Partial success, need advice

[Hornet600]

Hi chaps, had my first rolling road with my completed engine, very happy with the one power run we managed before a problem, it achieved 218bhp with excellent torque. The spec I have before I get to the problem is Newman stage 2 cams . Jenvey 45mm throttle bodies and a bespoke 4-2-1 manifold and all controlled by an emerald ecu. I have Vauxhall 440cc injectors probably from something like a calibra and running 2.5bar fuel pressure. Now the problem I have us after the initial setting up of the maps which took some time, the car settled down and was nice and responsive to the throttle. Run went well so we switched everything off and had a cup of coffee. When we restarted the car it was banging and spitting at any position in the map. After a lot of pissing about, once the engine warmed up again it kinda got better but as soon as the engine dropped in temp..... Same thing would happen. I have ordered new vxr turbo injectors and a 3 bar regulator as we think the fuel is the problem as its switching from lean to rich and rich to lean without any warning and seems to be related to temperature. I would really welcome any thoughts on any if this from you guys. Cheers John

[Graham]

is the coolant temperature reading correct? its easily seen in the live adjustment screen. if its fine when warm theres a good chance there isn't enough additional fuel in the temperature correction tables for a cold or nearly cold engine.
i had a car here recently which was properly mapped (during warmer weather) and it went like stink, but as soon as the outside temperature dropped down to single figures it didn't want to run properly until it warmed, i had to adjust the correction tables to get it to run properly whilst warming up. Infact once the temp dropped to near zero i had to adjust them a bit more

[LAWRENCEM]

As above sounds like your maps not very good or you have problems with a temp sensor

[Graham]

if it is in the temp correction maps, make sure you have the main map correct before playing with the corrections

[Hornet600]

Thanks for input guys but to eliminate the temp we set that to not be doing anything at the temps we had. The problem was anything below 80 degrees and ok above this. So confident it was not the temp map, or the ignition map or the fuel map.

[Graham]

sorry mate, dont understand what you just said. although 80 degress is a too high for warm up corrections, if the temp sensor isnt readying quite right and the main map is a bit off, then temp corrections could easily be your problem.

where are you reading temp of 80 degrees? live dajustment screen? or some other means? is that 80 degrees actually correct?
it could be something as simple as a duff plug or coil pack causing a missfire if its not properly up to temp.

[LAWRENCEM]

I believe 60 degrees is about right to have no coolant temp correction below that you need it as the car is still warming up so by disabling it you have proved that it's not doing anything to correct temperature

I did have an issue in my skyline that after leaving it sitting after running for about an hour it and then starting the car as the intake air temp had risen under the bonnet the fuelling was wrong and it actually required more fuel at higher intake air temps than at lower ones never did work out why as the logic is backwards but I just upped the fueling in relation to air temp and it fixed it

[Hornet600]

Thought I'd give you an update as it is now fixed. After all the expense etc the root cause of the problem was the crank sensor wires were the wrong way wround. Now I know you will say that shouldn't matter but I assure you it does on my engine.. It was causing an intermittent spark hence the poor running.

[alladdin]

Yes can cause weak signal issues

[Graham]

it causes issues because when the ecu is expecting to see a rising voltage it actually sees one thats dropping. it usually shows up differently though, like a artifically low rev limiter, or an engine which simply wont start