Discussion
Hi folks, the never ending list of problems continues with my 450SE, but if someone is able to help with one of them that would be nice.
The idle has always been a nightmare, despite 3 different stepper motors and a Mark Adams chip and just having had an engine rebuild. Yesterday I started it and it was stuck at 2000rpm even after driving 10 miles. I switched off for 10 mins and then started again for it to be ticking over at 1000rpm, like it should! Sometimes it's the other way around and keeps stalling which is a nightmare as you lose brakes! Most of the time it's stuck at 1500rpm. The only thing I can think is that it's temperature related but other than that I don't know.
Any ideas would be much appreciated. Also, if anyone has a 450SE it would be interesting to know how many miles you get to a litre of oil (max to min on dipstick), for comparison purposes after my rebuild.
Cheers
Nick
The idle has always been a nightmare, despite 3 different stepper motors and a Mark Adams chip and just having had an engine rebuild. Yesterday I started it and it was stuck at 2000rpm even after driving 10 miles. I switched off for 10 mins and then started again for it to be ticking over at 1000rpm, like it should! Sometimes it's the other way around and keeps stalling which is a nightmare as you lose brakes! Most of the time it's stuck at 1500rpm. The only thing I can think is that it's temperature related but other than that I don't know.
Any ideas would be much appreciated. Also, if anyone has a 450SE it would be interesting to know how many miles you get to a litre of oil (max to min on dipstick), for comparison purposes after my rebuild.
Cheers
Nick
you mentioned a stepper motor so i'll assume you've a hotwire system?
I'm no expert but did a fair amount of reading when I had my AFM / ECU rebuilt and sorted
From memory the idle could be impacted by 1) Stepper motor 2) ECU fault 3) Senor fault telling the ECU something
You say you've replaced the stepper and also the ECU so could it be a sensor.......the temp sensor perhaps???
I'm no expert but did a fair amount of reading when I had my AFM / ECU rebuilt and sorted
From memory the idle could be impacted by 1) Stepper motor 2) ECU fault 3) Senor fault telling the ECU something
You say you've replaced the stepper and also the ECU so could it be a sensor.......the temp sensor perhaps???
If you still have all the same components in the engine that were there before the rebuild then it could well be a thermotime or temperature sensor related issue..If there are no split air hoses or stuck EAV..Then it could be electrical..ECU could be at fault..This might be a stab in the dark but is the throttle plate moving smoothly inside the plenum inlet?..I have heard of the odd case of where its fouling ever so slightly but its enough to catch it...Hope you get it sorted...Ziga
"Idle Speed Hang-up" is a problem with multiple probable causes.
BEFORE you start chasing Electrical, Sensor or Electronic possibilities, be sure that you do not have a mechanical issue.
Such as the Throttle Plate not closing in the intake tunnel, seen with the intake hose removed.
Throttle mechanism FRICTION can vary with temperature making the varying idle speeds seem like electrical/sensor fault.
Likewise, an air leak into the air intake system will add unwanted air causng variable idle speed.
There is an Essay entitled "Engine Idling Problems" dealing with this subject (albeit for the Twin Throttle Plenum) that addresses even more probable causes and related issues on my vintage model airplane web pages.
http://www.vintagemodelairplane.com/pages/Download...
Moving away from purely mechanical causes, um-metered air leaks into the intake system will affect idle speed.
BEFORE you start chasing Electrical, Sensor or Electronic possibilities, be sure that you do not have a mechanical issue.
Such as the Throttle Plate not closing in the intake tunnel, seen with the intake hose removed.
- Some RV8 Efi systems have an adjustment to control the closure gap.
- Throttle quadrant and/or return spring adjustment.
- The plate can bind in the tunnel sides due to not being centralised.
- Throttle cable too tight.
- Accelerator pedal and/or return spring and/or shaft problems.
- Throttle Pot ill-fitted, preventing throttle shaft/plate from closing
Throttle mechanism FRICTION can vary with temperature making the varying idle speeds seem like electrical/sensor fault.
Likewise, an air leak into the air intake system will add unwanted air causng variable idle speed.
There is an Essay entitled "Engine Idling Problems" dealing with this subject (albeit for the Twin Throttle Plenum) that addresses even more probable causes and related issues on my vintage model airplane web pages.
http://www.vintagemodelairplane.com/pages/Download...
Moving away from purely mechanical causes, um-metered air leaks into the intake system will affect idle speed.
- Check the joints between AFM and intake hose, intake hose itself and intake hose to intake tunnel.
- Breached Rocker Cover gaskets play havoc with idle speed, likewise inlet manifold gasket and local rubber seals.
- Likewise check integrity of the complete engine breather system (breather hole, pipe, flame trap, plenum gallery, etc)
- And (of course, a complete nightmare if not addressed systematically) air leaks into the Plenum Chamber messing with idle speed mixture.
Edited by honestjohntoo on Friday 7th November 13:32
If you tried cheapo ebay steppers that might be your core problem, I have a box of them that did not work with the 500 Gredge. Buy a pucker one at +/- 70 quid to be sure if it is your problem. Eratic idling issues usually end up being stepper problems on the hotwire system in my experience. Once sorted no problems 
First have you got the diagnostic cable so you can plug in and use RoverGauge? I also use my ECUMate on the 14CUX system as it will tell you whats going on. If you have access to one or both then use the stepper retract and open function to make sure that the stepper is doing what it should
Happy to discuss if you like send me pm with your number on fella
Chris
First have you got the diagnostic cable so you can plug in and use RoverGauge? I also use my ECUMate on the 14CUX system as it will tell you whats going on. If you have access to one or both then use the stepper retract and open function to make sure that the stepper is doing what it should
Happy to discuss if you like send me pm with your number on fella
Chris
Bobby Shaftoe said:
If i were you i'd just blank off the stepper motor and set the idle speed with the plenum air screw to whatever rpm you need for the engine not to stall with everything electrical turned on. It'll probably end up a touch high, maybe 1000/1100 rpm, but preferable to 2000rpm!
This was the approach i went for after getting utterly pissed off with trying to get the megasquirt stepper valve code to work properly.
The 350SE 3.9cc which I have recently sold, had the stepper motor blanked off by the previous owner, I think for this very reason. The stepper motor was blanked off by removing the rubber pipe that connects the stepper motor to the plenum and the ends bunged up. thus no choke for morning start but it would still start first time in the morning winter or summer. I had no problems with it during my ownership and it went like a rocket. The new owner though, I believe, is trying to reinstate it because he claims that the idle is too low but the idle should be able to adjust via the plenum screw.This was the approach i went for after getting utterly pissed off with trying to get the megasquirt stepper valve code to work properly.
Tony. TCB.
my idle screw had a mind of its own and would unscrew itself during a good run..........when it was all set up on the rolling road we loctite'd it so it wouldn't move
idle is set at 1140 exactly now (but I do have a lumpy cam so any lower and the old girl wouldn't like it)
idle is set at 1140 exactly now (but I do have a lumpy cam so any lower and the old girl wouldn't like it)
Edited by gmw9666 on Friday 7th November 17:20
One thing that stands out in your opening statement is that you lose brakes when it stalls. This should not be the case there should be a vacuum reservoir held in the servo, if not it is faulty and could be the cause of your idling issues if it is allowing an air leak back into the plenum chamber.
Try clamping the brake servo vacuum pipe closed and see how it idles.
Try clamping the brake servo vacuum pipe closed and see how it idles.
Good spot - yes you should get 4 or 5 good pushes on the brakes before the vacuum servo disappears.
Another diagnostic here is to run the engine, stop it, then push on the brakes, release, repeat. When they go rock solid you've lost vacuum.
As HJ2 says check the throttle mechanism first - quite often a short small blip on the throttle will reseat the throttle and the idle will drop back to normal. This symptom is quite indicative of a bit of friction somewhere.
Another diagnostic here is to run the engine, stop it, then push on the brakes, release, repeat. When they go rock solid you've lost vacuum.
As HJ2 says check the throttle mechanism first - quite often a short small blip on the throttle will reseat the throttle and the idle will drop back to normal. This symptom is quite indicative of a bit of friction somewhere.
Thanks everyone for all the ideas. I'll try them out over the weekend.
gmw9666 -yes it's the hotwire. I have also noticed the idle increases slightly when the fan cuts in so temperature sensor could be along the right lines. I thought they fitted a new one with the rebuild though, unless there's more that one?
I've checked the throttle mechanism and it's definitely not that.
The stepper motor I bought was expensive original equipment and I've also tried a used one from a Griff 500 that was in good working order. Blanking off the stepper hole sounds like a possible option to try.
I'll look into the brakes. From what I remember they don't completely disappear although I wasn't going that fast when it's happened luckily!
Cheers
Nick
gmw9666 -yes it's the hotwire. I have also noticed the idle increases slightly when the fan cuts in so temperature sensor could be along the right lines. I thought they fitted a new one with the rebuild though, unless there's more that one?
I've checked the throttle mechanism and it's definitely not that.
The stepper motor I bought was expensive original equipment and I've also tried a used one from a Griff 500 that was in good working order. Blanking off the stepper hole sounds like a possible option to try.
I'll look into the brakes. From what I remember they don't completely disappear although I wasn't going that fast when it's happened luckily!
Cheers
Nick
I'd be tempted to get it closed then disconnect it and see how the car runs/ idles then.
You might get the old stalling issue but if the idle can be set to steady it's a start. If it still plays silly bu99ers then you have a clue that the cause may be other than the stepper (or idle stabilisation valve to give it its correct title - and there's a clue, it plays no part in the mainstream fuelling but was tacked-on as an afterthought
).
You might get the old stalling issue but if the idle can be set to steady it's a start. If it still plays silly bu99ers then you have a clue that the cause may be other than the stepper (or idle stabilisation valve to give it its correct title - and there's a clue, it plays no part in the mainstream fuelling but was tacked-on as an afterthought
).If you want to run without the stepper motor,then on an occasion when it is idling correctly and up to temperature, simply unplug the lead on the stepper motor. It may then just need a bit of throttle for a while after starting. I assume you have set the base idle correctly. It needs to be done with the pipe that goes from the stepper motor housing blanked off,and the timing must be correct. You should find more on the griff and chim forums.
I've just tried disconnecting the stepper motor. I got the car warm and then took the plug out of the stepper motor which made no difference initially as it stayed at 1500rpm. I then adjusted the idle screw on top of the plenum until it was just above 1000rpm. I drove the car after this and WOW, it's completely transformed the car! It runs just as it should with the revs dropping between gear changes and ticks over at exactly 1000rpm when you come to a stop. I'll just have to see how it starts from cold tomorrow. Can't believe I could have just unplugged the damn thing 3 years ago!!! Thanks for the suggestion.
Will let you know how it goes.........
Will let you know how it goes.........
1BigBadWedger said:
I've just tried disconnecting the stepper motor. I got the car warm and then took the plug out of the stepper motor which made no difference initially as it stayed at 1500rpm. I then adjusted the idle screw on top of the plenum until it was just above 1000rpm. I drove the car after this and WOW, it's completely transformed the car! It runs just as it should with the revs dropping between gear changes and ticks over at exactly 1000rpm when you come to a stop. I'll just have to see how it starts from cold tomorrow. Can't believe I could have just unplugged the damn thing 3 years ago!!! Thanks for the suggestion.
Will let you know how it goes.........
It should start easily in the morning but will take time to heat up and will probably stall at idle until it's warm. Another way of disconnecting the stepper is by removing the rubber pipe connecting it to the plenum and bunging both ends up but leaving the stepper plugged in. That is how my car was disconnected.Will let you know how it goes.........
Tony. TCB.
Another mystery...!!! The idle is miles better now I've unplugged the stepper motor which was a simple solution, but I'm having clutch slipping issues now!
It doesn't slip in 1st or 2nd, just 3rd, 4th and 5th. The strange part is that it doesn't always do it. Sometimes I can floor the throttle and rev it to 4500rpm and it's fine then other times it starts to slip as soon as you press hard on the throttle which makes overtaking risky!
When the engine was out they checked the clutch and said it was like new with a strong spring although they did notice a few spots of oil on the plate which they cleaned off. They fitted a new clutch master cylinder but that's not sorted it.
Does anyone have any ideas what is causing this? I'd rather not have the engine out again for the 3rd time this year if at all possible :O
Cheers
Nick
It doesn't slip in 1st or 2nd, just 3rd, 4th and 5th. The strange part is that it doesn't always do it. Sometimes I can floor the throttle and rev it to 4500rpm and it's fine then other times it starts to slip as soon as you press hard on the throttle which makes overtaking risky!
When the engine was out they checked the clutch and said it was like new with a strong spring although they did notice a few spots of oil on the plate which they cleaned off. They fitted a new clutch master cylinder but that's not sorted it.
Does anyone have any ideas what is causing this? I'd rather not have the engine out again for the 3rd time this year if at all possible :O
Cheers
Nick
A. It's quite normal for a worn clutch to start slipping in 3rd,4th and 5th initially together with difficulty engaging reverse.
B. It is not always possible to tell the condition of the clutch just by visual inspection.
C. Oil on the flywheel is not a good sign. Could be an indication of worn gearbox seal contaminating flywheel causing slipping.
Tony. TCB.
B. It is not always possible to tell the condition of the clutch just by visual inspection.
C. Oil on the flywheel is not a good sign. Could be an indication of worn gearbox seal contaminating flywheel causing slipping.
Tony. TCB.
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