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SteveX

Slow cranking

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Hi Guys,

Just had a G4 fitted to my mr2 1zz turbo.

I will be getting it set up in January, it has a base map loaded.

The issue is, on the factory ECU the car turned over perfect, since the G4 is fitted it cranks slowly (almost feels like the battery is low). The existing battery was 3 years old, so I switched to a new one today, but the same issue? The chap who re-built my engine and fitted the ECU said that aftermarket ECU's can take more juice, but I don't buy that this is causing the slow cranking.

I read on the forum that timing could effect starting and cause slow cranking? Could this be right? The battery as I said is good, alternator is good, even with the new battery fully charged it cranks slow (and takes a while to start assume that is the map). The earth is good etc, and starter. 

Any ideas appreciated, I don't want to take it to the mapper and it die / not start.

 

Thanks,

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If you have too much cranking advance it can cause the engine to kick back but it doesnt sound like that too me.  To test if this is the cause you can just unplug the coils and try cranking - if it cranks faster when there is no spark then you could possibly conclude it is related to a timing issue.

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Thanks good idea to pull the coils. I’ll try that.

i plugged the laptop in and looked at the mapalso, it’s 35 degrees advance up to 500 rpm. It’s a small 1.8 high compression Toyota petrol engine, seems high.

compression should be stock, stock comp pistons used, larger / heavier forged rods.

 

 

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Thanks JMP!

That's how I would like mine to start!

Slow cranking nearly sorted, earth strap needed sorting and it's cranking quite a bit faster now.

Still a long crank though, it literally turns for about 4 seconds before firing.

Do you recommend notching down the ignition timing 500RPM and below?

 

Thanks,

ignition table.png

Just to add the current table looks a bit all over the place, if you look from 50kpa then to 90 the it looks very off.

Not sure this base map is anything like sorted...

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Just a quick one, was the 1zz engine stock? IE stock compression? Did it have larger injectors? I just discovered an old map you posted, the fuel table on my base map and the fuel table in the map you posted is very similar at any given RPM, however my ignition table is hugely advanced in nearly all areas.

I will not be driving the car anything other than very light throttle to the mappers and getting it sorted there, but I may load in your ignition table to see if it helps the car, thoughts?

My 1zz block is running standard compression although it has forged rods and different pistons. I am not sure of the injectors but they are larger. The wastegate is set to only 7psi at the moment.

I don't have a wideband, and I am not familiar with mapping, but I do need to get it 80 miles to get it mapped in a few weeks, and again could really do with it starting better.

Thanks.

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Righto, loaded in some of the idle and ignition settings from your map, it started from cold in about three turns and fast.

But it wouldn't idle, just died.

I loaded back the crappy map I have, and reduced the upper left corner of the ignition table lower, cranking seems nice and quick now normal speed. Took it round the block and started and stopped it about 5 times, seemed a lot better, not perfect but cut the cranking time by at least half. Pulled over one last time at full temp, I left it ticking over while I was looking at some settings, but it started hunting at idle, bouncing around four boxes in fuel and ignition in a circular fashion. It's done this on the way home when I picked it up. I couldn't find out what was causing it, so I switched off, but then it was back to taking a long time to crank, at least 4-5 seconds, so I came home then parked it up and put the battery on charge after all of the starts.

I guess something needs adjusting for it to start better when hot?

At this point I assume I just need to be patient,  not really use it and wait to get it to the mapper and on the rolling road.

 

 

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I would suggest to first get the fuel and ignition map dailed in. After that you can look at the cold start, warm start, cranking enrichement and idle table's, because they al are based on the main fuel map ;)

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the 1zz turbo I did was a completely stock long motor, has been turbocharged for 10 years now and done more than 100,000km with forced induction.  I 2nd Shedley's post about getting the fuel and ignition maps tuned first

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Thanks guys, yep best to leave those in the know to do what they do best, I was just keen to try and get it starting better myself.

JMP your fuel and ignition table makes it turn over faster and arguably idle smoother (much less lumpy). I think the car you tuned is different loom wise and sensor wise though. For example my setup has no narrowband o2 sensors at all and the idle control is different for sure. It also had some changes made to the MAF.

I am not sure regarding injector size etc, so I can only assume that the map need to be set up properly and then hopefully as you guys say the rest can be dialed in.

Is it worth getting a wideband for after the car is mapped for the G4 to use, or once they have tuned it should it not be needed?

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the one I did had caldina ST215 550cc injectors and a walbro pump in the stock dead-end fuel system, stock static fuel pressure which wasn't boost referenced.  The map sensor is a generic 3bar GM sensor and IAT is a vipec sensor.  MAF wasn't used at all.  It also had an LC-1 wideband and the stock narrowband deleted.  Idle control was with the stock idle solenoid which is a simple 3 wire solenoid, power,  signal and ground.

I put wideband's in every car I fit aftermarket ECU's to, used for closed loop fuel trim and logging

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Thanks for that. This kit has no o2 sensor, do you recommend getting one? Will it make any difference once the car is set up and mapped properly with one on the RR?

I can't put one near the manifold as it is cast and it has a 200 cell sports cat fitted, if I should fit one where would be best?

 

Thanks! 

Oh and would a £70 Bosch one be ok?

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