Burned Ex. Valve...Why?

[weidnerl@wwt.net]

I have a 96' Tracker. 1.6 w/5sp manual trans. Compression on #4 cyl went to 35 lbs. Pulled the head to find the last exh valve in the head in #4 cyl burned. All exh valves were light gray in color accept that valve...it is white. I'm trying to find the reason why it might be burned. No codes, gas mileage around 22-24mpg. 72 K miles on motor. Has new wires, cap, rotor, plugs, EGR valve and EGR valve exhaust circuitry cleaned out.

What could cause this one valve in #4 to burn? Anything unique to this engine?

Thanks
Larry :-)

[tipover]

have the valves been adjusted or checked in the last 15,000 miles?

[m9b7v5]

lean cylinder due to injector issues maybe?

[jtgh]

you are smart to ask why, most just fix and go again.


egr , has the effect of keeping valves cool.
bad egr.

and valves run way too hot..

but Id bet bad injector on that cylinder.
or bad intake gasket on that runner?
air leak around #4 injector cushion at injector to manifold juncture.
bad gasket at EGR base allowing air to leak in and foul #4 first and worst.

too little fuel #4 or too much air.

[weidnerl@wwt.net]

Originally Posted by jtgh

you are smart to ask why, most just fix and go again.


egr , has the effect of keeping valves cool.
bad egr.

and valves run way too hot..

but Id bet bad injector on that cylinder.
or bad intake gasket on that runner?
air leak around #4 injector cushion at injector to manifold juncture.
bad gasket at EGR base allowing air to leak in and foul #4 first and worst.

too little fuel #4 or too much air.

JTGH,

I was hoping you'd respond to my inquiry. I hate doing things twice...especially messy jobs like this. It has a new EGR...replaced when I cleaned out the EGR system last summer. But I will check the gasket under it and look close at injector.

BTW, we use this Tracker as a towd behind our Classic MH. My Photo Gallery - 1686_p19771.jpg
A perfect towd...light, 4wd...at our age, easy to get in and out of.

Love "Jerry's Geo Tracker page" I've used it a number of times. Thanks for your efforts.

[jtgh]

send the injector off to witchunter.com
$18 and a flow chart , comes back with it. nice.
WitchHunter Performance - Injector Cleaning & Flow Testing Services

busy season 2-3day turn.

cheers.

[weidnerl@wwt.net]

Originally Posted by jtgh

send the injector off to witchunter.com
$18 and a flow chart , comes back with it. nice.
WitchHunter Performance - Injector Cleaning & Flow Testing Services

busy season 2-3day turn.

cheers.

Thanks for the tip!! Injector is on its way to WitchHunter today. Any tips on replacement/replacing "O" rings on the remaining injectors? All of that was disturbed when taking out #4.

[jtgh]

the are a pain to get, sadly.
i made a page just for them.
injector seal kits

some sell oring and no cushions (intake side)
others just cushions.
had to find a kit for both. but they are avail.

no air leaks, good injector should result in good air fuel mix that cyl.
it cant be ecu as it would starve for fuel 100% or flood. (stick open full or closed)
yours is weak. (gotta be injector, too much air )
weak compresion would make it rich on that cyl.
ecu makes the gross assumtion that all cyl. are working perfect. ( which yours was not)

cheers.

[weidnerl@wwt.net]

Originally Posted by jtgh

the are a pain to get, sadly.
i made a page just for them.
injector seal kits

some sell oring and no cushions (intake side)
others just cushions.
had to find a kit for both. but they are avail.

no air leaks, good injector should result in good air fuel mix that cyl.
it cant be ecu as it would starve for fuel 100% or flood. (stick open full or closed)
yours is weak. (gotta be injector, too much air )
weak compresion would make it rich on that cyl.
ecu makes the gross assumtion that all cyl. are working perfect. ( which yours was not)

cheers.

Saying that they are a PIA to get at is an understatement!!
I checked at O'Reilly's today and they had single cylinder injector seal kits that have "O" rings and cushions. Single cylinder kit is just under $3.00 so I bought 4....yes "single cylinder" kit.
Thanks again for your help.
TTYL

[jtgh]

yes, and the dealer price, "out of this world" $
they should blush.

no promises , finding these problems can be challenging.

bad motor?
EFI messing up? (ecu)
or bad input to ECU ( something is fibbing to ECU , causing it to mess up)
it takes patience to find it.