Overnight the weak spark issue kept playing in my mind, so I decided to trade the Opti out. It seems like quite a few people return their eBay Opti to AutoZone in place of the Duralast. Had to go through their entire stock to find a “genuine” one. At some point I will get a Petris, I know. But this was an easy call to at least get one that might have been made to some standard.

It took a good bit of the gas pedal, but it started again. I noticed #7 cylinder before this, the injector was just plain on, so the injectors are absolutely getting some attention before this becomes a driver.

I’ll try and let my son hear it later today before I do indeed pull the plugs. And we can figure out how many cylinders this is running on, etc.

 

Now run the log including the complete cranking, startup, and idle. I want to compare to the earlier logs.

 

I was going to get started on the plugs first thing, but I suppose I can push that back. Won’t be a very long log, the temp sensor gets angry quick.

Son got it started first go tonight, only a bit of gas to help it along.

 

Main thing I want to see is the cranking.

 

Took me a bit to get it started up this morning, before I remembered it does not like the temp sensor on the water pump hooked up. In this run, the MAF isn't hooked up either, but it started both times yesterday with it connected. My fault for not remembering what combo it was. So if I've been following along correctly, the engine doesn't like the "normal" trim setting as it thinks it is too lean. The car will also not want to start back immediately after you shut it off, although with what the head temp is reading, I'm not sure I want it to right now anyway.

So it wants to be cold, and it wants to be rich. Successful crank starts around position 2600 if you're viewing in Scan9495.

 

I'm having a problem following all this.



You just went to Auto Zone, bought a new Opti..... and installed it??????



What does this mean? How did you determine #7 injector was "on"? Do you mean it was wide open?


The main difference on the new log was you actually got an MAF reading briefly. Then DTC 48 for the MAF sensor set, and the engine started. Appears that by the code setting, the PCM was able to default to speed-density and was finally able to get the fuel right. But with the CLT and MAF sensors not connected, I have no idea how it calculated target idle speed and injector pulse width.

Before it started, the slow cranking was producing the same low RPM readings.... but the fact it has always produced RPM readings would indicate the Opti has been working all along. I'm not sure why you keep dwelling on the Opti, and feel that somehow that is producing weak spark? It either produces a low res pulse pattern, or it doesn't. If the spark is "weak" it's a function of the downstream system - ICM, coil, weak battery voltage, wires, etc. Before when I mentioned weak spark at the pugs, you corrected me:



I'm getting confused.

 

Yes? Before I button up the car I'll locktite the rotor screws. I have more time than I do money to burn, and if at any point it were to fail, I can get my money back and order a better one.



When I turned the car to run, I heard a noise coming from the engine bay, and traced it to #7 injector. Removing the harness stopped the noise, which sounded like it was just spraying fuel into the cylinder.


If you are referring to the log I posted today, the code set because I physically removed the MAF sensor plug. DTC 15 was set because I physically removed the water pump sensor. I don't know how it got the car started either, but those are the parameters.

The no-name Opti concerned me, so I opted to make sure I got one that was actually made for Autozone. I know Duralast doesn't have a great reputation, but I wasn't in a position to order one from Petris at the moment, and I wanted one that may have been made to at least some standard. It does work, so I'm not concerned with it anymore - which was the point. I can now put attention on other items. It cranks, it starts, it doesn't shut itself off at least in the minor amount I've had it running. Now I'm going to make sure the compression doesn't hold any surprises for me, then I can work on why it doesn't want to start with the temp sensor hooked up.

 

So after you changed the opti your not getting a DTC 16 and it is starting now, interesting?

 

I guess sometimes your gut matters, too.


After I put loctate on the rotor screws (which it appears had already been done to some extent), I lost track of the plug wires on the pass side. Even paint marking can only do so much when it wears away. I re-ran the plug wires and secured them, and wanted to test-fire again before the water pump went on. It's a good thing I did, because it was taking quite a bit of gas to get it going today. After my usual 20 seconds or so, I saw quite a lot of smoke. More than last time. I discovered the firewall was glistening behind the intake.

Thinking back to what Injuneer had said, I took a paper towel and wiped some and discovered it was gas. The entire front of the EGR was wet, so I'm going to start looking at the regulator. This might explain some of the symptoms like having to really get the foot down to get it started. I'll have to get a mirror back there while my son starts it to be sure.

Just another step in the process, I guess.

 

The problem analyzing the data logs is not having a narrative of what changes you are making during the log. I have to guess whether the code set because the sensor failed, or you suddenly decided to disconnect it. There's just too many changes being made at once.

The first semblance of a start (reaching 619 RPM) occurred at the same instant the MAF sensor readings appeared. Then you made 12 more attempts to start, and nada - nothing in the MAF sensor column. On the 13th attempt (after the 1st "start") it appeared to try to start reaching 575 RPM only after the MAF sensor in the log shows a reading.... but in this case it is the number I have seen with the MAF sensor disconnected (470.62 g/s). What did you do on this crank that was different than the previous 12? On the 14th attempt it actually starts, and runs, reaching 2,985 RPM. And the real "start" occurred only when the 470.62 grams/second MAF reading mysteriously appeared.

Are you saying the passenger side plugs were not connected in the correct order? Was that before the new Opti or after the new Opti?

 

To be honest, I don't know the changes I made a few days ago. I can be fairly bad at that, seeing a goal and just trying to achieve it.

My intent was not to have all those attempts on one log, just to give you the successful one. The successful ones I have seen so far are MAF connected, CTS disconnected. Lots of gas, but now I have an idea of why that last one is at least. I did discover that I have some cracks and ruts in the intake elbow where the two clamps go, so I'll need to get a replacement. I have held off for the time being until I decide what route I want to go, because I am also missing a connecting piece past the MAF to the airbox. I have the baffle that attaches to the fan shroud, but I think I need a rubber connector. I have no idea if that fully explains the MAF readings. This is a new sensor, but the old sensor without a screen wasn't showing anything before either.

Plugs were in the correct order the entire time, thanks to using a paint pen to mark the new plugs before assembling. Unfortunately those wore off when I was putting the cap back on, so I had to double check. I'll have to use some tape or something for the next time.

I'll probably fix the fuel leak before I put the water pump back on, and see if starting is easier.

 

I put a mirror back there this morning and had the car cranked. To my immense surprise, it started up immediately, so I didn't see the fuel leak I was expecting. Unfortunately I witnessed a horizontal line of something being shot at the firewall. So I have the intake leak. I could also have a fuel leak, but I can investigate that in the process of fixing this. The fluid that shot out looked almost white, but it's hard to tell. So, it's looking like the heads are going to have to be pulled as well. I'll have to determine how comfortable I am doing this. I think I'm capable, but I also have to consider my situation. I'll be doing a lot of research as well, I know fixing the intake leak is well within my ability.

I guess the plan is to put the water pump back on and the fans, so that I'm concentrating on one thing at a time. Then I'll change the oil, and determine exactly the condition there. What was on the dipstick looked fine, but I don't know. The oil could have been changed and it not run again with coolant in it until this time. And since I have not cranked it with any coolant running through it, I have no evidence to make a diagnosis. I'll have to assume the worst to have the best outcome, I guess.

After I'm ready to proceed, I guess I'll take the intake off and see what it looks like.

 

Does it make any sense to pressurize the cooling system with coolant and the plugs out to see if coolant is actually getting into the cylinders first? I'm not going to damage the engine more than it already is if there is a leak, but if it turns out there isn't one it would save me a lot of time and effort.

 

Might as well keep this as my build thread. Can you change the title to "Project Steal - A $1250 Z28 rescue"?



We put the cooling system back together today. New water pump, new coolant temp sensor (after we couldn't get the old one out of the old WP). I looked at the seal installed in the engine, it looked great - I think it had been changed recently and was in great condition - I left it for now. Water pump installed as you would expect - new gaskets, sealer, new O-rings. I didn't realize you should change the coupler until way too late, and there was some mixed opinion on that. Also retained for now. Air pump back on, I just now figured out the lower hose is supposed to duct into the intake hose. Have to put that on the to-do list.

Pressurized the coolant system, and man did some issues pop up. Thankfully, would rather address now. Fans came back off, and had to fix my own errors, and the ones the POs did. The reservoir would not hold pressure, so I had to go through the radiator cap. Not ideal, but I did get it up to 20psi. The gauge was leaking a bit, and the gauge did slowly lose pressure. I'm hoping it was due to the gauge. No leaks now. Plugs are being pulled tomorrow and I'm cranking it over to determine if there is a head gasket leak to the cylinders. I expect there to be, but hope not. I'll see if there's one to the intake valley when I pull that for the china wall fix. When we released the pressure in the system, I did notice a rush of fluid coming back toward the radiator cap. Hopeful that is a good sign of pressure being maintained in the heads.

One thing I did notice when pressurizing the system was a leak at the steam pipe where I put on a new hose, but didn't tighten it down adequately. This is right at the alternator bracket attachment, which prior to this week was very loose. Perhaps that could have been a source of fluid intrusion, if so that would be great news with it being addressed.

I know the odds are against me, but I choose to hold out a little hope that the gaskets are good, and I just need to fix the intake gasket/seal. Even in auto mechanics, we really didn't mess around with heads. I'd prefer my continuing education to come on a fresh build on a different motor.

Twelve hours or so to find out the truth.

 

Blown head gasket on the passenger side. Coolant coming out of at least number eight while spooling up without plugs.

Time to look at my options.