ECM upgrade (1227730) for stock 2.8 (Page 66/107)
3.6lvvt6spdgt JUL 07, 06:28 AM
i,ve decided to sell my car and have not put the 7730 ecm unit in it.
i have almost a compleat turbo kit, that i was going to install into my car. but baby forces sell
i will sell all my 7730ecm and turbo parts including injectors for 1500.00 obo
i will sell the car and all the parts i have to the first 6500.00
here is my build thread http://www.fiero.nl/forum/Forum2/HTML/087040.html
Darth Fiero JUL 07, 02:14 PM

quote
Originally posted by Daviero:

About the 7730 and the speedo....
My speedo registers about 40mph at a walking speed, and bounces off the pin if I go much faster.
I am running a 7730 ECM reconditioned by Ryan Hess for a Northstar and have implanted a Quad-4 differential into my 5 spd Getrag transmission. I did not keep the Fiero VSS and opted to use the reluctor VSS from the Quad 4 leaving the notched wheel on the new diff. I have wired the ECM and the VSS per Ryan Hess' diagram, which is exactly the same as info in this thread and on Darth's site as far as the VSS goes. I rung out all the wiring to confirm correctness, and found that I had grounded the speedo low wire (purple) on the chassis ground near the ECM (G503 I think?). I removed the ground but the problem prevails.
I am running the buffer circuit, powered by C203-F, but cannot check it since I cast the wiring like a circuit board for mounting puposes. The only check I have left is to replace the buffer with a new one to confirm correctness, but I am confident the one that is there is correct.
What might be causing the problem? Do I have to flash the ECM for a different pulse ratio?
Dave




Yes the chip in the ECM needs to be reprogrammed with the correct VSS pulse ratios for your application so your speedo will work correctly.
Darth Fiero JUL 07, 02:22 PM

quote
Originally posted by TiredGXP:

Hey Ryan,

I've been thinking about how speed density (SD) systems are sensitive to temperature changes, and the difficulties involved in properly adjusting bias values to help compensate for changes in intake air temperature. When running a MAF system, the MAF seems to handle air density changes due to termperature fluctuations much better than SD.

Are there any code masks out there for the 7730 that are compatible with a 3.1 DIS with both SD and MAF?

Cheers



Back when the 7730 ECM was first introduced, both a MAF and a MAP sensor were used. But GM had many problems with those very early MAF systems used with these computers and came out with the "Speed Density Update" which basically disabled the MAF sensor. With all the drivability problems they had with those early MAF systems, I would not attempt to retrofit one of these systems to use it.

Instead what I would do, if you have a new enough engine, would be to use a 1994-95 3100 A-body PCM which is MAF based, or step up to a full-blown OBD2 computer from a newer year. Trouble is all of these systems require a Cam sensor and 2 crank sensors. And I don't think there are any parts available to make a stock Fiero 2.8 or like engine compatible with these systems. Just FYI the 1993-95 iron-head 3.4 F-body V6 does have all of these sensors.
Darth Fiero JUL 07, 02:27 PM

quote
Originally posted by OH10fiero:

From here on the forum I clicked on your homepage link and went to general swap info, the only two links that did not bring up a seperate page under that heading were the two links regarding the 7730 info. I wanted to view both pages to see what info I needed before caontacting you on a custom chip.



Both of the following links on my "Fiero Engine Conversion Info" page should bring up / display a .PDF document showing the wiring instructions for the 7730 ECM swap (but that is ALL that is shown)...

"How to wire up a 1227730 ECM to your stock Fiero 2.8"

"How to wire up a 1227730 ECM and DIS using the stock Fiero V6 wiring harness"

I don't have any pictures or instructions other than the wiring instructions linked to from those headings. If you were looking for a step-by-step instruction page with pictures, sorry but I don't have those at this time.
TiredGXP JUL 07, 08:01 PM

quote
Originally posted by Darth Fiero:


Back when the 7730 ECM was first introduced, both a MAF and a MAP sensor were used. But GM had many problems with those very early MAF systems used with these computers and came out with the "Speed Density Update" which basically disabled the MAF sensor. With all the drivability problems they had with those early MAF systems, I would not attempt to retrofit one of these systems to use it.

Instead what I would do, if you have a new enough engine, would be to use a 1994-95 3100 A-body PCM which is MAF based, or step up to a full-blown OBD2 computer from a newer year. Trouble is all of these systems require a Cam sensor and 2 crank sensors. And I don't think there are any parts available to make a stock Fiero 2.8 or like engine compatible with these systems. Just FYI the 1993-95 iron-head 3.4 F-body V6 does have all of these sensors.



Thanks. Based on my set-up it looks like I'll be staying with a SD system. When I'm a bit further along with the engine build I'll PM you about getting a "starter" chip burned.

Cheers
Blacktree JUL 07, 09:43 PM

quote
Originally posted by mswenson289:

Ryan:
86 SE 3.4 4T60 7730 with EGR mod. Still fighting multiple issues so they may be related, I just don't know. At startup idle is about 1250 constant for 6-10 seconds then smoothly lowers to 900 as expected. After driving awhile hard downshifts (might be related to needed the adjustable modulator adjusted on the tranny) when coming to a stop idle is at 1300 till it comes to a complete stop like it is watching the vss signal and at 0, idle goes to 900 cough's, idle goes back to 1300- 1500 and the whole car surges a couple of feet. It is possible to do this upwards of 6 times for one attempt to stop, but mostly after the surge it returns to 900 and idles sometimes it just dies. If you slap it into neutral on your approach to a stop it will search a little but seldom dies. No error codes. I have cleaned IAC passages and TB. Disconnected TCC, have looked for a vacuum leak cold and warm. Does the ecm wait for the vss signal to stop assuming load is removed? Any ideas?
Mike


The first thing to come to mind is to check the throttle body, and make sure it isn't sticking partially open at idle. Mine was doing that, and it caused similar problems.
Daviero JUL 07, 11:06 PM

quote
Originally posted by Darth Fiero:


Yes the chip in the ECM needs to be reprogrammed with the correct VSS pulse ratios for your application so your speedo will work correctly.




I was hoping that would not be the answer Ryan. Is the reluctor VSS still 4000 pulses per mile? I have bought a chip burner but have not used it yet and still need the software. I'm not looking forward to learning how. I know you have some info on your site though. Wish me luck?

------------------
Daviero - 88 N* GT

Pyrthian JUL 07, 11:25 PM
I am noticing a weird thing after my 7730 swap. I am assuming it is happening because the car I got the ECM from was an automatic. When I am driving along, and come up to a light, and push in the clutch, or roll in neutral - the idle surges up & down until I am under roughly 20 MPH.
OH10fiero JUL 08, 03:02 AM
The only pics I was expecting was any mods that you mentioned on the additon grounding, but to get back on topic I donot even get a option of a PDF download from those links. I will try a friends computer next week and see if I get any luck out of that.


quote
Originally posted by Darth Fiero:


Both of the following links on my "Fiero Engine Conversion Info" page should bring up / display a .PDF document showing the wiring instructions for the 7730 ECM swap (but that is ALL that is shown)...

"How to wire up a 1227730 ECM to your stock Fiero 2.8"

"How to wire up a 1227730 ECM and DIS using the stock Fiero V6 wiring harness"

I don't have any pictures or instructions other than the wiring instructions linked to from those headings. If you were looking for a step-by-step instruction page with pictures, sorry but I don't have those at this time.
americasfuture2k JUL 08, 06:00 AM

quote
Originally posted by Pyrthian:

I am noticing a weird thing after my 7730 swap. I am assuming it is happening because the car I got the ECM from was an automatic. When I am driving along, and come up to a light, and push in the clutch, or roll in neutral - the idle surges up & down until I am under roughly 20 MPH.



i believe that is from the 7730 looking for an auto since it came from an auto car and now it doesnt see one. i swapped my 95 taurus to the SHO MTX-IV, and i had similar problems since the car was originally an auto and i had not changed the pcm/ecm or whatever fraud calls it. but my engine was stalling with every stop and everytime there was no load on the engine or the throttle was off.