injector test - Diesel Truck Forum - TheDieselGarage.com
Thread Details Posted by shwillis, this thread has received 8 replies and been viewed 1778 times.

 
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post #1 of 9 (permalink) Old 02-21-2008, 10:15 PM Thread Starter
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injector test

Does Anyone Know How Much It Would Cost To Have The Dealership Test My Injectors And Tell Me Which One Is Leaking. I Belive That They Call It An Injector Balance Rate Return Test, Or Somthing Like That. Hopefully Only One Is Bad. My Balnce Rates (according To The Programmer) Are All Within The Specified Parameters. So Thats Not Helping Me. Any Info Would Be Appriciated, Especially The Correct Name For The Test So I Dont Sound Like An Idiot When I Go. By The Way I Am Over The Millage For The Special Injector Policy. Thanks

1997 2500 Cummins 4x4 230k
Grinded Fuel Plate, AFC full foward, Starwheel Adjusted, Staightpiped
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post #2 of 9 (permalink) Old 02-21-2008, 11:24 PM
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i just had the scanner put on my truck a couple weeks ago at my local chevy dealer. im pretty sure it was a flat rate 90.00 to have the scanner put on it.

im sure their are shops that will do it for less, but im new to this area, and kinda prone to using a dealer anyway.

Ray McIntire

02 D-Max C/C S/B
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post #3 of 9 (permalink) Old 03-05-2008, 01:29 AM
 
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If you have fuel in the oil the balance rate will not tell which injector is leaking. The balance rate only tells you if it is adding fuel or removing fuel at that cyl to get the same amount of power out of it as the others. It makes it idle smooth. If it has a smoke problem the balance rate may help diag the injector.
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post #4 of 9 (permalink) Old 03-07-2008, 10:35 PM
 
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Quote:
Originally Posted by chevycummins5.9
If you have fuel in the oil the balance rate will not tell which injector is leaking. The balance rate only tells you if it is adding fuel or removing fuel at that cyl to get the same amount of power out of it as the others. It makes it idle smooth. If it has a smoke problem the balance rate may help diag the injector.
X2, balance rates although will point you in the right direction because if the injector is leaking in the body it most likely will have a f'ed up balance rate
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post #5 of 9 (permalink) Old 03-12-2008, 03:44 AM
 
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Quote:
Originally Posted by BullfrogJohnson
X2, balance rates although will point you in the right direction because if the injector is leaking in the body it most likely will have a f'ed up balance rate
Back in 2001 when these trucks first came out I was one of the first dealers in this area working on them. This was at the time that injectors were replaced individually and had to be diagnosed. A friend of mine started to work on them at another dealer. He decided that doing the return fuel flow test and the dye test for fuel in the oil was too much work so he started to use balance rates to diag them. He had multiple comebacks with fuel in the oil over and over again. I was doing injectors on 2 to 3 trucks a week and never had a comeback. The diagnosis on these trucks is time consuming but worth the effert in the end. Thank god gm finally changed the diag and put out the special policy on the injectors!
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post #6 of 9 (permalink) Old 03-12-2008, 04:03 AM
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Balance rates are the easy way.

But they dont diagnose every truck, my truck had perfect balance rates, no fuel in oil, no smoke no rough idling nothing.

Just hard starting and a loss of 1mpg.

Took it to two dealers told them my injectors were bad both replaced my fuel filter without permission and said my injectors were fine.

Third try was my original choice of dealerships and they replaced all eight under the TSB.

If one is bad, all should be replaced.

(2) 03 GMC EC/SB 4x4 SLT Duramax/Allison's
00 VW Jetta TDI/5spd
73 KW W923 NTC290
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post #7 of 9 (permalink) Old 03-12-2008, 07:20 PM
 
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Quote:
Originally Posted by Durallymax
Balance rates are the easy way.

But they dont diagnose every truck, my truck had perfect balance rates, no fuel in oil, no smoke no rough idling nothing.

Just hard starting and a loss of 1mpg.

Took it to two dealers told them my injectors were bad both replaced my fuel filter without permission and said my injectors were fine.

Third try was my original choice of dealerships and they replaced all eight under the TSB.

If one is bad, all should be replaced.
Yup seen that before. You need approximatly 1200psi fuel pressure while cranking to get the fuel injectors to spray fuel. If your return flow from the injectors is slightly high the truck may not start or will crank a long time before the pressure will build high enough to get it to start.
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post #8 of 9 (permalink) Old 03-13-2008, 03:17 AM
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actually 1400psi is more where they like it and youre correct when the return rate is high, she wont start because they wont pop.

(2) 03 GMC EC/SB 4x4 SLT Duramax/Allison's
00 VW Jetta TDI/5spd
73 KW W923 NTC290
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post #9 of 9 (permalink) Old 03-14-2008, 03:38 AM
 
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Gm has a spec. of 1450psi of fuel pressure to get it to run. I've seen that if you plot the eng rpm and fuel pressure on a truck that has just enough fuel pressure cranking to get it to start it will start at about 1250psi. Every truck seems a little different though. In general when craking it should build fuel pressure to over 1450psi very quickly. If it does not then you have a problem somewhere. I use to do lots of injectors on these trucks but seems to be slowing down some now. Maby the newer injectors are actually better! The first trucks I had injector problems on only had 32,000miles give or take. My 2002 made it to 101,000miles before it was a no start and I had to put a set of injectors in it. My 2002 was a good truck but I like my 2007 alot more.
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