It is currently Mon Nov 09, 2026 4:53 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: Air in fuel engine dynamics question
PostPosted: Fri May 13, 2011 11:32 am 
Offline
LOST Newbie

Joined: Mon Feb 14, 2011 4:54 pm
Posts: 44
Location: Oxford, MS, USA
As we all know, the Jeep loses power when air is mixed with the fuel. The engine can rev to 2,500 RPM with no acceleration.

Does anyone know what is going on inside the engine when this happens? If air is in the fuel, why doesn't the engine stall? Is it due to low pressure combustion creating low pressure exhaust, nullifying the turbo?

One of my friends thinks the engine should stall when the Jeep loses power like this.

--Loyd

_________________
2005 Liberty CRD Stone White

Image


Top
 Profile  
 
 Post subject: Re: Air in fuel engine dynamics question
PostPosted: Fri May 13, 2011 8:35 pm 
Offline
Lifetime Member
Lifetime Member
User avatar

Joined: Sat Jun 09, 2007 10:49 pm
Posts: 3554
Location: Aurora, IL
A very small amount of air in the fuel system delays the timing and reduces the quantity of fuel injected causing less than ideal running. More than a very small amount of air in the fuel system will cause crappy running because the fuel is not injecting properly, too late and not enough. Too much air in the fuel system will make it so the engine does not run at all, because of no fuel. To put this into perspective, lets say you are going 70 MPH at 2000 RPMs and getting 30 MPG. 2000RPM X 60 min= 12,000 rev/hour. Since the engine is 4 cycle the injectors will each fire 6,000 times every hour. 70MPH/30MPG=2.33 gal per hour. 2.33/(6,000 X 4) = 0.000097 gallons every time each injector fires when going 70 MPH at 30 MPG, that is a very small quantity of fuel and a bubble that small can cause a miss, more bubbles or bigger bubbles can cause more misses or no running at all.
Fix the air leak and install a lift pump and the problem will go away.

_________________
2006 Pearl Green CRD
Magnaflow 2 1/2" Cat Back
KJ Extra Leg Room Brackets, Carter Lift Pump, V6 Airbox, ORM
Fuel cooler, Oil Separator, Progard 7
Gauges EGT Boost Trans Temp Oil Pres, Michelin LXT AT2 245 70 R16
7,000# Draw Tight hitch, PML EX Deep Trans Pan
Centrifuge, SunCoast, Transgo, RAM TCM, InMotion Stage 2
Wife's 99 TDI VW Beetle


Top
 Profile  
 
 Post subject: Re: Air in fuel engine dynamics question
PostPosted: Sat May 14, 2011 5:19 pm 
Offline
LOST Member

Joined: Mon Mar 17, 2008 6:14 pm
Posts: 431
Location: RTP, NC
good answer.

if any fuel make it into the combustion chamber..it'll burn..if there is enough air..not enough air..black smoke

look at warp's number for the amount for fuel..what if 25% of that was air..yep 25% less power..this is a tiny fraction of the air already in the chamber..so the air isn't the problem its the missing fuel! if too much is missing..it will stall and died..How much load is applied to the engine. if you're try to haul a 5,000 lb trailer you have a vastly different fuel requirement that try to run at idle(noload).

the dynamics of a diesel are different that a gasser..if a gasser is starved of fuel it stalls/dies..what about too much fuel?..yep the same..

feed a hot gasser water instead of gasoline? it dies..a diesel?? only after the heat cannot make enough steam to keep it running..

-dkenny

_________________
84 BB school bus, DD8.2L turbo ->the transmission died..too expensive to fix..it'll be heading to the scrap yard..:(4/11)..Bus gone to Scarp 8/23/11 :(
06 Liberty CRD
'99 dodge ram 2500 quad cab, 4x4, 24v
all Biodiesel powered when its warm enough


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group. Color scheme by ColorizeIt!
Logo by pixeldecals.com