A/F all over the place (spark blow out???)

B

BKB

Registered User
Took car to dyno for second time, only change was a 10% jackshaft pulley. Last time A/F was rock solid no change from run to run. First new run was hot coolant around 190' and 10:0 A/F let car cool 150'and 14:0s at WOT. I have no fuel multipliers for coolant temp over 140' coolant is topped off and coolant temp sending unit is reading back to ecu correctly. I have a mechanical guage and autotap to compare.
Dyno curve looks good no jagged lines just a decline in power. I am running stock 94 SC plugs gapped to .054 and blow out has crossed my mind but dosent really make sence the way its acting or by the smooth dyno curve. Im lost no vacuum leaks i can find and nothing changed with my tune.

Motor is a 94 SC motor 15psi in my 94 stang, motor has been in this car for over 10yrs. Recent rebuild and 2k trouble free miles untill now. 360 Rwhp 430torque. EEC tuner
 
You say that you have 10.0 AFR when warm but 14.0 AFR when cold? What AFR are you commanding?
 
12.25 A/F is commanded 120% load and up. Yes A/F seems to be changing with coolant temp. Only change was the pulley taking me from 12psi to 15. I just cant think of anything mechanical that could cause this other then the ECT sensor but all seems fine. I am installing 103 plugs since that is what should probably be in it anyways. Mabe the plugs will tell me something.
 
Are you using the CBAZA computer that was in your mustang or did you swap it out to the SC one?

Just curious

Frit
 
Using a 94 mustang computer A4X2 with EEC Tuner GUI CCAQ. I havent really kept up with SC tuning but using this computer and GUI gives me many more peramaters to tune then SC Tuner.
 
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installed the 103s and car seems to run much better but still not right. My LC1 dosen't work right now so i cant tell what my A/F is right now.
 
You've had troubles with AFR as long as I can remember. I think you need to ditch the EEC tuner and get a more reliable tuning device. Seriously.

Sounds a little to me like you have an issue with your long term fuel trims. How did you tune in your MAF curve? Did you scale your injectors or are you commanding actual injector values and where did you get your injector values?
 
Once i stopped using tunes by other people and made my own the Tuner has been rock solid. For the last 2k miles the A/F has been consistant and followed what is demanded in my base fuel table. I have been using the EEC-Tuner in other vehicles the last 5 years and all have worked as they should.
For this car i force open loop 100% of the time, its been that way for about 9 years. So there is no long or short term fuel trims to worry about. I get 25mpg on the highway 21mpg in town. I have been extreamly happy with the car and the Tuner. For the injector slop i have both set the same to the 50lb injectors in the car. I edit the MAF to make the actuall A/F match the fuel table. This might not be correct but i have had better then factory drivability out of this car for many years. After instaling the new cam it has lost drivability but im working on it, Not having a A/F meter that works 100% of the time has slowed down my tuning.
 
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From FSB to SC;)
I wonder if this has to do with something a bit, less technical than your 'lectrical stuff. What boost are you running? Though you stepped to a different plug, did you close your gap any? What gap are you running? Sans that, what is your fp?

SWS
 
went from 12-15psi, was running stock heat range long reach autolights gapped .050, went to 103s gapped .040. FPR and fuel pump are working fine. I have an in dash mechanical fuel pressure gauge. EGTs seem to conferm the rich A/F only reaching about 1200'.
 
What about your cold start fuel table? I don't know what interface you are using for the EEC Tuner but some of them label things wrong and not all give you access to the ECT switch point for the tables...
 
I have cold start AF ratio-time (stock) and Fuel start A/F ratio load (stock). I did change the Fuel ECT multiplier to add some fuel when its below 150'. But like i said the tune hasn't changed in over a month.
On a positive note the Autolight 103s made a huge difference in power and drivability. I used to get a RPM dip when coasting down in neutral that is gone and response between shifts is crisp. Need to get the LCI working and log some A/F runs.
 
Knowing how old those boards are now, and being at WOT at some point and that board dies is not a combination I would want to be trying out these days.

Frit
 
fturner said:
Knowing how old those boards are now, and being at WOT at some point and that board dies is not a combination I would want to be trying out these days.

Frit
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Are you saying i should waste 3k on a FAST system? Only problem i have ever had with a EEC Tuner is a bad cable. I have been running 2 boards for a total of about 15 years between them without a single issue. I dont feel this is a problem with the tuner, if i get nowhere i can swap boards and see.
 
Oh well, if you think thats the only system that is out there that is available for your car other than the EEC tuner I guess you don't have a choice then.

Frit
 
BKB said:
Are you saying i should waste 3k on a FAST system?
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I'm not aware of anyone running a FAST system on an SC. If I were looking at an aftermarket EMS I would NOT be looking at FAST but either way, I was only meaning that running a chip is more reliable (and cheaper).

Only problem i have ever had with a EEC Tuner is a bad cable. I have been running 2 boards for a total of about 15 years between them without a single issue. I dont feel this is a problem with the tuner, if i get nowhere i can swap boards and see.
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Why do you run your car open loop all the time?

I guess it's possible for a spark plug condition to cause the drivability issues you described but its not something I see on a regular basis. Assuming a responsible gap and decent plug condition the only time I ever see spark blow out is at high load and high rpm. I would never try to run an OE plug at 350+rwhp though. You've probably been skirting the edge of both spark blow out and detonation due to too hot of a plug for some time now.
 
fturner said:
Oh well, if you think thats the only system that is out there that is available for your car other than the EEC tuner I guess you don't have a choice then.

Frit
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I know there are many choices but i already have the tuner and it does everything i need it to do. I paid $300 for the tuner, if i would have bought a chip i would have spent a fortune on dyno time and reburns. I have friends running FAST and AEM on there cars and for the thousands that they spent i just don't understand. My friend owns a dyno and uses SCT, my tuner and the SCT software is the same. So the fact that i can do everything that a SCT chip can do and it takes me 7 seconds to flash seems pretty good to me.
The reason i run open loop is because the person that original did the valve job on my heads butchered the exhaust valves on one side. This caused bank 1 lean bank 2 rich and would max out adaptive and the car would hardly run. Running open loop i was able to bandaid it enough to drive the car for a few years. Now that the motor was rebuilt and i have no mechanical issues i just got used to tunning and running in open loop. I like being able to run 15.5 A/F at 45% load and below. My motor seems to run a little smoother lean and i feel this is why my car gets decent MPG.
 
Here is a shot of the motor. Im going out to try and get this POS WB to work.

OC018.jpg
 
BKB said:
The reason i run open loop is because the person that original did the valve job on my heads butchered the exhaust valves on one side. This caused bank 1 lean bank 2 rich and would max out adaptive and the car would hardly run. Running open loop i was able to bandaid it enough to drive the car for a few years. Now that the motor was rebuilt and i have no mechanical issues i just got used to tunning and running in open loop. I like being able to run 15.5 A/F at 45% load and below. My motor seems to run a little smoother lean and i feel this is why my car gets decent MPG.
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The exhaust valves most likely didn't have anything to do with your adaptive issues. The 99% reason that your fuel trims maxed out is because you had your 02 sensor leads (left and right) mixed up. Sounds ridiculous I'm sure, but I've run into this more than once. Try running closed loop and I bet the same thing happens again even with the new motor.

On the 15.5 AFR, you can modify your closed loop parameters to run that in closed loop if you want to. Anyway, I was just curious.
 
No it was the valves. With that motor i swaped 02s and injectors from side to side and problem stayed the same. This is a 94 Mustang and impossible to get left and right leads swapped. The new motor the left and right side 02 voltage is the same, problem fixed.
My new problem is this LC1 that dosen't ever want to work. I just got it back from a warranty repair and again its acting up.
 
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