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I will also still happily take advice about what you would do as a next step, keeping in mind my level of mechanical ability.
I still have the fuel remaining in the supply lines that may or may not be good. The injectors may or may not be not functioning adequately.
Set up a container on the intake where I can observe the injectors and move some fuel through at the same time? How much slack do I have with the rails?
When I had the stock rails I was able to lift them with the fuel lines intact and flip them back on the windshield. Releasing the bracket that holds the hard lines near the FPR is tricky as I recall…. the screw that releases the top of the bracket is on the bottom.
I had a little bit of concerns because DTC 16 showed up a couple of times (out of ten or so cranking attempts). We know what that means. However, I did see someone say on a forum that it can trigger when there is low voltage. I have no idea how accurate that is, but I did get the voltage pretty low two or three times this session so that sounds plausible. It would also account for why I was getting weird readings on the injector pulses, I didn’t think to stop in between and let the voltage recover.
Except for number four harness, I could end up having an issue there still.
I also took the fuel I pumped last night out for a test. I have no idea if I was getting to the bottom of the tank or not, but that gas is certainly flammable. I think the plan is still to try and pump .5-1gal through the Schrader valve to clear the line and remove doubt at the tank. I also think I’m going to pick up a set of reman injectors from FIC instead of having mine rebuilt right now. It’s about the same price. I’ll have clarity and peace of mind in that respect, anyway. This will be after checking to make sure I don’t have any sort of fuel leak at the regulator, I know there isn’t one under the car anywhere. Fuel filter looks pretty recent.
I shot Petris an email, I can get one pretty quick if indeed DTC 16 shows up with good voltage.
Someone shot the parts cannon at this car more than I did, but aimed more like a shotgun. I wonder if these are the stock injectors with almost 180k on them. My assumption is that there were only a couple of bolt-ons done to the car, but I don't know that 100%.
(I then plugged the ITS and CTS in)
Last edited by It's Cochese!; Sep 28, 2023 at 06:26 PM.
I’m kinda having an epiphany that @chevykid may be right about the Opti. I stated that I was getting good spark at the coil, but weak spark at the plugs. Perhaps I should pursue this thought. I’ll note that it took a LOT of starter fluid just to get it to stumble yesterday. Way more than the can suggests.
Before I get into replacing the injectors (and I should inspect them before I do anyway), I should compare the Opti that I took off and the one currently on. Since the WP is still off, this is a trivial task. Maybe I can find a picture of the rotor inside pointing to where the spline should be for reference. Maybe the rotor inside is arcing/shorting and that is why I am getting weak spark. I would think there would be evidence of that if so.
All it costs me is time. Hell, I could put the old one back on and check it with the scope as well.
If you have strong spark at the coil wire, but weak spark at the plugs, seems like it would be the wires. I can’t understand how an incorrectly indexed shutter wheel would cause the spark to weaken after it leaves the coil.
Optical shutter wheel photos - Shoebox is amazing:
I'm going to take a look at your data logs this morning. I opened one on my iPad last night, took a quick look and spotted what appear to be several significant problems. It's just too hard to manipulate the files on an iPad. DTC 16 showed up, for example.
If you have strong spark at the coil wire, but weak spark at the plugs, seems like it would be the wires. I can’t understand how an incorrectly indexed shutter wheel would cause the spark to weaken after it leaves the coil.
Optical shutter wheel photos - Shoebox is amazing:
I'm going to take a look at your data logs this morning. I opened one on my iPad last night, took a quick look and spotted what appear to be several significant problems. It's just too hard to manipulate the files on an iPad. DTC 16 showed up, for example.
Brand new AC Delco wire set. I don't have enough experience to say the spark on the tester at the plug is weaker than it should be, only that it is weaker than it is from the coil.
I'm going down this morning and putting #1 at TDC and comparing where the rotor is on both Optis I have (the one the car came with, I cannot remove the shaft, which is weird - the new one was loose). My assumption is that if it shows the rotor where it should be, then it isn't an incorrect disc manufacture issue, and timing should be correct.
For the DTC 16, it showed up twice out of the ten times, and I thought it might be due to low cranking voltage. I will be happy to upload another log, the battery should be fully charged overnight.
Seemed to me you were using the weak spark at the plugs as a reason to follow up on the Opti shutter wheel being indexed incorrectly. I was just trying to understand the logic that connected weak spark to the misalignment.
Let me look at the 3 logs you posted before running another one.
And also clarify what the difference is between the three logs? Did you make any changes in between? Did you use the same sequence of events in each attempt? Is each one basically the results of cranking the engine trying to get it to start? In each case there is a period where 45 RPM is indicated, twelve seconds into the log I am looking at (3rd of the 3 listed above). The MAP is not changing, which indicates to me that during that initial 12 seconds the engine was not cranking. And the battery voltage did not drop until just before it appears you started cranking the engine again.
You crank the engine for about 4 seconds, closed throttle, appears you stopped cranking, the battery voltage recovers somewhat and the log then appears it was just recording, nothing was happening. 64 seconds later you try craning again, this time with wide open throttle. The log continues with intervals of cranking/no cranking.
Couple quick observations:
Your screen shot above indicates -40 degF for the IAT and CLT sensors. But in the logs (at least the one I looked at so far) both those sensors are working.
The battery being as low as 8 volts is not helping.
Seemed to me you were using the weak spark at the plugs as a reason to follow up on the Opti shutter wheel being indexed incorrectly. I was just trying to understand the logic that connected weak spark to the misalignment.
Let me look at the 3 logs you posted before running another one.
Just trying to follow any leads down a particular path before retracing my steps.
I looked at the indexing on both Optis I have, and after some minor uncertainty about getting TDC, can confirm both rotors are at or very close to the mark on shoebox’s picture. With good signal confirmed, and proper rotor location, I’m ready to move on from the Opti being the startup issue.
I will say that I may or may not have all relevant sensors hooked up on the early logs.
Seemed to me you were using the weak spark at the plugs as a reason to follow up on the Opti shutter wheel being indexed incorrectly. I was just trying to understand the logic that connected weak spark to the misalignment.
Let me look at the 3 logs you posted before running another one.
And also clarify what the difference is between the three logs? Did you make any changes in between? Did you use the same sequence of events in each attempt? Is each one basically the results of cranking the engine trying to get it to start? In each case there is a period where 45 RPM is indicated, twelve seconds into the log I am looking at (3rd of the 3 listed above). The MAP is not changing, which indicates to me that during that initial 12 seconds the engine was not cranking. And the battery voltage did not drop until just before it appears you started cranking the engine again.
You crank the engine for about 4 seconds, closed throttle, appears you stopped cranking, the battery voltage recovers somewhat and the log then appears it was just recording, nothing was happening. 64 seconds later you try craning again, this time with wide open throttle. The log continues with intervals of cranking/no cranking.
Couple quick observations:
Your screen shot above indicates -40 degF for the IAT and CLT sensors. But in the logs (at least the one I looked at so far) both those sensors are working.
The battery being as low as 8 volts is not helping.
No MAF sensor readings in the log I'm looking at.
My mistake for including the screenshot, it wasn't really relevant in the process. Yesterday was more getting accustomed to the software, what it was showing, and also looking up information that it was giving to me. I took that picture (I think to show my mechanic friend - not an F-body guy) what it was capable of. My son left the ignition on overnight, so even the trickle charger wasn't doing much - this was on about ten minutes of jump starting. I will say that the battery, while new and 700CCA, struggles with repeated cranking. I am assuming due to the still remaining friction in the cylinders keeping it from turning smoothly.
#1 plug when I pulled it for TDC confirmation was decently carbon fouled, which tracks. I'll work on getting those cleaned up again.
I again borrowed a fuel pressure gauge. This time I wanted to see how fast the pressure came down after priming the system. Key on, no start. Came up to 40 again instantly. Key off, started dropping. Not by much, though. After 40 minutes it had lost 10psi. After 70, about 15. To me that does not point to an issue with the regulator or leaky injectors, but that's just me.
As I said before, I compared the two Optis I have. The one that came with the car seems like an eBay special. Reflective back case, no markings. The AutoZone one came with a model number, but a search for it only brings up Chinese websites. It does not have the QR code and Duralast P/N on the back, so I'm thinking this is either an old one, or a return scam. However, both timed up correctly, and at least the new one was the one that I ran the scope on. I put that back on the car, verified I still had the right plugs going to the right places, and was done with that.
I pulled the entire driver bank of plugs. Light carbon fouling, only took a shot of carb cleaner to get rid of. Dry. Fuel smell, not oil. Back in they went, with making sure I got good plug contact. After #4 came up the same way, I ended that venture. It was not nearly enough to make it misfire or ground out.
I went around the engine bay looking for anything unplugged, or things I missed. I plugged back in the air pump, just for completeness. Before running another scan I hooked back up the intake tube with sensors. I sat the water pump on the intake and hooked up the coolant sensor. Battery was fully charged (or as much as 20 hours would do). I did see this at the back of the driver fuel rail, what appears to be the EGR solenoid. Does anything plug into this side, or is it just the two vac lines on the other side and the electrical connector?
All that done, I ran two crank attempts on the scanner. It ended up being three, because I forgot to hit scan the first time. DTC 16 immediately popped up. Cleared it, ran another scan. They are attached, and labeled this time.
Last edited by It's Cochese!; Sep 29, 2023 at 03:35 PM.
Why isn’t the MAF sensor working? It needs to be connected, and the elbow installed tight to the throttle body. The PCM looks at the air mass flow, and divides by the target A/F ratio to determine the fuel requirement, and sets the injector pulse width accordingly.
If the MAF DTC 48 sets the PCM ignores the MAF sensor and defaults to the speed-density method of calculating mass air flow. That requires an accurate reading from the inlet air temp sensor (IAT) and the manifold absolute pressure sensor (MAP). Both those sensors appear to be working. But DTC 48 can’t set until certain engine operating conditions are met.
As far as the MAP, it appears to accurately report the barometric pressure (BAR), but with the very slow cranking speed and the closed throttle blades (TPP = 0) the MAP reading seems very high, as if the reciprocating pistons were not pulling adequate vacuum.
Your fuel pressure results are OK, not indicating injector leakage. But leakage is only 1/3 of the issue. The flow rate has to match the injector flow rating. Any gunk internally is going to reduce flow rate and slow down opening/closing. The 3rd issue is the injector spray pattern. It has to place the flow correctly toward the intake valve, and it has to atomize the fuel. In the OEM injectors there is a disc that rises to open the injector and to expose a spray plate that has multiple tiny holes in it. Crud up a few holes and the flow rate, spray pattern, and atomization is compromised..
Why isn’t the MAF sensor working? It needs to be connected, and the elbow installed tight to the throttle body. The PCM looks at the air mass flow, and divides by the target A/F ratio to determine the fuel requirement, and sets the injector pulse width accordingly.
If the MAF DTC 48 sets the PCM ignores the MAF sensor and defaults to the speed-density method of calculating mass air flow. That requires an accurate reading from the inlet air temp sensor (IAT) and the manifold absolute pressure sensor (MAP). Both those sensors appear to be working. But DTC 48 can’t set until certain engine operating conditions are met.
As far as the MAP, it appears to accurately report the barometric pressure (BAR), but with the very slow cranking speed and the closed throttle blades (TPP = 0) the MAP reading seems very high, as if the reciprocating pistons were not pulling adequate vacuum.
That is a good question. It was hooked up properly, only thing missing on air intake side is the filter box. I do see that the screen was removed.
I did have a thought a couple of days ago about possibly not having vacuum, but everything I see it looks like is hooked up.
Last edited by It's Cochese!; Sep 29, 2023 at 06:21 PM.
