RS500 Running problems. Any ideas?
Discussion
Recently developed slight erratic running and flat response, narrowed down to MAP ( manifold absent pressure sensor) sensor. Changed unit for new, engine now quite smooth, however on starting from cold I can only get exactly 1 mile before I loose all power, engine revs stick at about 3,000, drops to 600rpm no power, engine coughs and splutters for about 10 secs then recovers and is fine to drive for as long as u want. If starting from warm no problem at all? I suspect maybe the manifold cold inlet valve or the ECU, maybe fuel filter? Anyone else out there able to shed any light on this?
Had the injectors ultrasonically cleaned and filters changed. Bloke that helped me out now thinks it is the crank sensor or the phase detector under the distributor cap. Any thougts on which one to change first or just do them both as ajob lot?
14 june 04:RESULT Changed both units (ECT (BLUE) water temp sensor and Air charge sensor (BROWN) on inlet manifold as advised by Simon at Woodford garage (Totnes). Instantly cured the snag "what a top bloke"
>>> Edited by andymann on Friday 11th June 20:03
>>> Edited by andymann on Wednesday 16th June 11:39
>>> Edited by andymann on Wednesday 16th June 11:43
Had the injectors ultrasonically cleaned and filters changed. Bloke that helped me out now thinks it is the crank sensor or the phase detector under the distributor cap. Any thougts on which one to change first or just do them both as ajob lot?
14 june 04:RESULT Changed both units (ECT (BLUE) water temp sensor and Air charge sensor (BROWN) on inlet manifold as advised by Simon at Woodford garage (Totnes). Instantly cured the snag "what a top bloke"
>>> Edited by andymann on Friday 11th June 20:03
>>> Edited by andymann on Wednesday 16th June 11:39
>>> Edited by andymann on Wednesday 16th June 11:43
Mikey G said:
I have heard of a similair problem before. could be water temp sensor? i think there is a secondary temp sensor on the Cosworth engine specifically for cold running. could also try the fuel filter as you suggest, would change this as a matter of course anyway.
Hope you sort it
Mikey G said:
I have heard of a similair problem before. could be water temp sensor? i think there is a secondary temp sensor on the Cosworth engine specifically for cold running. could also try the fuel filter as you suggest, would change this as a matter of course anyway.
Hope you sort it
thanks for the tip
Regards Andy
I'll let u know
If the water temp sensor is causing an erratic fault on an RS500 then the ECU warning light is usually illuminated. You can check if it is the water temp sensor by disconnecting the plud and bridging the terminals using a paper clip or similar. If the fault clears then the sensor is knackered
shawspeed said:
If the water temp sensor is causing an erratic fault on an RS500 then the ECU warning light is usually illuminated. You can check if it is the water temp sensor by disconnecting the plud and bridging the terminals using a paper clip or similar. If the fault clears then the sensor is knackered
NO! CAUTION! You cant do that. Its a SENSOR, not a sender!
Big difference is the voltage they run on. Sensor is a 5volt reference applied from the ecu and a ground connection, sender is 12volts.
Shorting the terminals WILL put the management light on, because these sensors are designed to be negative temperature co-efficient.
What that means is that the higher the temp, the lower the resistance.
At NO time will the sensor ever give a short circuit, so dont do it! Dont ever short one out.
What system is it running? If its EEC IV i can look up the fault codes for you.
As an anecdote, i had to diagnose a VW golf fitted with the digifantII system, it wouldnt run right when hot or cold.
Found out that the engine had been swapped at some point for an earlier k jetronic golf engine and the CTS sensor hadnt been swapped back.
It was in fact using the old thermotime switch that had been connected by someone and that was the reason it was playing up.
If you REALLY want to go playing and seeing for yourself, then you can get the specs for the sensor and plug a variable resitor into the terminals, bypassing the sensor and varying the voltage read by the ecu. You can then determine the function (or non functioning) of the CTS (coolant temp sensor).
HTH.
The Rs used a weber marelli system to control the fueling and ignition.
Has/is your 500 running any mods and are all 8 injectors connected?
coolant temp sensor might be a possible, and indeed it's one of the easiest and cheapest to replace.
RS 500 didn't have a MIL to show the presence of faults in the system.
Has/is your 500 running any mods and are all 8 injectors connected?
coolant temp sensor might be a possible, and indeed it's one of the easiest and cheapest to replace.
RS 500 didn't have a MIL to show the presence of faults in the system.
I think I said sensor in my reply and by shorting the sensor connection you will put the car into normal mode rather than warm up fuel mode which happens when the sensor fails. In my experience of working with ex Ford motorsport engineers on a variety of cosworths from 2wd to WRC bridging the terminlas has had no ill effect in terms of simple fault diagnosis. Any one who has knowledge of cosworths will alos know that apart from small turbo escort cosworths they all ran on Weber Marelli managemnet systems.
nighthawk said:
The Rs used a weber marelli system to control the fueling and ignition.
Has/is your 500 running any mods and are all 8 injectors connected?
coolant temp sensor might be a possible, and indeed it's one of the easiest and cheapest to replace.
RS 500 didn't have a MIL to show the presence of faults in the system.
Have spoken to woodford Garage in devon (Via Passionforfords.com)Simon, who was spot on for tech help and has been fixing cosworths for the last 15 yrs. He believes it is almost definately temp sensor you descibe which can cause an intermittent fault like i am getting and affects the ECU causing temporary short cct/open cct conditions but only at certain temps if defective and i need to change this unit first as the phase sensor is perfect with no broken insulation at all. Thanks for the tip
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