demented Posted June 3, 2013 Share Posted June 3, 2013 99 Escort 1.8gti When accelerator peddle released, there's a brief but abrupt drop in engine revs, causes car to jerk.Doesn't stall or attempt to, otherwise runs ok. This issue is more noticeable at lower speeds, especially in traffice but still occurs at 60 and 70mph but not as noticeable. Any ideas ? Recently bought the car and didn't notice issue during test drive but I did during my journey home, after money had exchanged hands ! Link to comment Share on other sites More sharing options...
Stu Posted June 3, 2013 Share Posted June 3, 2013 (edited) Most likely caused by a sensor problem or air leak. Edited June 3, 2013 by Stu Link to comment Share on other sites More sharing options...
demented Posted June 3, 2013 Author Share Posted June 3, 2013 Thanks, Judging by the rev counter, looks like the revs are not actually dropping. Whatever it is, it's really annoying. It occurs most of the time, only very briefly but enough to cause the engine to heritable slightly. Link to comment Share on other sites More sharing options...
demented Posted June 4, 2013 Author Share Posted June 4, 2013 What adverse effective on the engine Managment, if any, would temporarily unplugging/disconnecting the Vehicle Speed Sensor and using the car cause. Attempting to eliminate the abruptness of the accelerator release, been suggested its the VSS. Also be suggested, that by disconnecting the VSS, the ECU will enter limp mode. Any ideas ? Link to comment Share on other sites More sharing options...
demented Posted June 4, 2013 Author Share Posted June 4, 2013 " cause the engine to heritable slightly" I meant; engine hesitates slightly when accelerator is released, but very noticeable, especially at 30/40mph or less. Link to comment Share on other sites More sharing options...
Andy 3i Posted June 4, 2013 Share Posted June 4, 2013 A duff engine mount? Link to comment Share on other sites More sharing options...
demented Posted June 4, 2013 Author Share Posted June 4, 2013 VSS sensor; disconnection makes no different what so ever and doesn't appear to have any adverse effect on the ECU, such has limp mode. As for an engine mount, it doesn't feel severe enough, but I won't rule it out, thanks. I'm thinking more toward a issue on the fuel side, maybe TPS ? Today, like my Rs2000, the Gti has started the restless idle when comming to a stop.Revs increase to as much as 3000 then drop and raise then rest at 950'ish and remains steady. At all other time, idles perfectly (950'ish). Link to comment Share on other sites More sharing options...
roboboyo Posted June 4, 2013 Share Posted June 4, 2013 VSS sensor; disconnection makes no different what so ever and doesn't appear to have any adverse effect on the ECU, such has limp mode. As for an engine mount, it doesn't feel severe enough, but I won't rule it out, thanks. I'm thinking more toward a issue on the fuel side, maybe TPS ? Today, like my Rs2000, the Gti has started the restless idle when comming to a stop.Revs increase to as much as 3000 then drop and raise then rest at 950'ish and remains steady. At all other time, idles perfectly (950'ish). I check the plugs first mate, spray wd40 on your leads, then look at things like the icv, and then maf. Link to comment Share on other sites More sharing options...
demented Posted June 4, 2013 Author Share Posted June 4, 2013 I wouldn't of thought faulty plugs or leads would cause engine revs to go high or cause the hesitation when releasing the accelerator pedal; hesitation on acceleration maybe. I didn't give plugs n leads a second thought, but I'll check tomorrow and apply WD40 to the leads. Thanks for your input. As for the ISCV, been down that route before. Was wondering, on the Rs2000 and now the GTI, as the revs and idle are going up and down, does this prove the ISCV is not sticking ? Link to comment Share on other sites More sharing options...
demented Posted June 18, 2013 Author Share Posted June 18, 2013 Abruptness when releasing accelerator resolved. Replace PCV valve from another Escort and all good. Link to comment Share on other sites More sharing options...
Andy 3i Posted June 19, 2013 Share Posted June 19, 2013 What is this PCV valve I keep reading about? Link to comment Share on other sites More sharing options...
demented Posted June 19, 2013 Author Share Posted June 19, 2013 PCV = Positive Crankcase Ventalation.... Valve Prevents a build up of exhaust gasses which have squeezed passed the piston rings creating too must resistive pressure in the crankcase. So with the aid of vacuum from the inlet manifold, the valve releases the crankcase exhaust gases into the inlet manifold and back into the engine rather than into the atmosphere. The breather tube on the top of the cam cover does the same via the air filter box. I believe if the PCV valve is not connected and the gasses can escape into the atmosphere, this is a MOT test fail, if noticed. If the PCV valve is not operating how it should, it appears to act like a vacuum leak on the inlet manifold. Link to comment Share on other sites More sharing options...
Andy 3i Posted June 24, 2013 Share Posted June 24, 2013 Ahh I see. What does it look like? Link to comment Share on other sites More sharing options...
demented Posted June 24, 2013 Author Share Posted June 24, 2013 http://www.carid.com/1999-ford-escort-air-...em-8432137.html Link to comment Share on other sites More sharing options...
Andy 3i Posted June 25, 2013 Share Posted June 25, 2013 Ahh. I may have one of those...worth a punt if its cheap Link to comment Share on other sites More sharing options...
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