Really bad miss - killing gas milage!

[Vanquish502]

A while back I had hydrolocked my engine and killed the starter.


Since then I've got it back up and running and it starts whenver you turn the key. However it has had a really bad miss ever since then, that I just cant get rid of.

The only thing I've found on this forum that relates to this problem after flooding your engine, would be cleaning your MAF. Which I've done, and nothing.


If I floor it, the RPM drops by about 200 and it slowly, while missing and backfiring, it reaches high RPM. But when I ease into the throttle, its smooth, no miss no anything.

Any ideas? My guess would be TPS?

 

[jimbo74]

you eitehr have a bent rod or a bent valve...... your engine is going to pass soon.....

 

[dogfriend]

You should do a compression or cylinder leakdown test to determine if you damaged the engine when you hydrolocked. If that tests ok, then I would look at the ignition wiring, plugs and coil pack to make sure they are all good.

 

[Vanquish502]

Thing is, there are no signs of damage.

If I had a bent rod, it would have already blown. If I had a bent valve, I'd need new head gaskets and the valve would tick like theres no tomorrow. Also, there are periods where the engine runs just fine(ie. feathering the throttle.)

 

[jimbo74]

my truck ran for a month after i hydrolocked it... and this was a month of me doing well over 90 on the freeways and hotrodding around........

 

[Vanquish502]

I also never tried starting it after I hydrolocked it until I blew all the water out because my starter was dead.

 

[jimbo74]

I also never tried starting it after I hydrolocked it until I blew all the water out because my starter was dead.

well then, since you know it all and have dismissed everything both of us have said t otry and help you, there must be absolutely nothing wrong with your car at all, and you should apply to get an ase certification because your mechanical abilities far surpass anyone elses

 

[Runnin'OnEmpty]

A TPS is very easy to check with a voltmeter. Basically you're looking for a steady voltage increase from about 1-4v, on the signal wire, as the throttle is advanced. If you see spikes, or 0v areas, then the TPS is bad.

Of the three wires going to the TPS, one is ground, one is 5v reference, and the other is the signal wire.

Also, there are periods where the engine runs just fine(ie. feathering the throttle.)

If the TPS checks out, maybe a MAF problem.....If it was truly hydrolocked, there may be other damage though.....
:roll:

 

[Vanquish502]

Well there was quite a bit of water in the engine, which I know wouldn't have let it start.

 

[Four0Sport]

my 4.0L sputs putters misses backfires and chugs when you initially start it and feather the accellerator. when you ease into the throttle it levels out. and this is with 1 dead cylinder and 2 cylinders 35psi below acceptable compression range. do a compression test.