Chevy86 IROC-Z

iTrader: (17)

Hi guys. How does this spark table look? An other member told me that there were possible inconsistancies. So what do you think?

thomas1976

In combination with the SA graf. I use the knock counts as guide.

My SA tables end looking a little smoother. (Maybe because of the stock torque converter)

I also go for some uphill driving while datalogging, sensible areas are easyr to notice.

Chevy86 IROC-Z

iTrader: (17)

UUUHHHHH. What? I think you responded to the wrong thread.

thomas1976

Do you really?

Spin your grafic a little, for exemple at 1100rpm/160 LV8 you have a Valley, this could be because of the torque converter not putting load on the engine prior to this event.
You will figure it out quickly by smoothing it out and going for some uphill data-loggin. By looking at the knock count map.

lakeffect2

I'm seeing max advance at 48 degrees which strikes me as unusually high. Anyone else thinking the same thing?

dan0617

I agree that the light load timing is very high. Light load timing can be high but that is excessive IMO. I run a max of 42, and don't run it in very many cells on the table. Also, on my datalogs I see my idle load at around 60 to 70 LV8. If your rpms surge up just a little or if you are idling at 700 rpms or above I'd suspect you will get a surging idle because the timing jumps up so high so quickly as the rpms increase.

If this is a mainly stock engine with alum. heads I'd consider the ARAP timing table. If it is iron headed then even the ARAP might be pushing too much timing.

If it is a modified engine (higher compression, larger cam, etc) then you will need to experiment, but I wouldn't use a timing table as aggressive as the one you posted as a starting point.

Chevy86 IROC-Z

iTrader: (17)

I know. Its agressive for reasons that I cant disclose.

JP86SS

iTrader: (1)

Granted, I didn't even look in depth at the map you posted other than jumping right up to 34* in the mid range, the comment caught my attention along with other "aggresive" comments on it.
In the idle areas higher timing can help with stinky smell and idle quality, but...
IMO, When you find the need to be overly aggressive on timing overall, you could have missed the tune and are making up for over fueling.
Could be that you have so much fuel going in that it takes that much SA to burn it effectively. Its a false reality of where you need to be and your not getting the maximum benifit from it.
Take a step back on your fueling and restart with lower fuel and SA settings. It takes time and patience but your milage may significantly improve as well.
BTDT, several times now on my setup.
As the BLM shows lean in cruise area, lower your SA a bit instead of increasing fuel. See how it responds and work with it.
I have much better fuel consumption than with previous tunes that had the same "feel" as far as output that had much more fuel and SA tuned in.
If you end up in the same place then maybe that's what it needs, but its best to reconfirm your settings on it.
Just my opinion, HTH

dan0617

Race fuel?

Water/Meth Injection?

Orr89RocZ

iTrader: (20)

Did you disable PE mode spark advance? That timing table is certainly aggressive and will not need additional timing from PE mode.

I'd back down on the midrange/cruise timing. Thats alot. Shouldnt need that much. And smooth out the ramp up from idle timing to your max midrange stuff. You go from 20 to 40+ rather quickly. Does the car seem smooth when it does that? I cant imagine that it does.

I dont know what your combo is so its hard to tell where it should be. Thats something you will have to play with.

Chevy86 IROC-Z

iTrader: (17)

When the IROC turns on, It sounds and runs very smooth. It also has a very crispy throttle response. I have no complaints. But as more and more advice is posted, Im learning. I was just wondering because I checked other bins for a 350 TPI Auto, and the table and graphs are very differenet. When comparing the ARAP Spark timing graph, they both look different. I just wasnt too sure on which table should I use. I want to use the ARAP bin for my 86 IROC 350 , but there was a difference in the 89 bin. So my goal is to find a 87 TPI 350 Auto, modify the table just a bit to make it more aggressive.

Orr89RocZ

iTrader: (20)

Give it what it wants/likes but from most tables I've seen your values seem excessively high inthe midrange areas. 46-48 deg is alot. ARAP limits to 41.8 deg anyway as do most GM chips. In the constants region there is a value called max spark advance and its usually around 41.8 to 42.4 deg or something like that.

So no matter what you see inthe timing table, you will never go higher than 42.

I just road in a car with big cam on stock bottom end with heads/hsr and it uses ARAP 41.8 deg timing. Car drives around fine like that. Idle has 30 deg and it ramps in really quickly. Fuel is alittle off so there is some hesitation but overall the car was happy with the ARAP timing.

86-88 used 32B masks while the 89 used 6E. Slightly different how it works but the timing tables are similar layout, just different values IIRC.

Aggressive isnt always better. Some good heads out there do very well with less timing than expected. Older head designs seem to like more timing since the chambers arent as efficient. Again, not sure of your exact setup. You can download 87 TPI 350 bin and use 32B mask with modified ARAP timing table, just have to input the values over. But make sure to disable PE mode spark advance.

89 6E spark looks mild until you add in all the extra degrees that PE mode gives. Its easier to zero out PE mode spark advance and add in the timing you want the motor to see inthe main table.

RBob

iTrader: (1)

This is only true of what the ECM will program into the distributor. The base advance is then added in for the at-crank maximum timing. So the typical TPI with 6* BTDC base, can have 48* BTDC max timing at the crank. That is: 42* max into the distributor, with an additional 6* added by the position of the distributor relative to TDC.

Program too much timing into the distributor and the spark jumps to the previous cylinder. Basically shuts the engine off.


Relative to the OP: Chevy86 IROC-Z "I know. Its agressive for reasons that I cant disclose."

Without knowing the engine/trans/rear/vehicle/fuel-type set up. Can't even begin to know what a decent starting point is for the timing.

Although, it is as Orr89RocZ posted, give the engine what it wants. Not what you think it wants. Then you are good to go.

RBob.

Chevy86 IROC-Z

iTrader: (17)

Good info RBob. So then I'd be better off purchasing/donating $30 to moates and get the RT TunerPro and go from there then right? WOW. So much info with so little knowledge. My setup is almost stock. I got cast iron swirl intake heads, 94 Z28 LT1 cam, 350 TPI, 3.27 gears, 700R4, 86 IROC-Z, and a aftermarket MemCal. I will further investigate and study how to tune my own blank 27c256 EPROM. Well guys. Thanks for all the info and support. You guys are very knowledgable. By the way, did you guys go to school to learn this stuff or was it just from trial and error?

Orr89RocZ

iTrader: (20)

Interesting, I thought since the main table already factors in base timing, the actual commanded spark advance seen at the motor would not exceed whats listed in the constant's value of Maximum spark advance?

I've seen and logged an ARAP car that has 8 deg base timing (bin set same) and saw only 41.84 deg of spark in the logs in the cruise/light loads spots when the timing table clearly shows/commands much more than that at similar spots (46-48 deg.) I thought the computer would add to the base timing advance number a value to sum up to the total in the main timing table.

Example, 6 deg base timing, with commanded idle timing in the table of 28 deg. SO the computer would add 22 deg to make it total 28.

I verified this with timing light and logs on my own car before at idle. Matches what the computer shows.

Now with the cap of 41.84 in ARAP, I thought that would limit the ecm adder to the distributor base timing value so that the sum total would only be 41.84. But your saying that limit is what the computer can add in on top of base timing?

So if the log shows 41.84 deg timing at a load/rpm cell in the timing table that shows 48deg lets say, the motor is actually seeing 48 and not that 41.8 the log is showing?
If I had the timing light on the motor I would have seen 48 while the computer shows 41.8?
Interesting, I never knew that. We saw no knock counts or timing retard on that motor if it indeed was hitting 45-48 deg in spots.

xch3no2

Orr, base timing is added to bin table, other things may limit actual/max timing seen.

86IROC, Ya TunerPro RT is the ticket.. I learned EFI as an ASE tech in '86. I learned how to make it work by reading at LEAST 5 years worth of posts (in 3 months) on this site.
oh ya then there is my screen name..changing cells not pills these days.

RBob

iTrader: (1)

The main confusion is from the ECM data stream sending two timing values. One is relative to TDC, the other is relative to the reference pulse.

The one relative to TDC is not limited by the MAX SA parameter, and it does not have any knock retard removed. So it is an intermediate value, not a final value.

The timing value that is relative to the distributor reference pulse (DRP) is the final value. But would need the base timing added in for the true at-crankshaft timing (relative to TDC). It is this value that is limited by the MAX SA, has knock retard subtracted, and is programmed into the distributor.

Note that both $6E and $8D work this way.

This is not correct. The base (or initial timing of the calibration) is subtracted from the BIN SA. The position of the distributor (base timing) adds it back in. This is why it is important that these two match: distributor base timing and the calibrations initial SA value.

Then other then maybe needing to mentally add it back to the data stream timing value, the base/initial timing can be forgot about. The ECM subtracts it out, and the distributor adds it back. So no need to mentally add or subtract it from any timing tables in the calibration.

RBob.

dan0617

Orr, I am pretty sure with Tunerpro it is "what you see is what you get" in the max spark advance, as well as the timing table. Maybe someone can verify but if you are using tunerpro I believe you are correct in saying that if you set your max SA at 42, you will not get more than 42, as long as your base timing in the tune matches the base timing physically set with the distributor. (both set at 6 in most cases.)

Orr89RocZ

iTrader: (20)

Thanks for the clarification. I verified it in my log of another guys car. At WOT in the 5300 rpm range, I have 35.86 deg timing relative to TDC, with 27.77 deg relative to reference pulse. 8.09 deg base timing. That adds up. No timing pulled from ECM.

At 6000, I saw 36.21 with 3.4 pulled, 22.15 relative ref pulse. That does not add up, there is a few deg missing there and not sure where its at.


Now at cruise where I saw 41.84 deg which is ARAP's SA limiter, I have 33.75 relative to reference pulse. With 8.09 as base thats also adding up to 41.84. This is between 1700-2200 rpm with LV8s in the 70-80 range average. No spark retard.

This also happens in other spots like 3000 rpm, 65 LV8, same 41.84 rel. to TDC, 33.75 relative to Ref. Pulse.

It doesnt appear to be changing from the 33.75 deg relative to reference pulse as long as there is no timing retard going on. This gives the 41.84 deg cap when in certain spots the main table is commanding 46 deg. So the max spark advance value appears to be limiting the table.

RBob

iTrader: (1)

There are additional issues when looking at a data log. One is that the ALDL data is asynchronous to the running of the ECM code. The SA variable that is relative to the DRP has math done on it along the way. And possibly stored with different numbers in it.

So depending when the ALDL routine reads this value, it may not be the final value.

Note that the SA variable that is relative to TDC is only stored once. So it will always be that value. It doesn't matter when the ALDL routine reads it.

The ALDL stream is not a snap shot in time. It is what the ECM has for that value at the time that data byte/word is sent. If there is 10 packets of data per second, the software runs 8 times in both the fuel and spark routine for each packet.

So the data near the front of the packet won't match the data near the end of the packet. They are from different times within the ECMs software routines.

When figuring what the main SA value should be, there is more then just the Main SA table value. There are a bunch of modifiers to that value. Here is the data variables that create the SA relative to TDC value (L011E):

That is from the ARAP hac ($6E). At the end the SA value is stored in L011E. That is the value that is sent via the ALDL. Note that there is no limit test on it.

Skipping the GM heads up logic, next comes the subtraction of the Initial SA value. Followed by the MAX SA test & limit:

The value that is in registers A & B (D reg), has the Initial SA subtracted from it. And stored in L00A1. This variable (L00A1) is sent via the ALDL as the SA relative to the reference pulse.

It is then limited by the MAX SA parameter.

Further along it has any spark retard subtracted from it. Then checked for MAX retard (MIN SA). After that it goes on to be used to program the ECM hardware to control the EST line to the distributor.

RBob.

xch3no2

RBob thanks for taking the time to post that info.

"added" was a very poor word choice for "included" in my post..inverse result.

Orr89RocZ

iTrader: (20)

Thanks for the info. So if I read that right, L011E which is unlimited spark advance relative to TDC should display whats in the main spark table provided that NO other adders/subtracters are taken in the code. (lets assume no adders right now, no PE mode, no temp corrections, no knock etc) Because its sent to the ALDL unlimited...

So if I had 46 in my main table at a spot, and had no additional modifiers to L011E, so that LO11E was 46, I would see 46 in my datalogs rel. TDC?

Spark relative to reference pulse is the limited value, so it gets sent to ALDL after limit checks are done. I'll have to read the hac, but is it taking L011E and subtracting base timing out to get L00A1, and then comparing that with max spark advance?

So by that I take it to mean L00A1 is limited to max of the SA which is 41.84 in ARAP, but I only saw max of 33.75 which when added to base timing of 8.09, you see 41.84. That would imply L011E which is TDC timing? I guess I just dont follow the code correctly?

RBob

iTrader: (1)

Correct. If nothing else is modifying the SA, it will show the value from the main table.

Yes. When L011E is saved:

CFB6: STD L011E

The value is still in the D register (A & B together form D).

So when the :

... occurs, it is subtracting the initial SA value from the D register. Which still contains the value that was stored in L011E. This SA value minus the initial is then saved is L00A1.

L011E is relative to TDC. Although it is not limited by the MAX SA value.

L00A1 is relative to the reference pulse. Because the Initial SA has been subtracted out. Which makes it the value that will be be programmed into the ECM hardware for the distributor.

This value is also checked for MIN and MAX SA. The MIN & MAX SA values are dependent upon the distributor. Which is the limit of rotor to cap alignment and still have the spark jump to the proper cap terminal (or spark plug).


On the 8-cylinder set ups the MAX SA is usually 42*, and MIN SA (max retard) at -4* (both rounded).

On a 6-cylinder set up with a distributor (3.1l f-body), the values are:

MAX SA: 60*
MIN SA: -10*

The reason is that on a 6-cyl, the terminals in the cap are further apart. So there can be a greater mis-alignment before crossfire occurs.

RBob.

Chevy86 IROC-Z

iTrader: (17)

New question guys. Can I lower my coolant temp down to 160* just like in some aftermarket MemCals (ThermalMasters) and programming it into a blank EPROM? Will I need to change a lot of values if I where to attempt to change the temp if possible?

dan0617

No, just need to change a few values. Here is what I needed to change:

I found that when running a 160 stat, I could add a touch more timing in the 154 to 176 degree area, but alot of times you will find even with the 160 stat that the car will run 180 to 190 degrees. Only way to add more timing when at cooler operating temps was to use the "spark correction coolant temp vs lv8" table, then use the "coolant temp spark correction disable temp" to the max so it always looks at the table. Just was talking about this in another thread.

I run full open loop, and found that when running around 190 degrees, I need to add about 4% enrichment to the "OL afr%chg vs coolant temp" table compared to running 160 or 170 degrees. Was surprised that I need more fuel to warm up, then after the 160 or 170 degree area, I again need more fuel to keep from going lean. Must be something about efficiency I guess. One thing that did help some was a big old fuel cooler with a fan.

Chevy86 IROC-Z

iTrader: (17)

. I need to go back to the table and study what I need to do according to your info. Thanks for the heads up dan0617.

dan0617

Now keep in mind, I'm running open loop only and gave you what I found to be true with my setup when I went from a 180 stat to a 160.

If you are still running closed loop, your 02 sensor should "sense" the lean or rich condition that happens from the varying temps and adjust the blms accordingly. In other words, your computer just might compensate for what I'm talking about if you are still running closed loop. I needed to adjust my timing a little, but also keep in mind I'm running 12.2:1 compression on a 230/236 cam, so my timing is always right at the edge of detonation, so it is sensitive to temperature changes, much more so than most builds. You may be able to plop in a 160 thermostat and have to do nothing more than enjoy a slightly cooler running engine. If it does run a little cooler, you might be able to add in a touch of timing and pick up a touch of power.

Orr89RocZ

iTrader: (20)

How is that motor running with that high compression and relatively small cam? Interesting setup, is it still on pump gas? Timing would be much different than a typical 10-11 to 1 motor with similar cam.

dan0617

41.84 41.13 37.97 36.91 33.05 31.64 29.88 28.48 28.48 28.48 28.48 28.48
41.84 41.13 37.97 35.16 32.70 31.99 28.83 27.07 26.02 25.66 25.66 25.66
41.84 41.13 37.97 35.16 32.70 31.99 28.83 27.07 23.91 23.55 23.55 23.55
41.84 41.13 37.97 34.45 32.70 31.99 28.83 27.07 23.91 22.85 22.85 22.85
41.84 41.13 37.97 34.45 32.70 31.99 28.83 27.07 23.91 22.85 22.50 22.50
41.84 41.13 39.02 34.45 31.99 30.94 28.83 26.02 23.91 22.50 22.15 22.15
41.84 41.84 40.08 35.16 31.99 30.94 28.83 26.02 23.91 22.50 22.15 21.09
41.84 41.84 40.08 35.16 31.99 30.94 28.83 26.02 23.55 22.50 21.45 20.04
41.84 41.84 40.08 35.86 33.05 29.88 28.83 26.02 22.85 21.09 20.39 19.69
41.84 41.84 40.08 36.91 34.10 29.53 26.02 23.55 22.15 21.09 19.69 18.98
41.48 40.08 39.02 35.86 33.05 28.83 24.96 22.85 22.15 20.39 18.63 17.58
40.43 35.86 35.16 33.05 29.88 26.37 23.91 21.45 19.34 18.63 16.88 15.47
33.05 31.99 30.94 29.88 28.13 24.96 21.45 18.63 16.88 15.12 14.06 13.01
26.02 26.02 26.02 26.02 25.66 23.55 21.09 16.88 14.06 11.95 11.95 11.95
24.96 24.96 24.96 24.96 24.96 22.85 21.09 16.88 14.06 11.95 11.95 11.95
23.91 23.91 23.91 23.91 22.85 22.15 20.04 16.88 11.95 10.90 10.90 10.90
23.91 23.91 23.91 23.91 18.98 16.88 15.12 15.12 11.95 10.90 10.90 10.90

That's my timing table. I keep the AFR's in the mid 12's at WOT, and around 13.5 at part throttle. Had to pull alot more timing than I expected in the lower rpm/high load areas to get rid of detonation, but trust me, it pulls HARD at 3/4 throttle with the converter locked up and in OD. Doesn't need much timing to make alot of power. I think the AFR heads combustion chamber efficiency helps alot. I'm running a ton less timing than I was with the '113 heads.

-2.11 -2.11 -2.11 -3.16 -3.87 -3.87 -4.92 -4.92 -4.92
-1.05 -1.05 -1.05 -2.11 -2.11 -2.11 -2.11 -2.11 -2.11
0.00 0.00 -1.05 -1.05 -1.05 -1.05 -1.05 -1.05 -1.05
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70
0.70 0.70 0.70 1.05 1.05 1.05 1.05 1.05 1.05
1.05 1.05 1.05 1.41 1.41 1.41 1.05 1.05 1.05
1.41 1.41 1.41 2.11 2.11 2.11 1.05 1.05 1.05
2.11 2.11 2.11 2.46 2.46 2.46 2.11 2.11 2.11
2.46 2.46 2.46 3.16 3.16 3.16 2.11 2.11 2.11
3.16 3.16 3.16 3.52 3.52 3.52 2.46 2.46 2.46
3.87 3.87 3.87 3.87 3.87 3.87 3.16 3.16 3.16

That's my spark correction vs coolant temp table. I have it set to be always "active". I pull just a little timing in the hotter normal operating temps (198 deg and up area). In the cooler normal operating temps (176 deg area) it's 0'd out. In the 154 area I'm adding a little timing in. I think this is because of the high compression that I need to do this. Was picking up a hint of detonation and realized it was only when the temps were approaching 200 degrees, so I used this table instead of pulling it out of the main table and having less than optimal timing when the temps are cooler. Running closer to the line, I guess.

The setup is doing really well. No maintenance setup, haven't even pulled a valve cover in over a year. I drive it every weekend, my wife and I go out with the car as much as possible. Last year at the track, it ran a 12.08 on motor, and a 10.55 on the spray. This was with 3.07 gears and timing was only maxing out at 26 degrees on motor, pulling 10 from that on the spray. I was scared to push the detonation line then. It broke the rear on the 10.55 pass, so over the winter I put in a D44 with 3.45 gears. With the better tuning, lower gears (and now don't have to baby the launch since the rear is stronger) and extra bottle heater to get the pressures up, I am hoping for a 10.40 or possibly 10.30 this year. Last year I was quickly rolling the pedal to the floor, then hitting the spray about 20 feet out. This year I hope to stab the throttle and be into the spray about 5 to 10 feet out.

It runs fine on 93 octane, but if I run 92 octane that is 10% ethanol blended it wants to "run on" after I shut it off on a hot day and after a long heatsoaking drive. Leaning out the idle and lowering the idle rpms helped alot but the only way to completely cure it is to run 93 octane with no or little ethanol blend. (NO SHEETZ GAS).

The high compression and running this well begs the question.....what would water/meth do for me? I'm thinking of trying a snow performance kit, possibly be able to lean out the mix a little on the spray and not retard the timing at all while spraying. Bottom 10's or a 9.99 possible? I'd love to run that on a car that looks 100% bone stock and has a classic plate!

Chevy86 IROC-Z

iTrader: (17)

Wow. You guys are guru's. . Too many numbers for me. Ill just stick with the 180*.

dan0617

Orr, how is your setup doing. By looking at your sig, WOW! I have a friend that runs a supercharged Cobra with water meth, and he just pulled it off to install a 76mm turbo. He and I are always competing, and he won't quit modding till he beats me. When he does, I might need to copy your setup!

dan0617

Really, if you are running closed loop still (which I think you are), I would run the 160 stat.

Chevy86 IROC-Z

iTrader: (17)

I havent done anything to any PROM yet. I still need to buy the computer curcuit board and blank EPROMS. All Im doing is familiarizing myself and learning before I do something bad to my ECM. What do you mean "closed loop?" Do you mean as in when the IROC warms up, it's considered "closed loop" because all the sensors are initiated? So it's ok to run with the 160* thermostat even if I havent moded anything?

Orr89RocZ

iTrader: (20)

I was thinking the same thing here. That high of compression I would think a straight methanol injection setup would really boost power. COoler charge plus alot more octane for power. E85 cars vs pump gas are similar comparisons, and E85 always outpowers 93 oct pump cars.

But my setup is doing ok. Have some overheating issues with my cooling system so I havent really had much tuning time on it. ALot of street fueling sessions when it was cold outside and it didnt overheat and a few track runs to look at fueling but I havent played with timing in the boosted regions just yet. I threw in a basic table I created and it ran ok so far with no signs of detonation/pinging so I think I'm pretty conservative. I bet there is some power to be had with small advance. I am basically running about 32-33 deg at 100kpa which is about right for a n/a motor (my 383 ran 34 deg for max power) and then I pull around 1 deg per psi of boost. Simple enough and its working.
It runs like nobody's business as it sits so i really dont need to look for more power. Its already too much car for the street but not enough for the track to keep me happy

Orr89RocZ

iTrader: (20)

I ran a 170 with no tuning mods and it was ok. The main thing to change to get the most use out of the lower T-stat is the fan turn on temps. Ones with ECM control and the other is with fan switch on the passenger side head. I just wired that one to manual switch. Worked ok. But you want the fans to turn on and off around the Tstat setting. I think on at around 176 for my 170 stat and off at 166 or so worked ok and kept my motor fairly cool on most days. Winter was coolest, as expected. Summer time it saw 180 most of the time so fans were on all the time.

Closed loop is when the computer will use the o2 sensor to correct air fuel ratios. You will hear terms like BLM and INT. Open loop the ECM does not correct for fueling based on the o2 sensor, so whatever you dial in for fuel delivery, it will always deliver that much. This is ok if you want to tune often for changing weather conditions and such, but closed loop is best to compensate for air temps. I find my cars run richer in the summer due to less air density and leaner in the winter because the air is so much more rich with oxygen. The change isnt too dramatic but there is some hp left on the table, especially in my boosted case. Your talking about 11.0 air fuel ratio in summer versus 11.5-11.6 or so in the coldest winter days. I find going from 11.0 to 11.5 makes a decent amount of hp difference on my setup. I didnt want to go leaner than that on straight pump gas and 14-15 psi. On 10 or less I'll go for 12.0.

Chevy86 IROC-Z

iTrader: (17)

Orr89RocZ, Thanks. I have a clearer understanding of closed loop now. As for my fans, I live way down south in California, so my fans are always on. I rewired them with a relay which is using the "fan fuse" as a trigger to close the circuit. Today was 108* while I was at the junkyard getting myself a front control arm. I did have a aftermarket MemCal and it supported the 160* thermostat. But it took a dump. I just wanted my IROC to run cooler. But Im seriously looking for a 87 IROC 350 TPI auto bin so that I can have someone program it onto a blank 27c256 EPROM.

dan0617

Sounds like you are a little conservative on afr and on timing. That is a good thing though, we know how fast things can go bad on a nitrous or boosted setup.

The biggest part of my learning curve was:

I melted plugs and eventually and exhasut valve running at 12:1 on a 200 shot. After much research on nitrous forums, I find out that widebands are inaccurate when spraying. They are calibrated in fresh air, which has less oxygen content than nitrous. Had to determine how much hp comes from the spray and how much from motor, then put the numbers in a calculator to find out I should be running around 10.2 on the wideband. I upped the fuel jet to run me at 9.8 or so, and my plugs look perfect and my exhaust valves no longer melt.

Chevy86, it is great that you are on here learning. You won't hurt anything if you pay attention to the signs. Listen for knock. Read spark plugs for signs of detonation and going lean. When getting into tuning, Invest in a wideband when you can. Datalog. With what you are looking at doing right now you will be fine.

Consider getting an adapter and the 27sf512 chips from www.moates.net. Go to the moates website and under downloads, look at the stock .bin files. I'm guessing you will find the one you are looking for.

Chevy86 IROC-Z

iTrader: (17)

So right now I'm not sure what I want to do. There is so much to learn about programming PROMs that I really dont have time to learn because Im a full time student studing Computer Information Systems.

Chevy86 IROC-Z

iTrader: (17)

Thanks dan0617, I appreciate it when good guys like you give out encouraging statements. . I was thinking about buying the little board, ziff, and the blank chips, but I figured that I needed a EPROM as a one time thing. I dont have the luxary to program numerous EPROM's and go out to a track to test out which one works best. I have 3 kids and a crazy wife, I work at Target and I go to school to better myself for my family. I see my IROC as a project,,,, a long lasting project (because of my limited funds). But I may just buy the equiptment anyway. By the way, what are the signs of detonation and how can you read them in the spark plugs?

dan0617

I have an apyp and an apyu stock .bin file. I think you want the apyu but I'm not sure of that. I can email them to you if you find out they are what you need. Whoever is going to burn that .bin to a chip for you could lower your fan on/off settings in the chip, so you could rewire your fans back to stock and they would kick on and off at whatever setting is put in the chip. Would only take a minute to change them, heck, I'd even change them for you before I email you the .bin if you want. Do you have any tuning software? I think you can still download TunerproRT for free to try it out, then you can pull in the .bin file that I'll send you. You can look around at everything, search on here about things, make changes to it just to learn and not have a penny in it. Should you decide you want to burn it to a chip, buy an adapter and a chip from www.moates.net. Send the .bin file to me, then I'll burn it to a chip for you and mail it to you. Only money you will have in it is the chip and adapter which is like $50 I think. Or if you already have a friend that can put the .bin file on an older style chip for you and solder it in or whatever, you can still do the adjustments in Tunerpro to the .bin and send it to him to do for you.

In looking for detonation on the spark plugs, you will see little black specks on the white porcelains. Sure sign of detonation. You usually won't get much detonation because the knock retard system will pull timing out if it hears detonation. If you get into major mods in which the knock retard system hears things that sound like detonation (false knock) then pulls timing thinking it is real knock, you will need to disconnect the knock retard system and then listen for knock ( at high rpms it sounds like popcorn kernels being shaken in a tin can, low rpms sounds like a monkey hitting your engine block with a small sledge hammer). You can listen for it during a run, and then look for it on the plugs after a run.

dan0617

I think it is great that you work to support your family and go to school to do even better. These cars are a great project for us guys who are on a budget. Not many vehicles can give the enjoyment per cost that these cars can. I started out looking for an IROC, and ended up going with a 'vette because I found one at the right price. Everything I do is on a budget, and you are right, the longer I keep it the more I can afford to put into it. Most of the parts on my car are used and purchased from ebay or a forum (torque converter, rear, dist, ignition box, intake, rockers, pushrods, etc.) and I like it that way. Hell, I even re-used a flat tappet cam and have had no problems with it. It's been in 3 different motors now! The less I spend on one thing the more I can spend on another. The best ones are the ones that take a long time to build up. The journey is as much or more fun than the destination.

Chevy86 IROC-Z

iTrader: (17)

Yup. I agree with that. My IROC has history. 2002-threw a rod ( http://www.youtube.com/watch?v=nHja0312gSo ) , 2004-got stolen, 2005-found it in a junkyard, Oct, 2009-woke up from a 7 year coma. Its gone a long way and now I believe its time to take it a step further with programming and tuning the EPROM chips.

thomas1976

The 160 t-stat is to reduce detonation as much as possible using "exagerated" SA.
Minor possible fueling changes have already been pointed out.
Just keep in mind that running at the edge of detonation does not equal making the best available power.

Orr89RocZ

iTrader: (20)

NOt to get off topic here but thats the first time i heard this... I tuned my setup to near 11.8-12.0 to 1 or so with a 150 on my 383 that was 11 to 1 and it ran 10.63 at 127-128 with no problems. Heads didnt seem to have a problem with that, and I've heard the valves in AFR street 195's are not great valves. The comp ported heads got the higher quality valves. I picked up a good bit from 10.0 air fuel to 12.0 and 2 more degrees timing added.

dan0617

I didn't have a problem at a 150 shot either. Thought all was great. I think it's because a large percentage of the power is coming from motor. I didn't run it through the calculator just now that I got off the nitrous forum but from memory I think with my setup a 150 shot needs about a 11.2 or 11.5 to 1. So running at 11.8 to 12 to 1 would be a hair lean but not too far off. Jumping up to a 200 shot swings the percentages pretty good, and puts it to like a 10.2 or 10.5 to 1 afr according to the calculator. I think my compression compounded the problem. You can go to a nitrous forum of your choice and search for "wideband nitrous afr" and see this is talked about quite a bit on the larger shots.

Chevy86 IROC-Z

iTrader: (17)

No sir. The Thermomasters are programmed at 160* for better and higher performance. The cooler the engine and it's bolted on components such as the intake manifold and heads, the less the air becomes hot as it travels though the ducts of the intake. The objective is to keep the air as dense as possible ( http://www.hypertechpowerchips.com/p...p/Default.aspx ). As for the possibility of detonation, highly unlikely because IIRC, our 3rd gens came off the factory line with 210-220* thermostats. With that said, if your thirdgen is completely stock and in good condition as in sensors and such, then you shouldnt encounter detonation. Now if you got detonation occuring around 180-200*, then the issue lies with a sensor or a combination of other things, not a 180-220* engine block. Dont take it personal but I called Hypertech and spoke with a technition. I asked him about the Thermomaster and he told me that It's purpose was just to keep the incoming air as cold as possible for better combustion.

dimented24x7

iTrader: (2)

I dont know if anyone has mentioned this yet, but most SBC dist. wont give much more than 40 deg of SA before cross-firing.

With that said, I know some factory cars with EGR run quite a bit of SA. Ive scanned my malibu, and that routinely has 40+ deg of SA. Same thing with my old taurus. In later years to keep up, GM has made the tunes more power friendly. Unfortunately, it also hammers like hell sometimes when you step on it and the PCM is still in the high octane mode. We're talking rocks in a coffee can type detonation. Moral of the story is to be careful with the SA. It can be a fine line between making power, and blowing head gaskets, cracking pistons, etc. Also keep in mind that with timing, the idea is to burn the mixture at teh right time. Too little and the mixture ignites late, causing lost power. Too much, and the mixture ignites early, causing the piston to compress a burning mixture. This leads to work lost to compression, greatly increased heat to the CC and pistons, and possible detonation. Adding lots of SA increases the cylinder pressures as the piston is rising to TDC, which greatly raises the temperature in teh cylinder, much more so than an engine running at 230-240 deg F. In the grand scheme of things, thats not quite as hot as it seems.

A good way to tune is to start out with too little SA, and then build up to the point that the torque output plateus, or you start seeing knock. A dyno really helps for this.

As for unlikely detonation, its always possible, even with low compression. The old smog heads are a good example. They like to detonate due to a lack of swirl and need for large ammounts of SA.

dimented24x7

iTrader: (2)

I wouldnt do that. I found out the hard way with an electrical fire. Inside the fan motor, the commutator wears down to nothing, and then smears, causing a dead short. Theyre made for intermittent use only. Not for continuous operation.

Best tip is to get a new airdam if your car does not have it. That way you can only run the fans when needed. An engine will be fine if its at 210 or 220. Too cool can lead to water condensation not being driven off, which forms acids in the oil. When the car is in motion, it really doesnt make sense to have them on.

Chevy86 IROC-Z

iTrader: (17)

I agree that having the fans on at all times is not the proper way, but Im not a person who makes 20+ dollars an hour. I make a measly $8.75. I really dont want to get into my expenses because it has nothing to do with my thread, but on my budget, I dont have the luxuary to go on a spending spree and still be able to put food on the table. Bekieve me, If I had money, I would buy everything neccessary to have it wired correctly. As for the SA being above 40, thats how the SA is on my MemCal. And It's not eraseable. It's the type that can not be modified in any such way.

dimented24x7

iTrader: (2)

A fan switch, a relay from radio shack, and some wire and a fuse was all I needed after all my factory wiring burned up. Its not too costly, and may save some headaches down teh road.