Need Diacom Map KPA 2-bar readings

[Bob H]

Hi guys,
Got up nerve to ask about Diacom readings on 58 code. Been playing with 58 code on 128K and 256K proms but having prob with map (KPA) readings on Diacom. They read half of one bar so half to guess what would be for 30-100KPA to corrilate to 30-190KPA timing table in Promgrammer or TC. Have asked Rhinda and said nobody else has prob.

Anyone have a Diacom map reading on 7749 or 7730 with 2-bar map?

Sorry so long.

 

[smeagol]

I believe I've seen weird MAP readings in Diacom all along, and others have reported the same. Never trusted them much... used boost reading for my tuning info.

Started using Datamaster and they have issued several updated versions that seem to work much better.

Are you using regular 2 bar calibrations, or custom ? or ??

 

[Bob H]

Don't know if this works but?

Don't know if this works but?

Hi Brian,
Been working on this for 2-3 years with 8d code but 4 months ago with rebuilt eng started trying to get 58 code to work with 2-bar map. This would be real lenghty if tried to relay details.
Am using stock BBZB code and purchased 58 code set up for 7730. Am trying all combos in both 7730 and 7749. Have given up on 2-bar for now and gone back to 1-bar with both ECMs.

Using in 383 SBC in 88 S-10 Blazer test rig. Has Whipple blower, 58mm TB, PFI, 27-37lb inj., and etc.

My Diacom Idle 2-bar maps are 27-35kpa (2-bar) and 48-49 (1-bar). Surges 300+ RPM with 2-bar and steady at 700 with 1-bar.

All 2-bar maps are approx 1/2 of 1-bar readings.

Have looked at Datamaster instuctions but looks to difficult to figure out.

Need someway to rescale Diacom to display 30-190kpa instead of 30-100kpa with 2-bar. Trying to guess at conversion while looking at timing table in Promgrammer or TC is bugging me.

Open to suggestions or can call if would help.

Bob

 

[smeagol]

I believe the display of MAP is an error with Diacom, I think Scot Sealander was looking into this before. Meaning that the data communicated by the ECM is correct, but the display by Diacom is incorrect, and since we don't have the source code for Diacom.. we can't do much.

What you *could* do is alter the ALDL message table and display the MAP value from the ECM on Diacom as EGR or something, but it really doesn't give you an accurate reference as to where to change values in tables, unless you want to do some extra calculations.

I like using Datamaster, as long as you have a laptop that likes Datamaster

Datamaster's feature where it can plot fueling versus MAP & RPM is especially slick for VE tuning.

 

[Bob H]

Thanks for the thoughts Brian, will keep searching for someone to make me a bin or memcal or anything. Still waiting for guy in Cal. that said could do one but has been almost 3 mos. so loosing hope.

Talked with Rhinda Tech. again this PM but they still say no one else has trouble. Said will e-mail me.

Tried a guy from Z-28 Camaro Forced Induction gang that does a lot of blower proms but he wouldn't talk to me. Guess this Whipple is strange animal.

The 58 code works good up until boost but then hits retard limit of 12-15 deg ks sig. Surging 300-400 at idle is biggest prob. Have varied timing up and down but seems to like higher timing with smaller inj. Don,t figure!

Looks to me like 58 code will not work on 7730 memcal. Even tried using TY memcal with Camaro KS board soldered on in 7749 ECM, no such luck.

I tend to get carried away just like you have said you do so will cut short.

Still wish someone had a Diacom Map reading at low TPS up to atmospheric so could tell if my memcal combo or Diacom.

Thanks again- Bob

 

[smeagol]

Have you spoke with Bruce about such matters?

He's tried some weird program/ECM combos...

For idle, I set it a bit rich, and open loop... once there, it seems to be pretty steady. Not sure what your tuning technique is, but that would be a good start point to see if the engine can idle well at all on the 7749/$58.

Syty's don't idle well, so pretty steady is the best we can get

Do you suspect the ECM is retarding the timing for no reason, or you have too much timing or the knock sensor is too sensitive? What ESC are you using?

 

[Bob H]

Brian if can remember all that will try.

The idle is smooth as warms up and at 12-13:1 but starts to surge at 14-1 and higher. Have moved VEs around 120 for warm weather but vary a lot in FL weather. Have tried timing from 15-25 deg at idle. Only clue is Map in gear is steady 34kpa but in neutral surges from 26-33kpa (625-950 RPM). Was playing with 20-30kpa VE (closed TPS) table until discovered prob with map readings and then tried 40-50kpa areas. No luck.

The idle is solid with 8D code and 1-bar. 1-bar idles at 14.7:1 A/F and 48-49kpa (Neut) - 57-58kpa (gear).

Was reading your suggestions on open loop idle but not sure if will mess everything up. Had heck of a time just to get learn enable temp changed.

Seems to be worse with last 37Lb inj I put in so bought new set of stock Ty inj to try. No luck.

Seemed to run better with 27lb Bosch but ran for approx 8000 miles with 30lb Lucas before lifting ring land up in Maine.

Tried to start with 10lbs boost on this new 8.9 comp eng but quickly dropped to 6lbs am at now. Thought change to 76cc chambers with less dish and better quench area supposed to help detonation. No luck.

Forgot what else you said now and don't know how to change back and forth.

Rambling again but none of other forum guys would talk cause I don't have right vehicle.

Bob

 

[Bob H]

Will try again. Just spent 20 mins answering rest of questions and lost it. This typing stuff is hard!

Have changed KS sensors and designs, rerouted and insulated KS wire, and rerouted SP wires. No luck. (useing KS sensor for SYTY and 90-92 Camaro- same #)

Bruce P? E-mailed once-no luck. ECM guy or someone sent me to guy in Canada. He made me a 58 code loaded on 256K bin. I think came from a guy running twin turbo Camaro with 58 code.

Had long discussion on GMECM forum about this application. They say it can be done! (has to be someone smarter than me I guess)

Have played with timing some. Appears to like 45 deg at cruise. WOT doesn't seem to make much diff. except slower.

Canada bin had up to 15 deg more timing than BBZB TY all way up into boost.

Wish there was some place in FL to take this thing. Am back to 8D code with 1-bar now and idles great but back to original backfiring prob off of lights that had before.

This could tend to make me go back to airplanes!

 

[leroy]

If I remember correctly, you would need a V8 memcal from a *similar* application, syty code on chip with cylinder # set to 8. Maybe you've already been down that road.

I've never paid much attention to MAP on Diacom either, other than to notice it doesn't work right. Turbo boost pressure works well for boost. If you have a vacuum gauge, that can give you an idea where you're at on the VE tables.

I've seen a couple of knock sensor problems that were solved by relocating the sensor. You should probably verify it is false knock with a stethoscope first.

HTH,
Jim

 

[Rufus]

Bob,

If you download the latest Datamaster manual ( http://www.ttspowersystems.com ), in Appendix I there is a table comparing the calibrations of 2-and 3-bar MAP sensors. That may help you figure out your MAP calibration. However, the 1-bar is not included in the appendix at this time.

Oh yes - you can use DataMaster to display your Diacom files, this function is FREE and does not require registration of the product.

HTH,

Gary

 

[Bob H]

Hi Leroy,

Am using 7730 (Camaro TPI) memcals for loading 58 code onto and also tried SYTY stock memcal with cyl set to 8 in both 7749 and 7730 ECMs. 7749 memcal was most responsive at idle except for bad surge. Could snap TPS open and would not backfire.(never could do with 8D code) Another thing noticed was inj pulse diff # of times between Memcals. Same code requires 30-50% higher VE tables in 7730 memcal. Idle PW on 7749 is approx 1.3ms verses 1.9-2.0 on 7730. I think not reading one of add on tables or poss something about asynch thing. I see inj spikes to 30.0ms with 58 code.

Boost map readings appear ok and do have vac and FP guages. Baro Map is also correct on Diacom @ 100-101kpa. Only map readings for idle up to 0 vac (104kpa 1-bar or 54kpa 2-bar) on vac-boost guage.

Have tried using diff KS 3/8 stud sensor listed for SYTY that installs in bolt hole RR of cyl hd. but think is made for 2 KS circuit because resistance diff.
Tapped clutch pivot hole on D side for KS but won't clear headers. Have done usual desensitizing KS. No luck.

False knock? Been thinking this may be prob. Blower rotor brgs loose, rotors rubbing case under load, and etc. This Whipple does not have the rear brg grease fittings my other one had. Other blower ran 30-40000 miles on my 94 Sub with no problems. This blower is there Hot Rod model monted on real short runner (2 in) Roots style manifold. I plummed inj. 90 deg into intake runners beside blower. The false knock issue I don't know what to do about but it will change with diff proms. Ran eng for approx 8000 miles with 8D (7730 1-bar) code that a fellow in FL. made me by doing back to back Diacom runs. Only KS I got was 6-8 deg spike at downshift. (KS decay at 80%)

Rufus,

Have looked at Datamaster to see if could figure out. After looking and reading questions and comments on several forums about it, have gathered couldn't figure out. Also requires win 98 and serial port. Now useing Diacom on old win 3.1 and parrallel port.

If Datamaster will read Diacom files, might be I could load prog on this newer laptop (which won't link with Diacom) and read Diacom runs made on older one. Good info- will be checking today.

Thanks a lot guys. OH-BOY! Something new to try. Maybe can get correct map reading.

 

[Bob H]

Rufus,
Was good suggestion on Datamaster reading Diacom but tried for 3 hrs to download and no such luck. Click on SYTY prog link and just sits-nothing transfers. Did search on Web for anyone else to get from-no luck.

Will try again Sunday.

Thanks
Bob

 

[Rufus]

Bob,

I just accessed TTS download page http://www.ttspowersystems.com/dm_dload.htm and got disk one of the "TT" program no problem. Probably the net was just slow from your location.

Gary

 

[Bob H]

Gary,

Did go back and try again- took over 1 hr but got. Have been looking over some of my Diacom files with DM and am now getting correct map readings. Been checking some files with stock BBZB code on both 7730 and 7749ECMs. O2 readings look higher at WOT than remember. Never saw that duty cycle number before-COOL! Have to check my custom SYTY bin readings in both ECMs now. Surging hardly shows on DM. Must be real small graphs.

Overall looks like a nice program for reading files but don't think will ever scan ECMs with it. Diacom much easier to see when driving and can rearange sensors to group main display. Should have done this months ago.

Starting over again now. Maybe can find someone now with DM that can read my files and make me a TY bin or memcal that would be in ballpark.

Also noticed KS sigs on files so far look lower than were on Diacom, don't know how.

Thanks to all and esp. Brian for help and incouragment.

Bob

 

[Rufus]

Bob,

The version 341 of datamaster is using the full 16-bit value of the knock counter. Previous versions (and Diacom) just use the upper 8-bits of this value. This is why you see more counts. You'll also note the value increases in bursts of 100 or therebouts, this is normal.

Gary

 

[Bob H]

Gary,

Just have never seen term "counts" on readings before. All I am familia with is knock retard in timing degrees that I use to compair to advance vs ref or total advance and fuel delivery for causes. I have read on hear guys referencing KS count which runs right over my head. When discovered on DM, don't know what is used for. I assume all I care about is knock retard degrees. I guess I have been spoiled by an easy scanner since got back in 94 to try and fix my trucks.

Right now am just fumbling around to see if KS goes away. Can not seem to correlate any perticular changes to do it. Have tried fuel up and down, timing up and down, boost up and down, projection TV contrast up and down, opps. Guess you get the idea. What a pain!!

Thanks for the info and have a good one,

Bob