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S14 SR20 starting issues

Link G4 Plus Software Tutorial

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Hi all , bit of a strange problem here. Did a complete tune on the engine , drives fine , everything is ok when running.

starting from cold it perfect starts up every time , every temperature between cold and getting up to temp it starts perfect. when warm it starts perfect to.

BUT if you get out of the car and leave it for about 30mins to an hour it completly refuses to start. cranking over half a minute and more. when it eventually starts its on 2-3 cilinders till you rev it one time. I dont think its flooding as it not smelly , wideband(extra one which doesnt restart when cranking) doesnt show signs of flooding. when its has done the no-starting-issue it restarts perfectly when killed again and restarted.

i've tried numerous settings in the cranking and afterstart table from very low to 200% enrichment. doesnt make a difference. warmup table is configured and i aimed for 0.9lambda.

its a weird issue and quite hard to recreate as it takes a long time to get it warm and cooled down again.

SR20DET , stock except for injectors which are DW 750CC sidefeeds.

R8 coilpacks and igniter deleted. dwell times configured

98 fuel

fully stock engine.

G4X plugin

fuel table is configured on the dyno everywhere i could get (i got small rollers so i can get to 750rpm) and extrapolated where not reachable. Car can idle on 500 rpm perfectly on lambda 1.

input is greatly appreciated

Can you try to capture a PC log of one of these extended start attempts.

I can try , will make an ecu log to as the PC disconnects during cranking

i sended 2 logs to you Adam , cant find how to upload them here

Is the fuel pump running? What if you manually run the pump for several seconds before trying to crank? Does this help?

Is the fuel tank vented? Does removing the fuel cap allow the car to start?

if i set the fuel pump to always-on the issue remains. Tank vent doesnt make a difference

it does start after 30 seconds of cranking. If i turn it of and restart its alive in 1 crank. on the same temp range etc. i'm missing something but fail to see what.

it always happens when cooling down from 90degree C tot around 40C. However when starting from cold issue isnt there.

in tank pump is a DW200 which i know loses pressure when stopped( a walbro for example doesnt do this) but i never had an issue and placed a lot of these pumps.

issue still there. Tried over 2 weeks every day several times. Tried everything from crazy rich to 0 in the cranking and afterstart tables. No solution. Increased dwell, no response. I lowered first rev pulse to 30 , standard value is 40. nothing

Any input from anyone ?

I doubt that you find a solution, I hope not.

One friend of mine had the exact same issue, with a Link G4+ plug in ECU. The car had been tuned from a top notch tuner and he was straggling to make the hot start crisp.

He ended up saying that it had to do with the CAS being annoyed by the high temperatures etc etc.

If you like get a spray to cool down the CAS and please report back, we didn't had time to dig it ourselves.

The car is no longer in use.

That doesn't explain a reset of the ECU curing the issue. I would just reset the ECU as part of the start-up process.

Yeah, I looked at several logs from Kenny and all logs showed near-instantaneous sync so it is nothing to do with the CAS or trigger. After overlaying logs of many goods starts with many bad starts it became apparent that there was very little difference in terms of what the ECU was commanding - pulse widths, temps, pressures, dwell, batt voltage, inj and ign timing etc all almost identical. The original comment Kenny made "when its has done the no-starting-issue it restarts perfectly when killed again and restarted." wasn't really supported in the logs I had, but it could potentially be due to getting another dose of pre-crank prime helps sometimes.

My last advice to him was I was suspicious of the injectors as they are potentially modified with the diffuser removed. Some of the modified injectors have terrible atomisation and a large volume of liquid fuel pooled in the port can make starting difficult. I had certainly seen modified injectors make a big difference to start up performance before.

Hi all,

like Adam said i had multiple occasions where allmost all parameters were the same but the actual starting was different. I am now adding some pre crank prime pulse but it takes a lot of time as i need to wait an hour between each try. But it starts much better with the pre crank prime enabled.

it must be something to do with the injectors as those are the only part thats been changed when it received the ecu. Bit weird , i've fitted a lot of sets of bosch 1000CC's and havent had a single problem. Only went DW750CC injectors on this one because of the sidefeeds requirement.

as stated: sync is almost instant in the ecu and all parameters rule out it has to do something with the ecu. Changing the pre crank prime alters the situation a lot so to my opinion its fuel related 100%

I didnt include a " immediate start after bad start" log i think Adam. Never logged that

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