Calling on Stand Alone ECU Gurus ...

[scotty-2-forty]

I have been having a problem whereas after boosting I cannot keep the car idling; RPMs will just drop down and stall unless I keep feathering the accelerator pedal. Revving the engine while stationary produces a slight popping (not full-blown back-fire, just soft deep popping) and it's a bit stumbly as the revs climb (again, car not in motion). These issues may or may not be related. I have checked for boost/vacuum leaks and found nothing. I was hoping that a tuning guru here with the genius touch would take the time to review my ECU settings and/or any other imperfections I might have made (see pic below). I use the EMS 8860 stand-alone programmable ECU, and I did not do the initial tuning.

All my mods can be found here: http://www.cardomain.com/ride/3828985/1 ... 0sx/page-3 or http://www.nicoclub.com/archives/1996-2 ... -2010.html.

What concerns me is the Boost Cut and the Deceleration Fuel Cut parameters. Could this be a culprit? Also, I use 96lb MSD injectors which are 2.0 ohms, but my program shows 2.2. Problem? Should I also be concerned with the Acceleration Enrichment and/or Enrichment Duration?

Thanks to any of the high rollers that respond! I'm just wack right now; brain is fried and I probably couldn't tell the difference between 4 cylinder and an 8 if it jumped out from under the hood and smacked me right in the eye. I can email you the program and my tune file if you care to get really involved. Here's the screen cap of the ECU settings ...

[scotty-2-forty]

Thanks for relocating my post biggie! Anyway, anyone care to take a stab at this?

[Razi]

I know nothing about ECU tunes, but my car did this (it only has a ROM tune, though), but I tightened my BOV spring up and it went away.

However, I'd guess that having the injector ohms being correct on the ECU would be important.

Hopefully someone with more knowledge can chime in!

[corn322]

Boost cut = 152.5kPa = 22PSI. Boost over 22 pounds and the ECU shuts off fuel. I don't know what you boost to but that shouldn't be the problem.

Could be the decel fuel cut. It's set to -78kPa, which is 23 inches of vacuum. When your vacuum reaches this value it shuts off fuel, because you don't need fuel when you're decelerating. Where do you idle at?

Does it idle well at other times? Say you drive around the block at part throttle, not boosting too much. Does it fall to idle correctly when you come to a stop sign?

[klattr1]

using this Stinger EMS, does it still incorporate an idle air control valve? when it tends to stall, does it go pig rich during that scenario? I don't know too much about the system you're using, but on other systems, there's sometimes the option for a inj. pw minimum at lower rpm's to help prevent stalling (if no iacv is used)

[scotty-2-forty]

Boost cut = 152.5kPa = 22PSI. Boost over 22 pounds and the ECU shuts off fuel. I don't know what you boost to but that shouldn't be the problem.

The Boost Cut and Deceleration Fuel Cut parameters are the two values I've been thinking about. I'm not a tuner per-say, and frankly I'm still learning most facets of this EMS program.

As for where my boost numbers are, low boost around 12psi / high boost around 26psi. But I really don't hit that 26psi too much and the stalling at closed throttle post boost still happens. Do you think I should increase the Boost Cut kPa anyway?

Could be the decel fuel cut. It's set to -78kPa, which is 23 inches of vacuum. When your vacuum reaches this value it shuts off fuel, because you don't need fuel when you're decelerating. Where do you idle at?

Idle is around 925rpm. Stalling only happens after getting into boost and letting off the throttle. Aside from the boost cut (above), do you think I should increase or decrease the deceleration fuel cut? ... Both?? I guess I'm looking for comfort in some recommended "safe" numbers to tinker with.

Does it idle well at other times? Say you drive around the block at part throttle, not boosting too much. Does it fall to idle correctly when you come to a stop sign?

It idles a little rough on cold start up. Once warmed, it idles around 925rpm, give or take 25rpm. It will have an ever so slight hesitation when revving the engine out of gear (neutral) and my boost/vac gauge shows that temporary blip as an increase from 19hg to around 30hg. When driving, if I don't get into boost the engine falls back to idle without too much issue. The problem occurs directly after closing the throttle post boost.

[scotty-2-forty]

using this Stinger EMS, does it still incorporate an idle air control valve? when it tends to stall, does it go pig rich during that scenario? I don't know too much about the system you're using, but on other systems, there's sometimes the option for a inj. pw minimum at lower rpm's to help prevent stalling (if no iacv is used)

Just to clarify, it's the 8860 not the Stinger. However, I am not using the IACV.

[scotty-2-forty]

I answered the two posts above as if I've done nothing since my original question(s).

Continuing on now, this past weekend I did a little re-check. First, I ran another pressure check on the intake system. I found a few leaks that somehow did not show up the first time around, eh ... probably due to a faulty Schrader valve I was using on my $12 DIY unit. I had to re-fabricate one of my breather tube fittings to the cold side intercooler piping as the threading was stripped and leaking air. I also found that the pressure side of my HKS BOV had a tube going to nowhere AND that my throttle body had a port just blowing out air ... solved (maybe?).

Secondly, I did a little research. The MSD 96lb/2.0ohm injectors I used in the past were swapped to Siemens 83lb/2.35ohm units prior to my buying the car back from my past business partner. Long story, posted it last year. Anyway, this is simply something he forgot to tell me, or I may have brain-farted - yeah, probably that. I increased the Injector Ohms parameter to 2.4ohms since there is no in between setting from 2.0 to 2.4. I drove around for a bit getting in and out of boost and noticed a few things. First, it did not stall once - it seemed like it would, but something in the program caught it. The idle would drop down to about 400 to 500rpm and then raise up and smooth out; but it did not stall. I also noticed that my air/fuel ratio richened to about 10.2 ... okay, at least it's not leaner . And finally on one high(er) boosted pull I noticed some clicking seemingly coming from the EMS unit. But it only happened once.

So anyone making sense of this? I know it's confusing to me as I type it. Am I doing some good here or is there something in my attempts that is of concern with regard to ECU settings? Thanks guys, I appreciate the activity so far!

[WDRacing]

10.2 is retarded rich

[scotty-2-forty]

10.2 is retarded rich

Yeah, that's why I'm looking for some input here as I play and learn. But hey, I AM retarded, just not rich!

[kingtal0n]

If you have a MAF sensor, then realize that air exiting your closed loop system (via the bypass valve) will be registered by the MAF and the fuel will be added to the engine... for the air that exits the system. This is the majority of idle issues with MAF cars that retain atmospheric bypass valves.


On the other hand, if you have a MAP sensor, it probably just needs tuning

[scotty-2-forty]

If you have a MAF sensor, then realize that air exiting your closed loop system (via the bypass valve) will be registered by the MAF and the fuel will be added to the engine... for the air that exits the system. This is the majority of idle issues with MAF cars that retain atmospheric bypass valves.


On the other hand, if you have a MAP sensor, it probably just needs tuning

No MAF. What I'm really hoping to compensate for now is that it's running rich since I adjusted the injector ohms from 2.2 to 2.4 (@ 10.4 give or take a few tenths). The stalling seems to have ended so I just need some experienced advice as to what I can adjust from here to lean it out just a bit and retain idle. Anyone? I haven't had it on the road since my last post, but I'll be doing some more tinkering this weekend ... weather has been lousy and I work way too much! Thanks though!

[klattr1]

If it's running 10.2 afr's during decel conditions or when it's transitioning from decel to idel, then just lean out the relative cells in the lower part of the map. It should be more like 17-19 afrs during decel and should transition to 14-15 afrs once it gets under 1000 rpms in order to run correctly and smooth out (depends on the setup and type of fuel). Even though it's running really rich right now and stumbles, by not having an idle air control valve, it's not going to be perfect (especially during temp. change) and you still might notice some RPM drops when coming to a stop or shifting to neutral at a high speed.

If it's stumbling while revving up the motor sitting still, check those relative RPM's (using map tracing) and the AFR's recorded at those cells. Usually that refers to low load/higher RPM cells in the corner of the map. So if it's running too rich there, then lean it out. But depending on who setup the original tune, make sure the timing tables in those cells are built accordingly (usually <10 deg. timing) as that can have an effect too on stumbling issues.

As far as the ohm change for different injectors, not sure what that's affecting in that particular EMS, but most modern engine management systems have lag time/latency settings and/or battery voltage compensation tables. These tables seem to adversely affect driveability issues if not set correctly based on the injectors used (manufacturers usually provide these settings as recorded from a bench).

Feel free to send the map over to klattr1[at]ryanklatt[dot]com. I'm curious to see how this EMS system works and might be able to have more detailed assistance.

[scotty-2-forty]

If it's running 10.2 afr's during decel conditions or when it's transitioning from decel to idel, then just lean out the relative cells in the lower part of the map. It should be more like 17-19 afrs during decel and should transition to 14-15 afrs once it gets under 1000 rpms in order to run correctly and smooth out (depends on the setup and type of fuel). Even though it's running really rich right now and stumbles, by not having an idle air control valve, it's not going to be perfect (especially during temp. change) and you still might notice some RPM drops when coming to a stop or shifting to neutral at a high speed.

If it's stumbling while revving up the motor sitting still, check those relative RPM's (using map tracing) and the AFR's recorded at those cells. Usually that refers to low load/higher RPM cells in the corner of the map. So if it's running too rich there, then lean it out. But depending on who setup the original tune, make sure the timing tables in those cells are built accordingly (usually <10 deg. timing) as that can have an effect too on stumbling issues.

As far as the ohm change for different injectors, not sure what that's affecting in that particular EMS, but most modern engine management systems have lag time/latency settings and/or battery voltage compensation tables. These tables seem to adversely affect driveability issues if not set correctly based on the injectors used (manufacturers usually provide these settings as recorded from a bench).

Feel free to send the map over to klattr1[at]ryanklatt[dot]com. I'm curious to see how this EMS system works and might be able to have more detailed assistance.

Probably the most informative info I've received so far! I'll be sending you the map soon along with the program. I really appreciate the outside-looking-in ability.

[gaehrings13]

You can change your unit settings if you go to operational parameters and change the setting to pressure to psi instead of kpa.. and celsius to whatever you want. I work with these computers a lot.. I was the wiring guy in my job and we exclusively sold Ems.. I have a Stinger 4424 with a the aem 24+1 wheel in it. In the tuning area where you see the gauges and the maps go to the TRIMS tab. You can lower your fuel overall AFR's from here.. This is a bandaid to get you running a little better. Adjust your Fuel Trim percentage negative to see how it effects your afr's. If its a little better check it in boost. If its lean you need to re tune that car on a dyno.. You can do it yourself but its not that easy.. The only way your tune would be so out of wack is if you have different sized injectors with the same tune... Did this happens.. Play with the fuel trim to get it better. If I were you I would check to see where the timing is locked at. Just to be sure.

I looked at your setup.. you need to get rid of the piece of crap CAS wheel thats in there and get the aem one. Its 24+1... Your ecu is only reading 4 holes in the disc.. The motor runs much better with this wheel. I've seen people blow motors with that wheel in the distributor..

Oh yeah the 8860 is a awesome computer lol...!!! Controls A/c, nitrous, drag launch mode, 2 step rev limiter, rally anti lag mode, controls fans, controls most tachometers, can log egt sensors, datalogging, can run practically any motor. The list of what this can do is long lol.

Post here with any other questions.. I'm sure I can help you out some how.

[scotty-2-forty]

You can change your unit settings if you go to operational parameters and change the setting to pressure to psi instead of kpa.. and celsius to whatever you want. I work with these computers a lot.. I was the wiring guy in my job and we exclusively sold Ems.. I have a Stinger 4424 with a the aem 24+1 wheel in it. In the tuning area where you see the gauges and the maps go to the TRIMS tab. You can lower your fuel overall AFR's from here.. This is a bandaid to get you running a little better. Adjust your Fuel Trim percentage negative to see how it effects your afr's. If its a little better check it in boost. If its lean you need to re tune that car on a dyno.. You can do it yourself but its not that easy.. The only way your tune would be so out of wack is if you have different sized injectors with the same tune... Did this happens.. Play with the fuel trim to get it better. If I were you I would check to see where the timing is locked at. Just to be sure.

I looked at your setup.. you need to get rid of the piece of crap CAS wheel thats in there and get the aem one. Its 24+1... Your ecu is only reading 4 holes in the disc.. The motor runs much better with this wheel. I've seen people blow motors with that wheel in the distributor..

Oh yeah the 8860 is a awesome computer lol...!!! Controls A/c, nitrous, drag launch mode, 2 step rev limiter, rally anti lag mode, controls fans, controls most tachometers, can log egt sensors, datalogging, can run practically any motor. The list of what this can do is long lol.

Post here with any other questions.. I'm sure I can help you out some how.

Thanks for the info ... more great stuff! Do you have a part number for the CAS? I can't locate it on their site. I PM'd you as well.