miss/ lope at idle

[dpuckett]

My mom has a 92 D350 with 225K. It has been loping at idle for some time, mileage is about 18 or so around town. She had the pump and injectors rebuilt last summer by a Bosch certified shop. I did the R & R. I just lined up the timing marks back to where they were, torqued down the injector nuts to 44 FT-lbs per CHilton manual. Not sure what idle speed is- it does do better in PARK w/o AC. I think it is an injector- one tip got replaced, the other 5 just got disassembled cleaned and recalibrated. Could timing be a little slow? No guages of yet, but I'm talking myself blue in the face tryin to get her to buy them. WHen i owned it in Loveland and Ft COllins CO, it got 20 mpg IN TOWN, 21-23 hwy. I know local fuel isnt the best, but none of my other pickups have idled rough back here. I think an injector or two isnt quite up to par- shop said they were all good. The install kit had the thinner washers- could that do it? I had a rough idle after the same shop did my injectors on the 4x4 last summer, and thicker washers took care of it, but this is a little different.



ANy help is appreciated.

Daniel

 

[BushWakr - RIP]

There are a couple things that can "work together" to cause rough idle...

If you installed the injectors with the injector line even slightly off flush with the injector tip... and you have a low idle setting this can make a big difference.

First, bump up the idle speed in "P"or "N", go 1/2 turn on the idle screw and see what that does for you.

Next, bump up your timing a bit too... roughly 1/8" spacing between the factory marks will get you "in the ballpark".

Run a double dose of additive thru the system as well, assuming the filter is good of course.



You may, as a last resort, try removing each injector line at the injector. . then, tweak the injector line end so that it is dead flush with the injector tip, and not "cocked"... while holding the line flush and in contact with the injector carefully do up the nut(s).

I know this sounds wierd but in my case one line was almost invisibly "off" and the miss was nothing short of nasty... in gear the truck would darn near die. .



Bob.

 

[J DeMaio]

Install some Stanadyne or Power Services fuel conditioner. I had mine lope at an idle once, I filled up with fuel and it still did it, went in the truck stop and also purchased some PS conditioner and after I went up the interstate and idled again, the miss was gone. This will be the quickest and easiest fix, definately won't hurt to try.



John

 

[cguthrie]

I think that when i put my injectors in we used the thicker washers. Does anyone know what the idle speed for a 92 with an automatic is?



Chris

 

[dpuckett]

THanks, guys. Tried Bushwakr's injector line idea. Helped a LITTLE. still lopes. I also bumped the idle up a bit- sitting at a light yesterday, the oil pressure got to the first line (not thick one next to "L" 1st in arc); runs down hwy in the middle or higher. Also bumped timing. Still doesnt purr, but a noticeable improvement. Working on wheel bearings on rear. CHecked brakes, worn, but ok. Bearings shot. Hard to find them in half ton gasser country. I might try the thicker washers, that's what's supposed to be init anyway.



I will keep you updated.



Daniel