Radiator busted, now misfires on cylinders 5 & 4

[jac]

I will do the compression test with the hot engine in the morning as right now I don't have a helper to do it.

BTW, after the test drive, I was reading some more about the vacuum tests on the forum and it looks like just doing the vacuum test by pumping smoke into the boot (where the MAF would connect) is not thorough enough?

Some folks say the vacuum test should also be done where the brake booster vacuum hose connects to the rest of the vacuum hoses.

Is the the marked spot on the photo the place to push some smoke into to test from the brake booster side? I assume I have to block off the MAF side of the boot also?

[80stech]

I've never done a smoke test, but the entire crankcase, not just the intake or boot, is a potential leak because of the "closed CCV." Plus the brake booster and those lines.

[jac]

Well, the weather isn't cooperating today. Gonna have to wait until Saturday ��

[80stech]

If you haven't already, you might try pulling the MAF connector and taking it for a drive, you never know.
It would be a good idea to try to get the trifecta figured out as well.
Make sure the ignition ground wires are in place.

[jac]

Ok, I reset the codes, cleared all the adaptions and went for a ride to warm up the engine and test out the MAF theory.

To start with, the car threw the below codes while doing the hard acceleration. I also recorded it on video here.

246: Secondary Air system Bank 2
Error Frequency: 1
Logistic counter: 40

TCO_ST          14.76 Grad C
TIA_ST          16.25 Grad C
N_32           800.00 rpm
VB              13.46 V
Ocurred before (rel. BZ)      0.20 h

SL throughput too low
The fault is emissions related
Error debounced
Error currently present
Static error

------------------------------------

243: Misfire Cylinder 6
Error Frequency: 1
Logistic counter: 40

TCO             95.25 Grad C
N_32_TOL      6016.00 rpm
MAF_TOL        452.11 mg/stk
MAF_BOL        430.32 mg/stk
Ocurred before (rel. BZ)      0.00 h

Misfire CARB_A
The fault is emissions related
Error debounced
Error currently present
Sporadic error

After that, I parked the car, shutoff the engine and reset the errors. then I proceeded to disconnect the MAF and drive back home. The moment I turned on the engine the DME threw the below error, lit up a cogwheel with an exclamation sign on the dashboard, and the car was not exactly limping/rough, but it did feel off, so I did not push it, I just drove home.

8: Air mass meter
Error frequency: 1
Logistic counter: 40

N_32         1248.00 rpm
THR            13.29 Grad TPS
ISAPWM_ISA     42.58 %
VMAF           0.00 V
Ocurred before (rel. BZ)      0.00 h

KS --> Ground or interruption
The fault is emissions related
Error debounced
Error currently present
Static error

Also, after getting home I started to do the compression test, and guess what, that darn gauge tube broke, leaving the connector inside the spark plug hole. Luckily I started with cylinder #1, so I was able to use a pair of long pliers to unscrew it and get it out.

Anyway, I had to go buy another compression testing kit. By the time I got back, the engine was no longer hot, just warm. Nevertheless, the new compression tester gave me these results (I only let it turn over 3 times on each cylinder):

Cylinder compression test (warm engine, not hot, 3 turnovers per cylinder)
1: 160,  2: 150,  3: 150,  4: 155,  5: 165,  6: 150

I am feeling a bit better about it NOT being a catastrophic failure or anything like that and more like an air leak somewhere or the MAF giving bad readings.
. What do you folks think? Wishful thinking?
I am going to clean the MAF and see if that helps, if it does not, then I am going to take off the air intake and examine every vacuum component/hose on this thing.

[80stech]

Don't drive it hard when trying figure this out. The compression looks fine though so that's good but one thing that sometimes doesn't show up with a compression test and can be a bit random is worn valve guides, worn cam as well but that should be really consistent.
If you are setting misfire codes when driving normally and not when you are driving normally with the MAF disconnected then that helps. If you need to drive it hard to get the misfire (the one code was set at 6000rpm!) that's a clue too and probably not related to a vacuum leak but if you try too many things at once as far as driving goes it's going to be confusing.
The only way to be sure about the MAF is to replace it with a known good one.

[jac]

Thanks for continuing to help! The misfires only show up when driving it hard. If I drive it normal, the misfires don't happen, but instead the gear shifting is a bit delayed than normal and so the engine feels weird (underpowered a bit, but not wobbly).

I was only driving it hard so I could have the codes show up and then compare what would happen with the MAF disconnected.

The car used to switch gears much earlier. As you saw in the video, on the hard driving, it does not advance to the next gear until it hits 6000 rpm, and that's when it throws the codes (SEL comes on).

Yeah, I know the MAF can really only be debugged with a known good unit, which means I gotta buy a new replacement Bosch unit. Sigh. I am going to try cleaning it first before doing that.

[80stech]

If the misfire only happens at high rpm it could be something in the valve train, bad valve guides, slightly bent valve or maybe even weak valve springs which maybe fits at least a little bit into the overheating. I would concentrate on trying to get it running properly, and without codes without revving the crap out of it for the time being. If you haven't already, you could try disconnecting and reconnecting the connectors on the DME, trans controller and ABS (disconnect the battery) a few times to help eliminate oxidized connections.

[80stech]

Any progress? Hopefully you driving it a little less enthusiastically for a while to see if that gives some more clues.

[jac]

Sorry for the lack of updates. I have not made any progress on it and I also have not been driving it.

As my luck would have it, the vehicle state registration on it expired and so I am not able to get it registered because of the issues it has, but I also can't drive it (except around my small neighborhood) much to test... arghhh...