ECMlink Sputter and bucking

[Dert]

I had a leak on my filter to rail line so i replaced the entire setup from tank to rail with a fuel lab filter. Since the install the car will buck and sputter, lean right out and almost die when first pulling away and eventually will pick up after a few seconds and pull strong. If I do a pull and let off the gas for a 10 seconds and lightly hit the throttle again it will also sputter etc. Idle is fine although sometimes it randomly dies for no reason. Any ideas? I've seen a few threads with similar issues but nothing resolved. It's almost as tho fuel is being cut off.

 

[Dert]

I should also add that when stopped at a light and blip the gas I cam hear what I am guessing is fuel moving through the line. Can it be due to installing a bigger braided fuel line that fuel pressure has dropped and not flowing enough through the bigger line at light throttle? I'm stumped...

 

[Dert]

Been having an issue with car randomly leaning out, sputtering, and occasionally dies. I have been battling this for months now and can't resolve it. The car always dies after initial cold start, and when it does fire it leans right out and if I don't blip the throttle it will die. Once warm it idles fine, go drive, it will drive fine but randomly it leans out and sputters and occasionally it will even die.

When it started to happen my fuel line blew shortly after at the rail. I replaced the entire fuel setup from upgrading to a 255hp wally, STM tank to rail braided kit and fuel lab filter with a fuel lap AFPR. Has a brand new wideband sensor as the old one was starting to go. Also replaced the ISC.

I know the tune isnt 100% yet but the issue is with fuel I think. In the log fuel flow drops to 0 when the sputtering starts and goes lean. What causes fuel flow to randomly cut out? Fuel pump is re-wired with STM re-wire kit too.

You can see in the log various places where sputters happen, the end of the log the car dies and I am blipping the throttle trying to keep it going. Sorry for the long rant I need to get this sorted. The car used to run like a champ, still does, just not when this issue happens.

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[Nicklepage1010]

On my phone, cant open the log.
What are you seeing for AFR at cold start?

Im assuming youre using the factory MAF?

 

[delta448]

It appears something is wrong with your MAP sensor. You're running SD, right?

 

[Dert]

Yes, SD, I was wondering if my MAP sensor could be the cause, but all my searches of faulty MAP sensors don't bring the same examples of my issue.

But I have noticed sometimes my MAP sensor is reading -14inhg when my boost gauge is -20ish. My MAP is currently attached to my throttle body so I can have a short line to it. Good chance the heat/vibration is messing it up?

Perhaps I'll order a new one and attach it to the firewall and see if anything changes. Thanx for the input fellas, I'll start with the new/relocated map and see if it helps any. Anybody else with input, I'm always willing to listen.

 

[GSTurbo1]

Fuel pump beginning to go bad? Fuel filter getting clogged?

 

[Dert]

Brand new 255 waly, not even 200 miles on it, had a brand new 190lph waly before it for 1400 miles. Fuel filter is brand new, maybe 500 miles, new tank to rail braided lines as well.

 

[delta448]

What port on the TB are you using? Do you use either a stock or cast intake manifold? If it were my car, I'd tap the underside of the mani and hide the sensor out of sight.

You don't have any ignition issues do you? How are your plugs and wires?

 

[snowborder714]

No reason to go purchase a new MAP sensor if yours works. Just make sure you have a proper port as Zack suggested. Ideally, it should come from a dedicated port on the manifold. You can always tee the FPR vacuum line into something else to free up a port, if not done so already.

Or if you don't need your emissions, you can get a MAP sensor to directly replace the factory MDP sensor on top of the manifold.

 

[Dert]

The MAP sensor has its own dedicated port where stock MDP sensor was using RRE adapter on stock 2G manifold.

Brand new NGK wires and new BPR7ES plugs gapped to .028.

Do you need to do emissions delete to use MDP location? I still have all emission (although they are not needed where I live) except the MDP sensor.

 

[snowborder714]

If you have it wired up to the MDP input, your ECMlink settings are incorrect. You have it wired into the baro according to that and not the MDP. Change the input (if you are using the MDP) and lock the MDP input (same screen, bottom right corner).

 

[Dert]

When I first installed my SD I had it selected as MDP. The car would not start, a moderator (turbosax2) said it had to be selected as BARO. I switched it to baro and the car fired right up. This was in my thread "SD setup help" post #4.

I am using ECMTuning's SD cable if that makes any difference. So Brian, if I switch it back to MDP instead of BARO, isnt it going to not start again?

 

[snowborder714]

Nope, you're correct. Didn't know you were using the SD cable.

 

[Dert]

Is it possible that my MAP sensor is periodically fritzing out?

I have it attached directly on the throttle body held by 1 bolt, so the possibility of excessive heat and vibration is definately there and from what I've read, both can be bad for MAP sensors.

I've tried almost everything to get to the bottom of this random lean out sputter/die issue. The only thing left I can think of is bad MAP sensor or possibly TPS?

It seems as tho airflow drops to almost nothing along with fuel flow when it happens, so possibly the MAP sensor gives faulty low air reading causing ECU to cut fuel out or fuel flow is being cut out causing it to lean out and die. I'm baffled on how to fix this without replacing everything.

1 other thing, would a bad alternator be able to cause issues like this or a bad ground? I'm open to any possibility.

 

[delta448]

A bad ground might.

I'm not a DSMLink user, so I can't help with all the specific intricacies of DSMLink's GUI, but I understand what I see in the log well enough.

What I definitely see is the MAP going ape-shit, a slight rpm loss and then WBO2 going lean just afterwards and staying lean until the MAP value comes back in line, which usually means you're misfiring. When you misfire, the vacuum in the intake manifold becomes unstable and all the extra O2 dumping into the exhaust pegs the WBO2 to full lean.

However, in this case, the MAP is my primary suspect. Eliminate it as a problem first, mount it better, triple check the wiring at every splice, connector or solder joint and then get it on a dedicated tap. Those values are fluctuating like a bad electrical connection or a random vacuum leak.

 

[Dert]

Thanx for the reply, I never had to do any splicing as I used a plug n play cable from ECMTuning.

I'm going to try a new MAP sensor and mount it on the firewall. If the other one ends up being good still then I guess I have a spare sensor .

I'll also double check the grounds, as I'm wondering if my fuel pump rewire ground is a little iffy and making the pump be intermittent at times.

Thanx again-Gary

 

[camas90gsx]

Maybe im off here,but couldnt a 02 sensor on the way out cause this as well?

 

[Dert]

That's what I thought too, so I put a brand new aem wideband in as mine was a couple yrs old and they don't last long in front o2 location.

 

[Dert]

Update: put new MAP sensor in and the issue hasnt happened once since. Marking as resolved as its been 2 days of driving the car and the problem has not occured again. Faulty MAP sensor is going to be the culprit for now

 

[turboglenn]

Are you using the GM style MAP or the AEM style?

There's a few part numbers of the GM one and there's one that's known to only work where you can scale to it perfectly and know that it is the different one you're scaling too (no idea why it exists, I have one as my spare and can't use it but oh well, it was donated to me ) The ones you want to use in the GM variety have the 749 designation or the part number 12223861 (new updated number of same scaled 3bar as the classic "749 model)

The one to avoid is the 12219935 version, it's not capable of reading the full vacuum spectrum and reads into negative 3-5psi (not in/hg) when at a true zero on a non running engine because the offset for "zero" is in a different place. My car won't even run more than a few seconds when this sensor is in unless I tune the entire map to it and then "guess" were the boost really is...

It's supposed to read less vacuum to allow a LITTLE more boost, (up to 31.5psi) but to be honest the old school one 861/749 will actually read 31.5 when the ECU knows the correct altitude it's at and can compensate for it... not to mention the old standard reads a full 14.7 psi vacuum or 30 in/hg where the 9935 sensor only reads down to 14.8in/hg or-7psi vacuum, it sounds confusing and it is more than it's worth knowing about, the only thing to know is get the 3 bar meant for an old turbo trans-am 1987 IIRC and a few others...

Well, I passed out at desk, going to bd

 

[Dert]

Thanx Glen, good info, I'm using Omni 4bar MAP sensor from ECMTuning.