Reply
 
Thread Tools Display Modes
 
Old 10-13-2006, 05:03 PM   #1
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,116
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
IH MV404 gasoline engine misfire -- help!

I have gotten the carburetor jetting sorted out, but my 1981 MV404
still fails smog check. It puts out too much hydrocarbons at 2500
RPM. The source of the problem seems clear enough: the #1 cylinder
is not firing properly. It doesn't show up on the scope, but when the
analyzer cuts out each cylinder, the #1 does not drop any RPM.
Of course, we verified this the old way also by pulling the plug wire off;
no RPM drop. So I've been driving around on a 7-cylinder engine -- well
a 7 1/2, or so.

We switched the plug with another; the problem stayed on #1 cyl.
The plug wire measures 10.000 ohms, just like the others. The inside
of the distributor cap looks good. Compression is 120, just like
the others.

What da heck??

Could the ignition system be failing to fire one cylinder properly? It is
an electronic distributor. There is a "star wheel" where the points cam
would be on an older unit.

How about the governor system? I have no idea how that works. There
is a little electronic box on the firewall that says "electronic governor
control", with three wires. What does it do? Does it pull the carburetor
back or does it kill spark?

Help! What are we overlooking?
__________________
Elliot
Millicent The Bus - roof raised two feet, toy-hauler tailgate.
http://www.skoolie.net/forums/f11/th...gate-1564.html
Elliot Naess is offline   Reply With Quote
Old 10-14-2006, 09:35 PM   #2
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,116
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
Pulled the valve cover; no broken spring. Ran the engine with cover off;
normal valve movements and good oil flow on rockers.

????
__________________
Elliot
Millicent The Bus - roof raised two feet, toy-hauler tailgate.
http://www.skoolie.net/forums/f11/th...gate-1564.html
Elliot Naess is offline   Reply With Quote
Old 10-14-2006, 10:03 PM   #3
Bus Nut
 
Griff's Avatar
 
Join Date: Jan 2005
Location: Off-Grid
Posts: 740
Year: 1982
Coachwork: Thomas
Chassis: IH S1723
Engine: IH V345 Gas V8
Rated Cap: 66
Have you looked at the contacts of your distributor cap? Even though it is electronic, it still has a rotor button that translates the spark to the idividual wires. If the contact is burnt / broken, it may not fire properly, or if there is a crack in the distributor cap on / near the #1 cylinder tower, it could cause such a problem. (I had that happen on one of my POVs a long time ago, the distributor cap tower for that cylinder was the culprit.) Good luck!
__________________
~(G)Q Arduously Avoiding Assimilation
Griff is offline   Reply With Quote
Old 10-14-2006, 10:27 PM   #4
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,116
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
The cap looks good inside, but you are the second guy to tell me that a
cap can be bad even though it looks good to the naked eye, so tomorrow
I'm going to NAPA for a cap and rotor. And plug wires while I'm at it.

I was hesitant to invest in cap, rotor and wires if the problem was a flat
lobe on the cam! But now that I know the valves move OK, it's time to
go back to the ignition system. Thanks for the input!
__________________
Elliot
Millicent The Bus - roof raised two feet, toy-hauler tailgate.
http://www.skoolie.net/forums/f11/th...gate-1564.html
Elliot Naess is offline   Reply With Quote
Old 10-15-2006, 01:48 AM   #5
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
If you get it to fire and it still fails, go get yourself a used MSD6AL or similar sparkbox off eBay. You'd be amazed what a difference the hotter spark can make. It would appear that the RPM range they test you at is low enough that you would still benefit from the multiple spark events from a box too.

x2 on the cap, rotor, and wires. I go through probably 2 sets per year on my toyota. Even though they look great, I can feel the difference with my seat of the pants dyno and in my mileage.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Old 10-15-2006, 11:30 AM   #6
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,116
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
Two sets of ignition parts per year on your car?! Wow! Well, I sure don't
doubt it, because I know I can feel my car runs MUCH better after I
change the oil! I guess I'm re-learning how important these things are --
mechanical things thrive on maintenance. (As do human things, but that's
a different bulletin board! )

And I have heard good things about the MSD units for years, so that's
probably a good idea all around. (MSD stands for Multiple Spark Discharge.)

A friend suggested I might have a mouse nest in the intake port. Not
entirely impossible, since the bus sat for two years at the bus barn
before I bought it. But what are the odds?!

Thanks for the input! A pile of ignition goodies coming up!
__________________
Elliot
Millicent The Bus - roof raised two feet, toy-hauler tailgate.
http://www.skoolie.net/forums/f11/th...gate-1564.html
Elliot Naess is offline   Reply With Quote
Old 10-15-2006, 03:21 PM   #7
Bus Crazy
 
Steve's Avatar
 
Join Date: Jul 2002
Location: Central Iowa
Posts: 1,838
Send a message via AIM to Steve
Quote:
Originally Posted by Elliot Naess
A friend suggested I might have a mouse nest in the intake port. Not
entirely impossible, since the bus sat for two years at the bus barn
before I bought it. But what are the odds?!
Actually that happens more often than you would think. They will also make homes in exhaust pipes and fill you cylinder with crud through the exhaust valve.

I have a vintage car in my garage that was parked only a couple of months and when I started it up last week a bunch of walnuts shot out of the exhaust pipe because some critter was hording them in there.
__________________
View my 1972 Ward: Topic from the Build : The Picture Gallery
View my 1986 Blue Bird: Topic from the Build : The Picture Gallery
View my 1960 GMC: Topic from the Build : The Picture Gallery
Steve is offline   Reply With Quote
Old 10-15-2006, 06:27 PM   #8
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
The only "reasonable" solution I can see to the mouse nest problem is a 14-71 supercharger with a mechanical injection and huge injecter hat coming out of the hood. Show those mice what boost really means. :P
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Old 10-15-2006, 06:50 PM   #9
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,116
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
You mean like this little doohickey on my street roadster?



All right, it's fake. Full of radiator tank and carbonator and air filter and flat cap disturbinator.

Back on topic: Do any of you know anything about the electronic ignition
on my 1981 MV404? A friend has a 1983 SV392 from the same school
district and it has POINTS! So I'm wondering if my electronic is
aftermarket. It has three wires; the white one goes elsewhere and the
engine runs without it.

Good attitude, '03! It might come to that!
__________________
Elliot
Millicent The Bus - roof raised two feet, toy-hauler tailgate.
http://www.skoolie.net/forums/f11/th...gate-1564.html
Elliot Naess is offline   Reply With Quote
Old 10-15-2006, 08:57 PM   #10
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
The white wire is probably a tach signal wire. Ever notice if the tach stops when you unhook it? I won't claim to know specifics of that ignition, but they're all pretty similar. The only way you could be having a problem with spark on one cylinder that I can reasonably see is the cap and rotor combination since this is the only place in the system where the spark energy gets defined for being for a specific cylinder. A coil would have to be pretty intelligent to skip every 8th spark event

I saw in you post the you tried different wires with the same problem. Have you physically tested for spark on the #8 terminal? Take a nice long wire and put it on the #8 terminal with a plug in there and gorund it out to something while you crank it. Yes, it's possible to get shocked. Yes, they sell the correct tool for this, but it costs money and I'm cheap. Finding out if you're actually getting spark to that cylinder will go a long ways to solving this problem.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
running both LP and Gasoline in GMC engine captainkf Alternative Fuels | Electric, Propane, Wood Gasification, etc. 4 11-11-2012 08:05 PM
Swap a 7.3 with gasoline engine for parade float?? Elliot Naess International | Navistar Drivetrain 6 03-31-2012 05:13 PM
Looking for a MV404 for my 1981 international bus veralbama Everything Else | General Skoolie Discussions 2 10-11-2008 11:45 AM
International 404, 6.9 and 392 gasoline engines? Elliot Naess Conversion General Discussions 2 02-04-2006 04:48 PM
Convert Ford B700 from gasoline to diesel engine? Elliot Naess Conversion General Discussions 7 11-13-2005 12:23 PM

» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 01:12 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.