i sent my old injectors to diy and had them upgraded to stage II's...i sent my chip to back to tony to get it redone....so right now i don't have any programming in the truck....however i have noticed a miss that has just developed over the past week...new injectors have been in for about a month with no problems.....this miss you can't tell at idle, but when you have the rpm's between 1500-2000 is when you really notice it. that's in park, going down the road or under a load-you notice it worse under load uphill...i have changed the fuel filter which was due, i also cleaned the fpr screan which was totally blocked, i have a fairly new 6637(i think that's the #) with less than 10k miles on it...just wondering if you all had any ideas on what to check next...oh yeah i checked the hpop and it is full.....

 

do you have access to a scan tool to do a cylinder contribution test?

 

no....i don't have one but i'll check around a see if i can locate one....i hope i don't have to pull the injectors again...but i guess i'll do what i have to.

 

ALWAYS flowbench the injectors after opening them up. Some will miss at idle, some will miss under load, some wont work at all. You wont ever know until you get them benched. It could be sticking, the springs could be weak, the new parts could have a defect. Too many variables to tell. I refuse to sell remans for this reason.

 

these injectors were tested before installation.....i think my problem could be related to my chip....i sent it back to have if redone and it was after i took it out that i started feeling the miss...it will be back this friday so i will see what it does when i put it back in...if there is no difference i guess i will start pulling them out and checking things....i can pull them out several times for the cost difference between new and rebuilt.....and i have bought new things in the past that didn't work like they were supposed to either so i guess it's just a chance that was worth taking for me....

 

is it knocking, or just missing?

 

no it's not knocking.....just missing.

 

update....i got my chip back in. i still have the miss and certain rpm's have even started feeling it at idle some...if i put it on the highest setting it is not as noticable but i think it's because i'm passing the rpm range of the miss so quick....so i am going to pull valve covers and start pulling injectors....

 

ok.....update.... i got a fellow to hook my truck up to a scanner...he ran a contribution test on the injectors and he said they were fine.....there were two codes that came up, one was saying the oil temp. sending unit had a bad/short wire connection he looked and did find a wire rubbed against the frame so we fixed that but still misses....the next code was a waste gate code....he told me to run some sea foam for diesel through to get that opening and closing properly...any thoughts?

 

We don't have a waste gate. Does he know what he is talking about?

 

he's talking about the ebp valve near the turbo housing....he pointed it out to me.

 

Maybe he did a buzz test?
This will tell only you if the electronic portion of the injector is working..but that's all.
The injector could still be bad causing the miss.

A cylinder contribution test will tell which one of cylinders has the miss,
it tests more than just the injectors. It also tests the condition of your valves,
piston rings plus the injectors by measuring the amount of rotaional velocity
difference for each cylinder as it is cut off.
If the cylinder is weak/missing it will show up in this test.

 

well i checked with him this morning and he said he ran a buzz test and then he also ran the injector contribution test...he said that the injectors are not the problem..so i don't know where that leaves me.

 

Maybe you need another scan performed with a better/different scanner.
Did he run it at the RPM where your miss occurs?
A CCT will not be accurate with the engine at idle.

 

no he did not run the truck...he told me to bring it by monday and he would do that very thing...so i guess i'll take it to him and let him try that...he's not going to charge me this time anyway....but when i do find the problem i will be sure to let everyone know....thanks for all your help