High Idle (yes again!)
Discussion
Chaps,
My S3 (2.9 V6) is idling at 1800 rpm when the car is moving and 1400 rpm when stood still. It may be running rich too (smells like it - cough).
The throttle pot is giving 650 ohms closed, 3.9 K ohms open, and is progressive between the two. The engine speed increases if the TP is disconnected, so I think it's OK.
The ISCV seems to make no difference if disconnected. I even removed the solenoid and made sure the poppet valve was closed (and clean).
There doesn't appear to be any air leaks.
I have cleaned and checked all of the usual connectors including the multiplug under the coil.
I have cleaned the air flow meters and those sensitive wires. Using a multimeter, the resistance shown when opening the flap does not seem to be very linear. Is there a way of testing the air flow meters? That is, other than checking the voltage as described in 'the bible', i.e with the engine running, which is difficult to do - isn't it??
Otherwise, do coolant temperature sensors (to ECU) give problems?
Your advise would be much appreciated, before I have to take it to a specialist and spend some money
My S3 (2.9 V6) is idling at 1800 rpm when the car is moving and 1400 rpm when stood still. It may be running rich too (smells like it - cough).
The throttle pot is giving 650 ohms closed, 3.9 K ohms open, and is progressive between the two. The engine speed increases if the TP is disconnected, so I think it's OK.
The ISCV seems to make no difference if disconnected. I even removed the solenoid and made sure the poppet valve was closed (and clean).
There doesn't appear to be any air leaks.
I have cleaned and checked all of the usual connectors including the multiplug under the coil.
I have cleaned the air flow meters and those sensitive wires. Using a multimeter, the resistance shown when opening the flap does not seem to be very linear. Is there a way of testing the air flow meters? That is, other than checking the voltage as described in 'the bible', i.e with the engine running, which is difficult to do - isn't it??
Otherwise, do coolant temperature sensors (to ECU) give problems?
Your advise would be much appreciated, before I have to take it to a specialist and spend some money
Edited by stevetvrs on Wednesday 2nd May 22:00
I can't remember what car it was I had but that definately had a seperate engine temperature sensor to the dashboard temp gauge, so there were 2 sensors in the engine.
Thinking about it I think it was a 2 litre injected sierra, so guess V6 management system might work along the same lines.
Just worth considering - even if gauge seems fine ecu might be getting duff info if it has a second sensor ?
Can anyone who knows the system enlighten us.
Thinking about it I think it was a 2 litre injected sierra, so guess V6 management system might work along the same lines.
Just worth considering - even if gauge seems fine ecu might be getting duff info if it has a second sensor ?
Can anyone who knows the system enlighten us.
stevetvrs said:
I've just tested the coolant temperature sensor (hot and cold) and it's OK.
Kentish, how did you know one of your air flow meters was faulty? Diagnostics? Was it the top one of the two that you changed?
Steve
Kentish, how did you know one of your air flow meters was faulty? Diagnostics? Was it the top one of the two that you changed?
Steve
The garage I use tested them and yes I think it was the top one (not absolutely certain), one I know does nothing more than measure air temperature, apparently!
It was the other one which failed of course
Another thing it could be is the wiring loom and plug to the TP.
I had no problems for a good while after fitting the airflow meter but the car did start to play up again and I suspected the TP and even replaced it twice and this disturbed the wiring each time and the car ran OK so I thought it was cured each time for a short while but I eventually found a wiring fault at the TP.
Give the TP and wiring a good wiggle whilst idling the engine and see whether the revs change.
I had no problems for a good while after fitting the airflow meter but the car did start to play up again and I suspected the TP and even replaced it twice and this disturbed the wiring each time and the car ran OK so I thought it was cured each time for a short while but I eventually found a wiring fault at the TP.
Give the TP and wiring a good wiggle whilst idling the engine and see whether the revs change.
Hi,
Thanks for your advise so far. I've tested the air flow meters, and the output voltages are as stated in 'the bible', so I think they're OK.
The wiring to all of the usual sensors, coolant sensor, TP and ISCV etc seem fine, and it makes a difference if I disconnect them. I've also tried adjusting the fuel pressure regulator (power boost valve). I've disconnected the battery, and touched the +/- in an attempt to reset the ECU, taken it for a blat, but still idling high. Not a major issue, but damned annoying
Am I correct in thinking that there is no thermotime switch or cold start injector for the 2.9 V6 engine? Running out of ideas now
Thanks chaps,
Steve
Thanks for your advise so far. I've tested the air flow meters, and the output voltages are as stated in 'the bible', so I think they're OK.
The wiring to all of the usual sensors, coolant sensor, TP and ISCV etc seem fine, and it makes a difference if I disconnect them. I've also tried adjusting the fuel pressure regulator (power boost valve). I've disconnected the battery, and touched the +/- in an attempt to reset the ECU, taken it for a blat, but still idling high. Not a major issue, but damned annoying
Am I correct in thinking that there is no thermotime switch or cold start injector for the 2.9 V6 engine? Running out of ideas now
Thanks chaps,
Steve
Edited by stevetvrs on Friday 4th May 21:04
Edited by stevetvrs on Friday 4th May 21:05
It wouldn't be anything as simple as throttle cable too tight would it? That would hold the TP slightly on?
Do you experience any hesitation at all under acceleration at low revs? From my experience if you tamper with the fuel regulator (power boost valve as it is for some 'marketing' reason called), there is a very fine line between too much & too little pressure, about half a turn! If its too high then the engine management does not like it, can act wierd & the regulator whistles a bit.
Have you checked the fuel temp sensor also?
Do you experience any hesitation at all under acceleration at low revs? From my experience if you tamper with the fuel regulator (power boost valve as it is for some 'marketing' reason called), there is a very fine line between too much & too little pressure, about half a turn! If its too high then the engine management does not like it, can act wierd & the regulator whistles a bit.
Have you checked the fuel temp sensor also?
s3 rich said:
It wouldn't be anything as simple as throttle cable too tight would it? That would hold the TP slightly on?
Do you experience any hesitation at all under acceleration at low revs? From my experience if you tamper with the fuel regulator (power boost valve as it is for some 'marketing' reason called), there is a very fine line between too much & too little pressure, about half a turn! If its too high then the engine management does not like it, can act wierd & the regulator whistles a bit.
Have you checked the fuel temp sensor also?
Do you experience any hesitation at all under acceleration at low revs? From my experience if you tamper with the fuel regulator (power boost valve as it is for some 'marketing' reason called), there is a very fine line between too much & too little pressure, about half a turn! If its too high then the engine management does not like it, can act wierd & the regulator whistles a bit.
Have you checked the fuel temp sensor also?
The throttle is fully closed and on it's stop screw. I tried adjusting it in a little (naughty I know!), but it's practically fully shut. The car is great to drive, with no hesitation, flat spots etc. just the idle problem/running rich.
I guess the fuel temp sensor is the one on the fuel rail next to the dizzy and fuel regulator? Two wires?
Otherwise, I may contact Austec, who fitted a piggy-backed chip to the ECU some time ago (for a previous owner), and may be able to give some free advice on the phone
The fuel temperature sensor switches when the fuel temp is > 90 deg C, when more fuel is injected to counteract evaporation.
It makes no difference if I disconnect or short this sensor/wiring, probably because, for some reason, the system is already being enriched with additional fuel, i.e engine acting as cold.
Steve
It makes no difference if I disconnect or short this sensor/wiring, probably because, for some reason, the system is already being enriched with additional fuel, i.e engine acting as cold.
Steve
With all this fiddling, prodding and adjusting I think I would now decide its time to consult a professional - it could end up costing more if you go and break something or replace a number of perfectly good parts before you get the right one.
Just an observation - its a great feeling to fix something yourself but its also important to admit to yourself when you need some expert help.
Plus of course you're likely to get it fixed quicker - so you can enjoy driving it more !
Just an observation - its a great feeling to fix something yourself but its also important to admit to yourself when you need some expert help.
Plus of course you're likely to get it fixed quicker - so you can enjoy driving it more !
clarenceboddiger said:
stevetvrs said:
The ISCV seems to make no difference if disconnected.
Edited by stevetvrs on Wednesday 2nd May 22:00
Surely it should make a difference,is it working at all??
Hi,
It does work, as I can hear it open when the car is first started (shooshing sound). I've also removed the solenoid from the ICSCV when running, and have checked that the little valve spindle is closed and that it does seal properly. If I push it, it 'shooses', allows in more air, and the engine speed increases. So, it OK.
I've come to the conclusion that for some reason there is extra fuel being injected, and that the ISCV is fully closed, i.e trying to reduce idle speed, but can't.
So, it's either a fuel pressure problem or maybe even the ECU?
As regards barkychoc's comments...
This car is new to me and is my hobby. By spending a little time methodically fault finding, and getting advise from the forum, I may be able to fix the problem myself and not have to do a 200+ mile drive, spend £500 and use up a days leave to have an 'expert' fix something that may be a trivial fault.
Cheers guys
Fair comment - just be careful !
If you give up I'd try and find someone local to you who has been in business a fair while (so will know the V6) and knows ford engines well - got to be a few of those about !
I have a garage relatively local to me and describing symptoms over the phone 9 times out of 10 he often knows what the problem is.
Might be worth giving them a call yourself - Wilford Lane Garage in Wilford, Nottingham 0115 9816774.
Ask for Steve Westwood, and tell him he's been recommended.
I'd be economical with the truth about your location !
Chris
If you give up I'd try and find someone local to you who has been in business a fair while (so will know the V6) and knows ford engines well - got to be a few of those about !
I have a garage relatively local to me and describing symptoms over the phone 9 times out of 10 he often knows what the problem is.
Might be worth giving them a call yourself - Wilford Lane Garage in Wilford, Nottingham 0115 9816774.
Ask for Steve Westwood, and tell him he's been recommended.
I'd be economical with the truth about your location !
Chris
stevetvrs said:
Hi,
Am I correct in thinking that there is no thermotime switch or cold start injector for the 2.9 V6 engine? Running out of ideas now
Thanks chaps,
Steve
Am I correct in thinking that there is no thermotime switch or cold start injector for the 2.9 V6 engine? Running out of ideas now
Thanks chaps,
Steve
Sorry Steve missed this question earlier,Yes there is a Thermotime switch, a Cold Start injector and a Hot start module (Green)on the 2.9 set up, the 3 are linked by a brown and white cable, I dont know which way the system works though but looking at the diagram I would assume that the thermotime switch activates "closes" and cuts out the cold start injector.Maybe someone else could confirm thats the case. Its worth a quick check on the wire in the meantime.
I notice you mention there is a piggy backed chip on the ecu, it may be worth noting that some of these ( admittedly the bottom end of the market ones) are nothing more than a resistor placed across a sensor to trick the engine into thinking it is "under fuelling" consequently increasing fuel flow.
Edited by clarenceboddiger on Monday 7th May 14:05
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