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Discussion Starter · #1 ·
Ok, now this is just getting annoying.

Following on from my last thread "214 crazy engine - episode 2" I have recently replaced the throttle pot and stepper motor on my '93 214 Spi.

When started from cold, idles fine at about 1000rpm, it will pull off and drive fine until i stop, when it dies. A quick lift up of the clutch if it's still rolling and she fires straight back up, again drives fine. Once it's warmed up the stalling problem goes away, but the idle speed is now just under 2000rpm. Sometimes I can be sitting still with it idling normally and it will suddenly jump up to 2k rpm. Even then it sometimes jumps a second time to about 2250rpm.

Also, when driving at any speed, it seems to lose power and slow down, when I put my foot down, it takes a few seconds to react, and seems to misfire and cough before accelerating normally.

I can get it to slow down occasionally by putting it in gear and lifting the clutch while holding the brakes, then it will sit at 1500rpm when i release it. But this won't do my clutch any good and it doesn't work all the time anyway.

I've searched the forum and found idle speed seems to be a common fault on th spi (MEMS) system and there seems to be lots of different fixes, and an ECU change will only offset the problem for a few months. Anybody got any ideas? The throttle body isn't sticking, the inlet manifold doesn't seem to be leaking, throttle pot and stepper motor have both been changed already.
 

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Hi, If you have not tried this already I would renew the coolant temperature sensor, the symptoms are typical of intermittant sensor failure or a poor connection in the sensor wiring

Cheers gary :)
 

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Discussion Starter · #3 ·
tried the coolant sensor - nothing, no difference at all. Is this sensor that same one that runs the gauge on the dash? as this seems to be working just fine.

I've heard that you can reset the stepper motor somehow, how do you do it?

Help!
 

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aerosam99 said:
tried the coolant sensor - nothing, no difference at all. Is this sensor that same one that runs the gauge on the dash? as this seems to be working just fine.
No as far as I remember...One sensor for the gauge and a different one for the ECU.

Hope this is of some help: I have a similar problem to yours. I ve tried almost everyhting...till i gave up. I changed simple things such as HT lead, dissassembled the manifold+throttle body, checked the stepper, checked the throttle switch, checked the PTC heater and more. I opted for the diy solution of disconnecting the red vaccum pipe from the back of the manifold (runs from the thermac switch to the back of the manifold). This results in a raised idle while the engine is cold...and my emissions test during the MOT last week showed 0.57% CO (warning: this means the engine sucks unfiltered air so I don't reccomend it...at your own risk). A thing i noticed when i was trying to fix it is that the thermac switch was stuffed...that could be the culprit as it is used for aiding cold weather starting/running (it's similar to old carb engines that had a bypass (controlled by the switch)to allow hot air from over the exhaust manifold to smooth idle when cold).

Now that the weather is good (well better) it idles fine from cold, so i have left the vaccum pipe permantly unattached. If you find a solution please let me know.



ps. leaks in the manifold would result in exactly the opposite that you are experiencing...i.e. revs jump up all over the place and take time to settle (similar to a sticking throttle syndrome).
 

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Discussion Starter · #6 ·
Major Ingram said:
Have you replaced the injector body itself?
No, although i do have a spare injector body with injector, it's off a 1990 car.

I'll have another good look at it whe it stops raining, probably tomorrow now, if i come up with anything i'll let you know.
 
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