13 replies to this topic

[kommander]

I'm currently diagnosing an SPi mini with poor idling issues. The car cuts out when put into gear.

 

My initial scan revealed a MAP sensor pressure of 101kPa, on inspection the vacuum hose from manifold to fuel trap was missing.

 

I replaced all hoses and the fuel trap,however the MAP gave a reading of 66kPa....it reads 33kPa on my mini which runs fairly decent.

 

The lambda sensor voltage also fluctuated a little, then sat at zero. 

 

My next step will be to replace the lambda sensor. I am still concened about the MAP's value. 

 

Is there anything else that can contribute to this poor MAP value?

[hunterg30]

Check the rubber pipe that come off the metal pipes just behind the rocker cover ,check the purge valve pipe for splitting . Are all the elbows perfect on the vacuum lines especially the two on the inlet manifold

[kommander]

I replaced the vacuum lines with silicon tubing, so no issues with elbows.

 

Will check the other hoses. Thanks.

[kommander]

I got around to changing the lambda sensor and there was no improvement.

 

Suspecting the coil pack, there was no change in the idle with the removal of plug wires 1&4. 

 

The coil pack was switched to another Mini and had no issues. 

 

I am assuming it's the wiring or the ECU as the tachometer stopped working as well.

 

I read in another thread that a bad earth behind the dash or faulty wiring from the coil pack causes the tachometer to stop working.

 

Any suggestions on how I should proceed. The Mini is the later SPi with coil pack like the MPi.

 

If anyone has the electrical drawing for this model SPi, please share.

 

Thanks.

[humph]

Found this;

• Manifold Pressure (KPa): This displays the pressure measured by the external MEMS air pressure sensor. Normal reading with the engine not running is approximately 100 KPa and 30-40 KPa when the engine is idling. Very high values may indicate problems with the sensor or a blocked or disconnected vacuum pipe. Moderately raised values may indicate mechanical problems with the engine.

Also worth noting when I had a cutting out issue that was attributed to the O2 sensor the sensor was fine, but the electrical feed in the loom, in the area behind the fuel trap & throttle body was full of breaks. They tend to rub here and break, so check you have power to the 02 sensor.  You don't mention the coolant temp sensor, this shows no fault?

Edited by humph, 27 August 2019 - 10:18 AM.

[RooBoonix]

Check the servo vacuum connection, specifically the rubber grommet which connects the vacuum pipe into the servo

[kommander]

The scan tool showed no issue with the coolant temperature sensor. I suspect that the non firing of plugs 1 and 4 would contribute to the poor vacuum.

This iz what I need help with.

Edited by kommander, 27 August 2019 - 11:14 PM.

[kommander]

Disconnected the tachometer and the car idles the same, no spark to 1&4.

 

The resistance of the coil is within spec.

 

Can anyone advise how do I check the earth on the ECU?

[RooBoonix]

Earth point on the O/S inner wing near the subframe tower bolt, just remove and clean it all up

[Bobbins]

An earth issue would surely affect firing on 2&3 as well?

I had some intermittent stalling and bad running issues following fitting a new clutch, I could remove no.1 plug lead and no difference to the idle (didn’t try no.4). Traced the problem to the main ecu plug which wasn’t connected as fully as it should have been ... pushed it in properly and it’s not missed a beat since.

[humph]

An earth issue would surely affect firing on 2&3 as well?

I had some intermittent stalling and bad running issues following fitting a new clutch, I could remove no.1 plug lead and no difference to the idle (didn’t try no.4). Traced the problem to the main ecu plug which wasn’t connected as fully as it should have been ... pushed it in properly and it’s not missed a beat since.

I have had this also. The retaining clip on the harness had broken on mine, currently cable tied in place, looks crap but works.

[kommander]

Turned out to be the ECU.

[humph]

Thanks for noting the solution, many just leave their threads hanging. In what way was the ecu at fault? Loose harness? Needed the ecu repairing?  Sorry for being pedantic but on mine I've had both of these to rectify issues and the cost of the two is vastly different, so would be helpful if people reading this thred knew exactly.

[kommander]

Thanks for noting the solution, many just leave their threads hanging. In what way was the ecu at fault? Loose harness? Needed the ecu repairing?  Sorry for being pedantic but on mine I've had both of these to rectify issues and the cost of the two is vastly different, so would be helpful if people reading this thred knew exactly.

 

The ECU needs repair. It was swapped into another Mini and presented the same symptoms.