S14 KA24de problems after compression test

[Ktt88]

So my S14 KA24de was running and performing great up until I did a compression test.

I unplugged each fuel injector, unplugged each spark plug wire from all the plugs, removed 1 spark plug, inserted a compression gauge into the removed spark plug and cranked the engine over. I repeated this 4 times for each cylinder.

After I was done I reinstalled all the spark plugs, wires, and plugged in all the injectors.

Car is now running like crap, it sputters up to redline randomly at any rpm. Noticeable worse at lower rpms when coming from a stop.

Heres a video of the problem while idling.

http://youtu.be/uTocwInbQmI

Ive tried swapping in a known good MAF, no change
Checked all grounds, no change

Im thinking because I left the ignition on while testing I might have shorted something? not sure...

This problem happened right after the test so im thinking it has to be directly related

[Chaluska]

if all you did was remove the spark plug wires, and injector wiring, did you not push the spark plug boots down far enough?

there isnt much that can go wrong by removing those items.

sure you didnt do anything else?

[Ktt88]

Originally Posted by Chaluska

if all you did was remove the spark plug wires, and injector wiring, did you not push the spark plug boots down far enough?

there isnt much that can go wrong by removing those items.

sure you didnt do anything else?

Trying for the life of me to remember if I did anything else...Im 99% sure I didnt. Ill do a full take over tonight though.

Could the plugs be bad?

[OnTheChip]

Just fyi, you should remove ALL spark plugs while doing a compression test. Makes it much easier on the starter.

[Ktt88]

Originally Posted by OnTheChip

Just fyi, you should remove ALL spark plugs while doing a compression test. Makes it much easier on the starter.

makes sense. will keep that in mind for next time

[cerealwars]

take all of the wires back off.

make sure they're all plugged into the correct plug. check your cap too. it may have the corresponding numbers on it depending on your application.

also ensure the plugs are tightened properly.

if it sounds like a miss (which it does to me), unplug each individual plug wire and check for rpm drop. (if the idle drops, then that cylinder is most likely not the issue). a miss on a four-cylinder is typically pretty dramatic.

[Ktt88]

Originally Posted by cerealwars

take all of the wires back off.

make sure they're all plugged into the correct plug. check your cap too. it may have the corresponding numbers on it depending on your application.

also ensure the plugs are tightened properly.

if it sounds like a miss (which it does to me), unplug each individual plug wire and check for rpm drop. (if the idle drops, then that cylinder is most likely not the issue). a miss on a four-cylinder is typically pretty dramatic.

Yea it definately sounds like a miss to me too. I have a spare set of oem spark plug wires too. Ill double check all that stuff....
thanks!

[LoganDavenport]

Originally Posted by cerealwars

take all of the wires back off.

make sure they're all plugged into the correct plug. check your cap too. it may have the corresponding numbers on it depending on your application.

also ensure the plugs are tightened properly.

if it sounds like a miss (which it does to me), unplug each individual plug wire and check for rpm drop. (if the idle drops, then that cylinder is most likely not the issue). a miss on a four-cylinder is typically pretty dramatic.

^^^^^^^^^^

[Ktt88]

So I did as cerealwars recommended

All the wires are plugged into the correct places, all the plugs are torqued properly, and I unplugged each wire individually and the idle dropped accordingly.

This is blowing my mind...ugh

[Kingtal0n]

do another compression test

When you tight the plugs, how tight do you go? And what is the gap, how do you "drop" the plugs back into their respective locations?

Maybe you accidently re-gapped one of the plugs by dropping it. Maybe one of them is not tight.
Beware overtightening them, I have seen the head stripped before. They don't need to be too tight. Always put a little anti seize on the threads too.

[Ktt88]

Originally Posted by Kingtal0n

do another compression test

lolll im actually considering it just to re trace my footsteps

[redline racer510]

Maybe when you pulled the injectors you might have broken the wires and the injectors are getting an intermittent signal.

[Ktt88]

Originally Posted by redline racer510

Maybe when you pulled the injectors you might have broken the wires and the injectors are getting an intermittent signal.

Possibly...I guess ill have to inspect the harness better

[Ktt88]

Gave the injector harness a good visual inspection, it looks fine, just how it did before.

The injector plug on cylinder 2 looks slightly slightly melted, still tested good and got 12v though.

I did however find the ground on the top driver side of the block (there are 2 there, the closest one to to firewall) to be very loose.



Heres what I think happened, not sure how to fix it though

I unplugged the injectors and the ground was loose when I was cranking the engine doing the compression test. Could this have shorted something out? any insight would be helpful.