Having data issues in a 1227747 $42 TBI conversion from an aftermarket company.
I get data but it does have errors? Then data, then error, then data, then error? Never have I seen this issue in these old ECMs and have no idea where to look?
Did try a known good ECM and even chip, no change?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Mark are you saying that you replaced both the ECM and the prom and still got errors?
I would be looking at a ground issuse first. Make extra sure that the grounds are all correct. It has to be either a sensor or the wiring harness as you changed out the ECM and prom.
Square body stepsides forever!!!
Ground was the first thing I went for, looked to good but took it off and checked. Data looks good from all sensors. Just not sure if I should tune or keep looking for it?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Check ground between ALDL and the ECM/engine block. If this reference ground is poor you usually get a lot of errors.
The man who says something is impossible, is usually interrupted by the man doing it.
I'll give that a check. May have to go over the entire installation as it's an aftermarket harness in a 62 Rambler... one thing I see is the entire system is one ground wire for installation. Seems I always have 2 grounds when ever I build a harness...
Wonder if my O Scope would find some noise on the serial data line?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
I usually reduce all grounds down to a single point when I build a harness, doesn't seem to be an issue for me. I do usually connect the ground on the block near the main block ground or the back of the passenger side head in most installations.
The man who says something is impossible, is usually interrupted by the man doing it.
This ground is to head...
The reason I leave 2 grounds is that is the way TBI harness come from factory and I'm usually rewiring for stand alone harness. Works well to leave them, it's usually front and back of intake.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
most harnesses have 2 grounds a noisy one for all the injectors etc and a quiet ground for all sensors and both located in different places on the block.its a good idea to keep them seperate.i just fixed an engine swap that ran bad that had the earth connected to the vehicle body move the earth and viola sweet runner.you would be surprised what makes an ecu unhappy
Before I start to reinstall and rewire this brand new harness I may just run a new ground for the ALDL?
EDIT: Actually if it's noise... maybe... ahh crap I'd be rewireing all the grounds to seperate... and Six is getting away with one...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Are there less errors with engine off?
The man who says something is impossible, is usually interrupted by the man doing it.
I'll check today, that would lead back to engine electrical noise ay?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
might have a failer with the ecm pig tail.
Just looked at the car again. Not sure why I didn't look yesterday? I preach this stuff to others for EFI conversions... guess I'm just stressed with life right now and not paying attention... Car is very well built and a quick look yesterday showed a very well installed system as well as everything else on car so I wasn't expecting half ass work or shortcuts, there still was not but some simple mistakes.
There some EFI wires close to spark plug wires and alternator power out! Then noticed the ECM 12 volt power wire was run over top of distributor and put a O Scope on it.... 12 volt was spiking terrible! Closer look and spark plug wires are solid core...
He's going to change spark plug wires and re route some of the EFI wiring and we will try again...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Once I was fixing a friends 1996 northstar who kept throwing random transmission codes. Turns out that because they ran the transmission control wires under the rear sparkplug wires, so when the spark plug wire's insoluation deteriorates, it jumped on to the transmission wires and pissed off the ECM.
New SP wires fixed the problem...but really those trans wires should be moved!
1990 GMC C1500, 5spd, 1993 LT1 (ECM 16159278 $DA3)
most of the australian harnesses even have the ignition control wiring run down the inside of the front gaurds and the fuel and sensor wiring run on the engine just to keep them seperated as much as possible then they merge just before going through the firewall.makes for a mess of wires ive grouped them all together with no issues but some people do have issues when they run them all as one harness.
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