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Author Topic: Running lean when hot/ after boosting a few times. ?  (Read 7126 times)

Offline tjs91tsi

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Running lean when hot/ after boosting a few times. ?
« on: 02:26:12 PM / 27-Jul-12 »
Ok, I'm at wits end with this thing.   I have a ca18det with an eBay tubular manifold that came with as well as a fmic..  I also have a walbro 255lph fuel pump with an afpr in series with the factory regulator.  Other than that, it is all stock.  I am running the stock ca18ET maf sensor, my problem remains with my ca18DET maf as well.   

What's happening is that after the swap, it runs really lean at idle and runs even leaner with the DET maf installed. It has a lean bog when I go from off idle or go from decel/light cruise to a higher load or wot.
Right now, if I get up and go drive it when its cold, it fires right up and boosts normally and feels just fine (besides the slight bog on initial throttle). **  But after it gets hot, and I boost a few times, it start getting very lean and stumbling and not accelerating. (verified the lean condition with my wideband.)

It has a brand new ntk o2 sensor.  Fuel pressure was at stock level, it is now bumped up to ~40 psi and I still have the problem.  I tested my Coolant temp sensor and it tests perfectly, I even changed it a while ago with another one  that also tested ok.  I have voltage drop tested the maf sensor wires, verified the correct signals at the PCM of the cts, Maf, tps, on and on and on. All PCM grounds test ok.
I recently went to a drift event with 450cc injectors and an safc and after a few runs, the same thing happened.

  Why am I going lean after it gets hot or heat soaks?  Any ideas entertained at this point.
Tyler

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Offline nismo_200sx

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #1 on: 02:37:50 PM / 27-Jul-12 »
throw away that safc. this isn't 2001. those pieces of shit cannot ever be tuned correctly regardless of what anyone says. tune it right or sell it. take off the extra fuel pressure regulator and run stock. that may help. running them in series floods over the stock one if it is before the stock fpr. revert the fuel system and maf system back to stock. i will bet money your problem will go away.
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Offline tjs91tsi

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #2 on: 04:04:38 PM / 27-Jul-12 »
Lol, how much you willing to bet?  I'll bypass the safc for testing purposes and get back..  It has been nice having it on since I've been able to really help the lean idle and lean tip in.  I've had a problem with it being Lean since I got it running although I can't say for sure if it got worse as it got hot back then.  Also I just added the fuel pressure gauge and afpr to verify AGAIN that my fuel pressure and volume were sufficient.    The AFPR was not on when it first did it with the 450cc injectors and it went lean.   Also I only recently started daily driving it so I cant say for sure when it really began.   I'll bypas the safc again, that has the highest probability of being the culprit.

  But I still don't understand why it had that lean tip in and lean idle even when it was all stock.

Tyler
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Runs even worse with the safc bypassed, it's actually drivable with it hooked up.  This seems to be a slowly progressing issue.  I only have it adding 10% at idle, and tapering down to 0% at 3k.  Above that, in the dangerous areas, Im not adjusting anything.
« Last Edit: 05:47:04 PM / 27-Jul-12 by tjs91tsi »

Offline I_heart_VVL

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #3 on: 09:16:46 AM / 28-Jul-12 »
do what nismo_200sx and revert everything back to stock, especially that walbro.
also try getting/borrowing another ECU and MAF and try that out.

you have a stock engine, you dont need big injectors, aftermarket fuel pumps and all that jazz. keep it simple
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Offline tjs91tsi

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #4 on: 06:46:13 PM / 28-Jul-12 »
Ok, I'm running intermittently LEAN.  I have the fuel pump because the factory fuel pump was seized when I got the car, so I intallled the one I had, a dsm 255.  I tried the 450s and safc incase I wanted to turn up the boost at the event. The oversized injectors made it better.   I did try a spare ecu I had to no avail.   Both mafs do the same thing.  Also I bypassed the safc and afpr and it made it worse.   Next?

Offline tjs91tsi

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #5 on: 03:04:04 PM / 31-Jul-12 »
Any more ideas?  Im running lean, especially on throttle tip in.  Seems to get worse as it gets hot.  Ive tried two separate mafs and i have tried a different ecu (not known good.)  Gonna double check powers and grounds again at the pcm.    Fuel pressure is good, volume is more than adequate, injectors are stock and i have tried a different pair of injectors months ago.    Are there any wires that need wired during a det swap that if missed could cause this issue?    Starts right up idles just beautifully.   

Tyler

Offline nismo200sx16

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #6 on: 08:33:23 PM / 01-Aug-12 »
cant you just adjust for it with the afc? I have bin running the afc 2 on my car for like the last 6+ years with no problem. the car should run leaner when warmed up the ecu adds fuel for cold start. once its warmed up it backs it leans it out. so it sounds like for some reason you are not getting enough fuel flow to the injectors. pinched line? bad regulator?

Offline sideways_s12

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #7 on: 11:04:28 PM / 01-Aug-12 »
Try your cts cylinder head temp sensor check the wiring to it if the wiring is good the the temp sensor is prob on its way out...

Offline IggyEGuana

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #8 on: 01:15:56 AM / 02-Aug-12 »
have you checked your timing?

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Offline tjs91tsi

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #9 on: 04:34:58 PM / 07-Aug-12 »
Nismo  I can help it with the afc, particularly the lean tip in but i shouldnt have to.  Plus it does it when its hot, starts stuttering and hesitating bad, but boosts once or twice nicely when its cold.  I also have plenty of fuel volume.

I tested the cts and its been testing good. I also swapped it with a different one a while ago.  I will likely swap it back later.

Iggy, Thats actually next up.  Im gonna check timing and check my Cam sensor.  I just installed new plugs and checked for carbon tracking.  Everything looks good.      Thanks Guys.

Offline nismo_200sx

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #10 on: 05:13:48 PM / 07-Aug-12 »
if everything looks good is that problem still there?
1987 Nissan 200sx

Offline tjs91tsi

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #11 on: 05:51:57 PM / 07-Aug-12 »
if everything looks good is that problem still there?

Ah, Yea my responce was worded poorly, my appologies.   The plugs are fresh and gapped to 33 thousanths, and coilpacks all look good, the cts last few times I tested it was good, ohmed and checked voltage at the pcm.  I still need to check timing/cas either tonight or tomorrow.    But the problem IS still there.  I boosted once nicely yesterday when cold after plugs, after that she started acting up again.

It stutters badly and the wideband read lean, but i cant say for a certainty if thats it truly running lean or just because of missfiring.     Timing update coming soon...        Tyler.

Offline nismo_200sx

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #12 on: 07:56:42 PM / 11-Aug-12 »
seems like your feel pump is intermittant
1987 Nissan 200sx

Offline sideways_s12

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #13 on: 10:03:40 AM / 08-Dec-12 »
yeah my next guess was going to be fuel pump try that and see what happens

Offline Keith

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #14 on: 01:53:48 PM / 11-Jan-13 »
How is it running when the gauge shows lean?  The reason I ask is I have heard when the wideband o2 sensors start going bad, they show lean all of the time.  If the car runs normal when the gauge shows lean, then I would replace your wideband sensor.
What % of airflow is showing on your sfac at WOT?  If you're maxing out your CA maf, then that would be your problem....and would be time to upgrade to a Z32 Maf. With my Z32 maf, I am only getting to like 45% at 20psi .......where as with my CA maf I was hitting 100% at 14 psi
Did you have the 450cc injectors cleaned before putting them in? Might be a good idea to pull them and send them off to RC Engineering to have cleaned.  I sent my set of 450's off before installing, because I was uncertain of their condition.  Come to find out 3 of them were flowing at like 5%, lol.  After they cleaned them they are all flowing like new according to the spec sheet.
Also check the hose that goes to the fuel pump.  I forgot to tighten the hose clamp one time, and the hose slid part way off, and caused lean conditions
« Last Edit: 01:54:25 PM / 11-Jan-13 by Keith »



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Offline burritomannn

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #15 on: 12:02:26 AM / 12-Jan-13 »
Maybe something simple like trying a heavier oil? Sorry I'm noob lol
consideration won't hurt..

Offline sideways_s12

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Re: Running lean when hot/ after boosting a few times. ?
« Reply #16 on: 12:26:27 AM / 13-Jan-13 »
so whats the word?