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1998 Mpi Running Issues After Restoration


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#136 pete l

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Posted 11 December 2020 - 01:24 PM

Before you try setting it again, screw the throttle screw in until it moves the lever a mm, then start the process.



#137 leepol83

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Posted 11 December 2020 - 06:45 PM

With the throttle screw not pushing on the lever, then you will get the impression that the throttle body is sticking, because the butterfly, which is spring loaded, will be fully closed and pushing on the throttle body.

Broken wires in the loom behind the inlet manifold is a known problem. Especially after worn tie bar bushes, the engine rocks forward and backwards and the wires break. I had it on my MPI, but on the MAP sensor wiring.

R that makes sense with the screw 🙈 didn’t ha r the sticking throttle issue until I messed with that damn!!!! That was a waste of £60.00 😢 ow well you live a learn, I’ll check the wires behind the manifold are there any that are more prone to breaking, you mention the map sensor which one is this?
I’ll have a play in the morning, I’ll wind that screw out so it just touches and moves the arm 1mm then is that right so it acts like a stop ? I’ll get it warmed up and try to video it if I can
Thanks so much honestly for you’re help I really appreciate it, I know you do t have to it’s really good of you.
Lee

Edited by leepol83, 11 December 2020 - 06:48 PM.


#138 genpop

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Posted 12 December 2020 - 10:40 AM

Attached manual is not directly for a MPI but in basic it explains the same!

Attached Files



#139 Bruiser

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Posted 12 December 2020 - 03:53 PM

Been away for a while, but going back through this thread there is lots of info on set up and the position of the IACV but is it actually doing what it is being 'instructed to' by the ECU. I know you say you have fitted a new one, but have you ever visually checked it's operation?

 

I only mention this as my symptoms were very similar, but in the notes I made when I finally got it fixed I wrote this.....

'Plugged in the 2nd hand spare. Noted that when you put the ignition on, it doesn’t make a noise, but THIS ONE when you turn it off does, and you can see the stepper motor driving the ‘needle’ down to find its closed position. Cleaned up spare and just swapped over the stepper motor section. Fixed.'



#140 leepol83

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Posted 12 December 2020 - 09:00 PM

Cheers guys got a few more videos excuse my really bad camera work sorry
https://youtu.be/Nq-cMcJcbI0
https://youtu.be/rajePHlypiQ
https://youtu.be/2DujHCFI4_Y
https://youtu.be/o7tviAfws_Y

#141 tmsmini

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Posted 13 December 2020 - 11:19 PM

Some setting is off. Just an internet diagnosis, but I would back off the throttle screw until the throttle plate is closed. Theoretically the engine should not run at this point due to lack of air. If it does run, there has to be a leak somewhere. The throttle plate only needs to be barely open at idle. The stepper adjustment allows for the throttle plate to be set so that the stepper is in its working range.

 

In one of the videos when you cover the throttle body, it looks like the steps goes to around 30. To me this means the ECU is trying to correct things.

 

Are you sure the accelerator cable is slack when off? There should be no tension at idle.



#142 leepol83

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Posted 14 December 2020 - 07:28 AM

Some setting is off. Just an internet diagnosis, but I would back off the throttle screw until the throttle plate is closed. Theoretically the engine should not run at this point due to lack of air. If it does run, there has to be a leak somewhere. The throttle plate only needs to be barely open at idle. The stepper adjustment allows for the throttle plate to be set so that the stepper is in its working range.

In one of the videos when you cover the throttle body, it looks like the steps goes to around 30. To me this means the ECU is trying to correct things.

Are you sure the accelerator cable is slack when off? There should be no tension at idle.

Hi thank you
Yes if I cover the throttle body things do level out at seems ok ?
The accelerator cable is definitely loose I’ve double checked this
I have to agree I’m thinking an air leak but god knows where don’t know where to start with that, I’ve already replaced the manifold gasket, and injector seals as I thought this was an issue leaking air

Edited by leepol83, 14 December 2020 - 07:28 AM.


#143 pete l

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Posted 14 December 2020 - 08:12 AM

Some setting is off. Just an internet diagnosis, but I would back off the throttle screw until the throttle plate is closed. Theoretically the engine should not run at this point due to lack of air. If it does run, there has to be a leak somewhere. The throttle plate only needs to be barely open at idle. The stepper adjustment allows for the throttle plate to be set so that the stepper is in its working range.

 

In one of the videos when you cover the throttle body, it looks like the steps goes to around 30. To me this means the ECU is trying to correct things.

 

Are you sure the accelerator cable is slack when off? There should be no tension at idle.

 

Sorry but with the butterfly fully closed the engine will start, because the IACV is letting air in. It does not mean there is an air leak.



#144 pete l

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Posted 14 December 2020 - 10:34 AM

Just had a look at your videos, the third one, did you fully block the air when you put your palm over the throttle body ?



#145 tmsmini

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Posted 14 December 2020 - 04:34 PM

Sorry but with the butterfly fully closed the engine will start, because the IACV is letting air in. It does not mean there is an air leak.

 

Only if the IACV is operating properly.

My thinking is that the IACV is at 0 steps because there is already too great a volume of air. Closing the throttle plate(butterfly) will eliminate this as a source. And perhaps allow the IACV to come into range.

The IACV is acting like a controlled leak.

On my spare TBs, there is a very slight opening. You almost have to use a light to see it.


Edited by tmsmini, 14 December 2020 - 04:36 PM.


#146 leepol83

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Posted 14 December 2020 - 05:51 PM

Just had a look at your videos, the third one, did you fully block the air when you put your palm over the throttle body ?


I did yes and it was sucking pretty hard on my hand

#147 leepol83

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Posted 14 December 2020 - 05:57 PM


Sorry but with the butterfly fully closed the engine will start, because the IACV is letting air in. It does not mean there is an air leak.

Only if the IACV is operating properly.
My thinking is that the IACV is at 0 steps because there is already too great a volume of air. Closing the throttle plate(butterfly) will eliminate this as a source. And perhaps allow the IACV to come into range.
The IACV is acting like a controlled leak.
On my spare TBs, there is a very slight opening. You almost have to use a light to see it.

Are we looking like an air leak ?

#148 pete l

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Posted 15 December 2020 - 10:09 AM

I've never fully blocked off the air intake, but logic tells me that the engine should stall. Unless there is an air leak.



#149 pete l

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Posted 15 December 2020 - 10:11 AM

Unless the engine manages to get air from the carbon canister or rocker cover / oil filler cap.



#150 Quinlan minor

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Posted 15 December 2020 - 11:34 AM

Unless the engine manages to get air from the carbon canister or rocker cover / oil filler cap.

Which makes me think it'd be worth blocking those off to see if they might be the source of the problem.






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