Hey guys,

I'm new to datalogging and tuning. I just got the Autoprom and wideband today. So I started with just some simple datalogging with the cable and TTS Datamaster.

I noticed that at full throttle, the ECM wasn't going into open loop. Isn't it supposed to? My TPS was 4.27V at full throttle and 0.51V at idle. Attached are two TTS files each with a full throttle run. Can anybody give me any ideas of where to start?

http://www.2shared.com/file/aA7KD6AN/test3.html

http://www.2shared.com/file/VSFgItJ4/test4.html

Engine:
355 TPI
10.1:1 Compression
TFS 195cc heads
ZZ4 Cam
Edelbrock manifold
AS&M runners
Matching plenum
SLP headers
Catco Cat
Edelbrock cat back
700r4 trans
3.27 9 bolt rear

Car had a tune done a long time ago with much less aftermarket parts.

Car runs 13.6 in the quarter but I think it should do a bit better than that. So I am starting tuning.

Thanks,

John

 

I can't open that, but the state may say "closed loop" but still be not doing closed loop and have WOT fuel and spark. Open loop would be if something disabled the closed loop criteria, which WOT doesn't technically do, although it does disable actual closed looping.

What was your trap speed? That might show a little better how much power you're getting. ET is affected by tires and traction a bit.

 

At WOT, the INT and BLM should both jump to 128 and stay there. WOT is still "closed loop" even though it doesn't look at the feedback from the O2 sensor then. It locks the blm and int, and gives additional fuel with the PE settings. WOT is technically PE (power enrichment) mode, not open loop.

 

Thanks for dealing with a NOOB guys. Trap speed in the quarter is between 100-101mph.

Thanks for letting me know the difference between Open loop and PE. I always thought I've heard PE also called Open loop. I'll have to check the logs tonight to see BLM and INT. Although I think I recall them going to 128.

 

check what your o2 milivolts report. It should hit somewhere in the 900-930 mv range and stay there for the run and once you left off it will start cycling again high low high low.

Whats your elevation at your track? I would expect that car to trap 106-107 or so on a good day with good air. If your up in the atmosphere, its not going to run that fast compared to cars at sealevel. Just do the correction to sealevel. I'd expect maybe 280ish whp with that mild cam? Typical bolt ons can get to 250-260. heads/cam should do another 20-30 or more.

 

Yeah, I would expect 105-106 as well that is why I'm starting to look around. The track is basically sea level, maybe 200-300ft. I'll have to check O2 milivolts when I get home.

 

That ZZ4 cam is nothing special.

ZZ4
Duration @ 0.050" Lift: 208/221
Lift: .474"/.510"
Lobe Separation: 112

Stock cam :
~duration @ .050", 202/207
~Lift .413/.428 lift,
~114.5 LSA.

I'd go nuts trying to tune a car without a wideband though. $200 can get you an LC1 with a guage.

 

That cam is small for big horsepower, but so is the TPI intake. You have to let torque drive you down the 1/4. Get the shift points right for the combo, and run the proper torque converter (maybe a 2200 or 2400 stall). That will help you alot.

I'd put a set of 1.6 roller rockers (if you don't already have them) on it to help size up the cam a hair, and get a wideband. There is alot of power to be had by running mid 12's afr through the whole rpm range at WOT, and have the timing dialed in. Balancing proper timing and afr is a balancing act, but it is not a hard balancing act with the use of a wideband. It can be done with spark plug readings, and I still read spark plugs to look for detonation/too much heat/rich/lean, but I can't fine tune it without a wideband.

 

I agree, i dont want to try to tune a car without a wideband.

That cam may not be special but still capable of much better times with those heads. May be in the tune, hard to say. I still expect trap speeds to go up. On good days bolt on L98s are suppose to hit 101-102. I hit 103.8 on an exceptional air quality day. heads/mild cam like ZZ4 should beable to hit 105+

 

Guys, yes I know the ZZ4 is a little undersized and I plan to go bigger in the future but as it has been pointed out, I should be doing better than 101.

I am actually not looking to build a drag racer, but its a useful tuning tool. I do actually have a wideband O2 and will be using it when I start tuning shortly.

 

Here is some data for you guys. Please let me know what you think. This is from a 0-90 run.

Ambient Temp ~70 degrees
Intake Temp ~130 degrees
Coolant Temp ~185 degrees
0 knock detected

 

I few things that surprise me:

O2 Volts are very jumpy - is this normal?

Spark advance is between 28 and 29 during the whole full throttle run - is this normal? I would have expected some variation

Injector % DC maxes out under 70%. This is on 24lb Ford injectors. I would have expected much closer to 100%. Am I reading this right?

Air Flow maxes out well under the 255 g/sec. Am I reading this right.

Is there any other data that would be useful?

Basically I am taking the car out to a track day on Sunday and want to make sure I won't blow my motor by running too lean. Am I good?

 

Oh yeah I forgot to mention. The car was dyno tuned by PCMForLess several years ago before the heads and at the time the engine was burning a lot of oil. So I suspect my tune is way off since they were basically turning a 2 stroke at the time, lol. I should probably go back to the stock tune and do some scans.

 

Hey guys I could really use some help on this one.

I THINK the engine is running rich. I'd like to confirm this. I will be out on a road course on Sunday and don't want to blow the engine. At least rich is safe.

Thanks.

 

rich also washes the oil off the cylinders and contaminates the oil. I can't see the scaling on the graphs you posted so I won't be much help there. You mention that it isn't reading 255gms/sec, with your engine you should be there by about 4200rpm Id say. Bottom line is you need to get a wideband on it. We can't see what your O2 values are from your graphs, and a narrow band is nearly worthless for tuning anyway. We can help you once you actually have some usable data.

 

Ok, the O2 scale is the one the right, in mV. It is normally around 900mV but takes many dips down to about 100mV during the run.

I'm not looking for a detailed analysis, just a simple yay or nay for doing some road racing tomorrow. Can you help?

I do have a wideband and will be installing it soon. Like I said I'm just looking for a quick analysis.

 

spark at 28-29 deg is way low for that motor. Thats one thing I'd retune for.

Cant tell anything from o2 graph. I dont think it should be bouncing up and down like that at WOT. It should stay at one value depending on how rich /lean it is. I tried to tune My L98 like this before I got a wideband. Let it go WOT and watch MV. Generally 900-930mv is where you want it to be but that is just a general spot that may not actually mean air fuel is where it needs to be. Much lower than 900 is kinda lean.

 

Road racing is the hardest thing you can do to an engine, so until you know its getting enough fuel I'd stay home.

I bet thats about right for timing. I have CNC ported L98 vette heads (same thing as ZZ4 heads) on my 383 and it won't take any more than 26* before it pings at WOT, and thats with 12:1 AFR. They have small chambers and are decently shaped so I think the flame front travels really fast and not much lead is needed.

 

What pistons do you have and whats your final compression? All depends on the combination but i've seen some L98 head motors run pretty aggressive timing. Factory ARAP bin is an example.

He doesnt have L98 heads tho, he has TFS 195's from the original post. I would have expected 34-36 deg as typical starting point.

 

I have forged Mahle flat tops with 10.5:1 compression. I know the factory vette tunes are super aggressive but my 383 just will not take it. My heads are CNC ported Lingenfelter L98 heads. He reshapes the chambers somewhat compared to stock so maybe thats the cause. Stock chambers are 58cc and he does enough reshaping to cause them to be 62-63cc. I got away with 28 degrees in the cold but that doesnt fly in the summer with higher IATs...

 

Interesting. Flattops with 5-7 cc valve reliefs usually give 11 to 1 with 64 cc chambers and .040" standard gasket at zero deck. If you are over that with a smallish cam, I can see why it wont take more than 26-28 deg.

 

LOL well this side discussion of ours has caused me to pull up my old excel spreadsheet where I calculated my CR so I could order the right pistons. The LPE heads I have are 63cc chambers, my pistons are 5cc reliefs and I'm using a factory GM .028" head gasket with .025" deck clearance yields 10.92 CR. Made "worse" by the LPE 219 cam I'm running. No wonder this thing cranks hard when it's hot!

 

Well the car survived the track day.

Sort of.

I did have a re-occurrence of what I THOUGHT was a bad ECM from 3 weeks ago. Anyway the condition re-appeared and ended my day. But I got about 60 miles of track duty before it happened.

Basically what is happening is all the sudden the car loses all power, the engine is totally unresponsive to throttle input. Then 10 seconds later it starts stumbling. I come to a stop and about five seconds later it shuts itself off. No trouble codes.

I wait about five minutes and its starts up like normal. I can drive about 1 mile then it shuts off again. If I let the car completely cool it will give me a lot of run time before it occurs again. The problem seems to be heat related. I'm suspecting something in the ignition. Fuel pressure tests fine but I haven't yet been able to get the gauge on when the problem occurs.

 

So all in all it was a fun day. The engine was great before it conked out. The trans did fine (700R4). The brakes were fantastic (130 to 60 in turn 2) and the suspension was very neutral.