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Gtir Motorsport club » Tech room » Help and Advice » Startup Issue

Startup Issue

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1 Startup Issue on 12th June 2018, 4:27 pm

grim_d

grim_d
Hi all,

I haven't posted here for some time, sadly life has got in the way of pulsars for me to the point where I'm going to sell one of mine so it is no longer sitting outside rotting away, I now have 4 cars and that's excessive, and a baby on the way so my spare time/money isn't going to increase any time soon!  Laughing , for 3 years this poor car has sat only being started occasionally and driven about a bit just to keep things moving, it was parked up partly because of this problem and I because I suspect a gearbox bearing is starting to go.

The car is almost ready to go but I just have one niggling intermittent problem that I can't solve.

Sometimes the car will start and behave absolutely fine, turn the key, fuel pump primes, fires up and is happy as ever, 55 on the ECU check.

More often than not however when I put the ignition on the radiator fans come on full whack and the fuel pump does not prime the rail, it will start up but it will be very unhappy, lumpy, struggling to idle and misfiring when revved, Check engine light will be on. When the fans are on I cannot access the ECU fault code check. the light wont even go out when the pins are bridged.

I initially thought it was an ignition problem,  have replaced the plugs, leads, dizzy cap and rotor arm, the coil is good.  I thought perhaps there was a fuel supply, fuel pump or relay issue with it not priming, bridging the relay contacts so the pump runs all the time changes nothing.

As I understand things the fans will run all the time if the ECU has no or a bad signal from its coolant sensor so that certainly seems to be part of the issue, but will it really make it run so badly?

I'm going to see if I can find my consult cables to check the coolant sensor but does anyone know if it might be something else? it seems very strange.

Thanks much for any thoughts
Graham.

2 Re: Startup Issue on 12th June 2018, 6:08 pm

nomad

nomad
Admin
Admin
Can you hear the pump running after/ the bad start with the fans ... Just wondering If it isn't pumping any fuel up and that's why it's running so bad ?


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3 Re: Startup Issue on 12th June 2018, 8:01 pm

johnny gtir

johnny gtir
moderator
moderator
My guess is coolant sensor / cold start valve issues
Sure if the coolant temp sensor plays up the ecu retards and kicks the fans in as a safety measure. It’s the one with plug on. The single spade is just for gauge and won’t affect anything

4 Re: Startup Issue on 12th June 2018, 9:45 pm

Mr B

Mr B
gtir technician
gtir technician
I would be suspecting possible ecu fault due to no pump priming (you need check and confirm that) and not able access fault code mode.
Perhaps poor grounds/feeds to ecu !
Second suspect is temp thermistor or wirng and this best looked at first over jumping gun on ecu ...
Issues with the fan circuit not uncommon, I done 2 ecus with faults related to this .
Easy enough do some checks on the coolant sensor which common fault (would make run real bad/not even start but not effect key on pump priming that i'm aware of), check signal ecu getting with or without consult but the software can eliminate things quicker .
First thing I do on these is check coolant sensor value at sensor then at ecu input see it same and no wiring issue, if got software can see ecu value suitable for signal voltage ecu receiving.
To eliminate intermittent temp thermistor I use resistors and variable resistor to mimic good values for cold start and hot idle etc .
is couple threads and pdf that may help eliminate things .

https://drive.google.com/open?id=0B7Ub2apq5-pfOXY5MnFQZVk1Q0U

http://www.gtir-motorsport-club.com/t5912-fans-won-t-turn-off

5 Re: Startup Issue on 12th June 2018, 10:42 pm

grim_d

grim_d
@nomad wrote:Can you hear the pump running after/ the bad start with the fans ... Just wondering If it isn't pumping any fuel up and that's why it's running so bad ?

Yep pump runs fine, it's actually severely overfueling rather than misfiring it turns out.

@johnny gtir wrote:My guess is coolant sensor / cold start valve issues
Sure if the coolant temp sensor plays up the ecu retards and kicks the fans in as a safety measure. It’s the one with plug on. The single spade is just for gauge and won’t affect anything


That was my first suspect too, have checked the sensor value, the wiring to the ecu and the ground for it, even tried using resistors to trick the ecu, no dice.

@Mr B wrote:I would be suspecting possible ecu fault due to no pump priming (you need check and confirm that) and not able access fault code mode.
Perhaps poor grounds/feeds to ecu !

https://drive.google.com/open?id=0B7Ub2apq5-pfOXY5MnFQZVk1Q0U

http://www.gtir-motorsport-club.com/t5912-fans-won-t-turn-off

This is sadly the conclusion we have come to, we have spent the whole evening poking and proding things with a meter, a faulty coolant sensor shouldn't affect pump prime, as you say the lack of being able to access the ECU (I couldn't even access it with the laptop) point to the ECU not operating correctly probably due to iffy ground or feed, this seems to be backed up by the overfueling since the injectors are bigger than standard. time to start poking around under the dash. Mad

It started fine this morning. then all day it just wouldn't play ball, then last thing before throwing in the towel tonight it was fine again.

Thanks for the replies guys.

6 Re: Startup Issue on 13th June 2018, 2:00 am

Mr B

Mr B
gtir technician
gtir technician
does ecu have daughterboard 'nistune'
what sensor reference voltage like when fault present .
does it seem play up more in heat or cold or completely random .
Seems been sat outside i'd be looking at wiring connectors and harness for green corrosion and damage, if that and basic check of earths and feeds plus a visual look at ecu board find nothing some swaptronics to a standard ecu/injectors maybe quick in-house way to verify bad ecu board .

7 Re: Startup Issue on 13th June 2018, 2:29 am

grim_d

grim_d
Yes it's a Nistune.

Coolant sensor connector voltage was 4.8v with fault present.

Seems totally random.

We have been checking for signs of corroded terminals etc but everything so far has looked ok, it's been outside but in a fairly sheltered spot.

Could look at swapping ECU and injectors if need be.

8 Re: Startup Issue on 13th June 2018, 8:23 am

mike74

mike74
I had a quick look and it appears that the A/C & fan relay's are somehow tee'd into the consult wiring.
Seems a bit strange but that whats it says!?
This diagram might help, along with Mr B's linky's Smile

9 Re: Startup Issue on 13th June 2018, 11:17 am

ducie54

ducie54
Check your battery terminals and earth cable insides for corrosion. Also check what the battery voltage is when its running like crap.

To me it sounds like a power or earth issue.

10 Re: Startup Issue on 13th June 2018, 12:33 pm

Mr B

Mr B
gtir technician
gtir technician
hopefully it grounds or feeds and seems likely due to way it acting intermittently .
If don't find much pull ecu and inspect board especially the nistune 20 pin connector solder joints to main board and daughter board mounting .
could even reflow the main board 20pin joints .
have seen standard ecu faults cause fan and pump control issues .
Interesting see conclusion on this when get to bottom of it .

11 Re: Startup Issue on 30th June 2018, 8:52 pm

grim_d

grim_d
Finally got some time to tinker again.

You were spot on Mr B, through trial and error with standard ecus and plugging in the nistune ecu without the nistune board plugged in and even returning the nistune ecu to standard breifly we have narrowed the problem down to either the nistune board itself or the header.

the installation of the header was poor at best and re flowing the 40 pin connector sadly didn't fix it so it has been desoldered and a new header ordered.

In the meantime the car has a standard ecu and injectors in it and the problem appears to have gone, the car starts fine but obviously runs poorly with the z32 and different cams etc.

12 Re: Startup Issue on 30th June 2018, 10:55 pm

Mr B

Mr B
gtir technician
gtir technician
^
Glad here you likely concluded issue.
Intermitant ecu faults can be awkward conclude .
I've redone one nistune before but lucky enough just original solder effort poor and able remove clean and refit .
Keep us posted on nistune ecu repair .

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