help me diagnose a miss

Cowboy_Customs

Cowboy_Customs

Rhinestone Cowboy
Joined
Jan 20, 2007
Messages
232
Here is the deal, the truck in my sig, isnt running so healthy.
The symptoms:
*low idle for about 10 second at initial start up
*SOMETIMES misses on a cyl at startup
*misses on a cyl, not BAD, but misses, up to around 1800 RPM and goes away after that, more when its comming up to temp, not so much cold.
*no smoke
Things I have done:
*OFV
*Fuel filter
*lots of fuel treatment/cleaner (Howes)
*Cleaned heater, did find some junk and metal shavings in the heater filter screen
*NO fuel leaks anywhere

Truck runs great past 1800, not low on power, obviously down when its missing, it isnt smoking, a little injector haze in the morning but its got 309K miles on it, turbo is fine, air filter is fine.
Warm idle is smooth. Lift pump seems just fine, it will prime very quick, and gets hard to pump after its primed. Just dont have the money for a fuel pressure gauge right now.
A big line kit is on the list of mods in the near future.
 
Mine did the same thing for about 6 months before dropping a cylinder for good one morning. Ended up finding one of the barrels split!
 
Acctually I will be checking and setting my timing this weekend.

YkDave, interesting, maybe I will pull the DV's and have a look at them as well.
 
My barrel split right around where the DV seats to the inside of the barrel. so it was quite obvious that i had an issue when i tried to crack the inj line and the DV holder was loose and could be screwed down into the pump another 1/4" lower than the rest of them! LOL
 
I would agree with YkDave! Pull the pump and have it benched before you go farther. If the pump is bad have it fixed before doing any adjustments and you will have a better performing truck.
 
I'm having an issue similar to yours, mine is worse when its cold though. It has more of a flutter than a full on miss most of the time, but sometimes taking off in first gear it will miss and have a little puff of blue smoke.
 
I agree with YkDave and the Reiffster. The pump may very well be the culprit.
 
if all else fail to find the cause..... this is what caused my truck to have a miss. It was very slight and ran great past 1800rpm could really only notice it at idle. It dyno only 50hp less that what my truck has with the valve like that....

valve.jpg
 
YIKES!! Now im gettin skeered! Oh man I cant afford a pump, or to pull the head right now.

N its not a FULL on obvious miss, but something aint right. Wow, guess I am pulling DVs this weekend.

Now whats got to happen should I have a lazy DV? Please tell me it isnt a rebuilt pump!
 
Not exactly a 'lazy' DV...

007.jpg


I actually split 3 barrels EXACTLY like this in the same pump. I popped the first one on #5cyl, then just threw in a barrel from another pump (not expecting much) and managed to get another day out of it before it split #5 and #2 barrels.
 
my truck has had the same symptoms that you described. but i would call it a studder before i call it a miss. and i only noticed it after i put bigger sticks in. it will not studder when its under more than light throttle. and it only occurs upto 1150 rpm at the highest. the funny thing that i noticed is that when i take my OFV out and put it back in, the studder almost completly goes away for a day or 2. by the way the ofv is brand new.
 
Wozxxx86 said:
my truck has had the same symptoms that you described. but i would call it a studder before i call it a miss. and i only noticed it after i put bigger sticks in. it will not studder when its under more than light throttle. and it only occurs upto 1150 rpm at the highest. the funny thing that i noticed is that when i take my OFV out and put it back in, the studder almost completly goes away for a day or 2. by the way the ofv is brand new.
Click to expand...

Similar problem as the other pump...with wear and tear the pump loses performance and it's time to have it gone through and freshened up.
 
Well, small update. Havent found the issue. The truck sat for a little while before I got it I am finding out. The other day I noticed it wasent really doing it. Of course I mentioned this to my buddy, the next day I put 50 miles on driving around town running errands. Yea, back to square one. Noticed, now, once its up to temp, and doing the miss, it is noticable at idle. So going to, one of these days, check it out loosen up injector lines and see what we find.
WOW talk about ANNOYING!
 
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