Mpi Injectors Information: Help Needed!
Turbo Mini Forums

Hi,

It seems I encounter a problem with my injectors. I failed at MOT and my engine runs weird.

I tried to get any information on several websites about the injectors, and i got those:

reference is MJY100460
flowrate:480CC (i must believe it is per minute?)
impedance: 15.6 ohm

Sooo... I took my injectors to be tested, and i got those results

flowrate was 103 and 107 for 25 seconds testing wich is around 250 cc/min, and the impedance was 17.3.

Can someone confirm the original information I found and explain me the difference with my results? is the impedance difference critical?

Thank you

I had a set of MJY100460 injectors cleaned andd tested at around 480 cc/min.

I am not sure if the high impedance is the cause of the problem. It is more likely that they need cleaning.

Have you checked all the sensors, particularly the coolant and air temperature?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Whether the impedance being slightly out makes a difference or not depends on the test rig used.

Some test rigs just hold the injector fully open (ie, 100% duty) and some rigs pulse them at a lower duty (often 50%, well my last set were tested at 50% anyway....) so you need to know whether they were at 100% before doing the maths to get 250cc/min.

If tested at 100%, impedance is likely to make no difference whatsoever. If they were being pulsed it MIGHT make a slight difference.

But first find out at what duty the test was performed.

And, as above, were they cleaned first ???

Schrödinger's cat - so which one am I ???

Good point Rod,

My injectors were tested for 30 seconds at 50% duty cycle and flowed 120-122 cc.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Thank you for your answer guys!

>Paul S: I didn't check the other sensors yet. I'm still looking for the test values and process. I've got my ohmmeter ready!

>Rod S: I'll call the garage where they re being tested this afternoon to know their method. Thank you for that information.

The impedance value will change with temperature and i'll bet there is a brass monkey in the blokes workshop somewhere

Ok, I called the garage, and it seems the bench opens 50% for testing, which gives the correct value after calculating.
They cleaned my injectors, and changed gaskets and filters.
I'll test the impedance by myself after leaving them in a warm place.

Thought that might be the case.

I wouldn't worry too much about the impedance as they have been cleaned and flowed correctly (with the new calculation) on the test rig.

As per Paul, the poor running is most likely one of the sensors giving bad imformation to the EMS/ECU.

Schrödinger's cat - so which one am I ???

With the sensors, bring them indoors and get them to 20 Deg C, if you can.

The resistance should be around 2500 Ohms.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I was thinking about this, but I didn't find on the forum a way to test the different sensors.
Which sensors do I have to test, and how to do it?
I tried to find the values or a method in the rover rave cd, but there's nothing about it.
I was thinking about testing air temp, air pressure an water temp sensors, is that enough?

The air and coolant temp sensors will be 2500 Ohm at 20 Deg C.

With the air pressure (MAP) sensor, it will probably give a voltage ouput dependant on vacuum. Probably best try that on the car whilst idling and again with the ingition on but engine not running. One of the wires will have a steady voltage, one will be an earth and the other will have the signal voltage.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Thank you Paul, I'll try this next week after I got my injectors back.

I'll probably test the temp sensors tonight
Thank you again.

Hi everyone!

I'm back after a few vacation, and reinstallation of my injection.

I've tested the temp sensors, everything is OK.

I went to a garage to verify the CO values, before going to the MOT, but there's still a problem. The lambda value is still to high.

I joined a picture, engine is idle.

I checked everything, reinstalled the exhaust to be sure there is no leak.

My last MOT control 2 years ago was ok. the only modification i made since is to install a 1:5 rocker. Do you think if it can influence on the CO emission and lambda value?

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That's running very lean. You need more fuel.

Have you checked the fuel pressure?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

No, I didn't even think about it.

How can I test it?

You will need to fit a pressure gauge. Not simple on the MPi.

Probably best to get a garage to test it.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I recon that could be a leaky exhaust.

Idle with 1.2 lamba will ve VERY unsteady, if it idles at all, and the engine would faulter when the throttle is applied.

What also confims this is that the CO2 is not far off reading right. No CO and minimal HC means that the cat is working its magic. 3.7% O2 does not represent the lambda value of 1.2. The O2 could be from a missfire if the post cat temperature is hugely different to the pre cat.

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Thank you Sprocket, I'll check this during the weekend.

What is the running problem with the engine? you mention this in the first post but did not elaborate on this

Hi everyone.

I had to leave my mini and my problems in the garage for a few months.
As I have a few days of vacation, I went to the garage to check the mini.

I replaced the 1:5 rocker by the origin one.

After a quick CO check, the problems stays the same for the pollution.

I also had this weird running problem. The engine runs at too high RPM. I was stucked in traffic jam, and the engine stayed at 1700-1800 rpm, and sometimes at normal 900 after opening big (more than 4000)

I'll continue checking this afternoon. All your advises are welcome.