Ignition issues

Author
Discussion

Daston

Original Poster:

6,074 posts

202 months

Thursday 15th June 2017
quotequote all
Hi guys,

Just hoped I could bat some ideas off you folk who have been here and got the t-shirt.

I have been issues with my RX7 running rich from day one but it has not caused any problems driving the car. I recently fitted a new intercooler and standalone ecu hoping that with some mapping we could get the fuel useage down and all will be well.

The problem on the rolling road was the spark was being blown out at high RPM and boost by the amount of fuel going in. The good news is all the injector duty cycle was bang on so no vacuum hoses are loose and the injectors don't appear to be stuck. Which therefore suggests the issue is with the spark.

I have so far tested the following:

Resistance on all coils (these are within manufacturers tolerance)
Voltage going to coil harness with ignition on reads 11.8v (battery reads 11.5v)
Changed HT leads
Changed sparkplugs

I will be checking the spark on all the coils with a spark plug tester using the old leads and new leads just to eliminate a lead or coil fault.

Apart from that I am not really sure what else I can check, any ideas?

GreenV8S

30,150 posts

283 months

Thursday 15th June 2017
quotequote all
Why have you only got 11.5V?
I have no idea what coils you have or which ones you need - what reason do you have to believe these are suitable for the boost you're running (which you haven't mentioned, by the way)?

SlimJim16v

5,617 posts

142 months

Thursday 15th June 2017
quotequote all
Battery should be over 12v with engine off.
What gap are you running on the plugs?

Daston

Original Poster:

6,074 posts

202 months

Thursday 15th June 2017
quotequote all
It's was reading under 12v with the ignition on but not running.

It's currently running 0.6 bar of boost which is below stock and using stock coils.


GreenV8S

30,150 posts

283 months

Thursday 15th June 2017
quotequote all
Is the coil driver circuit in the ECU rated to drive the coil type that you're using (I mean in terms of output impedance)?
If the coils are grounded at the ECU, is the coil power supply rated to supply the current you expect the coils to draw?
What dwell time are you using? Does your ECU enable you to adjust that?
You mentioned that the engine is running rich. How rich is it when this problem happens? Do you actually need to run it that rich? If not, what happens when you take out some of the excess fuel?

stevieturbo

17,229 posts

246 months

Thursday 15th June 2017
quotequote all
Daston said:
Hi guys,

Just hoped I could bat some ideas off you folk who have been here and got the t-shirt.

I have been issues with my RX7 running rich from day one but it has not caused any problems driving the car. I recently fitted a new intercooler and standalone ecu hoping that with some mapping we could get the fuel useage down and all will be well.

The problem on the rolling road was the spark was being blown out at high RPM and boost by the amount of fuel going in. The good news is all the injector duty cycle was bang on so no vacuum hoses are loose and the injectors don't appear to be stuck. Which therefore suggests the issue is with the spark.

I have so far tested the following:

Resistance on all coils (these are within manufacturers tolerance)
Voltage going to coil harness with ignition on reads 11.8v (battery reads 11.5v)
Changed HT leads
Changed sparkplugs

I will be checking the spark on all the coils with a spark plug tester using the old leads and new leads just to eliminate a lead or coil fault.

Apart from that I am not really sure what else I can check, any ideas?
So did whoever was mapping it not offer suggestions as to the problem ?

As others say, that voltage reading is terrible for a running engine....and pointless testing it with the engine not running.

And " the injector duty cycle was bang on" is a meaningless statement. Bang on to what ? IDC is never something you target.

And what plug gaps ? are the plugs correct ?