Remember that MAP reports out absolute pressure, not gauge pressure. So subtract the MAP reading from atmospheric and that is gauge pressure (engine vacuum).
here is a local forum thread on this topic. has some links to other threads with pictures of my setup.
https://www.gmsquarebody.com/threads/lmc-truck-150mm-headlights-for-my-1989-burb-led-bulbs.47142/#post-1003801
I run the LMC housings and diode dynamics SL2 LED in both the high beam and low beam. the low beam bucket needs to be trimmed a little bit at the 6 o'clock position. get them aimed properly and you will have plenty of light.
Tune up parts (plugs, cap, rotor), maybe O2, cat condition, maybe run some top end cleaner through it. Otherwise I don’t think MAP, TPS, CTS, or knock sensor are going to do much for emissions.
TPS and MAP share the 5v signal wire and TPS and CTS share the ground wire. If you verify ground and signal wire are good at the TPS, and the other sensors are not throwing a code or having issues, I’d highly suspect the TPS is the problem. I’d replace with a AC Delco branded one. You may or may...
I would do neither of those. If the worst symptom is a hunting idle, I’d just drive it until something bigger breaks. But I’d exhaust all the other things mentioned first, including getting a cable and a way to see what the ECM is doing. Cable and software, even if you had to buy a computer, is...
I think there is a relay involved. and maybe a resistor. assuming the system is similar to my 1990 burb. I'd check those out before i dug too much further.
Have to look very closely. You most likely have some voltage leakage from cap, coil, coil to cap wire, or plug wires.
Spritzing a mist of salt water around the area may show you where it is coming from. Carefully inspect all plug wires and cap-coil wire for insulation or boot cracks. Carefully...
hope th
hope they get it figured out. sounds like that new TB might have some sort of other issue. hope you also gave them the old one to help trouble shoot.
I know it opens it with key on for sure. It might also open it with key off using the constant power to the ECM, good catch and better safe than sorry. I will edit.
If you are sure the IAC is plugged in properly, you might try:
1) jumping AB on ALDL and turn ignition on for 1min. Disconnect IAC harness.
2) turn ignition off, remove jumper
3) try to start the vehicle
4a) if it starts and idles fine, close the idle stop screw until the the engine just...
When you say “unplug” do you mean the electrical connection or removing the IAC from the TB?
Is the electrical connection tabs not broken so that you are sure the plug is going on properly?
If it is worse with the new TBI, then there are some issues there.
It makes me wonder if the idle stop screw is way out of adjustment or something. But I’d think the IAC would be able to adjust for that, just the counts would be off. If you could scan, you could see IAC counts and have an idea...
Unless the shop has a scan tool, I don’t know what they will do for you if there are no codes.
Seeing what the ECM sees and how it is adjusting fueling is needed to help. And that still isn’t a silver bullet.
If it idles cold fine, but hunts in closed loop, it is something the O2 sensor is...
I’d probably not mess with the base idle until after you have a peek at what the ECM is seeing and doing with fuel. But otherwise,yeah, just hook everything back up and fire it up
For some reason I was thinking that if you run with it jumpered, the frequency of flashes has to do with open vs closed loop. But I might be remembering that wrong.
Sounds like a short to ground of some fashion. Does it blow during cranking or just when you turn to IGN? Have to see what is on that fuse and look for a shiny wire. There are also ways to track short to ground using a meter, I’ve read about them but never done it. I have been lucky enough to...
It doesn’t matter. I have mine always plugged in to aldl. I plug it in to power when I want to use it. Added a plug by the aldl port so I can just plug it all the way in quickly while I am driving.