7 replies to this topic

[orac69]

Hi guys,   '95 SPi.   

 

Im in a mess...  A bit of advice please.  Searched a ton over the years here, think ive read every post on this forum!

 

My mini has never run quite right.  Hesitating, high idle, running rich - the usual SPi stuff.

 

Despite changing all the sensors, all vacuum tubes, fuel trap, o2, fuel filter, throttle cable, refurbed the intake manitfold, new TPS, Lambda, stepper motor removed and wires checked -  and pretty much everything else - its now running worse than ever, high idle, running rich...

 

Ive got a cable and a laptop running windows 10 and it connects / works fine with MemsFCR - I get info, charts.     (BUT the same cable wont work with mems-rosco on the same laptop for some reason)

 

Anyway. MemsFCR headline says I have a coolant sensor fault (it was new 9 months / 100 miles ago) and an intake temp sensor fault (brand new one just installed and im getting 5v to the cable pins) and also TPS fault (its brand new).   Cant be right.

 

Ive been trying to set the stepper motor, after ignition on, moving the trottle cam open/closed, and the little line up thing is bang in the middle, ignition off to save, click, click - but I cant get the reading to go lower than 94 (should be 30 or I believe).  Ive tightened it, loosened it, checked it a million times but just cant get the number down.. 

 

Do you think the "screw that shouldnt ever be touched" has been touched by previous owner which is why I cant set the stepper motor correctly?

 

Im starting to wonder if my ECU or wiring is also shot - but the green air intake sensor is showing 5v to the cable which is odd if the ECU isnt turning it on..

Advice or comments appreciated.  Thanks.

 

 

[68+86auto]

Remember that behind the ECU, it still has the same old potential problems as a carburetted engine. They can be diagnosed the same old ways. Vacuum leaks, exhaust leaks, valve issues, ignition issues and the list goes on. There is very little that the MEMS ECU will actually report. Even if you bought a modern car, you would still need to do those tests as the ECU doesn't know everything.

 

I believe there are two temp sensors errors which will permanently be there as the associated sensors aren't fitted to SPIs.

[Ethel]

High idle & rich - could that be limp home mode?

 

If it's multiple sensors could it be a shielding, earth or supply issue. I don't really know anything about Mems but electronic sensors usually run off a reference voltage & the ECU senses the voltage drop via their grounds. So a fault causing increased resistance on the reference side could mess with all of them.

[orac69]

Thanks both. 

I dont think its mechanical.  There are no air leaks, vacuum leaks, plugs, leads, coil, gaskets, intake manifold gaskets, exhaust are all new - ive checked and renewed everything.

So thinking logically I have a plan.   

1. swap out the coolant sensor and test that cable - as Ive read that this sensor can initiate bad readings on other things.  My existing one is virtually new, but its not unheard of new stuff to be bad so lets rule that out.
2. check the earths, ECU wires, plug, and all sensors cables for voltage and for chafing etc.
3. replace the vacuum tubes again with silicone
4. As I cant get my IAC anywhere close, I will follow Rogers excellent guide and move the "screw that should not be moved" https://memsfcr.co.u...-stepper-motor/
5. replace the fuel trap too - only thing I havent swapped but its not blocked.

 

Will report back!

[pete l]

I don't know about SPIs but my MPI was having problems too, the wiring loom behind the intake manifold was broken. once redone it was fine.

[sonscar]

Two things are vital,map and coolant temp.You need realtime values whilst running and see if the values are sensible.Is the running rpm displayed steady.Be methodical.Steve..

[R32Egor]

The guide for adjusting the screw is great
I used it when I was setting mine up and got it all setup great.
Obviously do this after checking everything else (looks like you have)👍

[orac69]

Intake Manifold off, I've checked all the sensors are giving readings, have power - and what do you know, my brand new 100 miles ago coolant temp sensor is giving resistance readings all over the place, but never gets lower than 1k ohms. Sometimes goes to 0, sometimes up to 2k. Waiting on a new one then I'll put it back and start on the stepoer/lost motion.