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| Accelerator unresponsive at idle http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=74029 |
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| Author: | Steve_S [ Tue Feb 05, 2013 7:49 am ] |
| Post subject: | Accelerator unresponsive at idle |
Hi, I have a year 2002 CRD 2.5 Manual transmission. I bought it as needing repair so have only just started driving it. The issue I have is that there is a very slow response from the accelerator at idle. If I floor the pedal I can count about 3 seconds before the engine hits high revs. This makes it very difficult to pull away but once driving I find it goes well and accelerates well. I have been reading this forum for over a year as this vehicle has been a spare time project for me. I am confident that the engine/timing/hoses/turbo are all good. The fuel has been bled of air and is fresh. If I was to guess I would consider accelerator position sensor (unlikely?) or mprop (slow to move?) maybe injectors? Any input welcome. Steve |
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| Author: | papaindigo [ Tue Feb 05, 2013 10:07 am ] |
| Post subject: | Re: Accelerator unresponsive at idle |
Not sure how the throttle on an 02 works but you can get a copy of the FSM from http://colorado4wheel.com/manuals/Jeep/KJ/ which might help. |
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| Author: | ChooChooman74 [ Tue Feb 05, 2013 10:35 am ] |
| Post subject: | Re: Accelerator unresponsive at idle |
Are you talking about revving in neutral or getting moving from a stop? Sent from my Nexus 7 using Tapatalk HD |
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| Author: | Steve_S [ Tue Feb 05, 2013 1:54 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
papaindigo wrote: Not sure how the throttle on an 02 works but you can get a copy of the FSM from http://colorado4wheel.com/manuals/Jeep/KJ/ which might help. Hi, Thanks. I have manuals. I will do what testing I can without the DRB III. Was hoping maybe symtoms were familiar to someone. Steve |
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| Author: | Steve_S [ Tue Feb 05, 2013 1:58 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
ChooChooman74 wrote: Are you talking about revving in neutral or getting moving from a stop? Hi, This is when in neutral. If I manage to get the clutch out at low revs without stalling then naturally the problem is still there as I accelerate from low revs. As said Jeep will accelerate well at higher revs when driving and seems to have full power. Thanks, Steve |
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| Author: | papaindigo [ Tue Feb 05, 2013 4:24 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
I've glanced at the 02 FSMs and the 03 parts fiche so I'll speculate (aka guess) a bit. Looks like you have some sort of assembly (PN 52850616AE) on the firewall behind the engine that serves as a accelerator position sensor/cruise and is hooked to something via a cable. I presume??? there is a sensor(s) physically mounted on the accelerator pedal (at least there are on the 05/06) that communicates with that sensor (electrically like the 05/06 or cable I don't know). Assuming the cable that runs out of the sensor is accessible and assuming your rpms are idle are normal can you try moving whatever the other end of that cable attaches to and see if the rpms come off idle like they are supposed to. If so I'd think that would narrow the problem down to between the "other end" and the pedal itself. If that's the case the sensor appears to be something you can open up in which case I'd open it up and see if the cable is binding. If it works fine once you get going then I doubt that it's injectors. Sounds more like a throttle position issue. Hope this "guess" helps some. |
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| Author: | Steve_S [ Tue Feb 05, 2013 5:27 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
Hi papaindigo, Many thanks for your input. You're right it has an accelerator pedal position sensor (APPS) near the bulkhead. This is connected mechanically to the pedal but there is no sensor on the pedal nor any electrical connection to the pedal. Looking at the manual the APPS has the expected variable resistor but also an on/off switch that is presumably closed at idle and open when off idle. I will be testing this as best I can tomorrow. Any thoughts on the mprop sticking as I think this would cause a delay in raising the fuel pressure off idle. I may be wrong here! If I can rule out the injectors that would be great. I really only have the other two items in mind. If neither of them pan out them I am lost! Cheers, Steve |
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| Author: | papaindigo [ Tue Feb 05, 2013 6:17 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
My old school thinking says the fuel delivery system is not dispensing enough fuel to bring the rpms up when you press the accelerator. The provide some more quesses: 1. obstruction in the fuel supply lines or lines that collapse under demand (I saw the latter once on a gasser that wouldn't accelerate unless you did so gradually) 2. fuel filter head problems I don't "think" these relate to your problem as you say it has power at higher revs. 3. bad "signal" from throttle position sensor. I still am not clear on how the accelerator pedal communicates "go faster" on the 02 but however it does there could be a problem in that communication at lower rpms. 4. one or more sensors not building injector pressure properly at lower rpms. Could be on the front or back end of the system. For example the 05/06 has a pressure sensor/solenoid at the back of the fuel rail that can cause poor running by sticking and not allowing pressure to build properly if at all. That's about the best I can do. I still don't think it's the injectors rather I think it's related to getting proper fuel supply under proper pressure to the injectors but.... You might send an email to Keith at GDE (http://www.greendieselengineering.com/g ... ethod=home) and see if he has any thoughts. |
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| Author: | Steve_S [ Tue Feb 05, 2013 6:31 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
Hi again, Well I couldn't wait until tomorrow (it's nearly 23:00 here) so I went out and removed the APPS. It all seems to check out fine. It has a variable resistance as I move it throughout its range and it has an on/off switch which is open at idle and closed as soon as the pedal is moved. I will move on to the fuel rail pressure sensor and maybe the fuel quantity solenoid (mprop) on the fuel pump. If I can't test them satisfactorily them I may just replace them if cheap enough. Thanks, Steve |
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| Author: | ChooChooman74 [ Tue Feb 05, 2013 6:36 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
When my turbo vanes were stuck, I had no low end but ran fine at the top end. I wouldn't count turbo out. Sent from my DROID BIONIC using Tapatalk 2 |
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| Author: | Steve_S [ Tue Feb 05, 2013 6:50 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
ChooChooman74 wrote: When my turbo vanes were stuck, I had no low end but ran fine at the top end. I wouldn't count turbo out. Hi, Thanks for your input. I don't know if that would be an issue as I have a wastegated turbo not a VNT one. I will however make sure that the turbo is not causing the problem. I will remove a charge hose and see if it revs any better. Cheers, Steve |
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| Author: | ChooChooman74 [ Tue Feb 05, 2013 9:50 pm ] |
| Post subject: | Re: Accelerator unresponsive at idle |
Steve_S wrote: ChooChooman74 wrote: When my turbo vanes were stuck, I had no low end but ran fine at the top end. I wouldn't count turbo out. Hi, Thanks for your input. I don't know if that would be an issue as I have a wastegated turbo not a VNT one. I will however make sure that the turbo is not causing the problem. I will remove a charge hose and see if it revs any better. Cheers, Steve There goes my theory. Sent from my DROID BIONIC using Tapatalk 2 |
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