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Mpi Only Starts With Throttle Depressed


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#1 Ratty165

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Posted 04 June 2019 - 08:33 AM

Hi all,

 

Wonder if any of you guys can help?

 

My 1997 MPI recently came out of the garage due to starting problems. In short, he was very unwillingly starting on about the seventh try, or sometimes not at all.

 

The garage struggled to diagnose the problem. Although they have undoubtedly improved the starting, he now only starts with the throttle depressed at least half way, whereas before the original problem, he was starting with no need to depress the throttle at all. Once started, he runs fine.

 

With my limited knowledge, depressing the throttle on an MPI is simply allowing more air into the engine. So does this workaround indicate that not enough air is getting in to start it?

 

As an FYI, the garage replaced the coolant sensor, crankshaft sensor, and the throttle body (the previous one wasn't closing properly). They also had all electrics checked, twice. 

 

Any advice or pointers gratefully received.

 

Cheers.

 

 



#2 Ethel

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Posted 04 June 2019 - 10:32 AM

I'm no injection expert but I do know the Mems engine management is reactive. If it had been adjusting itself to try and start with a faulty throttle body it'd take time to adapt back to normal unless it's reset.

 

Opening the throttle also moves the throttle position sensor and will also have an effect on what the idle air valve is or isn't doing.



#3 pete l

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Posted 04 June 2019 - 12:45 PM

If they replaced the throttle body then you need to get the IACV (inlet air control valve) set up properly on either a T4 or one of the other diagnostic units, don't know their name :-)



#4 Fast Ivan

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Posted 04 June 2019 - 12:47 PM

If they replaced the throttle body then you need to get the IACV (inlet air control valve) set up properly on either a T4 or one of the other diagnostic units, don't know their name :-)

 

I've never had to do that Pete, sorry to contradict

 

But I would certainly be looking at cleaning/replacing the IACV

What was the "work around" they've come up with?



#5 ukcooper

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Posted 04 June 2019 - 02:01 PM

when thet/b on mine was changed to a 52mm type there was a peace of paper with it to set it up with ignitions on and offs and pedal presses , cant get down the  shed to look sorry for it.... 

 

http://sucarb.co.uk/...body-prfmc.html


Edited by ukcooper, 04 June 2019 - 02:06 PM.


#6 pete l

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Posted 04 June 2019 - 02:43 PM

Ignition on, down and up five times on the throttle within 30 seconds. This only resets it, it doesn't set it up correctly.

 

Ivan, yes you can get away with not setting it up, but seeing as he's having problems, it should be done correctly to check it is working as it should, there are, I think, 4 different windings in the IACV, and if one of them is faulty, open circuit, then it's not going to perform.



#7 Ratty165

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Posted 04 June 2019 - 03:21 PM

Thanks very much for your replies so far.

 

In fact, they did replace the IACV with the throttle body (apologies - overlooked that in my original posting).

 

As for setting it up, I don't know whether this was done, but I can ask the garage.

 

I will also try the 'set up' procedure you've mentioned.

 

Any further ideas welcome as I really want to get this sorted.

 

Thanks all.



#8 tmsmini

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Posted 04 June 2019 - 07:31 PM

I would check the code reader thread to see if someone is close by. If you are in London, there must be some one relatively close.

 

With an ACR you can see if the sensors are working at least. I would suspect the TPS initially even though it has been changed. Often people have made creative rewiring attempts and some times the wires to the IACV and TPS get chaffed.

 

But if it runs after starting, then there may not be an issue here.

 

If people have made adjustments to the throttle stop at some point, then it needs to be reset, not just indexed.



#9 tmsmini

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Posted 04 June 2019 - 07:56 PM

Attached File  Burlen TB Instructions ALT 9923.pdf   321.94K   13 downloadsHere are the installation instructions for the Burlen TB replacement. Section C has the indexing info, although they call it a "reset."


Edited by tmsmini, 04 June 2019 - 07:57 PM.


#10 Fast Ivan

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Posted 05 June 2019 - 06:53 AM

 

 

As an FYI, the garage replaced the coolant sensor, crankshaft sensor, and the throttle body (the previous one wasn't closing properly). They also had all electrics checked, twice. 

 

are they a mini specialist?

have they had this car running while using diagnostics equipment such as the ACR?

 

What have they actually done to get the car running?



#11 Ratty165

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Posted 05 June 2019 - 08:44 AM

Thanks for your efforts. I think I will get the car code-read. I know of one garage who can do this.

 

 

 

 

 

As an FYI, the garage replaced the coolant sensor, crankshaft sensor, and the throttle body (the previous one wasn't closing properly). They also had all electrics checked, twice. 

 

are they a mini specialist?

have they had this car running while using diagnostics equipment such as the ACR?

 

What have they actually done to get the car running?

 

 

 

Ivan, the garage is not a Mini specialist, so the key drawback here was lack of diagnostics.



#12 Fast Ivan

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Posted 05 June 2019 - 09:50 AM

Thanks for your efforts. I think I will get the car code-read. I know of one garage who can do this.

 

 

 

 

 

As an FYI, the garage replaced the coolant sensor, crankshaft sensor, and the throttle body (the previous one wasn't closing properly). They also had all electrics checked, twice. 

 

are they a mini specialist?

have they had this car running while using diagnostics equipment such as the ACR?

 

What have they actually done to get the car running?

 

 

 

Ivan, the garage is not a Mini specialist, so the key drawback here was lack of diagnostics.

 

yeah you're going to be up against it without access to mini specialist with the correct kit.

Have you thought about buying the Sykes Pickavant ACR? you will definitely need access to one as an injection owner.

 

But getting back to it - what have they actually done to get it going?



#13 Ratty165

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Posted 05 June 2019 - 10:43 AM

 

Thanks for your efforts. I think I will get the car code-read. I know of one garage who can do this.

 

 

 

 

 

As an FYI, the garage replaced the coolant sensor, crankshaft sensor, and the throttle body (the previous one wasn't closing properly). They also had all electrics checked, twice. 

 

are they a mini specialist?

have they had this car running while using diagnostics equipment such as the ACR?

 

What have they actually done to get the car running?

 

 

 

Ivan, the garage is not a Mini specialist, so the key drawback here was lack of diagnostics.

 

yeah you're going to be up against it without access to mini specialist with the correct kit.

Have you thought about buying the Sykes Pickavant ACR? you will definitely need access to one as an injection owner.

 

But getting back to it - what have they actually done to get it going?

 

 

 I will look into the Sykes Pickavant ACR - thanks for the suggestion.

 

They did a number of things. They felt that two parts were responsible for getting it going. Replacing the throttle body - the old plastic one was warped and not closing properly. And replacing the crank sensor. They have actually improved the starting considerably, but just with the remaining issue that the throttle needs to be depressed to start the car, which wasn't the case before.



#14 Fast Ivan

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Posted 05 June 2019 - 12:17 PM

strange thing is that warped throttle body would normally cause a high idle

 

I would invest in the ACR - anything else sensors wise is just guessing and you just end up blindly replacing sensors

 

in the meantime make sure that everything is in good serviceable condition, including all the earth points, spark plug gaps, rocker clearance, make sure all the sensors (including the cam sensor at the rear of the engine) are all clean, in good condition and well seated. Check the loom over looking for squashed bits or damage -  pay close attention to the rear of the throttle body/manifold area



#15 pete l

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Posted 05 June 2019 - 01:01 PM

+1 on getting a code reader. Without one you're just blind and making guesses at to what could be wrong.






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