I posted this over on the ImpallaSS forum as well, but I know there are some EFI savy folks hiding out in here among the rocks
, so thought I would ask here as well:
http://www.impalassforum.com/vBullet...=1#post1849238
Here is my latest mystery:
I pulled the original engine, harness, PCM, etc. out of a 9C1. That one did not last long after we got it running...
I have a 355ci LT1 long block with a mild cam from Golen. I have been very happy with that part of the equation. I have had some wiring issues, but think I have them licked. Now I have a significant power loss that I am trying to figure out.
Here are the symptoms:
1. Cold starts on first try, idle is a little rough.
2. Driving, I can move along ok, but about 1/2 or 2/3 the power this thing usually has.
3. I can cruise down the highway at 75 without issue
4. HOT Starts are a nightmare! It will usually studder to a start on the 3rd try and roughly catch up, run the RPM's up to 12-1500 and then gradually settle back down to a rough idle
5. While sitting, if I run the RPM's up to 15-2000 and drop off the throttle, it shuts off as iff it can't get back down to idle.
What I have tried to date:
1. First thought it was on the ignition side considering the opti and my recent hunt for and solving a grounding issue.
a. check the plugs ... I expected them to be wet...WRONG! They were gray/white
b. all the same, verified no arcing of wires
c. replace the pigtail on the opti (had a new one in the tool box)
2. Considering the color of the plugs, I headed toward the fuel side of the equation.
a. Fuel Pressure:
1, Ignition on = 42psi
2, Idle = 38psi
3, Pull the vacuum hose off the regulator = 44psi
b. New fuel filter, just 'cause it seemed like a good idea
c. Checked signal at each of the injector connectors (12+V across each)
d. While running, pulled one injector connector at a time and did get a slight response from each as well as a slight response once plugged back in. Not as much of an impact as I expected, but a response..
I must add that this thing sat for about 14 months while I was deployed this last time. Someone in the house was supposed to drive it around the block once a week, but that did not happen.
The engine has less than 5k miles on it. I am running an MSD opti that was installed when the Golen engine went in. It does have the vent system in place. I do not think this is a ignition issue considering the plugs. This may just my attempt to avoid the thought of replacing the opti.. ?
I ran a bottle of techron fuel system cleaner through the last tank of fuel without any impact, but I am not sure that would do much if the injectors are varnished up. Would ALL of them be acting the same?
The only vacuum leak I have found is the opti vacuum hose works its way off occasionally. I am going to put a clamp on it (the connector I used is a little too small for the size of the hose).
So basically, I am trying to figure out what the most probable thing is to go after next. Replace the injectors? Are there sensors involved that I am not considering?
Thanks in advance for the input.
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