Ok, I had another thread but its old and I think it's best just to start a new one with all the info i have now.

Specs (what i actually know)
383 Stroker
Paxton supercharger (5psi)
Dual exhaust
MSD ignition module
42# injectors
Car has a cam. I'm working on getting all the paperwork today.

Problem: Car is running super rich (i have black marks on the ground behind my exhaust and thats with cats which are probably destroyed by now). I've replaced spark plugs an o2 sensors. O2 sensors are covered in carbon after only a half tank of mostly idling in my garage and a couple short runs behind the apartment complex. Terrible fuel mileage (6mpg). I was just logging the computer, it was idling terribly and could barely stay running. I gave it some throttle and it went into close loop then after i let off it started idling bad again..and the O2 sensors no longer seem to be functioning right.

I looked underneath the car to see if maybe i didn't plug in the right o2 sensor (i had it out this morning). The cat on that side was smoking. Lots of unburned fuel burning in the exhaust right?

I'm getting some detonation/backfiring. I dunno why I didn't think of this sooner but it has to be timing! Does anyone agree??

Here's my main spark advance


XXXX 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
x400 16 16 27 28 28 26 24 24 20 20 18 14 12 11 9 8
x600 24 24 27 30 30 29 27 25 24 21 18 16 13 11 9 8
x800 27 31 32 33 33 32 29 26 25 22 19 16 14 11 9 9
1000 32 38 39 36 34 33 31 29 26 23 20 16 14 11 9 9
1200 34 40 39 38 37 35 34 33 29 25 22 18 16 14 12 12
1400 35 40 41 40 38 36 35 34 32 28 25 22 20 17 14 14
1600 35 41 41 41 40 38 37 35 34 31 27 23 20 18 16 16
1800 35 40 43 43 41 39 38 37 36 34 30 26 23 21 19 19
2000 35 40 43 43 41 40 39 38 37 35 31 28 25 24 23 23
2200 35 40 43 43 42 40 40 39 38 37 34 31 28 28 27 27
2400 35 40 43 43 43 41 40 39 39 37 35 34 32 31 30 30
2800 35 40 43 43 42 41 40 39 38 37 36 35 35 35 34 33
3200 35 40 43 43 42 41 41 40 38 37 36 36 35 35 34 33
3600 35 40 43 44 43 42 41 41 39 38 37 37 37 35 35 33
4000 35 41 43 44 43 42 41 41 39 39 38 38 37 35 35 33

Can someone help! I'm sure it's timing but i don't know where to start. I'm super new to tuning and this seems way screwed up for a beginner.

datamaster
http://www.mediafire.com/?hbbc6ud3202m50j

CATSTuner
http://www.mediafire.com/?hbbc6ud3202m50j

 

That looks like a stock timing table... nothing wrong with it. Compare to the stock table shown in my scanner writeup:

http://www.injuneer.com/ScanMast.html

Go down to the "SP" section. Quick jumps don't work.

Drivers side O2 sensor is reading extremely lean because it can't use the short terms in open loop to compensate for what it reads as a lean condition. When it finally goes (briefly) into closed loop, the short terms skyrocket, to cure the lean condition.

It went into closed loop at 206 seconds. That's the normal "timer" that has to be met before it goes into closed loop. Just a coincidence that you stepped on the throttle at that instant.

Even with the short terms pouring in fuel, the passenger side O2 sensor is reading dead lean, and then the sensor goes completely dead (reads 448mV) at record #1655. Once it dies, its preventing it from operating in closed loop.

You have virtually no vacuum (~3"Hg) at idle. Could indicate misfires, incorrectly adjusted valves or timing issues. But the timing issue isn't the table. It's the fact that you have no vacuum.

IAC valve is wide open, and its still not able to rise above the 450RPM idle.

Always helps to have all the info about the car. (Why not add a "Signature" so people don't have to ask every time????). Is it a 94 or a 95? If its a 94, has it ever run right? Is it possible the Opti was installed with the splined shaft one tooth off? That would totally screw up the timing.

Do you have O2 sensor harness extensions? Have you checked them? Could be shorting to ground, or completely open on the passenger side.

 

Added a signature but its a 94. I'll be picking up the paperwork for all the work thats been done to the car tomorrow so hopefully then i'll know specs for the cam and all.

Forgot to plug in the right o2 sensor when i was cleaning it earlier. dumb mistake. I'll check the opti tomorrow. I'm not sure what's up with the vacuum/poor idle. sometimes its good (idles steady with 13"Hg) other times it does what i posted above. Unfortunately, I don't think I have a log of it actually running ok.

Once i have the specs for the cam and engine build, I'm going to pull the pcm and send it into PCMforLess to get a solid baseline tune. Surely with the cam, supercharger and stroker setup the stock timing is not really the best. It'll be a couple days so if someone thinks thats a bad idea, you've got some time to stop me.

 

How are you "cleaning" the O2 sensor? The sensing element is enclosed in a metal shell. The membrane can be contaminated by things like silcone, etc. Other than spraying some kind of cleaner, with unknown ingredients into the tiny slots in the metal shell, there's not much you can do. After you spray the cleaner in the slots, where does it go?

It's also possible to contaminate the sensing element from the outside, since the outside of the element has to be exposed to ambient air, and the air travels through the same passage as the wires. Spray penetrating oil on the outside, and you can ruin it.

 

It really doesn't look like your car is tuned for 42lb injectors to me.

Your BPW and AFGS do not line up at all. At 10g/sec reported on the maf you should show about 2mS NOT 6mS. No wonder its running like crap. When you gas it, it gets moderately better.

Your maf seems to be working correctly at idle. I expect about 10-20 g/sec of airflow when idling an engine similar to yours.

I think you're just way over fueled dispite what the fuel trims are doing. I think they're just picking up on raw air because its missing from being flooded. Pull a spark plug or two and see if its just soaked with fuel.

When you started giving it gas to get it above 500rpm, it took way more air than I would have figured at nearly 30g/sec to get to 900rpm again should be about 3mS for the injectors and is more like 5-6.

Last comment is that your extremely low idle speed is causing the voltages to drop down to 12 volts which is making things worse becasue the injectors will add more fuel due to the pcm compensating for the poor response of the injector at low voltage, which is for starting but your engine is actually running down there.

To sum up, I think you're running more like 5-9:1 a/f ratio if my quick and dirty calcs are correct. If it is not resolved it will be engine damaging very quickly, and you will be getting a hone and putting rings in it.

I can look over what your tune is if you would post it. Since you obviously have access to it. Or you can pull the tune with this http://carputing.tripod.com/pcmread.exe for free. If that turns out to be the case, it would be a very quick and easy change pcm wise, then you just need to change plugs and probably the oil (will smell like gas) if its run like this much may need new o2 sensors too but only time will tell. Then you can give it a try again to check our work.

 

Injuneer: I sprayed it with electrical component cleaner. and let it air dry. Wiped the carbon off the outside

WS6T3RROR: Sorry, I thought I posted it in my first post but apparently not.
Here it is.
http://www.mediafire.com/?ua7liomdo6ljagi

 

Well, scratch that. I can't find anything in the file you posted that would explain it looks like its tuned for 42lb injectors. Your pulsewidth still looks out of line to me based on logs I have from my car and others i've tuned.

I am still bothered by the seemingly low voltage you have should be more like 13.5v with it running and you're between 12 and 13 even with the engine revved up. You've got a good connections to the battery right? Your voltage before you cranked it up was 11.9 which should look more like 12.8V on a fully charged new battery.

 

Yea, i've looked at the file too and its set for 42#.

I just looked at an older log and it's 12.7 v while running too. Guess i'll have to check that out.

 

You don't get good alternator output at 450-450RPM.

 

Well, i thought i hadn't plugged in the o2 sensor but apparently i had. Why would a sensor (one thats practically new) just die? And why did the left O2 sensor flatten out as well? It was reading ok then stopped????

 

Even when he stepped on it he had low voltage, and before he cranked it up he only had 11.9 a good 12v battery will show 12.8v fully charged with the engine off.

I still say its something tune related. Socriscul have you considered putting a new stock tune on it only changing the desired idle speed and the injector constant to 42 as a test.

Like I say the inj pw you're currently showing is way out of line for the airflow if that's the right size injectors.

 

the stock tune for the 350? its a 383 stroker, and it has a cam. Is a stock tune really a good idea?? its also supercharged but maybe thats not as big of a deal. I'm thinking a baseline tune from PCMforLess would probably be better.

 

I didn't mean go rip on it, just see if the problem goes away so you can eliminate a tune corruption issue.

As long as the maf sensor is working it won't make any difference idling it in the garage to see if it runs better. Maf doesn't take into account engine size it should run acceptably.

 

Anyone have a stock tune

 

I have a stock 94 Z28 bin file. It's for a 2.73 gear auto but should work for trouble shooting. If you want it give me an e-mail address I can send it to.