Background...I left the radiator cap loose one day after checking my fluids, and my son drove the car next. Boiled off the coolant, and blew the head gasket (constant air in radiator hose after refilling, air bubbles from under upper intake manifold). Car ran fine before this. Did my first ever head gasket replacement, based on lots of youtube videos. Went fine. Re-assembly took a while because I didn't take photos of where each plug of the wiring harness went. But finally found a home for all the plugs. Broke the vacuum hose for the purge valve solenoid & replaced with some clear air hose. Other than that, no issues re-assembling.

Now I start it, and it'll catch and run for maybe 2 seconds before dying. It sounds normal, up until it dies. If I start it with the accelerator all the way to the floor, it'll run (poorly) for maybe 4 seconds before dying.

I know that it must be something I did wrong in the re-assembly, but where do I start? I have no idea how to even diagnose something like this. Any ideas on what I can check first?

I'd look at the MAF sensor first. See what it does when you disconnect it.

I pulled the plug on the MAF, and it ran normally for a minute or two before it started to sputter a little (probably from having the MAF disconnected). So, that it encouraging.

But why would the MAF be the problem? It was fine before the overheating incident. And this MAF is only a year old (though it is a cheaper chinese part and not the more expensive OEM MAF). I cleaned it with MAF cleaner, plugged it back in and the car went back to dying after 2 seconds. Unplugged again and it runs.

Cheap Chinese MAFs can cause a myriad of issues. The best choice is either a clean junkyard MAF or a HITACHI from Amazon. Hitachi is the OEM for these throttle bodies. The name HITACHI is stamped on the side of the throttle body. If you look on Ebay you can get a junkyard MAF for about the same price as the cheap Chinese junk. I got burned by trying to go cheap so I speak from experience.

Thanks! I'll get one and see what happens.

This should run with the MAF unplugged.

UPDATE: I cleaned both the old, OEM MAF that I still had, and the replacement chinese MAF, and neither would allow the engine to run more than 2 seconds. But with the MAF unplugged, it cranks and runs. I ran it for about 15 minutes today. It idles rough below 1500 rpm, and has a clatter that it'* never had before. I took a video of it, and you can see the tensioner pulley jiggling the whole time. I'm assuming that clatter/rough idle is due to it running without a MAF. Going to get a new OEM one from rockauto.com and see if that does the trick. I've learned my lesson with the cheap knock off parts.

Here'* the video of the engine running/tensioner with clatter:

You Tube

Thanks for everyone'* help!

Pepper...

Buy a new OEM airflow sensor.

Do we know then this engine is timed properly and no spark plug wires are leading to the wrong spark plugs?

UPDATE 2: I installed the new MAF from Hitachi, and it now cranks and runs. The clatter isn't as bad as it was, but it'* still there. It'* throwing a DTC P0300 code, and after checking online, one of the common causes is air leakage in the intake manifold. I did install a new one when I replaced the head gasket, but after I did that, I read somewhere that I was supposed to put a large glop of RTV in each corner of the Upper Intake Manifold. I didn't do that, so will try the "squirting water" technique today to see if that'* the problem.



MERRY CHRISTMAS to all !!!