Fast355

iTrader: (2)

Well I thought about posting this in with my old thread about the PCM swap, but it would not do this swap justice. Yes this is the reason I swapped to the PCM, but it is more than a simple PCM swap.

You can read about the PCM swap here.

https://www.thirdgen.org/forums/tbi/...6197427-a.html

Dimented24x7 really did his homework on the $0D MAF code. I was able to switch the Peanut roller cam for a ZZ4 cam and the 193 swirl ports for a pair of overly worked 081 TPI heads (1.94/1.60 valves, 240 CFM intake/ 175 CFM exhaust, 54cc chambers, milled .025"). That took care of three things at once. The sick 8.42:1 (18cc dished pistons) compression was bumped to 9.85:1, the cam is now much larger, and the ported 081s flow much better than the 193s did with only a bowl clean-up. I didn't even have to change the fuel pressure to the injectors as I was already running 30 PSI on 61 lb/hr injectors. The only changes that I made were I added timing to the PE table to go from 28* total to 34* total advance @ WOT, and richened the PE A/F ratio from 12.8:1 down to 12.3:1(from past experimenting with the same ported 081s). I have a couple of movies on YouTube showing the idle and the throttle response in an untuned state. It really only needs some minor Timing, AE, and TCC changes as well as MAF sensor table correction and correct the VE tables for backup in case the MAF sensors signal is lost.

I put 200 miles on it this morning and the thing ran great. The 0-60 has dropped from roughly 9 seconds to the mid 7s when, timed both with a stop watch. According to DD2003 and other similar combos, I went from 275 FWHP/400 FWTQ and should be making around 350 FWHP/415 FWTQ through the exhaust. That figure should jump to about 375FWHP/425 FWTQ through cut-outs. I should be solidly in the mid to low 15s AGAIN, despite the 3.07 gears.

I definately have some low-end torque loss from the cam, but it is not too bad. I am sure I will notice a big dip as soon as I hook the trailer up. I have a new pair of 3.73s to replace the ones that I chipped in the 14 bolt rear when I had the Weiand on this engine so I can get away from these 3.07s. That should more than make up for the low-end torque loss that I am experiencing. I was able to bump the shift points to 5,800 rpm, up from 4,700 rpm. Hit PE and it just flat goes now.

The Tach is not Crazy, it is YouTube's sorry quality.

http://www.youtube.com/watch?v=3Byd1ejQknU

http://www.youtube.com/watch?v=km90bzN2f6A

The injectors are VERY noisy at 30 PSI despite the composite housing around them (It is from a Caddy and they run silently from under it on a stock 4.1/4.5/4.9)
The headers are also leaking slightly due to the head swap and the fact that I have the thick, soft aluminum style gaskets that will take weekly re-torques for about a month to make them silent.

Try not to laugh too hard at my extra OIL fill cap that I found wedged up on top of the engine after losing it and put to good use.

Also forgive the extra wires out of their looms, I recently put a 125 AMP alternator in place of a 78 amp unit and had to rewire the charging circuit, as well as add in the wiring for the 2nd battery and 1500 watt power inverter (the front one is 350 Watt and I use it for my Laptop, etc)

One last thing, please forgive the 60 year old red wood fence around my back yard and beside my garage. It is really showing its age and lack of paint/ maintainence.

dimented24x7

iTrader: (2)

Thats cool that it works well. I designed it on paper to work with most setups, but I was never really sure how it would actually behave.

Also, I noticed on the AFR gauge that it seems to hang around the richer AFRs for a bit after revving. Does it only do this for a second or two and then return to normal? IIRC, I set it up to take at least a second after the AE PW decays out to update the integrator, so it may just be an issue of the computer dipping down into a little used BLM cell and running rich momentarily.

dimented24x7

iTrader: (2)

That setup you currently have is actually pretty quick. My friend used to have a similar setup with a Q-jet and it did low 13's in a stock 3rd gen.

Fast355

iTrader: (2)

It does hang a little rich, but usually not for very long. I believe it is due to the BLM cells and dropping into one that is rarely used. Might have been when I turned the A/C on, as the A/C has its own BLM cell. It might also need more Decel Enleanment. Also I am not commanding a Stoichiometric A/F ratio, rather direct lookup off the Open Loop A/F ratio table, so that might be affecting it too.

Which setup? The ZZ4 cam with Ported 081s or the Swirlies and the Peanut cam?

I am wanting to setup an Aeromotive Fuel Pressure regulator as my idle pulse width is .8-.9 when the engine is fully warmed up. I am thinking of creating a table in the unused portion of the code to allow for Flow Constant Lookup Vs. MAP. Much like the EBL has.

http://fullsizechevy.com/forums/showthread.php?t=117719

I am not cutting the factory fuel lines on mine though. The lines join right at the rear of the engine and I am planning to run the AN lines from the frame up to the TBI, then the Aeromotive is going to reside on the right rear of the engine mounted on top of the passenger side valve cover. I have more space there than the front of the engine and it will be easier to fit in and adjust there.

dimented24x7

iTrader: (2)

The setup that Im reffering to is the ZZ4 setup.

For the vac AFR adjustment, you could also just use an 8 bit multiplier to scale back the inj. constant as the vac. increases. You could also di look up the injector constant, but it would require the use of the 16 bit 2D lookup routine, which takes a little more time, although without the need for multiplication afterward, maybe youd break even.

With the table lookup, its worthwhile to note that closed loop corrections are likely suspended while non-stoich AFRs are used. I know at the very least that BLM updated are barred when your at something other then 14.7:1. Also with the MAP and TPS AE, there is no enable thresholds. The AE lookups are always done. The lowermost cells should always be zero, and the cells above that are used to control the AE. I set the PCM up to only look at the final AE duty cycle. If its above a certain threshold, the PCM blocks INT updates untill the AE has tapered off.

dimented24x7

iTrader: (2)

Im thinking of making a few updates to the code at some point. I wanted to tighten a few things up to reduce processor consumption. Im also thinking of nuking the CCP code to reduce some overhead. In addition, I can also add in a routine to allow for a variable injector constant based on vacuum, as well as a dedicated vacuum term that can be filtered to match the response of the vac regulator.

Fast355

iTrader: (2)

Sounds good. Have you thought of Nuking the Catalyst Overheat stuff, Torque management, etc, rather than just having it disabled.

dimented24x7

iTrader: (2)

Catalyst reaction temp has been on my list of things to delete. The torque management code is long gone.

Fast355

iTrader: (2)

Dimented, you are right, this combo is Faster than I thought it would be. It definately is shaping up as I fine tweak some things.

Just thought that I would let everyone know how proud I am of this NA TBI build. It took the jump on and held off a LT1 Camaro to 85 MPH, we were dead even at 90 where I lifted. I switched over to a Spark Table similar to SU-AUJP and have been manually shifting at 6,000 (I think I floated some valves at 6,300 when I tried that). I played with the governor in the transmission to make my WOT 1-2 shift and 2-3 shift right at 6,000 rpm.

Well long story short, on my way to work this morning, on the service road I was cruising along with a mid 90s Camaro. Definately a LT1 car, Raspy exhaust, Automatic, etc. A couple of younger guys (16-18) in it. Well, we both catch this light across from a flat section of road about 1 mile long. As we slowed to a stop I flipped the switch for the electric cut-outs, slipped the shifter into neutral, and blipped the throttle. ZZ4 cam singing. He looks over and nods for the go with this huge grin. As the other lights turn yellow, I load it up against the 2,600 rpm converter. Light turns green and we both put the hammer down. It is his mistake though out of the hole he spins. I get a little wheel hop, but nothing major (3.07s with an Eaton Posi, Caltracs, and P295/50/R17s with 3,000+ lbs of heft over the rear axle). I immediately get the jump on him and pull about 1/2 car length on him. The 6,000 rpm WOT 1-2 shift comes up quickly, now it is back to 3,700 rpm in 2nd, up to 6,000 in 2nd, 2-3 upshift @ WOT, we are now neck and neck and up to 90 mph, not to let things get any stupider, I lift out of it and call it good. About 1/2 mile after slowing back down, I spot the Police car sitting there that would have gotten us both had I not let out when I did.

Well its always good to know where the police officer sits and can radar from (driven this route 5 days a week for 3 years). It also makes for a great sleeper concept. The police don't expect Vans to run down the road with open headers.

Fast355

iTrader: (2)

I actually believe the closed loop corrections are still taking place. The INT and BLM both move around and appear to be operating normally. IIRC, from what HaulinA$$ said, it simply inserts the value from the look-up table into the closed loop air/fuel ratio target. My idle target is 14:1 and BLM learn/correction is definately active at idle. I unplugged my ECM overnight and it erased the BLM data that was stored in it. The next morining it was at 128 BLM and the BLM cell values changed, despite the fact that it never had 14.7:1 as the stoich value.

Damon

So you add oil to your engine through the air cleaner? Heh heh. Just kidding.

That's a pretty wild setup for a work van (I still liked the blower, personally). A MAF-equipped TBI setup..... mmm, mmm, mmm. That's definitely goes in the "now I've seen everything" file.

Heaven forbid you should ever put some of this knowlege to use hopping up a 3rd gen F-body! I know who I'm contacting when I need to get some wild combination of engine/intake/EFI system together in a bizarre vehicle.

dimented24x7

iTrader: (2)

Im having a hard time finding something else to top it. Too bad the misaligned automatic destroyed the pilot in my crank. I could've added a computer controlled automatic trans. with paddle shifters to manually change the forward gears. That would really turn some heads.
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Now that is interesting. I couldnt find anything in the code other then the thing that forbids BLM cell # updates. The closed loop PID doesnt really target an AFR. It targets the stoich voltage for the O2 sensor, which is around 14.7 or so. Potentially, the PID could be fighting your target AFR and trying to force 14.7, regardless. Its unusual that it allows the AFR to be looked up when in closed loop. Maybe GM had some other use for it.

Fast355

iTrader: (2)

Guess you never heard about what my coworker built and I tuned. The 1970 500 cadillac that got port fuel injecton run by a 7730, backed to a TH425 (FWD TH400) with ECM controlled switch pitch converter. All this in a compact 5 ton hot rod with 6 wheels and front wheel drive! Give up on what it is? How about a 1978 GMC Motorhome. The weakling 403 gave up and was replaced.

Fast355

iTrader: (2)

It is your setup, so why would you have to top it? A paddle shift 4L80E with my Weiand 142 sure would be fun to run.

FWIW on the other, I have not seen a GM ECM that did not have a target closed loop air/fuel ratio. It has to be something. It is trying to target 450 milivolts or so (530 in my case, BHMC 305 settings). But 530 milivolts still has to represent a certain A/F ratio.

dimented24x7

iTrader: (2)

Always gotta keep pushing the envelope, or youll never continue to learn new stuff. Thats my take, anyway. Im probably going to try and dip into the OBD-II at some point after the OBD-1 stuff is all mapped out.

As far as the target AFR, yes, all the ECMs do have them, and 14.7:1 is what it usually is. IIRC, in the PCMs PID O2 routine, it assumes that the target is stoich for the fuel in use (14.7:1 for gas), and the setpoints are calibrated around that. Other AFRs will cause the routine to try and correct for the apparent error in fueling, thus driving the AFR toward stoich no matter what the target is. In the older PCMs, if the AFR wasnt 14.7:1, then there was no closed loop.

Fast355

iTrader: (2)

Dimented-
Actually I noticed today that I lied about the BLM and INT both moving when targeting other A/F ratios. The BLM value is fixed at 128, AFTER I reset the ECM by removing it from power. The INT however functions the whole time, even in lean cruise at 16:1 a/f mixture. O2 voltages are down in the 50-100 Milivolt range, so it is definately in the lean cruise range.

dimented24x7

iTrader: (2)

Ok, so the PCM only blocks BLM updates. I looked forever for something else that blocked all the PID fuel corrections when using AFRs other then stoich but couldnt find it. I would assume that the integrator then just maxes out in lean cruise. It can add a couple hundred usecs. of pulsewidth through the integrator and proportional term, but probably not enough to really be noticed in lean cruise.

Fast355

iTrader: (2)

I know that HaulinA$$ has posted in a different thread that he checked the operation with a Wideband. He claims that it definately targets the A/F ratio and gets pretty close to it.

dimented24x7

iTrader: (2)

In the closed loop O2 routine, theres only really the following for the setpoints:

;
;-Loop and perform four table lookups based on airflow
;
; 0x4CD7, integrator delay vs airflow table
; 0x4CE0, mean rich/lean O2 threshold
; 0x4CE9, rich O2 threshold vs airflow
; 0x4CF2, lean O2 threshold vs airflow
;
; 0x028E, stored INT delay
; 0x028F, stored mean rich/lean O2 threshold
; 0x0290, stored rich O2 threshold
; 0x0291, stored lean O2 threhsold
;

The PCM cant really target anything else other then stoich with a NB O2 as it has a steep, non-linear response on either side of stoich and theres no temperature control or compensation like there would be with a wideband. Looking at the INT would say for sure. If its really high when your running at 16:1, then the computer is trying to force 14.7:1.

Fast355

iTrader: (2)

When I looked at it cruising at 16:1 it was right at 132 IIRC. I can tell you that I tried setting the min A/F ratio vs. vacuum table at 16.4:1 when I started and found out that it was limiter used at idle only. It made it idle terrible at 16.4:1. Set it back to 14.7 like stock. The idle smoothed out. I then noticed that it went to 16.4:1 as soon as the AE timed out and I was out of idle mode.

Fast355

iTrader: (2)

Here are what the numbers look like. I freeze framed my Scan Tool at various rpms with an unloaded engine and wrote down the numbers to share. Keep in mind the BLM learn is off and I am still using stock GM MAF freq vs. flow number for my MAF. It seems to be dead on with the commanded air/fuel ratio.

With the engine unloaded at high idle

The BLM is locked at 128 for the duration.

RPM = 650
A/F = 14.5:1
PW = .9 to 1.1 ms
MAP = 50-55 KPA
TPS = 1%
INT = 123

RPM = 1,000
A/F = 15.4:1
PW = .9 ms
MAP = 43 KPA
TPS = 6%
INT = 115

RPM = 1,500
A/F = 16:1
PW = .8 ms
MAP = 38 KPA
TPS = 10%
INT = 114


RPM = 2,000
A/F = 16:1
PW = .9 ms
MAP = 35 KPA
TPS = 12%
INT = 116


RPM = 2,500
A/F = 16:1
PW = 1.0 ms
MAP = 34 KPA
TPS = 15%
INT = 122


RPM = 3,000
A/F = 16:1
PW = 1.2 ms
MAP = 34 KPA
TPS = 18%
INT = 122

Fast355

iTrader: (2)

Finally got all the little bugs worked out and it is running great on the MAF setup. Much better than SD ever did. It has WICKED pull through the mid-range for what it is.

The only issue that I keep having is a Random MAF Error report. It only occurs when I hammer the accelerator to the floor, then quickly get back off of it, such as losing traction and getting back off of it.

dimented24x7

iTrader: (2)

Im surprised it does throw a code 17. It could be due to reversion causing the frequency to bottom out. I set the parameters for setting a code 17 to be when the MAF frequency falls below 150 Hz for more then 1/8 of a second. Even with the engine off, the MAF frequency is still usually around 180 Hz or so, just from convection. You could try changing the time to be around 1/2 a second and see if it helps. So long as the lowest value in the MAF table is set to be something like 8 gms/sec, it wont die at idle while the code is pending. Also, see if you can get a datalog around there when it happens. Would be usefull to see whats going on.

dimented24x7

iTrader: (2)

One thing I do like is how well it does run. Maybe a little too well. My TKO has developed an apparent leak around the case plug and has started shedding metal into the fluid. I dont know how it is for the TKO's, but for T5's, once they start leaking around the case plug, the case has streched, and the trans is nuked. So far, this 350 has managed to eat everything Ive put behind it

Sure is fun to drive, though... Just have to make sure I dont drive any farther then Im prepared to walk.

Fast355

iTrader: (2)

I agree, I killed another 5 pinon planetary set in my 700r4 (RIP 700r4/4L60E # 4, 12/12/06). Just tears the gears completely away from the pinons or breaks the drive shells. I have serious thoughts of building a TH400 this time around, that is if the present 700r4 does not hold up, DOUBTFUL. Even with the TH400, the cruise RPM with my 3.07s will be like 2,400 RPM @ 70 mph.

Fast355

iTrader: (2)

I did another MAF swap this last weekend. I have been putting off my brothers work van for some time. He has been begging me to help him convert his over. We converted his 1992 TBI Astro work van. The van is almost stock and loaded with 1,000 lbs of tools at all times. It usually has a 2,500 lbs trailer behind it The 200,000 mile 4.3 is essentially stock. Edelbrock TES headers, high flow 3" cat and single 3" cat with a low-restriction muffler. It has a stock TBI unit with a pair of 305 injectors in it (4.3 HO 170HP/235TQ stock). I used the bin from my van after changing alot of the constants to stock 4.3 constants. I did not even have to touch the MAF sensor table. Fired right up. Started loging it. Cleaned up the idle. By saturday night it was running better than ever. Here are a few snap shots of the datalogs from the tired 4.3 Astro. We pulled the valve covers and put on 1.6:1 rockers. Pulls well for a high mileage 4.3. The more we drove it, the better it ran.

It flat goes from 60-90ish. Its like a light switch at 90 mph though and falls right on its face. No matter how hard we tried, we could not hit 100 mph on the 2 lane country road. Come to think of it, we had trouble getting it over 4,200 rpm in 2nd too. It is either a valve train problem or fuel problem. We left it alone.

dimented24x7

iTrader: (2)

Id imagine its probably an issue with valve float with the new higher ratio rockers if its RPM dependant, especially with the old stock valvesprings. The PW looks ok on the datalog. Its good to hear that it works reasonably well on a 4.3L. I was concerned with reversion issues with an open style MAF like the LS1 MAF and a V6. With my vortecs and the large TBI, at low RPMs I get the 'thud... thud... thud...' intake note from the sudden pressure pulses. What ever it is, it really seems to rub the MAF the wrong way as the fueling leans out at very low RPMs and full throttle. At less then 800 RPM and full throttle, it starts misfiring from the leanness.

Theres also some logic with how the BLMs are layed out. Theyre mapped out over the MAF table at even increments. This can be adjusted for a smaller motor like a 4.3L to help give better use of the BLMs. Keep in mind that the MAP and RPM bounds are NOT used. I dont know why I didnt remove them from the constants section when I updated it. See LBLMP00-LBLMP03 in the MAF source code.

Fast355

iTrader: (2)

GM DOES use the large open style MAF sensor on the Vortec 4.3 that is still being produced.

Its NOT rpm dependent. It is definately load dependent. At 3/4 throttle it will go clear to 5,600 rpm in 2nd. IF I did my math correctly for the injector duty cycle, pulsewidth, static thing, the V6 has 25% more head room than a V8 does.

Thanks for the heads up on the BLM Cells. I am still running the old code though and have not updated to the new one. I have not had time to repin the TCC connection.

On a side note, would you mind downloading Scanner Pro and trying my definition for me. I am curious if it works for you. It worked fine for me for about 30 minutes, now it will not link at all. I think my ALDL cable took a dump on me. I cannot even get TTS Datamaster or Tunerpro RT to link to the PCM properly. On either vehicle. My scan tool still works fine though.

http://www.scannerpro.net/

dimented24x7

iTrader: (2)

Ill give the def. for scanner pro a try. IIRC, so long as teh first three bytes are sent properly, the PCM will always respond with a full frame of data. The first byte specifies the desired mode (F4=engine, F5=transmission), and the second two bytes are the address within the PROM of the desired table that you wish to transmit through the ALDL. Once thats complete, the PCM begins uploading data to the TX buffer untill all the addresses have been sent though the ALDL. If they arnt recieved properly, the PCM does nothing and waits for data to again appear in the RX buffer.

As for the van, if its load dependant, then my best guess would be a dud fuel pump. With the MAFs, GM appears to use both the MAF and the MAP for the fueling, so they may use one or the other at certain points. It seems like alot of the MAF manufacturers are really pushing the baffled type MAFs, so maybe there is at least something to it on the smaller motors. If it runs ok, then its probably not an issue.

Fast355

iTrader: (2)

Yeah, that is what I thought too.

My brother got to looking back at his records for the van. It seems to still have the stock GM fuel pump in it, with 200,000 miles on it. I think he is going to change the pump, the strainer, and the fuel filter this weekend.

The ONLY thing I have noticed with the MAF setup is that with stock type AE settings it bogs bad. Both went rich during light throttle transitions. Both went dead lean for a split second if hammered. Right after the lean bog, the transition to PE is abrupt. So abrupt that both Vans will burn the tires on a 2-1 downshift.

dimented24x7

iTrader: (2)

The MAP AE is actually dutycycle based. There is also an RPM multiplier table. This allowes for smoother AE as its syncronous, and allows finer control as the ammount of AE can be varied with engine RPM if its needed. Might be something to tinker with. I didnt really put alot of thought into the AE tables in the source code. More of a default place holder then anything. All the constants in there, even the stock stuff, really needs to be tuned. Im still working through alot of the startup spark and fueling to get a smoother startup, especially when cold.

Its interesting that you mention the momentary leanness on full throttle. Ive been thinking about the low end lean bog and Ive noticed that its variable with temperature. The AE temp compensation also needs adjusting, and the two seem to go together. I remember with the analog setup that if it went lean during transition to WOT at lower RPMs, the AFRs would go dead lean, and the engine would never recover. It would basically sputter along at 600 RPM or so at WOT untill I lifted. With the right ammount of AE, it would take off smoothly (well, more like smoke the tires) from a WOT drop at a dead stop. Im wondering if its some sort of vicious circle loop when the engine goes lean at lower RPMs. Maybe there is some backfiring into the intake and across MAF or something.
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Fast, Ill see if I can test the scannerpro def. this weekend. My burner and all flash roms are back with the car so I cant use the bench and Ill also be out of town on buisness for the remainder of the week.

Fast355

iTrader: (2)

On my G20 I put the stock 350 BJYN startup stuff in there (pulled about 40% for the increased injector flow), fires right up without hardly turning the key, and settles down to a smooth 750 rpm cold idle. It was 28* here this morning too.

Thanks for the AE tips, I am afraid if it makes more power during the downshift it is just going to smoke the tires or break more transmission parts.

Mine hesitates for about 1/2 second then takes off like someone just rear ended it at 50. VERY ABRUPT transition to WOT, then again it seems this Van has always had an abrupt PE transition since I have been tuning.

Thanks, no big rush on the Definition.

dimented24x7

iTrader: (2)

My main beef with the startup was the timing. I had to add loads of timing to get good performance with low compression so the choke timing gave me upwards of 35-40 degrees of timing at idle when it first started. Too much. Also the timing came in too quickly to get a smooth startup. Also had too much choke fuel. Idles much better, but is still a little unsteady at very cold temperatures after initial startup.

dimented24x7

iTrader: (2)

Now that I have my burner I can try out scannerpro. Keen on seeing how it works.

Also, with the AE, youll need to add some TPS AE if your having momentary leanness (< 1 second). The TPS AE is very short and is meant to cover for the transient response of the MAP and MAF. There is a small table and filter coeff. for it. With the MAF, theres going to be some lag in transient response due to the way its read in. The pulses are collected over 1/80 of a second and then the mean frequency is calculated. This means that the computed flow is the average flow over an 80th of a second, and not the flow at that instant. If there is a sudden change in flow, it wont fully register and itll be lean for a few injection cycles..

Its possible to read it in faster by setting up a periodic interrup at 250 Hz or something, or reading it in with the main vector handler, but it adds lots of overhead, and the resolution starts to take a dump.

Another thing that can help is to limit the filtering. In the MAF filter table and transient filter coeff., these can be moved closer to 255, which reduces the filtering. Better throttle response, but the engine can get a little choppy at low loads.

dimented24x7

iTrader: (2)

As far as the scannerpro def, the bad news is that its not set up properly.

The good news is that I have all the ALDL recieve/transmit routines thoroughly commented.

The other bad news is that I cant remember how the hell it all works...

I'll have to look at the routines and see whats needed to initiate a proper scan. It will hook up in other modes with some random string so long as the string checksum is correct. Faulty checksum causes the PCM to dump the connection. Its a matter of seeing what the start string is for the scantool data and how it calculates the checksum. Basically it needs the mode, address of the desired transmit table, and the checksum and after that itll puke the data back out the ALDL, but Im not entirely sure. Tunerpro always worked even though the string was bogus. I never quite understood why. I think the computer just defaulted to teh scantool data.

Fast355

iTrader: (2)

Thanks,

I will get with Mark about this and take a further look into the ALDL stream. It was simply an import from Tunerpro along with some additions. My ALDL cable died before I got to play with ScannerPro much. I thought that my problem with ScannerPro was due to the ALDL Cable, but looks like it was not. The cable DID die though.

1badz71tahoe

Any more progress on the MAF .ATX file for scannerpro? If you don't mind posting it, i'll test it a little on my truck in the next couple weeks and see if I can help you pull out some symptoms.

- B

Fast355

iTrader: (2)

https://www.thirdgen.org/forums/atta...maf-tbi-od.zip

I am working on a response for your other thread on the DIY prom board. About to eat dinner though, then I will get back on it.

I never have messed much with getting it going yet. Really haven't had the time.

dimented24x7

iTrader: (2)

Im thinking that it may be possible to just send some null values to initiate dataloging. IIRC, the computer just needs to see the right checksums for the data to be considered valid, and then itll default to the scantool data if the right address isnt transmitted, but I still have to look into it when I actually have some time.

Street Lethal

iTrader: (16)

You need to spend more time with me and Dave('s12secondv6) lol. I'm currently building a TBI inspired engine, and will definitely be considering your PCM configuration once installed. Already fabricated an air box to house the "one of a kind" throttle body (wait til you see it), and will have the flange on one of the Edelbrock headers welded on soon for the turbo charger. It's for the '91 Firebird in my sig....

Dimented, lemme know if you ever swing by E-Town. It'd be nice to meet up with you bro....

dimented24x7

iTrader: (2)

Post some pictures up of that bad boy...

Turbocharging would definatly be interesting. Currently Ive only set my setup up to deal with NA engines. Im thinking that you could use a two bar MAP with minimal effort. Pretty much just rescale the table axis in the tuner software so they represent the right values (0-200 kPa instead of 0-100 kPa). The major changes would need to be to the backup speed desity routines and baro handling. The MAP is interwoven in very subtle ways in these PCMs, though, so Im hesitant to say it would be an easy change. Ive sort been thinking of making the SA tables and other items based on the grams per cylinder of airmass rather then the MAP kPa. Its much less intuative, but preferred and more accurate, and you could leave the rest of the stuff in place.

One of these days I would like to make it to a meet if my shitheap stays running long enough. Lol... When I got the SC, it was a nice, rust free, but extremly slow secretary special with a mint interior. I promptly swapped the 350 into it and turned it into a twisted piece of scrap metal. Man, I really miss that nice interior...

Street Lethal

iTrader: (16)

I'm going to start a thread soon with some pics, I just need to finish the throttle body up. The air box is nothing special, it's the throttle body that I want you to see though. The engine is just about finished up. Still deciding on a cam, as well as what size turbo though....

Dave just had a little baby girl, so the header w/new flange will be delayed. Definitely need to swing by the track though. If you can make it out this weekend, that would be cool. Weather is supposed to be in the 70's. I'm really anticipating tuning this thing, not in a good way, however lol....

avst03

I'm trying to find out which air filter and flex tube Fast used in this setup.

Is the flex tube from a 5.3 truck?

Thanks

dimented24x7

iTrader: (2)

The flexible duct is from a vortec truck AFAIK. I have the same one from a Yukon on my car.

avst03

Thanks dimented24x7 I'm hoping to try your MAF code for the 7427 PCM.

I'm thinking of using a paper or K&N filter, the paper would be nice because there would be no oil to contaminate the MAF.

Does anyone make a disposable paper tapered cone filter?

Fast355

iTrader: (2)

IIRC the duct came from a 4.3 powered GM Astro/Safari van.

avst03

Thanks Fast