engine running problem
Discussion
i have two problems with the running of my engine .the first problem is the car seems to be hunting forward and will travel 25mph on its own and as a result i have to dip the clutch when i need to stop.problem two is the rev counter goes from 1 to 2 thousand revs on its own up and down untill i turn the engine off .the car will not run smoothly untill i get over 3 thousand revs .,ive changed the plugs ,vacume advance unit,leads and have had the injectors cleaned on a electro sonic machine and as a result only slight i inprovement
Stepper motors seem to be the source, or at least get the blame for problems. I had running problems untill last week. I took my stepper completely apart, cleaned it, the butterfly, the AFM and anything else i could get at with carb cleaner. Put it back together then re-set the stepper and the difference was amazing. Worth a try i think. Good luck
Just in case you need them, there are instructions for stepper motor cleaning at http://www.tvrcc-south-wales.co.uk/stepper.asp
What are the instructions for "resetting" the stepper? I've been disconnecting the ECU but not sure if that is enough. Sure I read somewhere that there's a weird ignition on for 10 secs, off for 10 secs, stand on one leg, 3 hail marys, start engine type of procedure but can't find anything definite.
Adjusting Idle Speed : The following steps must be taken in the proper order, even if they seem dumb.
1. Verify once again that the throttle, timing, and TPS adjustments are to spec.
2. Start the engine and operate the vehicle until it reaches normal operating temperature.
3. Attach an accurate tachometer.
4. Switch the ignition on. (Don't start the vehicle!)
5. Disconnect the electrical connector on the Bypass Air Valve.
6. Switch the ignition off.
7. Listen for a "click" sound from the main EFI relay. (On Range Rover, it's under the right front seat.)
8. Reconnect the electrical connector on the Bypass Air Valve.
9. Switch the ignition on. (Don't start the vehicle!)
10. Disconnect the electrical connector on the Bypass Air Valve.
11. Start the vehicle out-of-gear (or in "neutral"
without touching the accelerator.
12. Adjust the "base idle speed" screw on the plenum with a 3/16" Allen wrench to 550-650 RPM.
Turning counter clockwise will raise the speed and vice versa.
13. Reconnect the electrical connector on the Bypass Air Valve.
14. Switch the ignition off.
15. WAIT for main relay "click" sound.
16. Switch the ignition on, start the engine and rev briefly to 2000 RPM.
17. Note the idle speed. It should stabilize at 665-735 RPM.
18. Install a new "tamper proof" plug.
1. Verify once again that the throttle, timing, and TPS adjustments are to spec.
2. Start the engine and operate the vehicle until it reaches normal operating temperature.
3. Attach an accurate tachometer.
4. Switch the ignition on. (Don't start the vehicle!)
5. Disconnect the electrical connector on the Bypass Air Valve.
6. Switch the ignition off.
7. Listen for a "click" sound from the main EFI relay. (On Range Rover, it's under the right front seat.)
8. Reconnect the electrical connector on the Bypass Air Valve.
9. Switch the ignition on. (Don't start the vehicle!)
10. Disconnect the electrical connector on the Bypass Air Valve.
11. Start the vehicle out-of-gear (or in "neutral"
without touching the accelerator.12. Adjust the "base idle speed" screw on the plenum with a 3/16" Allen wrench to 550-650 RPM.
Turning counter clockwise will raise the speed and vice versa.
13. Reconnect the electrical connector on the Bypass Air Valve.
14. Switch the ignition off.
15. WAIT for main relay "click" sound.
16. Switch the ignition on, start the engine and rev briefly to 2000 RPM.
17. Note the idle speed. It should stabilize at 665-735 RPM.
18. Install a new "tamper proof" plug.
Edited by miniman on Thursday 9th August 18:04
daren parker said:
that seems very complicated may be its not a good idea for me to take the stepper motor out .i thought it would be simple
It is simple as far as I'm concerned. Disconnect, unscrew, clean, screw back in, reconnect. If you still have problems and want to know whether the stepper is causing them, simply get the engine up to temperature and idling steadily then disconnect it and see if the problems go away. It's possible that the stepper motor is a red herring.I tried as you suggested, and the tickover is rock solid with the stepper disconnected. Problem was (or still is) its a brand new stepper, and as soon as I connect it the revs are all over the place. Up to 2000 rpm when you first stop, then drops sharply untill near stall, and then up to 2000 again, so some control signal from the ECU must be doing this. As non of the external sensors could be giving a fluctuating signal like this to the ECU, it must be part of the ECU calibration / learning sequence ??. I can only assume that this strange on / off procedure to reset the stepper must be some sort of max / min limit test for the stepper for the CPU to store. Odd however as there is no position feedback signal from the stepper motor the ECU to know the postion of the plunger, so it would have to rely on testing engine RPM. I try this reset sequence and try and see how it cycles the stepper motor. Meanwhile it works just fine with just the base idle uo at 900 rpm, and the stepper feed pipe simply blocked off.
blitzracing said:
I tried as you suggested, and the tickover is rock solid with the stepper disconnected. Problem was (or still is) its a brand new stepper, and as soon as I connect it the revs are all over the place. Up to 2000 rpm when you first stop, then drops sharply untill near stall, and then up to 2000 again, so some control signal from the ECU must be doing this. As non of the external sensors could be giving a fluctuating signal like this to the ECU, it must be part of the ECU calibration / learning sequence ??. I can only assume that this strange on / off procedure to reset the stepper must be some sort of max / min limit test for the stepper for the CPU to store. Odd however as there is no position feedback signal from the stepper motor the ECU to know the postion of the plunger, so it would have to rely on testing engine RPM. I try this reset sequence and try and see how it cycles the stepper motor. Meanwhile it works just fine with just the base idle uo at 900 rpm, and the stepper feed pipe simply blocked off.
Precisely the problem I have with mine. Where did your stepper motor come from? I might hazard a guess at the job lot of really cheap ones that were on eBay recently - same place I got mine?Gassing Station | Chimaera | Top of Page | What's New | My Stuff