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Spi Over Fueling/ Running Rich


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#1 ROD

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Posted 20 November 2019 - 08:28 PM

I have a 96 spi,( spi Virgin) I bought it after it had been sitting for around 18 months without any use and before this over the last 4 years it had only covered 400 miles.

I replaced the battery and got the mini started( on the old fuel that was in it)

Starts up fine from cold and doesn't smell rich.
If revved around 2.5 rpm it has a miss fire that clears @ 3k if you boot it around this rpm it will hold back and then clear and rev fine thought the rev range when driving.

At first I thought it could have been old fuel,

I have now done over 200 miles since getting it and has new fuel in it.

I have changed the plugs and coolant temp sensor as I thought it might be these.

When I removed the plugs today Cylinder 2-3 the plugs are very black 1-4 are slightly lighter black.

What I am after is some pointers as to what could be wrong without changing everything insight

Edited by ROD, 03 December 2019 - 10:34 AM.


#2 Fast Ivan

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Posted 20 November 2019 - 10:03 PM

Work your way through the pinned posts by Sprocket, they are very comprehensive and informative.
Buy yourself a Sykes Pickavant (or similar) diagnostics unit and learn how to make the best of it, and don’t tell me they’re to expensive; you’ve just purchased a mini so you must have an abundance of cash, time and patience

#3 Wazzah

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Posted 21 November 2019 - 02:30 AM

Vacuum leak for sure. Culprits are the ECU to Fuel trap hose, the fuel trap itself, the fuel trap to manifold hose, the manifold to temp switch in air cleaner and the air cleaner temp switch to warm air flap on the air cleaner nozzle. Sometimes the fuel tank to charcoal cannister to purge valve to throttle body line can leak. Lastly the low speed engine breathing circuit can leak. This is the steel pipe and rubber hoses that run along the rear base of the rocker cover.



#4 genpop

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Posted 21 November 2019 - 07:38 AM

Did you realy change the coolant temperature sensor? The sensor on bottom of the intake manifold? Not that sensor on bottom of the radiator!



#5 ROD

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Posted 21 November 2019 - 09:09 AM

Did you realy change the coolant temperature sensor? The sensor on bottom of the intake manifold? Not that sensor on bottom of the radiator!



It was the sensor on the bottom of the inlet manifold that I changed.

#6 ROD

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Posted 21 November 2019 - 09:10 AM

Vacuum leak for sure. Culprits are the ECU to Fuel trap hose, the fuel trap itself, the fuel trap to manifold hose, the manifold to temp switch in air cleaner and the air cleaner temp switch to warm air flap on the air cleaner nozzle. Sometimes the fuel tank to charcoal cannister to purge valve to throttle body line can leak. Lastly the low speed engine breathing circuit can leak. This is the steel pipe and rubber hoses that run along the rear base of the rocker cover.




Thank you for the helpful advice.

#7 dmandan

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Posted 29 March 2020 - 01:07 PM

I have a 96 spi,( spi Virgin) I bought it after it had been sitting for around 18 months without any use and before this over the last 4 years it had only covered 400 miles.

I replaced the battery and got the mini started( on the old fuel that was in it)

Starts up fine from cold and doesn't smell rich.
If revved around 2.5 rpm it has a miss fire that clears @ 3k if you boot it around this rpm it will hold back and then clear and rev fine thought the rev range when driving.

At first I thought it could have been old fuel,

I have now done over 200 miles since getting it and has new fuel in it.

I have changed the plugs and coolant temp sensor as I thought it might be these.

When I removed the plugs today Cylinder 2-3 the plugs are very black 1-4 are slightly lighter black.

What I am after is some pointers as to what could be wrong without changing everything insight

 

I've got almost exactly the same problem on my 94 SPI, just checked plugs 1,3,4 look black 2 is nice and brown, misfire on startup around 2.5k but once ou push through that sorts itself out, car is quite juicey and smells like it's running rich.

 

Did you get o the bottom of your problem?

 

I read the advice about vaccuum leaks, does anyone have advice on how to go about checking the different systems mentioned by Frankston?



#8 tmsmini

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Posted 29 March 2020 - 04:11 PM

Here is a diagram for the SPi system. Replace all the pipes and connectors. Check to see if any are missing. There are some pictures with color coding someone posted before.

 

spi.jpg



#9 dmandan

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Posted 01 April 2020 - 09:37 AM

Here is a diagram for the SPi system. Replace all the pipes and connectors. Check to see if any are missing. There are some pictures with color coding someone posted before.

 

spi.jpg

 

Does anyone have reference material on sensor readings that could come through the decoder?



#10 tmsmini

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Posted 01 April 2020 - 02:28 PM

Which reader are you suing? The SP ACR has some information built-in. You press and hold one of the keys and it is displayed.

 

The SPi has less info than the MPi, not sure which ECU this is from. It was sent to me by someone awhile back.

 

1. RPM Revolutions per minute 

2. Idle Switch Closed/Open - Closed at Idle -Post 1993 SPI's do no have the switch, the ECU is interpreting the TPS as closed

3. P/N Switch Closed/Open - Closed at startup - Only for Auto -  Shorted on Standard

4. MAP Sensor Strategy manifold pressure in kPA, expect 100 kPA Key on and 30 kPA at fast idle

5. Coolant temp Temp in ° C 6. Inlet Air Temp Temp in ° C Expect 20°  to 50°  on hot engine

7. Ambient Temp Reads 200° C engine off Calculated value from other sensors

8. Battery Voltage Battery voltage in volts

9. Throttle Pot in Volts

10. Lambda Volts O2 volts Oxygen Sensor Bank 1 (pre-catalyst) in mV


Edited by tmsmini, 01 April 2020 - 02:31 PM.


#11 dmandan

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Posted 01 April 2020 - 02:45 PM

Which reader are you suing? The SP ACR has some information built-in. You press and hold one of the keys and it is displayed.

 

The SPi has less info than the MPi, not sure which ECU this is from. It was sent to me by someone awhile back.

 

1. RPM Revolutions per minute 

2. Idle Switch Closed/Open - Closed at Idle -Post 1993 SPI's do no have the switch, the ECU is interpreting the TPS as closed

3. P/N Switch Closed/Open - Closed at startup - Only for Auto -  Shorted on Standard

4. MAP Sensor Strategy manifold pressure in kPA, expect 100 kPA Key on and 30 kPA at fast idle

5. Coolant temp Temp in ° C 6. Inlet Air Temp Temp in ° C Expect 20°  to 50°  on hot engine

7. Ambient Temp Reads 200° C engine off Calculated value from other sensors

8. Battery Voltage Battery voltage in volts

9. Throttle Pot in Volts

10. Lambda Volts O2 volts Oxygen Sensor Bank 1 (pre-catalyst) in mV

 

reader is the SP ACR...

 

I found leaks on the vacuum was pushing up the MAP reading, added some cellotape to the pipe got the reading down to 40KPa just ordering replacements now hopefully this will sort it out, the lambda voltage is now going below 1 i'm hoping this solves the rich running issues.

 

I found on another thread the amb temp is default 200deg



#12 dmandan

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Posted 03 April 2020 - 07:37 PM

So an update on my progress.

 

checked my plugs after improving the MAP reading (and having given it a good run) 1,2,3 now lean with 4 spot on????

 

Head scratching!






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