car hesitates when cold, fine when warms up

[driftin8ez]

I had a CA MAF then switched to a KA-E MAF becouse i was told it was a small upgrade. Both gave me the same hesitation. However i didn't want to open my mouth about this becouse it doesn't make sense but it seems that after i replaced my stock KA fuel pump with a walbro 255 about 2 days ago it has been a little better. The car is still a little slugish. Im guessing becouse when its cold the timing is retarded so it will heat faster. but no more hesitations or bogging out and needing a second start.

[biosehnsucht]

I have KA-E MAF since the swap (never had a CA one), also have a RB20 MAF I haven't gotten around to wiring up and reprogramming ECU for..

Don't have a SAFC or such myself. I do have a Walbro 255lph and a Nismo FPR cause the stock one couldn't return enough fuel and I had crazy fuel pressure and ran crazy rich

[eliterit]

i have been experiencing the hesitation(car runs like crap) issue with my ca when cold when i put my motor back together recently.

I am posting right now because that issue has gone away completely.

things I have added/changed to the car that magically made the issue go away:

-switched to a very used t25g (upgraded from stock ca turbo)-added fmic (removed smic which had a busted endtank (huge leakage btw)) -added turbo xs rfl bov(non recirc)-removed huge gauge amp wire running across engine bay(removed subs)

my car runs great now. no need to warm it up at all no matter how cold it gets and i'm running 12psi which is decently quick(much better than 7psi on stock ca turbo)

hope this helps some people out

[biosehnsucht]

Your problem was probably the massive boost/vacuum leak at the SMIC.

[dekansnowman]

Ok, so there is no one major fix other than leaks. This makes me feel better that I'm not the only one. The previous owner told me its just one of the bugs CAs have and hell, if this is all I have to worry about its still better than the headache my SR was. I don't mind letting it warm up a bit, I just tell people to give me advance warning if we are gonna leave someplace.

But I also have a FMIC and have checked all the possible leaks.. The only thing I'm really seeing different from the other guy is I am recirculated and he isn't. Could that be the difference? From what I read, recirculation is almost a must because of the maf.. Why can't everything be cut and dry?

[float_6969]

For some reason the CA is just kinda cold blooded. Your recirculated BOV shouldn't cause any problems.

Things to check for are leaks in the system, an adjustable FPR if you're using the walbro, a SAFC if you're using the KA-E MAFS (some people have problems others don't), coolant temperature sensor (the 2 wire for the ECU, not the single wire for the gauge cluster), correct ignition timing, and make sure all of the idle control valves are working properly and recieving signals from the ECU like they should be.

[dattodude]

The cold idle valve under the throttle body can be pulled apart. These can fill up with crap too. Clean it out with carby cleaner and a little WD40. Also make sure that this valve is routed in such a way that it does bypass air around the throttle body. This means having a 5/8ths pipe welded into your intercooler piping if you are not using the factory pipes. The cold idle valve just has 12v applied to it, you can use the injector 12v supply if you are wiring it from scratch.

Fuel pressure is a big thing on fuel injected cars. I replaced my pump/reg and needed to fiddle around with the reg so the car would start or even idle. Ended up running less than factory fuel pressure at idle to keep the car running. I'm getting an ECU tune/dyno shortly, so I'll reset the fuel pressure then.

I have removed all plenum and throttle body heater lines. They are a blown headgasket waiting to happen. I'm happy I live in sunny Australia where 'icing' of the components is not a problem.