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Savanna surge

Shopdog

New Member
Messages
10
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1
Location
Hillsboro Oregon
Thread starter #1
Been having trouble with a 2011 Savana with an engine surge at light throttle pressure from 1,200-1,600rpm. You can push through it by adding throttle. The dealer said it needed the the fuel system replaced. That was done. Only to have the problem still there. We replaced the crank sensor suspecting a breakdown in the signal, no luck there either. Short of replacing the ECM, I'm running out of ideas. Anyone have any experience with fixing this problem?
 

WarWagon

Well it hits on 7 of 8...
Messages
8,609
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3,277
Location
AZ
#4
Warranty or did you get "took" for that repair bill?
The exact reason the fuel system needed to be replaced was fuel contamination, high miles , bugs in fuel?
New parts don't mean good parts.

This said you need a scanner and watch rail pressure commanded and actual during the surge condition. Next watch EGR and turbo vane position.

Have you checked the simple stuff like the air filter?
 

Shopdog

New Member
Messages
10
Likes
1
Location
Hillsboro Oregon
Thread starter #5
The Truck is beyond warranty at 220k miles. The Air and Fuel filters are replaced every 20k miles on a pm schedule. When we first started having a problem the first thing we did was check for any codes using our Tech 2 scan tool. No codes stored. FPR is steady with demand and actual. EGR is showing at 0% at that rpm. With the history or recent HP fuel system failures, we just replaced the fuel system with the belief of possible contamination causing the problem. Out of the 40 Savana's this the first to have this problem. Not sure about Turbo vane issue, the surge/ pulse is quick and rhythmic. I Don't believe a turbo issue would respond so quickly. But I'll check that next.
 

WarWagon

Well it hits on 7 of 8...
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Location
AZ
#6
Do the vans have the same or similar fuel filter housing as the pickups with the hand primer? This is starting to sound like an air leak. maybe a bad primer or cracked fuel filter housing. Also are you using the plastic body Wix fuel filters? They leak air at the WIF threads due to the bad Wix design.
 

Shopdog

New Member
Messages
10
Likes
1
Location
Hillsboro Oregon
Thread starter #7
The p/u use a different filter mount with a hand pump. The earlier vans ( 07-09) turned on the electric fuel pump when it saw a rpm signal. 2010 & newer come on with the key and are timed out if they don't see the rpm signal. We use NAPA Gold filters which are made by WIX. But since this is the only truck giving us the problem, I'm leaning towards it not being a filter issue. We've had problems with pigtails on the EGR & IA flow valves, so I've wondered if the #2 FPR pigtail might be giving us trouble due to a certain rpm vibration. But the signal never drops out and my ref voltage is good along with the ground. It's got a few of us stumped. It's definitely not the normal type of problem, that's why we're reaching out to see if anyone has ideas to try.
 

btfarm

330,000 Worth and counting
Staff member
Lead Moderator
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Location
Sandwich, Illinois
Staff #8
I'm thinking air is getting into the system somewhere. But since vans have a lift pump that shouldn't happen. All the balance rates in the right range?
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
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Location
ZEPHYRHILLS FL
Staff #9
The lift pump only runs for 30 seconds before startup, and I believe for about 15 seconds after startup. They do not use a continuous duty rated pump in them as I know somebody who bought one and verified the part number with RACOR as not being a continuous duty rated pump. It's there to prime the fuel system after filter changes since they don't have a hand primer pump due to the remote mounted fuel filter underneath. I'm not real versed in the LML myself as it is pretty different from the LMM.I would suspect air entering the fuel system fro mthe plastic WIX filter(known to happen ALOT), a fluctuating rail pressure condition for one of many reasons, an APPS issue, EGR issue, or a turbo vein fluctuation problem.
 

WarWagon

Well it hits on 7 of 8...
Messages
8,609
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3,277
Location
AZ
#10
I have walked over the Wix fuel filter and the AZ DOT pays to have their trucks towed in when the WIF sensor falls clean out of the fuel filter. Mine was bad enough to also leak fuel and limped the engine due to low rail pressure.

Try an AC Delco fuel filter and see if it solves the issue.
 

Shopdog

New Member
Messages
10
Likes
1
Location
Hillsboro Oregon
Thread starter #11
So we have finally found the cause of our surge issue. The cam sensor. It wouldn't set a code for it, nothing indicated that being the source. We have had many issues with connectors on different components that we just planned on doing everything in a systematic manor. We built new harness's for the CAM & Crank sensors with new pigtails. The crank sensor was already replaced, the ECM and finally the cam sensor. Before if the truck was cold it ran great. Once it warmed up is when we had the problem. At between 6-7% APP in Park, the truck would jump in rpm anywhere between 500-1000 rpm in an instant. After roughly 16 hrs of running time, it runs like it should. Just thought i would share the fix.
Thanks for all the input.
 
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