Cylinder contribution test - Ford Powerstroke Diesel Forum
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post #1 of 11 Old 04-30-2013, 05:57 PM Thread Starter
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Cylinder contribution test

I was playing with my otc scanner today. Did injector buzz test and everything passed. Then I did a cylinder contribution test and got code p0281. The truck runs fine have not noticed any kind of problems. I am ordering stage ones this week. Is this an injector issue or something more major?

1996 F250 crew cab. Hypermax intercooler, Gearhead tunes, 4" exhaust, 6637 intake, Autometer gauges, Dana 60, 6.0 cooling fan, Built e40d, Firestone airbags, Full Force stage ones more to come. SOLD

2003 7.3 F250 Lariat. Mostly stock.
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post #2 of 11 Old 05-01-2013, 09:25 AM
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Since it passed the buzz test I am going to assume that the coil on top of the injector #7 and the wiring to it are good. The PCM is reporting that when it gives the signal (or more when it removes the signal) to cylinder 7 to stop firing there is no difference to the idle. Meaning the test is to see how much more the other cylinders have to work when the PCM kills one of the cylinders. The more the other cylinders have to make up for the dead cylinder the more that dead cylinder was contributing to the overall performance of the truck. If the cylinder was dead the whole time (or so weak that at idle it really wasn't doing anything) the PCM will set a code for the particular cylinder that when killed showed no change in idle quality.

What this all means, since it passed the buzz test the wiring _should_ be fine. The injector itself may be weak or dirty, not just dead. Pull the right valve cover and watch the injector while the motor is running. Is there oil coming from the injector exhaust port (injector opening issue)? Is there oil coming up from base of the injector at the head (injector o-ring issue)? Pull the connector off the injector, did the idle change (electrical issue)? Pulling your own injectors is not hard just messy and time consuming. Does the truck drive fine (dirty nozzle issue)?

Matt
'97
-Bean's: 160/100 (FF Injectors), 2/ 6-POS chips (TW & Beans tunes), Overboost controller, E-Fuel
-BANKs: downpipe, full exhaust, gauges, intercooler
-Irate: T-4 kit, IC pipes, 3" Irate Plenums, BASB Turbo
-Stage II trans.
-Mag-Hytec trans. and pumpkin covers
-6637, CCV, IDM, 6.0 Fan, 49-Federal PCM swap, MAP line Mod
-370 Amp alt., 40k trans cooler, ADRENALINE PUMP
-twin on-board air w/ 10 gal. tank

-Oh, and a 2015 F350 6.7L DRW 4x4


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Last edited by BigFuel; 05-01-2013 at 09:48 AM.
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post #3 of 11 Old 05-01-2013, 09:27 AM
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That is exactly what happens when I run a cyl cont test, but I get a different code iirc, guess its time for sticks?

-Kris-
2000 excursion V10 2wd 230k
2000 Excursion 7.3 4x4 246k
1995 CCLB DRW 324K
2001 CCLB DRW 319K
Dp tuner infinity, exhaust, intake, chipped, tricked, and wrecked
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Quote:
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The stock downpipe in an OBS is flat because I'm a ginger.
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post #4 of 11 Old 05-01-2013, 09:44 AM
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Sorry the d-rail this thread but while u guys are on the topic. I try to run a cly cont test with my aeroforce interceptor gauge but i keep pulling a code that says my ac or heat is on(witch there off) and It wont run the test is there anything else that i have to turn off to run the test. I know the eot has to be at opperating temp. The gauge will do the buzz test fine. Any ideas ? Iv used a snapp on scaner in the past and it ran the test just fine.

-Brenden-

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post #5 of 11 Old 05-01-2013, 09:59 AM
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What code is it? Being a 95 (I don't know if it is an early or late 95 you have) your PCM would have needed to be flashed for proper OBD II port reporting from the PCM. First thought is that your gauge just isn't syncing to the PCM well. This might be fixed by going to Ford and having the PCM flashed again. But if the Snap-On is running fine Then I would tend to think that the issue is the gauge itself not communicating correctly with the '95 PCM. Did the gauge ever work correctly in performing this test? I don't know why it would report that if the heater was on it would affect the test but if the A/C or Defroster was on yes that would drag on the engine when the PCM dropped the cylinder. Possibly stalling the motor durring the test. About the only thing I see happening is that there might be a short to ground on the A/C clutch connection and the PCM thinks the A/C system is on. Disconnect the connector on the compressor and try again.

Matt
'97
-Bean's: 160/100 (FF Injectors), 2/ 6-POS chips (TW & Beans tunes), Overboost controller, E-Fuel
-BANKs: downpipe, full exhaust, gauges, intercooler
-Irate: T-4 kit, IC pipes, 3" Irate Plenums, BASB Turbo
-Stage II trans.
-Mag-Hytec trans. and pumpkin covers
-6637, CCV, IDM, 6.0 Fan, 49-Federal PCM swap, MAP line Mod
-370 Amp alt., 40k trans cooler, ADRENALINE PUMP
-twin on-board air w/ 10 gal. tank

-Oh, and a 2015 F350 6.7L DRW 4x4


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post #6 of 11 Old 05-01-2013, 11:36 AM
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Ill run the test again tonight if i have time and get the code #. Im leaning towrd the gauge being the culprit bc i did un hook the ac compressor connector but same code was spit out. to turn the defroster off its as simple as putting the dial to off right ??

-Brenden-

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M.B.R.P down pipe,4" pipe to 5" turnouts, 6637 INTAKE, FPR SHIM, FP gauge, P.H.P. CHIP, Dana 60 swap, ccv mod, Issapro A-Piller Gauges, Aero force obd2 gauge, Rear 32gal bronco tank, 35" coopers(with no lift
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post #7 of 11 Old 05-01-2013, 11:36 AM
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If the HVAC control is set to anything but the upright OFF position, the HVAC fan runs. IIRC, if it's set to the windshield defrost position it will run the AC compressor.
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post #8 of 11 Old 05-01-2013, 05:57 PM Thread Starter
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Quote:
Originally Posted by BigFuel View Post
Since it passed the buzz test I am going to assume that the coil on top of the injector #7 and the wiring to it are good. The PCM is reporting that when it gives the signal (or more when it removes the signal) to cylinder 7 to stop firing there is no difference to the idle. Meaning the test is to see how much more the other cylinders have to work when the PCM kills one of the cylinders. The more the other cylinders have to make up for the dead cylinder the more that dead cylinder was contributing to the overall performance of the truck. If the cylinder was dead the whole time (or so weak that at idle it really wasn't doing anything) the PCM will set a code for the particular cylinder that when killed showed no change in idle quality.

What this all means, since it passed the buzz test the wiring _should_ be fine. The injector itself may be weak or dirty, not just dead. Pull the right valve cover and watch the injector while the motor is running. Is there oil coming from the injector exhaust port (injector opening issue)? Is there oil coming up from base of the injector at the head (injector o-ring issue)? Pull the connector off the injector, did the idle change (electrical issue)? Pulling your own injectors is not hard just messy and time consuming. Does the truck drive fine (dirty nozzle issue)?
The truck runs great. I have not had any weird driveability concerns. That being said the truck does have 225k on it. I bought it with 170k on it and can only assume that the injectors are original. I have stage ones on order just need to get the chip pulled and have it changed.

1996 F250 crew cab. Hypermax intercooler, Gearhead tunes, 4" exhaust, 6637 intake, Autometer gauges, Dana 60, 6.0 cooling fan, Built e40d, Firestone airbags, Full Force stage ones more to come. SOLD

2003 7.3 F250 Lariat. Mostly stock.
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post #9 of 11 Old 05-01-2013, 09:04 PM
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Mine starts putting pretty hard during test, I finally tested after running it a while and getting oil and coolant to temp, throws code p0281 after its putts a bit at end of test

-Kris-
2000 excursion V10 2wd 230k
2000 Excursion 7.3 4x4 246k
1995 CCLB DRW 324K
2001 CCLB DRW 319K
Dp tuner infinity, exhaust, intake, chipped, tricked, and wrecked
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Quote:
Originally Posted by marine5811
The stock downpipe in an OBS is flat because I'm a ginger.
Quote:
Originally Posted by alberta 7.3
Finding a decent woman is like shopping for a used truck. You spend most of your time picking through the money pits, wrecks, and basket cases until you find one that you can tolerate
Quote:
Originally Posted by JJFLASH
Well at least you caught the loose bolts before they cause any damage. Nothing worse than a sloppy hole
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post #10 of 11 Old 05-02-2013, 08:53 AM
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Quote:
Originally Posted by toad View Post
The truck runs great. I have not had any weird driveability concerns. That being said the truck does have 225k on it. I bought it with 170k on it and can only assume that the injectors are original. I have stage ones on order just need to get the chip pulled and have it changed.
Well, there may not be anything wrong with injectors. Kris confirms that the same thing happens to him too. Pull the fuel bowl cover and check the cleanliness of the fuel (should be clear with a hint of blue cloudiness if the sky is clear), pull the dipstick and see if the oil is "off" (Feels really thin, smell like fuel or coolant), look in the degas bottle and make sure the coolant is clean and not smelling of fuel.

With your coming stage I's, do consider also doing the injector cups at the same time. With 225k miles on the stock cups I'd hate to see you swap injectors and then have to go back in to replace cups in a few thousand miles. Get it done at the same time.

Matt
'97
-Bean's: 160/100 (FF Injectors), 2/ 6-POS chips (TW & Beans tunes), Overboost controller, E-Fuel
-BANKs: downpipe, full exhaust, gauges, intercooler
-Irate: T-4 kit, IC pipes, 3" Irate Plenums, BASB Turbo
-Stage II trans.
-Mag-Hytec trans. and pumpkin covers
-6637, CCV, IDM, 6.0 Fan, 49-Federal PCM swap, MAP line Mod
-370 Amp alt., 40k trans cooler, ADRENALINE PUMP
-twin on-board air w/ 10 gal. tank

-Oh, and a 2015 F350 6.7L DRW 4x4


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