85 K5 Blazer with TBI retrofit

**EagleMark** · 01-12-2014

I'm not sure about $4F... but $42 you also had to change some IAC parameters to add IAC counts to make it work.

The purpose of it all is not to increase RPM when AC comes on! Not to raise them. It's actually dangerous at a traffic light with foot on the brake and AC comes on and RPM increase a little makes you roll into car in front of you... well almost if your not paying attention and increase brake.

**rokcrawlin85** · 01-13-2014

Mark, do you believe this wouldn't be a good way to run it, the way the bin was edited? Is the a/c raise more done by just opening the IAC more to keep the motor from stumbling more than a quicker RPM?

**EagleMark** · 01-13-2014

If it works and the AC is not hooked up to it? It will be fine. I should have been clearer and said it's purpose was to keep idle steady/not lower when AC came on! It's purpose was never to raise idle and make a dangerous... if AC and street truck... situation! Think about it? With the V8 it's really not that big an issue. But on little four cylinder engines it is calibrated much more as AC at idle is a pretty big load on them.

Just saying that with $42 there is more that needs to be done then just raise AC RPM... not sure how $4F will react?

I've seen some rare TBI units that had extra components for raising idle for commercial trucks that had PTO options.

**rokcrawlin85** · 01-13-2014

Ok, good to know. Hopefully it really won't be used unless its in park anyway. I haven't had a chance to burn the latest to a chip to find out, and it will be a while before i post with an update to this case since I'm currently adding a tubed engine cage to the K5. But I'm anxious to get it back together and start tuning again!

**EagleMark** · 01-13-2014

It was great on my 90 Blazer when I had it! 300-400 RPM really made the altenator keep the battery charged while winching, others, from outside. When I was using winch and driving I could control idle up if need be.

But I did have to disconnect my AC from the ECM for above reasons at traffic lights...

**rokcrawlin85** · 01-17-2014

I have a question with regards to how the Dakota Digital VSS would be able to be hooked up to a non-computer controlled 700R4 and output a signal the ecm can use? Would i need to install a reluctor ring on the transfer case output shaft in place of the driver gear?

**dave w** · 01-17-2014

The 1228747 requires a 2000 pulses per mile (2K) VSS. One possible source for a 2K VSS is: JTR http://www.jagsthatrun.com/Pages/Spe...eedometer.html Lots of good information on the JTR website for VSS options!

There are factory applications that use a Speed Buffer / DRAC that convert the 40 pulses per driveshaft revolution to 2K pulses for the ECM.

dave w

**rokcrawlin85** · 01-17-2014

Dave, you made me remember from a while ago i had brought this up.... http://www.gearhead-efi.com/Fuel-Inj...e-do-i-go-with
Now i need to actually get this looked into and see if i have the optical eye, and get a new speedo cable. Now from searching and remembering, the optical eye is not "programmable" like a DRAC correct? So if my speedo is off from larger tires and gears it will throw off the signal sent to the ecm? Also, i've read here that these old ecm's just basically want to know if the vehicle is moving or sitting still? So if the calibration is off, what may that screw up when it comes to drive-ability, or will it even screw up anything?

Edit: it is confirmed. I do have the optical eye on my speedometer

**rokcrawlin85** · 01-19-2014

Bump for info on whether its needed to change the speedo gears to get it reading as close to the real speed as possible, or if running it 7-10 mph off won't really effect the ecm?

**EagleMark** · 01-19-2014

The only thing you need accurate speedo info for is TCC lockup. Since your 700R4 is non computer controlled there's no issues.

IIRC the optical eye on Speedo feeds the DRAC...

**rokcrawlin85** · 02-09-2014

Ok, so a couple more questions with this optical eye, if i'm understanding the threads right, it will be yellow (or brown?) to ECM pin A10, black to ground, and pink/black trace to +12v switched? Also, since this is a retro fit, where would these wires be wired into since they really weren't needed for controlling anything being prior to ECM, ABS, etc? Below is what i have for wires from the optical VSS

1507572_259660920860562_1392387831_n.jpg

**rokcrawlin85** · 02-11-2014

Bump

**Fast355** · 02-11-2014

Originally Posted by rokcrawlin85

Ok, so a couple more questions with this optical eye, if i'm understanding the threads right, it will be yellow (or brown?) to ECM pin A10, black to ground, and pink/black trace to +12v switched? Also, since this is a retro fit, where would these wires be wired into since they really weren't needed for controlling anything being prior to ECM, ABS, etc? Below is what i have for wires from the optical VSS

1507572_259660920860562_1392387831_n.jpg

Yellow wire should feed the cruise control atleast it did on my 83 G20. I simply spliced into it and hooked it to the VSS pin.

**rokcrawlin85** · 07-06-2014

I know it's been forever since I've gotten anything done on this. I finally got the blazer back in one piece (well mostly). I need some helpful ideas of where to start looking for my latest issues with the TBI now that it's back up and running. Its running with a crazy high idle whether its cold or warm. I need ideas on how to go about pin pointing my problem area. I'm suspecting a vac leak, but with it spinning so fast it's really hard to try to do much of anything around the motor. Starting fluid and I don't get along so well.... Any help with ways to track down potential faults?

**rokcrawlin85** · 10-09-2014

Just wanted to see what a custom eye sees with my park and drive idle. I think generally it looks pretty smooth and clean just need to pull some fuel out to help the BLM's. Wanted to know if something else stands out to some of you? This is on a old 1228747 ECM using $4F

Thanks for any replys.