90 Lumina Sedan 3.1 wont start, was repaired for this recently but now will not start again

start
chevrolet
lumina
sparkplugs

#1

((First time it had starting issues Recently))
About 2 months ago my lumina’s engine would die when i pushed down on the gas pedal. After 2 days of trying to fix the issue it would’nt start at all, i replaced:

  1. TPS
  2. MAP/MAT Sensor
  3. Fuel Filter

None of these helped so i sent it to a shop, they replaced:

  1. ECM
  2. Multi Port Injection (All 6 Injectors)
  3. TPS (even though i had just installed a new one)
  4. Serpentine Belt (it broke when they were test driving it after the Repairs were done)

the car would not start even after they replaced the first 3 parts on the list, so the tech looked further at the engine and found frayed and open wires, on the bottom near the front side passenger door, he repaired these wires and the car started and ran.

the only issues i had after their repair was a rough idle while braking and/or when i was at a full stop, the rough idle went away after a few days of driving.

((Current No Start Issues))
A week ago i had what i am guessing is a few electrical issues: Speedometer Twitching and then dropping to nothing while driving, temp and oil light popping on and then off, when the engine was at a good temp and the oil was fine when i had checked the day before.

i went out a few days ago to run some errands and on my way home i turned a corner and when i put my foot down on the gas pedal the car just went “Put-put Put-put” every time i pushed the pedal more than a 1/4 of the way down. i reach a stop sign and being i was in the middle of nowhere and no one was coming down the road for miles i braked slightly and went past the stop sign halfway through my turn the engine died and i coasted to the side of the road, i got out and checked the engine, i had coolant not a whole lot but enough, then i checked the oil and it as far as i could tell it was at the add line even though it had been fine a few days before,(there has been no indication of an oil leak) i re checked the coolant and it looked like there was more in there than there was a few minutes before but i couldn’t be sure, i was able to get the car restarted and headed towards home (about 2 miles away).
at this point i was able to get the car going at around 25-45mph on the next sharp corner i turned the engine died again so i restarted and kept going, it died once more right before i reached the driveway but i was able to coast the rest of the way, once i parked the car i turned the engine off and tried to restart it a minute later and it started again so i left it be and called someone to bring me some oil, when they got to me with the oil i put some in and and it would not start at all.

  1. i checked one of the spark plug wires and it is not getting any spark.
  2. The ground terminal on the battery seems to be stripped
  3. the battery / altenator / starter---- All read to be between 12.15 and 12.36 volts
  4. the head lights, instrument panel and such still turn on properly.

I’m at a loss here, it was just in the shop 20 days ago and now it isn’t working again any suggestions would be helpful, i would prefer to not have to put it back in the shop, if it might be something i could repair from home.


#2

Solved:

The Wiring Harness From below the Coil Packs Leading to the Crankshaft Positioning Sensor was run between the serpentine assembly and the motor (i am assuming the wiring in that area was done when i had the block replaced, whoever wired it that way did not think it out that well) The wiring harness had a stripped wire, we found this out when the engine actually fired up while jiggling the wire. To fix it properly, we bought new wire, a pin connector to connect into the Crankshaft Positioning sensor, insulated heat shrink wire connectors and plastic tubing to cover the wires, we rebuilt the harness and ran it to the sensor on a safer route before reconnecting it, but the car still would not start although it was now actually trying to start and sounding like it was misfiring in the process, we went out and bought a new Crankshaft Positioning Sensor and installed it, the car now runs and drives.

A Side Note: if you attempt to make a new wiring harness to run from your CPS to right below your coil packs, you should twist both wires together like a twizzler from end to end, this is the way the manufacturer does it, you want as little slack as possible between your sensor and its other hook-up just below the Coil Packs. (Although be sure you leave just enough slack so you will be able to move the wires aside if you ever need to) I’m not sure why the wires need to be twisted together like that other than it may be to decrease the wiring distance between the CPS and the hook-up below the coil Packs (it could possibly be the theory of loss of signal the longer the wires are, but don’t quote me on that.)

I hope this helps anyone who has been experiencing similar issues, I Apologize if the way i explained it is hard to understand, feel free to Private message me if you didn’t understand the way i explained how i fixed the issue with my car.

Until Next Time, Happy Repairing^ ^


#3

The wires are twisted together to reduce electromagnetic interference


#4

Sorry you had so much difficulty over what was probably just a wiring harness problem initially. You’ve discovered the hard way that w/modern computer controlled car design, when they work, they work well. But when they don’t, sometimes it can be a bear to diagnose what’s wrong.

About the reason to twist the wires. An analogy would be how a football half-back who has broken free of the first line of defense, then runs down the field, trying to score a touchdown. He’ll rarely run in a straight line, because it could be easy for the defense to knock him down if he did. Instead, he’ll go left, then right, then left, avoiding the defenders. The physics of how wires pick up stray signals in the presence of a magnetic field turns out to be similar, and if the wires go straight, their orientation to the field direction remains constant, and they’ll be more likely to pick up stray, unwanted signals. When they twist, changing direction back and forth, the effects tend to cancel out.

Glad you got the problem solved. Thanks for filling in the details of the solution.


#5

So u think the issue was cps wire which u fixed but than it seems crank sensor was also bad? I am leery of thinking wire harness AND sensor were both bad together? But u say so.