Thanks in advance for the help, I have a 1999 Suburban I got to use as a tow vehicle and for camping etc.
I am lost if I should keep going down this rabbit hole of diagnostics or if I should just figure out a way to swap it to a carburetor and HEI set up. The third option is just part out the truck, maybe put the motor into an RX7 I have thats waiting for a build, sell the transmission and get something else.
Sorry in advance for how long this post is, but what was supposed to be a simple transmission swap turned into a project. What I hoped would be a couple weekends has ballooned into a project for just over a year, so there are a lot of details (here are the highlights).
If I do swap it to a carburetor, any ideas on how to still run the 4L60E transmission, is the only input I will need to account for the throttle position? I figure I will try to take out the unneeded sections of wiring harness if possible.
Here is the back story:
I bought it for $750 since it needed a transmission, on the way home, engine got added to that list when it threw a rod through the pan.
I had a friend rebuild the transmission and found another truck with an engine that I was told was recently rebuilt (seals looked fresh and it ran well in that truck). I pulled the upper intake on the motor and put in a new set of injectors to replace the spider injectors with the MPFI set up).
My wide and I had a baby so I had a friend pop the engine and trans in as I didn't have time to get out to the work on the truck. I timed it well enough to run (since I didn't have the GM scan tool to set the timing properly). It was running poorly, but there was no exhaust on it and the timing was questionable. I had a dual exhaust put on it at an exhaust shop and they plugged in a few connectors that my friend had missed, hoping getting the O2 sensors hooked up and the exhaust back-pressure might help it run a little better.
The transmission was still not shifting. The servos were good, fluid level ok, all the basics checked out so I brought it to the transmission shop as I was getting sick of working on it. The timing was still off so they wanted to start with that, after setting the timing, rebuilding the valve body and checking a few other items they came to the conclusion that there was an issue in the wiring or the computer. They sold me a new computer and still not right. They eventually found an issue in the park neutral safety switch and got it to shift properly.
When I picked it up, it was not running quite right (misfire cylinder #8, and there was a slight surge). I drove it around for the day doing some errands, then the next day it wouldn't start (power was getting to the fuse in the dash but no signal through the park neutral switch to the starter solenoid. I was able to start it by jumping the solenoid but once it started it ran too poorly to drive, I made it about 1 mile and had to turn around because it was lacking power so badly it wasn't likely to make it very far without breaking down. There was a code for the O2 sensor and the driver's side O2 sensor was unplugged and the connector melted on the exhaust.
I brought it back to the transmission shop as I thought that perhaps there was an issue with the wiring from their repair. The transmission shop thought it was a fuel issue, they checked the running pressure and thought that it was low so they replaced the fuel filter in case it was clogged from old gas (still the tank from when I bought it).
After putting some new gas in the Suburban it ran a little better but was rich on the driver's side and wasn't running very well. I tried replacing the other O2 sensor to see if there was perhaps an issue with the new and old sensor throwing the computer off.
The truck still wasn't running properly, so since the fuel injectors were still under warranty I tried replacing them under warranty. The rich condition moved to the passenger's side then seemed to clear up a little, but cylinder 1 has a dead misfire, I unplugged the spark plug wire and it didn't change the way it was running, and the header doesn't really heat up. I checked the header temperatures and cylinder 8 was only at roughly 250f, whereas most of the others were close to 500f, cylinder 1 was only about 150f.
I changed the distributor cap to see if perhaps there was a short or crack in it. No improvement.
I am lost if I should take the top of the intake manifold off again and try putting back in the old injector set (took 2-3 hours when I swapped it in the car). Any other suggestions? Any way to see if the injectors are firing since they are inside the manifold?
