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cold start problems (maestro)

heavyboost

New member
Location
AB
I have a mafless file, Rs4 injectors, GT3071. Have had the car with this file for several years, runs good all around, made 400whp etc., but it will not cold start.

Have read through many eurodyne threads and tried different things to try and reduce my injector on time which is 2ms at cold start. It actually starts better when its really cold in the winter since its not overfueling as much then.

I tried changing the inj. correction, alpha n and tps vs. airflow maps with limited success. When it starts up cold it fires up good initially, then starts opening the throttle way too much and injector timing goes way too high. Reducing or increasing expected airflow hasn't really helped. My injector constant is good, my idle and partial load l.t.f.t. are good. It's just this cold start issue. I have also zeroed my warmup fuel table at anything above 0C air/coolant.

Would really appreciate it if any of you had any ideas on where Im going wrong, or would share a file for me to look at.

Here's a log of a cold start this morning. You can see it idles good (cuts down inj. ms) when it goes closed loop.

https://drive.google.com/open?id=0BxBbk87g4C1zZmRlZHVCSFIyZ3M
 

613B6

New member
Location
Ottawa
I've had more success running the car rich than lean for cold starts. I believe its lambda vs coolant temp map that made the biggest difference. That being said its well know RS4 injectors are not the best. At 400whp, you might want to swap out for S3 injectors, they will drive and start like OEM.
 

heavyboost

New member
Location
AB
I've had more success running the car rich than lean for cold starts. I believe its lambda vs coolant temp map that made the biggest difference. That being said its well know RS4 injectors are not the best. At 400whp, you might want to swap out for S3 injectors, they will drive and start like OEM.
I know its not gonna start like factory but is it normal that rs4 injector cars stall during a cold start and buck like crazy with the engine rpm bouncing 200rpm because its chocking itself on fuel?

I dont even have a lamda vs temp map, only a warmup fuel table which ive zeroed, but its still running 2ms of on time. When the 02 starts correcting it brings it down to 1.3ish ms and it idles good. I just can't get any map to reduce that startup fuel. Have tried alpha n, injector correction, warmup tables, fuel pressures..

I can video a start to show how bad it is and see if thats normal for rs4s...

Was wondering if you had a cold start log you could share so i can compare?
Or a maestro file to see if im missing maps would be awesome.

Either way, thanks for any suggestions, been fighting with these cold starts ever since i got maestro 4 or 5 years ago.
 

heavyboost

New member
Location
AB
Here's a cold start at 10 degrees C. Is this typical for you maestro users on rs4s?

https://drive.google.com/file/d/0B8MIqRDzARf-ck03cGpaMndqVkE/view?usp=sharing

Also, the only map I have that that uses coolant temp and lambda in the same map is the acceleration fuel map. Is that what you used to make a meaningful change to your cold starts?

Again, any help is greatly appreciated. Would be awesome if someone could share a mafless rs4 file to try cold starting with it.
 

Joshohol

New member
Location
Troy NY
My car drove fine with rs4s for 6 months before I pulled manifold and installed Hpa. Since then I get slighy cold start misfires due to runner flap. not enough to feel yet just enough to throw a code. I dont think it has to do with injectors

Sent from my SM-N920P using Tapatalk
 

dubber2k

New member
Location
Canada
sorry to resurrect this thread, i also have cold start issue with my rs4 injectors. i've replaced it with new injectors, replaced injector harness, fuel rail, hpfp pump (APR seized). Cleaned my intake valves, all the works and I thought it disappeared, but just today i started it up and got that cold start issue. I have PTE 5858, car runs pretty good but during cold start, it dies and has same symptom as OP posted. Misfires as well. Could this be solved?? Could it be because of the spray pattern of the rs4 Injector that's causing this issue?
 
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