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Finally got everything in place to try starting this thing. Put 5 gallons of gas in, filled the radiator and power steering tank and put in a new battery. Couldn't get it to turn over with the key at first. I knew the wiring to starter was good because it cranked by
shorting out the solenoid. Used my factory service manual to narrow it down to theft-deterrent relay. Luckily had a spare relay, replaced it and now she cranks. Doesn't start yet. I can hear the fuel pump working, and I just pushed in the schrader valve and there's fuel at the fuel rails. I figure it must not be lighting up the plugs. I'll work that angle tomorrow.
Anyone know what kind of OBD reader will work on a '95? As I recall the 945 is not OBDII compliant. My code reader says it cant communicate with the car.
One thing I do need to fix is the fuel gauge pegged out at the top. Saw a spot in the manual to troubleshoot that at some point. Sure hope I don't have to take the tank back out.
You need either an OBD-1 reader, or a combination OBD-1/OBD-2 reader.
Did you install the 95’s 16-pin OBD-2 “style” DLC socket? If so an OBD-1 reader with a 12-pin connector needs either a 12-pin to 16-pin adapter (Auto Xray made one) or jumper the pins per Shoebox's photo:
Be careful with dual OBD-1/OBD-2 readers. The ones from Innova and Equus have a corrupt database for LT1 engines. They will alway return a set of seven bogus codes, including a few codes that don’t even exist.
At first I thought “48Z28” was a typo, and I figured I’d be helpful and edit the thread title accordingly. But then I saw your username, and I realized that it’s not, so I edited it back. I now understand that you’re putting the engine from a ‘95 Z28 into what I assume is something from 1948. Right? What is it? Sounds like a fun, interesting project.
Looks like I have a 16-pin socket in my '95 wiring. It appears it is still OBD1 so I'll find a OBD1 ready and do the jumper thing. Only 2 wires needed for the scan tool?
Once I get it started I need to put the front calipers on, bleed the brakes, put driveshaft in and then pull it into the driveway.
There is no question that the 1995 LT1 PCM is OBD-1.
Many scanners only need the data pin and the ground pin. But some require 12 volts also. The 94 DLC does not have 12 volts, so you have to provide a12 volt source from the cig lighter or other. In the 95’s 16-pin connector 12 volts is available in pin 16, as shown on the schematic.
Interesting, yes. Fun? Only when things go my way. With a build like this just about everything has to be fabricated in some fashion. On the good side my welding and metal-working skills have improved dramatically, so when I get done with this one hopefully the rebuild of my '75 Camaro-powered '39 Chevy sedan will go smoother
Bought an Innova OBD1 reader. It did not list my 95 as a car it would work on, but I figure that's because it won't plug into the 16-pin socket I have. I made up some jumpers and connected pin 5 (gnd) to what I believe is the ground pin on the reader and pin 9 to the serial data pin on the reader. Turned on key and the MIL just stays on, no blinking. I see some videos saying the use a jumper between the 2 pins on the DLC to get the codes. Not sure I want to do that but don't know what it would harm.
Anyway, I shot a little starter fluid in the intake and it fired! Which leads me to believe the issue is in the injector circuit so I'm working through that now. Getting closer.
Reading through some old posts, I saw this from @Injuneer
"Also, make sure the rubber 90° elbow between the MAF sensor and the throttle body is soundly connected on both ends, has no tears, the plastic silencer tube that runs down in front of the engine is there, the inlet air temp (IAT) sensor is plugged into the elbow and the harness connected, and the bottom edge of the elbow hasn’t slipped off the bottom of the throttle body flange."
I had to remove the silencer tube because there's no room for it. I don't think that would have any impact on my no-start but wonder what the impact will be?
Since this engine sat for 25 years I suppose the injectors may need cleaning or replacing, but I figure if they are getting power at least a couple of them would be working.
If you haven’t plugged the opening in the elbow, you are pulling unfiltered air into the engine. Worse than that, air is bypassing the MAF sensor, so the PCM isn’t adding any fuel to that air.
I did plug the opening because I figured it wouldn't be a good idea to bypass the air filter, etc.
I did the checks in Chart A-3 and also those in another long thread by @It's Cochese! where you check out the connector to the ICM. From what A-3 says I need a new distributor.
My tach registers nothing when I'm cranking it but the engine does fire when I spray in some starting fluid, so I guess there will still be spark even if the PCM does not tell the injectors to work. I'm going to go back through and see how to check the injector pulses. I'm guessing I can connect a test light to Positive terminal and then to the ground wire on an injector plug and if it lights up that means it is being grounded. If that occurs I'll do your suggestion of taking he fuel rails off and see if gas comes out of the injectors.
There cannot be any spark at the plugs if the ICM is not receiving the signal to fire from the PCM. The PCM only sends that signal if it is receiving the required low resolution pulse form the Opti. A reading of 1 to 4 volts AC on pin B (white wire) while the engine is cranking is the proof that the Opti is sending the low res pulse to the PCM, and the PCM is sending the timed pulse to tell the ICM to fire the coil. Doesn't tell you if the spark timing is correct - that could be off if the Opti was not indexed correctly to the cam dowel pin.
Also check for spark at the plugs while cranking the engine.
Possibly the starting fluid is igniting from the compression.
You need a "noid" light to check for injector pulse. There should always be (key on) 12 volts to the pink wire in each injector harness connector. The PCM supplies the ground to fire the injector. Pulse widths can be a matter of "milliseconds". A conventional test light may not be fast enough to show the pulse.
Well, I have no spark and no voltage at the white wire of the ICM harness. I guess that means a new distributor. Should I bother getting a noid light to verify the injectors also aren't firing or just go ahead and replace the Opti-spark?
And, suggestions for a replacement unit? There are a lot of opinions out there about which one is best. I have to take AC stuff and radiator out in order to replace it, so I only want to do it once.
I have the original Delco unit with 30K miles. Should I consider cleaning and new cap and rotor before shelling out the $450 for new Petris unit? I suppose I can try cranking the thing after cleaning and before putting water pump back on to see if it worked.
Depends what's wrong with the Opti. Check for a corroded harness connector - both the connector that inserts into the Opti casing, and the gray connector on the bracket on the passenger side of the intake manifold.
Check to make sure the Opti is receiving 12 volt power, 5 volt reference voltage from the PCM, and has a good ground. That's the second set of tests in the link I posted in post #12.
As far as cleaning, that only works if there is corrosion, oil or some other foreign material interfering with the optical module - could be blocking the shutter wheel or the LED's in the module.
What part of the 41-post ls1tech thread am I supposed to read?
01-11-2024, 07:12 PM
I now understand that you’re putting the engine from a ‘95 Z28 into what I assume is something from 1948. Right? What is it? Sounds like a fun, interesting project.
