OBS 7.3 “stutter” issue - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 24 (permalink) Old 03-09-2019, 05:53 AM Thread Starter
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OBS 7.3 “stutter” issue

Hey everyone I’m new here but have been looking to these forums for a while now and reading everything you guys have to say it’s its great.. so thank you first off. Anyway I have a

1997 OBS 7.3 f350 crew cab automatic I have a few questions but mainly why under low rpm mainly in OD does my truck kind of “sputter”? It runs very very healthy fires up even in very cold weather right away and when you get into it or normal driving runs just perfect I am a mechanic and have watched scanner members closely but am seeeing no issues would really love some input thanks.. sorry for long post my mods are..

Ts6 position chip K&n intake Ccv delete 35” muds Straight pipe Fuel bowl fuel flow mod And for some reason my 97 has all 8 AB injectors?
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post #2 of 24 (permalink) Old 03-09-2019, 02:04 PM
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Re: OBS 7.3 “stutter” issue

Sounds like your 97 may be a California model. Cali 97s have splitshot injectors, a fuel pulse damper on the top of the fuel pump banjo assembly, and a shunt on the Glow Plug Relay (along with GP monitoring circuit wiring). It will use a DPC-312 PCM with MME series code. The DPC-312 PCMs are very hard to find and pinned out completely different than the DPC-202 PCM used in the 49-state (Federal) trucks. I am unfamiliar with your Fuel Bowl fuel flow mod nomenclature, so what exactly is that? What's your fuel pressure look like at idle? You might need to physically remove the chip and see if the stutter remains. Cheers!

97 F250 SC 4x4, E4OD, 4.10 LS, Basically Stock, Relocated Block Heater Plug, Ext Trans Filter, Tru-Cool Max, I/C Mounted but not Plumbed

SOLD: 94 F350 CC DRW PSD, 5 Speed, 4.10 LS, SBC Con-O, Baldwin Filter, Tymar HPX Hose, 3 DP, Bilsteins, $12 AIC, Coolant Filter, Explorer O/H Console, Trans Temp, Boost, and Pyro, Pedestal Mod, Gutted EBPV
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post #3 of 24 (permalink) Old 03-09-2019, 02:25 PM
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Re: OBS 7.3 “stutter” issue

Welcome to PSN,
So when you say stutter/sputter in OD, can you provide a little more information like what RPM range? Does it do it in all your chip settings? To better understand the stutter/sputter, is this a sound or the engine actually lurching,missing? Reason Im asking, is with straight piped trucks Ive owned over the years when under say 1700 rpm noise coming out the exhaust would not be smooth, would be kind of a staccato exhaust note. Would be pronounced when driving beside no post concrete guardrail as the exhaust note would reflect back at you. Truck would run fine was just exhaust pulses not being dampened. I usually leave on the cat, (or run a resonator) just have it gutted to act as a resonator, this softens the exhaust note. Hope that makes sense.

Fuel bowl flow mod meaning youve increased fuel pressure by modding the fuel regulator spring?

Thinking your truck is a California emissions truck, as ABs are split shot injectors as I recall.
j

Tan white tan 97 ECLB, D60 RSK SD springs front, airs bags rear, E4OD 4:10, intake, DP 4 exhaust
Red 97 F250 CC 3:55, D60 Air Locker front, 175/80s, T500, TW files, Tymar, SD I/C, 6.0 fan, E-air, E-Fuel, RSK, SD springs front/rear, 145 litre rear tank (now ZF-5
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post #4 of 24 (permalink) Old 03-09-2019, 02:41 PM Thread Starter
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Thanks for the replies guys.. so first I don’t actually think it is a Cali model I’m all the. Way on the east coast and I’m thinking someone just put them in as number 8 is not a different injector code and yes the bb in the regulator at idle I have 600 psi and wot about 2500 2600 the thing is it does it only when truck is warmed up which is still only about 1/4 maybe a little more it never gets to half on the temp gauge.. it does it wether the chip is on or off just more prevalent with the chip on I think bc it’s getting more fuel I’ve been chasing it forever and can’t figure it out. If the truck is cold it runs so much better I’ve actual had the pcm replaced bc of this issue it only happen between about 1500 and 1700 rpm it’s the actual engine stuttering if I push threw it it goes away also if I make it downshift it runs smooth.. I’ve tried oil and fuel additives as I thought it was a oil issue (cold oil is thincker hence the running perfect when cold) still no results
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post #5 of 24 (permalink) Old 03-09-2019, 02:46 PM Thread Starter
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Sorry also I have replaced 3 injectors because I thought they might be the weak link.. (watching the poppett valve) done the rear diff speed sensor.. throttle position sensor, the crank sensor, of course, the icp basically anything that could cause an issue I’ve replaced and have still never been able to pin point it
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post #6 of 24 (permalink) Old 03-09-2019, 03:49 PM Thread Starter
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Didn’t reply correctly I guess still trying to learn the forum
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post #7 of 24 (permalink) Old 03-09-2019, 04:59 PM
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Re: OBS 7.3 “stutter” issue

How many miles on it?
I'm in no way an expert so this is more of a question/random thought, is the ebp sensor tube clogged? Could the manifold pressure sensor (map?) be acting up?

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post #8 of 24 (permalink) Old 03-09-2019, 05:20 PM Thread Starter
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Quote:
Originally Posted by Blue-Truck-Nut97 View Post
How many miles on it?
I'm in no way an expert so this is more of a question/random thought, is the ebp sensor tube clogged? Could the manifold pressure sensor (map?) be acting up?

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290,000 and the map sensor is working just fine all parameters are good the ebp sensor tube I’m sure is clogged again but had cleaned it and the sensor and still have the issue like I said for some reason it will only do it once truck is warmed up it’s very strange if the teuck is cold it runs 100% better



The map sensor is working fine and I’m sure the ebpv
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post #9 of 24 (permalink) Old 03-10-2019, 07:45 AM
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Re: OBS 7.3 “stutter” issue

What Id do is figure out if its a 49 state truck or a Cali truck first. Refer to what Patrick noted in second post regarding IDing Cali truck. When you say turning chip off does this mean pulling it right out? Id remove it totally and see how it runs.

As I recall split shots will run on a 49 state PCM truck, but not the other way round. If for noted is the case this could be the problem with stutter at given rpm. Solution then would be to swap in some single shot injectors.
j

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Red 97 F250 CC 3:55, D60 Air Locker front, 175/80s, T500, TW files, Tymar, SD I/C, 6.0 fan, E-air, E-Fuel, RSK, SD springs front/rear, 145 litre rear tank (now ZF-5
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post #10 of 24 (permalink) Old 03-10-2019, 09:20 PM Thread Starter
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Quote:
Originally Posted by JCart View Post
What I’d do is figure out if it’s a 49 state truck or a Cali truck first. Refer to what Patrick noted in second post regarding IDing Cali truck. When you say turning chip off does this mean pulling it right out? I’d remove it totally and see how it runs.

As I recall split shots will run on a 49 state PCM truck, but not the other way round. If for noted is the case this could be the problem with stutter at given rpm. Solution then would be to swap in some single shot injectors.
j
Just looked right now as I’m cleaning my ebp sensor tube and It definitely is not a Cali truck no blue sticker on valve cover and my fuel pump does not have the pulsing dampener.. I’m very confused as my truck had this sense I bought but how is it even running good beside slight stutter??
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