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BMW E30 M3 i88 - not starting


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I'm at the moment struggling to get my BMW E30 M3 S14 engine to start with an i88. I did a complete rebuild of the car and the engine - now everything is finished and we wanted to fire up the engine, but it's not starting correctly.

If we try to start it, it's backfiring trough the throttle bodies, sometimes into the exhaust or even in the compression phase.

When we crank the engine and check with the timing light the TDC everything seems to be correct. The sensor on the crank shaft trigger is located about 90° before TDC and with the strob light we catch the TDC mark at around +90°. The ECU shows while cranking about 250 rpm - which seems for me correct and doesn't show any trigger error.

When we try to start the engine, at one stage it backfires and then we get an trigger error - the rpm's go somewhere.

We tried already several ignition angles, fuel injection timings, checked if the timing is not 360° offset, etc…

It seems like the ignition timing is way off, but if we check the values it looks correct!

Injector test done - ok

Ignition test done - ok

Oscilloscope check of trigger 1 & 2 - looks ok

Ignition cables checked & changed - no change

Wiring pin layout checked - couldn't find anything wrong

Sensor & power ground checked - couldn't find anything wrong

Details to the engine:

BMW S14 engine

2,3 L naturally aspirated

Crank trigger wheel 36-2 reluctor/inductive type sensor

Cam trigger BMW E34 M5 reluctor/inductive type sensor

LS1 single ignition coil

Injectors Bosch 0 280 150 804

Mapped by TPS

Has somebody experienced similar issues?

Somebody a good idea what could be the problem or what to test?

Thanks & regards


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  • 3 weeks later...

Hi Andreas,

sorry for the delay.

I have been sick and also had carpel tunnel surgery on both of my wrists, so I have been out of action for awhile.

Please try the attached pcl file I have created.

It is crude but have got the triggers set up correctly and also set load source in your configuration you had set to OFF.

I have changed your FUEL and IGNITION table Y axis to MAP, I am assuming this is a turboed application.

You can set to MGP or TPS if you wish your call.

I have also created a basic Timing table to start you off.

Please exercise caution with the ignition table, it is just a lot better than the one you were using.

Please recalibrate the TPS, MAP sensor and then turn the fuel from sequential to OFF and do your IGNITION ANGLE TEST , set the trigger offset to correct your timing.

Let me know how you go.



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Hi Dave,

1st I wish you all the best, that you are fully well soon.

Thanks for your help with the map.

As I'm at the moment in Le Mans and will be back earliest in 8 days, I will then have a closer look and try the map.

One thing, the engine is a naturally aspirated one, not turbo charged - this is why I map it with the TPS.

Will keep you updated on the progress.

Thanks & regards


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  • 2 weeks later...

Hi Dave,


I noticed something in the help file in the chapter "Trigger 2 Sync Positioning". 

There it is written, that with Mutli-tooth / Missing the trigger 2 edge shouldn't occure in the rigger 1 gap.

I made a snap shot with the trigger scope - see attached file.


Can it be, that there is a mistake, that I have to reposition the trigger1 or trigger2 sensor?


I also found in the chapter "trigger offset", that If the gap passes the sensor before TDC1 in normal engine rotation direction then the offset number will be negative.

In my case I get the missing tooth of my 36-2 trigger wheel about 90° before the engine reaches TDC. If I crank the engine I catch the TDC marking at 90° but if I read whats written in the help file, I shoul catch it at an offset of -90°. If I look from the front onto the trigger wheel, the engine rotates clock wise (so anti clock wise when looked in driving direction).

Thats also not clear to me.


Thanks & regards



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The trigger 2 signal doesn't look like it should.

You will have problems with how the signal is rising above 0V after the tooth is past.

If this goes above the arming voltage it will think it is a second sync.

This could be due to the shape of the tooth or the sensor.

It also happens to be very close to the gap which is also better avoided if possible.

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Hi Simon,


thanks for your feedback.

I'm working on the Trigger2 signal, that it looks proper.


One question - would it be best to have the Trigger2 signal short before the gap of the crank shaft trigger and before TDC is reached of cylinder 1?

In my case, the sensor for the crank shaft trigger is about 90° before the gap reaches TDC cylinder 1.

What would be the best position for the trigger2 signal?


Thanks & regards


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  • 2 weeks later...

Hello Simon,

Trigger2 (camshaft) signal is sorted & the engine is starting - thanks for the help!!

I have now a question concerning the oil temp. sensor.

The BMW E30 M3 has a original oil temp. sensor fitted and a gauge in the dash.

The sensor has only one pin for the signal and sensor ground is via the engine.

Can I also use this signal to have the oil temp. in the ECU?

Can I split the signal or do I have to mount another oil temp. sensor for the ECU?

Thanks & regards


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  • 5 weeks later...


I still have the problem with my oil temp. sensor, that I don't get the signal into the ECU - see also topic above. In the orignial dash I have the signal and it looks like, that it shows the correct value.

It's a standard NTC sensor - see also attachment.

Do I have to connect it instead to an analog temp. input to an analog volt input like wiring a NTC temp sensor in a piggypack situation?

Thanks vor your help!



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Hi Andreas

As it is running the gauge the gauge will have an internal pullup.

So if you treat it like a piggy back and wire to an AN volt or turn the pullups off on a temp input and do a custom cal.

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