Fortunately for you, the 8051 and 1333 PCMs are incredibly robust pieces of engineering. They don't have the same tendency to degrade over time that the earlier TPI ECMs had. In addition, thanks to Flashhack, your chances of bricking one while flashing it have been reduced to almost 0 (versus using TunerCat or JET where you actually have a fairly high chance should something go wrong mid-flash). With Flashhack you could even accidentally knock the cable out and spill coffee on the laptop and you'd still be able to recover.

 

Stupid question here maybe.

In the VATS scaler in TunerPro it says x = enabled. In the window there’s a block with a check mark. Is that what they mean by x? In other words, box checked = x and thus enabled? Then, un-check = disabled?

 

I'm not sure what you're looking at, but yes, 'x' refers to the check mark. So un-checked would be disabled.

 

Multiple things I’m finding are gradually improving the situation.

1. Brake booster is leaking and so we’re the pcv grommets. Bypassed temporarily and confirmed improvements in fuel trims.

2. I’ve got fluctuating voltage at the injector power leads. Between 1/2 and 1 volt. Whenever it drops its only for an instant but that’s when the idle stumbles. The feed for these is coming through the Malibu original ignition wiring so maybe there’s a fault in there somewhere . My plan is to add another relay to the mix. In addition to having the Malibu wiring ignition feed power the injector circuit, I’ll also have it trigger a relay that will provide direct battery voltage to injector circuits whenever the key is in run position. A sort of redundant system that will ensure maximum voltage with minimal fluctuations on the injector circuits.

 

If you haven't already, I would also check the rubber line that goes from the throttle body to the CCP solenoid, and the one that goes from the CCP solenoid back to the hose next to the blower motor that heads back to the charcoal canister. If it's never been touched, it's probably rotten and leaking.

 

First off, I really appreciate you helping me, thank you very much!

The CCP solenoid has been removed an the vacuum port at the throttle body has been capped so theres surely no vacuum leak there. BTW, I had previously cut the CCP harness plug off and tucked the loose wire ends into the harness loom and removed the solenoid because I thought it wasn't needed. I now looked back at your review of the tune parameters and see that you mention the CCP being left functional in the tune and that it was for a reason. Ive been getting no DTC’s related to CCP. The only DCT I get is #18 for injector circuit and that only pops up when I unplug an injector while the engine is running. I just clear the code and continue.

Is it possible that because I removed the CCP solenoid that its contributing to my problem with engine miss, idle stumble and random pop in bank 1 exhaust? I still have the CCP solenoid and plug but I'm not sure if I have the Camaro canister. I'm not sure exactly how I would connect it to the stock Malibu charcoal canister. Should I try and trick the PCM into thinking the CCP stuff is present and functional somehow?

Another weird thing is happening. The fuel pump prime time length for KOEO, is initially normal at about 2 seconds in length. At some point after the engine has warmed up really well, the pump prime will be much longer. I can turn the key to the on position with engine off and the pump will prime for like 30 seconds or thereabout before shutting off.

Again, the engine runs smooth and idles nicely with smooth exhaust pulse from a cold start. It does not start acting up until sometime after running for a while and not exactly when it enters closed loop, but well after that too. Vacuum at idle is good at over 20 hg throughout. When it begins acting up, the idle drops slightly and stumbles slightly and the exhaust pulse gets fluttery on both sides, with an occasional moderate pop from the drivers side

As I gradually improve this and that, the BLM has come down a little and the spread between bank one and two is narrowing. Still showing more lean in bank 1 though, which is the side the exhaust popping is happening. Getting better though, little by little.

Im gonna fiddle with it some more but at some point today I plan to turn off the vats on my space PCM from the Fleetwood and see how it behaves with that PCM controlling things.

 

Edit; I just discovered that the longer fuel pump prime time only happens when the ALDL cable is plugged in.

 

If the CCP circuit has failed, it will set a DTC 26. However, your tuner disabled DTC 26. The code should still be operating, though; if the BLMs update as expected, then the code routine that interacts with the CCP duty cycle is operating normally.

Just plugged in, or when EEHack is connected? There's an important difference there.

 

Just plugged in but not while any program is open. I have not tried EEHack yet but I will soon. I'm still using the antiquated Scan9495 to read live data. However, I've have used Flashhack to pull bin from the spare PCM. I then used TunerPro to turn off the VATS. Flashhack to rewrite the bin onto the spare PCM and it now runs without cutting out. I re-flashed and took out a bunch of stuff that was throwing the codes for the stuff not relevant to my application and also lowered the fan on temps a little bit. So that's good news that I'm now able to pull, modify and reflash bins.

The Fleetwood PCM ran the BLM's with very little split from bank to bank but it was adding even more fuel than the other PCM. Maybe that's because the Fleetwood injector setting is correct for factory 24's, unlike the tuner setting who had it a bit higher on the other PCM. So, the spare PCM is also recognizing a lean condition and adding fuel to compensate, its just that the data reports a larger compensation due to the difference in the injector setting. Does this make sense? I have a pic below of the BLM's on the spare PCM.

I'm beginning to think I messed up an intake gasket change and that is what my problem may be.

Here's some more history on the matter. I wanted to put the 1.6 roller rockers on so I pulled the valve covers. I was shocked what I saw. Gunk / sludge!!!! You know the crap that builds up from lack of proper oil changes over a long period. I've seen it in smaller amounts before but this was alot. It was too much to ignore and just about blocking the drain back holes. I had no choice but to clean it all out as best I could, including pulling the intake and cleaning out the lifter valley. Long story short I made quite an effort and cleaned it up pretty good.

Anyhow, I may muffed up the intake gasket install. I used a Fel-Pro 1284 steel core with the printed seal bead around the ports. I usually spray a thin coat of copper coat on these for good measure but I could not find my can of that stuff. Instead I grabbed Ultra Copper 81878 RTV I only used a thin skim coat around the ports, even though I was questioning the need to use any at all. I followed tq specs and sequence in the installation process, this is not my first intake gasket job and I dont remember messing one up before. But maybe the RTV messed it up or maybe the gasket slid out of position enough to be a problem, or both. Either way I'm gonna redo it so if anyone has any tips how to ensure not messing it up I'd appreciate it. If you have a specific gasket to recommend I'd like that too.

I thought I had messed up the rocker arm adjustment initially and maybe made them too tight so I redid that and went 1/4 turn past zero making sure all the adjustments were done while lifters were on the base circle of the cam.

I did a cranking compression test and all cylinders are 150psi give or take 2 or 3 psi at most difference between any of them. With these numbers am I safe to assume no major mechanical head gaskets or leaking valves?

Here's a snap shot of the BLM's on the spare Fleetwood PCM

 

I forgot to prop the throttle body open on the compression test. Maybe I'll get higher numbers if I do the test over and prop it open

 

150 PSI seems a little low. Normally I'd expect something like 180. Also opening the throttle body is more about setting the PCM to "flood clear mode" than it is actually affecting mechanical compression. It makes sure the injectors do not come on. This is programmed into the PCM--any TPS over 80% will set the PCM to clear flood mode and turn the injectors off when cranking.

I don't have any recommendations for you on gaskets as I haven't done that job myself yet.

 

I think my compression gauge reads low. I’ll check a cylinder on the vette and compare. At least the reading across all 8 are consistent. It would be odd for that on a worn engine. You would think there would be some differences between the cylinders. Mine are really even.

Furthermore, if I had a worn engine I’d imagine it would act up consistently. This engine is smooth and normal until it warms up really good. Not until substantial time after reaching full operating temperature does it begin to act up. In addition to the symptoms I’ve already described, when it’s acting up, is stumbles off of idle when you thump the throttle. But if gradually bring the rpm up to 1500, you can thump it from there and it revs up quickly without stumble.

That’s what has me leaning towards intake gasket leak. One other thing I might try is isolating the ignition module and coil from the head. I’ve seen some discussion that heat from the head soaking into the module has caused some people problems with ignition missing after the engine warms up for a while.

 

The ignition module thing is very much real, but it generally only happens if the module is old, or a new module was installed without applying thermal paste to the backside first.

 

Just curious but does the thermal paste go between the module and head, and actually make contact with the head?

Also, have you heard about people relocating the module or using spacers to provide air gap between head and module, thus preventing heat transfer from the head to the module?

Head temperature can get up there !!!

 

Thermal paste goes between the metallic surface on the back of the ICM and the ICM/coil bracket. The bracket acts as a heat sink.

If you use spacers to give an air gap it will absolutely cause the module to overheat. The people who did it properly created their own heat sink and mounted it elsewhere (such as down by the radiator).

 

I'll do some more research on the module relocation before moving on with that idea.

I have a new set of NKG tr55 on the way and I'll check all the ignition wires to make sure resistance is within tollerance.

Good news on the compression test results. I tested a cylinder on the 96 vette to compare. The vette has under 60k miles and is in very good running condition. The reading was 153psi on my gauge. So that is the same numbers I got on the Camaro engine. I conclude that even if my gauge is reading low, the psi reported is the same as on the healthy vette engine. Its a big relief to discover this :-)

 

Glad it's just your gauge! Good stuff.

Here's a post with an example relocated ICM done properly: https://www.corvetteforum.com/forums...post1599287815

 

Just nabbed this on ebay

Copper heatsink

It has mounting holes in the base and the base is thick enough to drill holes to mount the ICM. In the 79 Malibu wagon application I can mount it on the passenger side fender well.

I'll use spacers and mount it with the cooling fins facing up. The spacers will allow room for the ICM to be tucked in under the heatsink and basically not visible, except for the wire harness coming out

 

This approach keeps the ICM, heat sink and coil as a unit but spaces the whole thing away from the head.

http://shbox.com/1/4th_gen_tech2.html#ICM_cooling

 

Saw substantial improvement tonight although still lean on bank one. I did two things so I’m not sure which or both may have helped.

1. My new NKG plugs are delayed delivery and I could not wait to fiddle some more so I narrowed the gap on my current AC 41-943’s from .050 to .040. My thought was maybe ignition misfires could be decreased if they so happened to be part of the problem.

2. I don’t have the heatsink I ordered yet and I’ll follow through with relocating the ICM when I get it. But, I used spare rocker arm pivots to space the module and coil assembly away from the head. Pic below.

The car no longer pops from the exhaust and the stumbling off idle is drastically reduced if not gone completely. I used EEHack for the first time and I agree it’s way better than the antiquated scan9495. EEHack also reported bank 1 lean with pcm adding 15%. Bank 2 also lean but pcm adding less over there. Cylinder efficiency test has me thinking intake gasket install was botched and that would explain lean conditions towards the front of the engine. When I look at where the intake lines up with the heads on each side, there’s a larger gap on the drivers side. I compared the gaps on the vette engine and they are equal. I think I mis- aligned the intake and or gasket may. I’ll redo the intake gasket and see if the lean conditions are improved.



Gap created with rocker arm pivots. Please excuse messy wiring as things are not finalized yet. It will all be probably routed and secured in the end.

Screen shot of cylinder efficiency test in EEHack