Stalls/Lean condition under Electrical Load - b18 CRX

[sugarbear7979]

Hello All! So been taking the car out for some test runs and its running pretty good. Working with the map, finally got the TPS adjusted, the idle/IACV/throttle blade adjusted on the skunk2 TB, and ignition set. All is going well until I hit the brakes, the car seemed like it wanted to completely stall. Wideband showed that I was going from roughly 13.5 AFR to 17 lean only when brakes applied. I thought maybe it was vacuum related, but already diagnosed that as not the problem..

Under further inspection, found out it gets worse the more electrical load you apply, headlights will dang near run it into the 18 AFR and stall it out.

Setup:
1990 CRX
fresh b18c1/b16 head
gt35 turbo
custom wiring harness
new distributor
Injector dynamics 1000cc
p06 s300 ECU

Im running an Odyssey Battery mounted in the front, battery disconnect, with all my electronics such as fuel pump, fans, and vtec off separate fused voltage supplies. If i turn on the headlights, and check all major connections (ecu power, battery, fuse blocks, fuel injectors) and it shows 13.75-14Volts with headlights, 14+ without headlights, ELD voltage shows no less than 2.5V w/headlights on, 3.6V w/o headlights on. Ive traced nearly every wire to verify no shorts. Ive driven the car for over an hour thus far and no charging issues. Basically been working on it every day after work and no progress.

Currently modifying the maps using the Open Loop (closed loop disabled) option, dead times set to 1.67 @10v, 1.55 @ 12v, 1.25 @ 14V, 1.00 @ 16V. I know people say that I.D. dead times are low that they supply you with, but those are all old posts and curious if maybe theyve updated or changed some in their injectors?


At this point, my assumptions are:
A faulty connection somewhere (even tho I'm confident in my wiring and I've checked nearly every wire I can find that could be it),
Possibly one of the inputs that goes to the ECU could be causing a fault that tells the ecu there is more electrical load,
Bad ECU
Bad Alternator
Incorrectly set dead times
Bad ELD
Incorrectly wired Alternator

Would like to have this issue corrected before I take it and start dyno sessions, any input would be mucho appreciated!!!
BTW, no check engine codes either.
Cheers!

[Spunkster]

If you are using the supplied dead times from ID then that is probably the cause of the issue. Start there.

[skullbasher]

Did u by any chance get a new fuel pump as well?? I have also been experiencing this similar problem after i switched my walbro 255 and stock fpr to a walbro 400 and aem fpr with larger orifice. But it only happens when i have a quarter tank of gas. Basically every time i apply the brakes especially when slammed on the car stalls just like u say and i am guessing the when i hit the brakes the fuel flings forward and the new stronger pump catches an air bubble which stalls the engine. Basically when i hit the brakes the rpms shoot really low and bounce like at 250 rpms for a second and shuts off. If i hit the brakes slowly it wont happen. i also have an odyssey battery and 60psi fuel base pressure.

otherwise keep playing with the deadtimes

[Spunkster]

Did u by any chance get a new fuel pump as well?? I have also been experiencing this similar problem after i switched my walbro 255 and stock fpr to a walbro 400 and aem fpr with larger orifice. But it only happens when i have a quarter tank of gas. Basically every time i apply the brakes especially when slammed on the car stalls just like u say and i am guessing the when i hit the brakes the fuel flings forward and the new stronger pump catches an air bubble which stalls the engine. Basically when i hit the brakes the rpms shoot really low and bounce like at 250 rpms for a second and shuts off. If i hit the brakes slowly it wont happen. i also have an odyssey battery and 60psi fuel base pressure.

otherwise keep playing with the deadtimes

This sounds more like you have the sock installed incorreclty in the tank and it is just no longer sucking fuel in.

[sugarbear7979]

Ya no fuel pump issues, I don't even have to be rolling for this to happen. If u hit the brakes, lights, fan, basically any external electrical load will cause my condition.

Haven't been able to work on it this weekend but i will see what I come up with soon.

[sugarbear7979]

Okay, further investigation of the issue:

Ive changed dead times all around, seems like the issue still persists. My plan of attack now is to try and increase the duty cycle of the 1000cc injectors above 2ms, I have read that large flow injectors tend to not have a linear flow curve below 2ms, and at this point its the only thing I havnet tried. Currently at idle at 14.7 afr it is at like 1.5-1.75 ms, and I think this is from too much fuel pressure. In my past builds, I usually tune static fuel pressure to 45psi and I'm starting to think this is way to high for the 1000cc ID injectors. I had a B&M fuel regulator but wasnt able to lower the pressure below 44psi with the deatchworks fuel pump.

Within the week, new AEM fuel regulator should be here. I was going to try and set static at 35psi, so with vacuum port connected maybe 32 psi ish, just need to see how far it lowers it if any. Im hoping the increased duty cycle will alleviate this lean condition under electrical load. To me this all makes sense since I've been able to start the car with just the fuel in fuel rail with no pressure at all (when i first put a base map on it).

My question now is:
What fuel pressures do you guys use with 900cc + injector sizes on GAS?

[MadVTI]

I have this exact same issue in my dc2 turbo. Lights etc... on, runs lean. Can anyone help? Is it an eld issue? Tried everything possible, ecu, looms, You name it......in stumped. Thanks marc

[Spunkster]

This is most likely either a injector dead time setting issue, or possibly battery/alternator problem. ELD has nothing to do with this.

[MadVTI]

This is most likely either a injector dead time setting issue, or possibly battery/alternator problem. ELD has nothing to do with this.

Changed the battery, the alternator, still the same. Im on RC 750s. Haven't played with dead times. What should i be looking at? The reason i suspected
eld was because unplugged, afr goes rich again.

[Spunkster]

Try swapping in a known good alternator.

[autobacs]

Hello All! So been taking the car out for some test runs and its running pretty good. Working with the map, finally got the TPS adjusted, the idle/IACV/throttle blade adjusted on the skunk2 TB, and ignition set. All is going well until I hit the brakes, the car seemed like it wanted to completely stall. Wideband showed that I was going from roughly 13.5 AFR to 17 lean only when brakes applied. I thought maybe it was vacuum related, but already diagnosed that as not the problem..

Have you found out the problem?

Do you have an aftermarket throttle body by chance? In my opinion, it sounds like the IACV is not able to duty cycle quickly enough to regulate the amount air bypassing the closed throttle plate. This will affect your AFR as well as your stalling issue.

[Rosky]

Had this exact same problem for a few years after spending well over $4000 now, doing everything imaginable, turns out I had really bad luck with finding the fix for this issue, thought I had it figured out one while but car proved that, that was also a lie.

I can tell you the issue lies within the link between your ecu and Hondata not saying that either is bad, but the way they function with each other may not always work the way it should no matter what you do.

Got with my tuner, as I and everyone else believed it to be the dead times but after sitting for hours trying different figures nothing worked, So we tried 4 different ecus all with Hondata installed.

First ecu was my original p28 that had this issue 2nd ecu was a p30 with Hondata that came from a working car that also had the issue when It was plugged it into my car.

3rd ecu was an p30 that already had Hondata and my car ran perfectly fine! no more stalling when the fan comes on or leaning out under electrical loads! we was completely baffled! thinking it was too good to be true we tried the 4th ecu p30 and the car ran perfectly fine again, all ecu's was loaded with the same map!

As for which is actually the problem the ecu or Hondata? I cannot say for sure, 4 ecu's with Hondata already installed, we were going to mix and match working ones with bad ones to pin point the issue but the tensioner pulley let go on the motor after a few pulls on the Dyno after the fix - figures.

I really hope that this helps you guys and I also hope that Hondata can look into this issue for a fix or actually finding some feedback on what actually causes this issue, I wouldn't want anyone to go through what I went through over the years with having this issue.