Hello Folks - First post on the forum but long time lurker. Canadian owner of a 1994 Pontiac Firebird Formula Lt1.

I have posted about this issue on another forum but I am not getting many response there. I tried documenting my whole story and troubleshooting steps but I think it just got too long of a post for people to follow. I am not sure if I can link to another forum, so for now I won't. I looked through the FAQ and didn't see guidance against it but if a mod/admin can clarify that would be great. I am completely out of ideas but I do have some theories on what my issue could be. I will try and provide everyone with everything I have done/tried to date.

It all started in 2021 when I finally got a good paying job and wanted to get my dream car up an running again. While in university, I couldn't afford to drive it so it say for a couple of years. After doing the basics to get it up to snuff, I noticed it still have some hesitation when accelerating. Long story short, it was a bad opti due to a intake manifold China wall leak. Opti, intake manifold gasket, timing cover gasket, water pump, plugs and wires were all replaced in 2021. Since then, it has been running alright, but still some hesitation when accelerating. At this point I started using Scan9495 and trying to diagnose the problem. While trying to diagnose the problem I learned A TON about cars in general. In search of the cause of this issue, I ended up doing the following mods to my car.

• EGR, AIR, EVAP delete
• Long Tube Headers and Magnaflow exhaust
• Transmission and driveline overhaul with TransGo shift kit, New tires
• Throttle body bypass mod
• New O2 sensors
• Fixed multiple vacuum leaks
• New PCV valve
• Lashed the rockers
• Cleaned injectors with Carb Cleaner
• New plugs - NGK TR55s gapped to 0.45 I believe. 2021 plugs were AcDelco.
• New ICM and Coil (no change, returning these)

I will admit, some of the above things needed to get the engine running in a good state but some were not. I am at my witts end with this issue.
Symptoms:

• Ticking from drivers side valve cover. Not very noticeable at idle, but get up to 1200 rpm and you hear it. Cannot notice the ticking from inside the car. Not rod knock.
• Knock Retard when accelerating or above a certain rpm, you can feel hesitation
• Slight whine when hard accelerating- almost sounds like alternator whine when accelerating and heavy knock retard is observed. (Maybe unrelated, I don't know if this is spark knock).
• Idle Fuel trims are a bit lower at 122 - for you obd2 folks thats like -5%. [(122/128)-1 ]

Some things to note:

• Have not observed blue/white/blank or really any type of smoke out the exhaust.
• I get slight oil mist on my passenger side valve cover after a drive. I don't think this is excessive blowby because my TB is clean and when I take the oil filler cap off it doesn't have much air coming out.
• Always use 91 Octane

Here are my theories now:
1. False knock due to lifter tick. I get a loud tick sound when above 1200 rpm. Can’t hear it from inside the car, but you can when the hood is opened. If it’s a bad lifter, it could have worn the cam too so I will take a look at that when I replace the lifters soon.
2. Something in the valve train is affecting the A/F ratio. Worn rockers, springs, valve seals, valve guides etc. I don’t get the valve seal symptom of black smoke on startup.
3. Intake manifold gasket leak causing oil to be sucked into the intake from lifter valley which would then in turn reduce the octane in the gas causing knock. I ruled out head gasket leak because no white smoke from exhaust and oil in the head isn’t pressurized.
4. excessive blow by. Not sure about this one since I am not getting much air movement when pulling my oil fill cap. PCV is ok, not much oil in the throttle body or intake.


Thanks everyone for taking the time to read my story. Any feedback or troubleshooting things I can do would be appreciated. I have attached a .csv file if anyone wants to take a look.

 

It seems to be some sort of valve train noise. You are correct it happens at rather low rpm under 2800rpm but only during quick Throttle transitions. (Almost like knock burst). I would start with that ticking on the driver side and if that doesn't do it then perhaps try the Knock sensor.

I have attached your original scan and highlighted the knock retard events in red. You can see the pattern of events occurring with quick TPS % changes.

 

Usually when troubleshooting an excessive knock retard problem, putting some higher octane fuel in there is helpful. If you've got a collapsing lifter, that needs to be fixed. And, if it doesn't turn out to be valve train noise, don't overlook the possibility that you could have a header leak causing a tick, and that can also mess up the mixture. And these knock sensors don't last forever, so yours might just need replacing. That wire coming from the knock sensor should be well shielded and protected from the headers and ignition wires, too. Also make sure the headers aren't hitting something when you accelerate. Old engine mounts sag and that can reduce the clearances for things that could make contact when the engine is moving around when its under torque.

 

If I am not reading this wrong..... do you have any runs that are significantly above 2000rpm? I am wondering if this is normal knock with speed vs. engine load. I have known those to become abhorrently obsessesed with knock retard and doing everything imaginable to try and stop it to no avail because it turned out to be normal. You need to put your foot into it and then see what your KR says.

 

Hey folks.

Quick update. I’ve changed so much on this car lately I forgot to mention a few things.

• Engine mounts were replaced
• knock sensor and wire were replaced (with the 94 version)

I haven’t tried the race gas trick yet but I will after I take a look at the tick. The tick is enough of an annoyance to make rip in the intake manifold off so I will let you folks know what I find!

Thanks

 

Reading in more detail... have you ensured all plugs are tight? A loose spark plug can produce a tick especially at idle which can be mistaken for a loose rocker. How clean is the engine? You can use simple green to clean it up and then pinpoint the source of oil spray whether it be from a valve cover gasket or VC grommet or from the dipstick tube.

 

Are you sure you lashed the rockers correctly? I assume you are still on the stock rockers from your list. Can you get a video of it at idle from the drivers side?