4/28/2021

8.0L LPG ramping up to 4300RPM by it self - DTNA Solutions

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> 8.0L LPG ramping up to 4300RPM by it self

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@ Mic_Loschuk
Knuckle Buster

04-07-2021 03:54 PM

8.0L LPG ramping up to 4300RPM by it self%

Vehicle Information

VIN: 4UZABRE23GCGT7842 Model: B2 106 CONVENTIONAL CHASSIS
Model Year: 2016 Mileage: 74444 kilometers
Make: FCC Are you currently seeing this same issue on

other DTNA vehicles at your location?: no

Base Model: B2 106 CH

Vehicle Systems Involved

POWER TRAIN VEHICLE SPEED CONTROL

Unit came in for CEL and unit revving up on it own and jumpy acceleration.

Active engine code for ECM mass air flow torque calculation high (2432/15), T/S for this code
as listed

no other related or engine codes and no history of 2432/14

Sprayed down intake and used propane sniffer around intake assembly (limit expectation
due to access but no issues)

No modifications visible (good), no damage, kinks or restrictions found on exh system
(good), no damage or issues with throttle plate (moved freely on key off and hold during
key on), MAP sensor 0 ring damage (quoted to replace), MAF sensor and pipe it mounts in
are damage (quoted to replace), engine harness looks to have been recently replaced (no
damage to pins at harness side MAF and MAP), air filter is clean and new but housing is
damage and filter not fully snugged down (quoted to replace full assembly)

MAP reading 4.93PSI (key on and engine off)

MAF reading 4.2-4.5lb/hr (key on and engine off)

ECM was loose on top of manifold minor rubbing on ECM and oil cap was missing. Oil
level looks ok and clean (possibly recent service)

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4/28/2021 8.0L LPG ramping up to 4300RPM by it self - DTNA Solutions

Noticed during drive in unit almost throttles up and pulls on its own. Let unit idle in the shop
and found around the 5Hr mark the unit would ramp up by it self to 4300RPM and hold there.
Also during manual snap of throttle unit ramps to requested RPM then flutters back up as it
drops (example would be 1O00RPM, drops to 800RPM then back to 1000RPM then back to idle),
then slow to fully drop back to idle. Do not believe this is related too 2432/15.

Charted Accelerator pedal position - engine (j1939 (high)), Accelerator pedal position 2 -
engine (j1939(high)), throttle position 2 - engine (j1939(high)), throttle position - engine
(J1939(high)), engine desired throttle valve 1 position - engine (J1939(high)), and engine speed -
engine (j1939 (high)).

During randomly rev up, found accelerator pedal position at 0%, and throttle and desired
throttle reading 36.4% (normal reading 14% at idle), 2432/15 come back active, no throttle
response (unit can only rev to 3000 with pedal max), and have to shut down unit to get unit to
reset. Also when reving unit as soon as you release the pedal RPM's drop then pop up again
another 200RPM then slowly drop back. Unit is also showing engine is low idle govnor/ no
request in torque template.

Customer brought a doner unit Vin - GP2967 (unit with no issues), swapped throttle valve
assembly, ECM, TSM and MAF sensor, unit a bit ruffer to start (longer crank time), idled unit for
5 minits with same issue.

| am not to sure what | am missing but from what | cant see the engine is not seeing any
accelerator pedal input but engine demands throttle. Seems like a nice controlled rap up as if
its a high idle but unit indicates its in a "low idle gov" state. During intal start with original parts
and doner parts, unit has a squeal under intake manifold and during key on engine off after
running for the first few mins? Im almost leaning more toward unit having issues regulating
fuel flow.

Any thought or ideas would be great.

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8 log of unit acc.DrumrollLog &

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W Michael_Palumbo
=
King Pin

04-07-2021 07:12 PM

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4/28/2021 8.0L LPG ramping up to 4300RPM by it self - DTNA Solutions

Where you using the 8.0 TS guide. It is under DTNA Resources, then FCCC Info and Technical
Support, then FCCC Engines and Technical Support.

Whether you think you can or you think you can't, you're right. — Henry Ford

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> (@ Mic_Loschuk
e
© Knuckle Buster

04-08-2021 12:59 PM

T/S above is from them manual.

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e “® Kyle_Siebert
Optimus Prime

04-07-2021 07:32 PM

Spray either around intake manifold connections with it running. If it suddenly revs up you
have found the intake leak. That's what it sounds like. You could also buy fog machine and fill
the intake to check for leaks that way. Does the unit have vacuum brake booster? Is that
holding a reservoir of vacuum with the engine off. You could also use a vacuum gauge to
measure vacuum of the engine while it’s running erratic.

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4/28/2021 8.0L LPG ramping up to 4300RPM by it self - DTNA Solutions

| just had this same complaint with my Mercury sable. Would run poorly and then suddenly rev
up. A vacuum hose fell off the intake. Sprayed the intake with little bursts of either till | heard it
rev. Checked the area where | sprayed with either and found the vacuum hose off on the
intake after the throttle. Probably 10 seconds to find with either/ starting fluid.

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, (DMic_Loschuk
© Knuckle Buster

04-08-2021 12:59 PM

Just tried either and brake clean to get a more direct shot under the manifold, no change in
engine rpms.

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= Keith_Jordan!
Lube Tech
04-08-2021 10:10 AM

Check for possible in range coolant temp sensor failure, |.E. sensor reads -35 when it really is
110 degrees.

Have also ran into PCV valve problems. | would question the MAF reading KOEO it should be 0
or very close.

The MAP seems off as well, common V-ref or signal return?

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4/28/2021 8.0L LPG ramping up to 4300RPM by it self - DTNA Solutions

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@ vesse_Gutierrez
Solutions Pro

04-08-2021 01:30 PM

A very common issue on these engines is under the upper intake manifold , there is a access
cover and this cover will leak over time , there also happens to be a fuel block off fitting on the
rail located right under this intake cover will also happens to leak from time to time ...

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