all guys who helped on this thread, really appreciate.

--Jarko

ps: For all the 'what the F I am doing' and 'is this really worth this' thoughts are immediately set to null when you have 40-50km/h on the clock, third gear in and slam the pedal to the metal -- and upshift. The push, the grip and the noise. Love it.

Last edited by JakeS2; 08-02-2016 at 01:00 AM. Reason: brags
JakeS2 is offline  

Thread Tools
Search this Thread
Quick Reply: There she blows (928 S4 '89 manual running rich)


Contact Us - About Us - 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: