another strange 14cux behavior (idle problem)
Discussion
Good evening everyone. As a (very) long-time silent participant in this fantastic forum (the current account is quite new), may I ask the experts a question about a 14CUX issue? Here's the symptom: When the engine starts (last time: cold, after a battery reset), it immediately accelerates on its own to mid-range RPMs. Then it suddenly drops to normal idle, but immediately accelerates again, and so on. The last time this happened, I kept it at this RPM level (about 3000 or 3500) manually for a few minutes (until it had been at operating temperature for some time). After that, the idle returned to normal.
Unfortunately, I actually don't have the ability to conduct empirical tests or so, so the circumstances of the issue as described are not entirely reliable. Sometimes the engine doesn't act like described (or doesn't do so as strongly) but instead has a stable, but high to very high idle (~1500). Other times, everything is completely normal. As a result, I can't definitively say whether this only happens when the engine is cold, only after a reset, or under other specific conditions. Plus, the occasions for me to play with the car have been VERY rare in the last years, so...
At least it seems clear that the ECU is intermittently opening and closing the stepper motor. But why? The lambda values (if that's relevant in this case) are (almost) fine, meaning at idle and also at constant elevated idle they're minimally (!) too lean (with four-year-old gasoline actually, if that matters). I am quite sure there are no air leaks, as I checked with brake cleaner etc. Could an incorrect speedometer signal (speedometer only works up to 80 km/h) play a role while stationary?
At any rate, I’m quietly hopeful that I’m not the first person to encounter such a symptom, and I’m absolutely certain that there are people here with far more experience in dealing with 14CUX idle issues than I have. With that in mind, I’d be very grateful for any suggestions or ideas you might have. Unfortunately, just heading out to the car to try this or that isn’t something I can do quickly these days, so along with your help, I’ll also need to ask for a bit of patience. Thank you in advance!
flo
Unfortunately, I actually don't have the ability to conduct empirical tests or so, so the circumstances of the issue as described are not entirely reliable. Sometimes the engine doesn't act like described (or doesn't do so as strongly) but instead has a stable, but high to very high idle (~1500). Other times, everything is completely normal. As a result, I can't definitively say whether this only happens when the engine is cold, only after a reset, or under other specific conditions. Plus, the occasions for me to play with the car have been VERY rare in the last years, so...
At least it seems clear that the ECU is intermittently opening and closing the stepper motor. But why? The lambda values (if that's relevant in this case) are (almost) fine, meaning at idle and also at constant elevated idle they're minimally (!) too lean (with four-year-old gasoline actually, if that matters). I am quite sure there are no air leaks, as I checked with brake cleaner etc. Could an incorrect speedometer signal (speedometer only works up to 80 km/h) play a role while stationary?
At any rate, I’m quietly hopeful that I’m not the first person to encounter such a symptom, and I’m absolutely certain that there are people here with far more experience in dealing with 14CUX idle issues than I have. With that in mind, I’d be very grateful for any suggestions or ideas you might have. Unfortunately, just heading out to the car to try this or that isn’t something I can do quickly these days, so along with your help, I’ll also need to ask for a bit of patience. Thank you in advance!
flo
Edited by 1994griff500 on Sunday 9th February 18:09
Id check the throttle potentiometer is performing as it should, there is a lot of useful info here.
http://g33.co.uk/pages/technical-fuel-injection.ht...
Im not an expert on the speed signal but dont think its responsible for that large an uplift in the revs.
http://g33.co.uk/pages/technical-fuel-injection.ht...
Im not an expert on the speed signal but dont think its responsible for that large an uplift in the revs.
Sounds like you have RoverGauge , yes ?
If you do then run a data logfile as follows and send it to me, I can then check all the inputs and outputs for you and hopefully point you in the right direction.
Fwiw this looks like either a bad stepper or a vacuum leak but the logfile will help narrow that down.
Assessing the 14CUX
1. Plug the 14CUX cable into the loom connector on the car
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed -mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get
varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO
NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
If you do then run a data logfile as follows and send it to me, I can then check all the inputs and outputs for you and hopefully point you in the right direction.
Fwiw this looks like either a bad stepper or a vacuum leak but the logfile will help narrow that down.
Assessing the 14CUX
1. Plug the 14CUX cable into the loom connector on the car
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed -mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get
varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO
NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
Good morning. As for TPS, yes, I also will check this. Maybe it is faulty because of its age now. other than that, I is untouched for at least 20 years now. Unfortunalty I don´t have rover gauge. Lambdas has been checked at the last official emission check. Little to lean, as said, but somehow it passed the test ;-)
Thanks all for helping!
flo
Thanks all for helping!
flo
Belle427 said:
Id check the throttle potentiometer is performing as it should, there is a lot of useful info here.
http://g33.co.uk/pages/technical-fuel-injection.ht...
Im not an expert on the speed signal but dont think its responsible for that large an uplift in the revs.
congratulations btw, this is you 10.000 post! wow... http://g33.co.uk/pages/technical-fuel-injection.ht...
Im not an expert on the speed signal but dont think its responsible for that large an uplift in the revs.
1994griff500 said:
Belle427 said:
Id check the throttle potentiometer is performing as it should, there is a lot of useful info here.
http://g33.co.uk/pages/technical-fuel-injection.ht...
Im not an expert on the speed signal but dont think its responsible for that large an uplift in the revs.
congratulations btw, this is you 10.000 post! wow... http://g33.co.uk/pages/technical-fuel-injection.ht...
Im not an expert on the speed signal but dont think its responsible for that large an uplift in the revs.
Good afternoon,
A quick update: Car idles okay so far, so right now all is good.
What did I do? 1.) Fresh fuel in tank 2.) New stepper from Motoclan. Looks exactly as the old one, which is only about 5 years and 300km old, and very clean. 3.) Battery reset 4.) Drive the car through all gears and conditions on the garage lift.
Starts and idles much better now hot and cold, with only once or twice a little reminiscence of the old symptom as describes above (like, revs rise from normal idle to about 1500 and drop back to normal within 3 seconds or so, all very smooth and civilized (not as crazy and erratic as before).
Conclusion: I don´t know if it was the old fuel, or the (not so) old stepper, or the fact that the ECU did not get a decent speed signal up to now, or if it was a combination of two or all of these points (or just good luck...).
Besides, I installed Rover Gauge on my Win7 ThinkPad and followed exactly the instructions, but IBM did not speak to Lucas. Cable is new and obv. ok (green light in RG on), and the test of the three pins on the ECU side is ok, too. Several restarts of laptop and car and repeatedly studies of the instructions and this and that, but no ECU signals in RG.
Anyway, right now the car idles, so I´m happy. Any hints and tipps for the RG problem highly appreciated.
Thanks for helping!
Kind regards,
flo
A quick update: Car idles okay so far, so right now all is good.
What did I do? 1.) Fresh fuel in tank 2.) New stepper from Motoclan. Looks exactly as the old one, which is only about 5 years and 300km old, and very clean. 3.) Battery reset 4.) Drive the car through all gears and conditions on the garage lift.
Starts and idles much better now hot and cold, with only once or twice a little reminiscence of the old symptom as describes above (like, revs rise from normal idle to about 1500 and drop back to normal within 3 seconds or so, all very smooth and civilized (not as crazy and erratic as before).
Conclusion: I don´t know if it was the old fuel, or the (not so) old stepper, or the fact that the ECU did not get a decent speed signal up to now, or if it was a combination of two or all of these points (or just good luck...).
Besides, I installed Rover Gauge on my Win7 ThinkPad and followed exactly the instructions, but IBM did not speak to Lucas. Cable is new and obv. ok (green light in RG on), and the test of the three pins on the ECU side is ok, too. Several restarts of laptop and car and repeatedly studies of the instructions and this and that, but no ECU signals in RG.
Anyway, right now the car idles, so I´m happy. Any hints and tipps for the RG problem highly appreciated.
Thanks for helping!
Kind regards,
flo
Edited by 1994griff500 on Saturday 29th March 15:55
from ex Auto sparks....now 81 years....make sure the 2 octane sensors right at the front of manifolds are clean on the pins where they plug into the wiring loom each side...as the type of pins on those plugs tended to Diss- colure [ old style lucas plugs back in the day ]....make a poor connection after time...also open to the elements where there placed...check fully...if they look poor..the idle will keep changing..up / down / all the time....if you clean fully..to be honest i would go through reset idle procedure again...ie...unplug electric idle control..block the idle pipe....reset base idle...un-block pipe...reconnect electric control.. road test to full temperature.....the ECU relies on those octane sensors to work with idle control. Peter
Gassing Station | Griffith | Top of Page | What's New | My Stuff