MPI starting problem
Turbo Mini Forums

Non turbo question for a change.

I'm having a problem with starting a MPI Mini. I went thru some other topics, usually connected with alarm a crankshaft position sensor but this time it's different.

i have to crank it for a bit until it finally decides to start. It does caught and misfire couple times along the way. Once it starts it is running good. Pouring a bit of fuel into throttle body will allow the car to start straight away, so my guess is fueling problem.

Injectors cleaned and checked. They work good now. Swaped them with another set but there is no difference. Fuel pump works everytime after switching the ignition on. Fuel pressure checked and it's 2-2,5bar after switching ignition and the same when car is idling. Even after removing injectors the pressure builds up nicely once ignition is switched on.

I checked everything with ACR4 but everything seams to be normal. I run out of ideas for now.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Changing the IAT sensor cured MPI running issues I've seen in the passed.
Also wiring would be good to look at, refer to below link.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=567979

Dazed and Confused....

Shouldn't the pressure be higher:
The FPRs on the standard car is 3.0 bar, plus or minus 0.2 bar

I clipped that off another site as I dont have access to my documentation right now.
and when was the filter last changed?

Edited by tmsmini on 4th May, 2016.

Filter changed last year, car did only 2000-3000km.

Reading may not be accurate on the pressure as I only had oil pressure gauge in hand to check it. T-pieced supply line to be sure the pump works and gives pressure straight away. I was suspecting it may not give enough pressure once it's energized for few seconds before cranking the car. Besides car works normally once it's up and running. Under load as well.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

I have found with "odd" problems on MPi s its usually down to bad earths, usually the one below the expansion bottle.

I'd be looking at the coolant temp sensor first and the air temp sensor second. Cold start requires anywhere up to 4 times more fuel at the coldest, with little or no extra fuel when fully warm. Faulty coolant temp sensor will prevent a cold engine starting as the ecu substitutes a fixed value of 60c.

Without actually seeing the live data, I am simply speculating

Thanks, I'll plug in the ACR again tomorrow and write down the data.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Ok here is how it looks like:

5 codes received
1) 07 IAT sensor circuit, logged, sensor output voltage too low
2)06 MAP sensor circuit, logged, sensor output voltage too high
3)09 O2 sensor 1 circuit, logged, sensor output voltage too high
4)07 IAT sensor circuit, active, sensor output voltage
5)09 o2 sensor 1 circuit, active, sensor output voltage

After clearing codes both IAT and O2 faults come straight back. It's the same in any MPi I checked I think.

While we are at it "logged" means there was an issue and ECU stored that in memory, and "active" means issue is currently present? At least in theory?

Readings from sensors with ignition ON, engine OFF.
ECT 12
IAT 11
MAP 101,4
Throttle pos. 4,8
Throttle switch OFF
Battery volt 12,3
O2 1,99
Stepper pos. 152
Crank signal sync BAD
cam sync BAD

While cranking I managed to check
Battery volts droped to 7-8V
injector pulse is somewhere between 21-25

IAT raised to 13 but the sun came out so it seams to be working fine.

I'm no expert but readings are looking OK. I cranked the car but didn't managed to start it this time. Battery died. Will try again later and post a video in the evening. Both without help and with some fuel added in to throttle body. Will look at the readings later again as well.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Fast forward 2 hours

Ignition ON, egngine OFF

ECT 20
IAT 19
more or less exactly the same as outdoor conditions.

It started after 2 revs, first one misfired but then it started nicely. I turned it off and give it another go. A bit more misfiring, couple revolutions but it started again more hesitation this time and I have to keep the starter running for 2 more sec. cause it only started on 2 cylinders I think.

Then:
MAP - 47, I'm used to SPI so it seams a bit high.

ECT and IAT kept climbing nicely and MAP dropped a bit.

when fan kicked in:
RPM 900
ECT 105
IAT 57
MAP 39-41
O2 0,5-3,8mV
Injector pulse width 1,0
stepper 44
crank and cam sync GOOD

I cover the throttle body with my hand and it kept running, it died when I pluged the inlet from crankcase to TB. No other signs of vacuum leak.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Finally some videos:

Fisrt one is from the morning attempt - 10 degrees or so outside
http://vid1290.photobucket.com/albums/b527...zpsl9gf2x7n.mp4

And then 2 hours later:
http://vid1290.photobucket.com/albums/b527...zpsjoong1j9.mp4
http://vid1290.photobucket.com/albums/b527...zpstv0bi6ae.mp4

Thought anybody?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Bottom line here is i dont know, but can only suggest possable causes.

Ok so i would agree, that the temp sensors were ok at this point but i wouldnt rule it out.

Does the ACR not give you the ignition timing value?

Check the basics, compression test, leak down test, plug gaps and heat range,

I seem to remember something about the IAC valve body cracking causing an air leak, and the plastic throttle body warping. Not seen the latter, but have seen the IAC valve cracked.

What about the injectors? Have they been cleaned and flow tested anytime recently?

The only other thing i can think of is the fuel pump....... does the car drive well enough without hesitation and backfire? If it hasitates under acceleration id usggest testing the fuel pump. Ive seen those fail.

One of the VEMS tuners in Sweden had suggested a method for checking for air leaks to, find it here http://www.vemssupport.com/forum/index.php...1.html#msg15111

As stated earlier:

injectors were cleaned and checked and swaped for another set. No real difference. Fuel pressure checked and reading somewhere around 2-2,5bar (using oil pressure gauge ), builds up nicely even after fuel rail was dead empty. And yes car drives normally once it starts.

Will look into other suggested areas.

Nope ACR gives only coil charge reading. No ignition timing figures.

It does seam like it's igniting a bit to early, I can only try to check it with a timing light. But then again once you give it a decent amount of fuel it will start straight away.

I'll go thru earth connections as well and will report back.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

No sollution yet. But for the record:

CR test - 12,0-12,5 bar on all cylinders.
old plugs were good, a bit dark and gapped at 1,0mil. Put a set of ne w ones anyway with 0,8mil gap. Swapped for the set of original cleaned and tested injectors. No big difference. It did started a bit better this time round but it may be due to 20degrees outside temp. It does sound like it starts on 2 cylinders sooner than the other two but other then that no change.

Next on the list is swapping ECU and maybe engine loom if I can put my hands on a second one.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

One thing I did come accross in the past with bad starting was a broken wire to the cam sensor caused by a lot of driving with bad engine steady bushes. Remember if you change the ECU you must change the alarm also or reprogram the code.

I'll have a full set of ECU + alarm unit + key fobs

I forgot to add I went thru the earth connections on the ECU side. Cleaned the thread and changed connectors. No difference.

Actually if you think about it the cam sensor or it's wiring might be a good hint. But shouldn't it cause the engine to not start at it all if it is damaged? Plus once it running ACR show that cam sensor sync is OK.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Check the wiring as described in the link I added.
Grounding was a mess exactly as described by KLAS.

Edit: typo

Edited by Yo-Han on 9th May, 2016.

Dazed and Confused....

An intermitent fault can come and go as you crank the engine due to vibration. The alarm gets its earth from the earth point behind the expansion bottle.