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Discussion Starter #1
What are the normal injector balance rate numbers????? At what point does gm say to replace them + or - what number????? I read in my shop manuals that the norm is below+2.5 to above -2.5, but have done searches on here and it seems that anything over 4 then you might have problems. Also how much should those rates change when changed from park and put into drive??? Should they go up or down or stay relatively the same???? Obviously this is all done when engine is warm, as i tried it the other morning upon start up. Balance rates showed 0 for about 5 minutes until engine warmed up..........is that normal??? Thanks Jeremy
 

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Gm is +5 to -5 but Eric said he likes to see +4 to -4. When I check mine sometimes the will all sit at line .82 for a while, then start changing.
 

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The technical answer according to GM, is +/- 4.0 at idle hot, in park. In gear +/- 6.0


But, Yes, I like to see less then +/- 4.0
 

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Jeremy,


At the following post and towards the end, I copied what was in my Helms Service manual for the 2002 truck with respect to balance rates.


http://dieselplace.com/forum/forum_posts.asp?TID=4290


My manual indicates +/- 4.0 for in park with A/C off and +/- 6.0 for in drive. The engine must be up to temperature. There is a substantial change on my truck from park / no A/C and then to drive. (It is really about loading the engine slightly.)


For park, most of mine are around -0.6 with the exception of one which is around -1.6 (or so). Put it into drive and the numbers diverge rapidly (example: the -1.6 goes to -3.5). The balance rates are always being calculated while idling. So they will drift around constantly. Even the A/C cycling on/off will make them change.


With respect to 0.82, as soon as the engine is brought off-idle, the balance rate calculation is no longer performed by the ECM. The rates are all set to a default, the same number,,,,, 0.82.


The main purpose for performing the balance rates calculation is to smooth the engine out during idle.





The above is my understanding,


Alan
 

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Discussion Starter #5
My #6 injector is +3.3 to +3.8 at idle, when put in park it lowers to +1.5 to+2.5. All the others are -1 to +1 or around zero. Will be keeping an eye on #6 to see if it gets worse. Erics on speed dial if it gets out of range



BTW i looked in the shop manuals and it stated that the normal balance rates were -2.5 to +2.5. Seems that gm has changed the allowable rates, maybe due to a bigger flucuation than thought at the beginning of the dmax release so to not be changing every single trucks injectors.
Edited by: heartbeatcanada
 

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heartbeatcanada said:
BTW i looked in the shop manuals and it stated that the normal balance rates were -2.5 to +2.5. Seems that gm has changed the allowable rates, maybe due to a bigger flucuation than thought at the beginning of the dmax release so to not be changing every single trucks injectors.

Yup, they changed it. There a lot of changes made to the service manuals. If you have a paper version you should see if there are any updates before you follow a procedure.


SMU - Revised Fuel Injector Balance Test with Tech 2 (Automatic Transmission) #03-06-04-054 - (09/26/2003)
 

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I want to have my dealer do the test the next time I bring my truck in. What's the normal charge for this test, how much time does it take. Thanks
 
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