HarryD

No updates--I re-cleaned the IACV valve, throttle body, and MAP sensor. No change.

I don't *believe* I overreved, but it's possible. Billman says the symptoms of an overrev include:

"The first thing to go would be bending the exhaust valves at 10,700. The idle would be lumpy, and you'd hear puffing and light popping out the tailpipe."

Those are my symptoms right now, but only at idle when the car is warming up.

How would one rule out bent exhaust valves? Will a compression test cover it? Retainer inspection?

Slowcrash_101

They are an issue in older cars, moreso than fuel pump issues.

O2 sensors, and coil packs can also affect idle running.

Slowcrash_101

A leakdown test, you put each cylinder at tdc and pump air in through the spark plug hole. Put in 50psi and listen where the air is leaking from. If you hear it from the intake manifold, intake valves are leaking. Hear air escape from the exhaust, exhaust valves are leaking. Have you tried resetting the ecu and see if that helps?

HarryD

Compression test today:

Cyl 1 188
Cyl 2 185
Cyl 3 194
Cyl 4 185

Inspecting the retainers--can someone please look at these and give me your opinion?

I will try my first leakdown test tomorrow.

I want to rule out catastrophic engine damage (e.g. an overrev).

Thoughts/opinions please? Thanks guys!






Spark plugs, <10k miles on these:

Slowcrash_101

Retainers look fine, compression is a little low but consistent.

HarryD

Here's a video of the symptoms:

http://youtu.be/0UvraTFpOuE

Slowcrash_101

Random misfire, could be caused by a bunch of things really. Have you tried resetting the ECU? It could be coil packs, fuel injectors, ECU problem, or it could be engine related. Compression test hints at it not being engine related, but you should do a leak down test to know for sure. If that checks out then look at the other things like fuel injectors, again coil packs, the ignition control module is in the ECM so if that's bad you'll need a new computer. Sometimes an exhaust leak can cause that, so can a vacuum leak, a faulty sensor(s) can as well. See if you re-do the valve adjustment if you can go just a hair looser see if that calms it down, staying within specs obviously.

HarryD

It looks like a misfire to me, but why no CEL? No pending codes, nothing!

ECU was reset and I will remove the injectors and get them ultrasonically cleaned. I don't have a compressor so the leakdown test is still in limbo.

Slowcrash_101

Probably not causing a big enough rpm change to register on the crank sensor.

Dead Serious

Have you recently done any work that may have compromised the vacuum system or MAP? Does it miss at high/med/low load? My car MY05 started doing the same thing 3 days ago with no CEL. At first the engine was running perfect, then I removed the air box and intake tube to do some mock up of a cold air intake. I re assembled the stock intake and stock air box after wiping some things down and inspecting the intake for oil (the only bolt on my whole power train is a catch can). Now i have the same misfire as you. Ive got a late MY05 that already has the MAP holder. My first though was I may have yanked the wire for the MAP and damaged it but it still reads 14.7 PSI at key on engine off and around 5 PSI at idle when its missing. My OBD reader is super slow and wont catch a micro miss of the MAP so it could be the MAP/MAP wiring. My engine is also worse when cold and worse with the A/C on. It stumbles at low RPM under load but gets better with engine temp. If i sit at a light and give it just a little gas and hold it at 1300 RPM the miss goes away but when the light goes green it will miss through 1st and 2nd gear. Not trying to thread jack but if i figure mine out it may help you. Im going to replace my MAP and look again for vacuum leaks. Mine is too obviously tied to me messing with my intake.