Stuck Injector, argh... Options

[yarin]

Just when you think you take every precaution possible....

YEpp.. i pinpointed my problem tuning megasquirt. I started the car up today, the #4 cylinder was dripping fuel on the ground, leaking from anywhere possible. I touch the exhaust pipe, COLD, actually only one was really hot.

So I pulled the injector out of the manifold and run the fuel pump with nothing else powered. SQUIRTTTTTTT, gushing stream of fuel into my water bottle.

I had these injectors tested and cleaned. What gives? Is it possible that I somehow damaged this injector during tuning to cause it to be stuck open? The impedences across all four are equal and normal ~3.4Ohms or so.

I guess i'm looking for another 2.0 injector, ASAP!

Thanks.

[mightyohm]

Is it possible you miswired something such that the injector was still under power, or maybe it was damaged by excessive current? Are you running injector resistors?

[yarin]

Nope.. nothing miswired. injectors dont have polarity. The are fed a constant 12V and are pulsed by switching them to ground.

I'm using PWM with MS II V 3.0 board. No resistor board.

Funny part is one of these injectors was stuck open BEFORE i sent it out to have them cleaned. Who knows what the happened here.

Anyone got one to sell me (IMG:http://www.914world.com/bbs2/html/emoticons/chowtime.gif)

got some on the way... 914club RULES! (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif)

[yarin]

I did some thinking and this whole thing makes a lot more sense now. All symptoms lead me to believe this injector was stuck open from the first time i tried to crank it over.

I found it really difficult to crank, i attributed this to the several month period that it wasn't started. However the problem kept repeating itself, the starter just didnt have enough ooomph to turn the engine over right away.

I ran the engine today, it smoked initially then stopped. What damage could have been inflicted by this? Bent valve? bent rod? after all fluid isn't exactly compressable.

Testing for a stuck injector is so easy I would suggest everyone do this before turning the key on a new install. One by one pull the injector connector off, stick the injector in a bottle and just run the fuel pump for a few seconds. Easy enough and will save you hours and possibly $$.

[DNHunt]

I had the CHT fail one time with Megasquirt. It thought the engine was -40 degrees and dumped mucho fuel in. The engine just quit. Trying to start it caused a hydrolock. End result a tow home. When I got it home the cylinders were empty and I saw that the Warmup enrichment was out of control. I swapped the CHT and changed the oil and it fired right up.

Incidently, you can eliminate a problem in MS if only 1 injector stays open. Being batch fired the other injector on the circuit will be open if MS is at fault.

Dave

[yarin]

QUOTE (DNHunt @ Apr 9 2006, 08:26 PM)

I had the CHT fail one time with Megasquirt. It thought the engine was -40 degrees and dumped mucho fuel in. The engine just quit. Trying to start it caused a hydrolock. End result a tow home. When I got it home the cylinders were empty and I saw that the Warmup enrichment was out of control. I swapped the CHT and changed the oil and it fired right up. Incidently, you can eliminate a problem in MS if only 1 injector stays open. Being batch fired the other injector on the circuit will be open if MS is at fault. Dave

Glad to hear you recovered from your failure. However with a bad CHT sensor you would inject 180% of fuel into your cylinders. With a stuck injector I would guesstimate that at least 50X the fuel is injected into the cylinder.

MS wasn't at fault in this case, just a pure injector problem.

[crash914]

yarin,

You should have received the injectors yesterday afternoon...

The damn board went down so I don't know if you got my message and tracking #.

Whew!!

I was going through withdrawls....

Thanks Andy!

[yarin]

yarin,

You should have received the injectors yesterday afternoon...

The damn board went down so I don't know if you got my message and tracking #.

Whew!!

I was going through withdrawls....

Thanks Andy!

I slapped one in yesterday as soon as they came in. Checked it out, no leaks. Went to start it up, fired and sounded absolutely awful. Metal, banging, chaos.. it was bad.. so was about to freak out then i figured it must be somethign stupid. turns out a water bottle fell into the impeller cavity. that was a huge relief...

so then went to crank it again. started and died. couldn't restart. now what?! turns out no fuel pressure. why? no GAS! so someone tell me where 2 gallons of gas went in 10 minutes of idling? yep... either straight out my exhaust or into the oil pan through the rings. Yikes. changed the oil sunday so i'm ok.

Finally got it started and ran for a few minutes. Still idling at 2500rpm so i can't really tune idle. One step at a time.... Here is a datalog from yesterday afternoon:
http://www.innovatemotorsports.com/forums/...65&d=1144878939

[crash914]

datalog is not too bad...

You are still in warm up mode. That could be some of your rough idle problem. are you using the stock AAR valve? Autotune won't do a great job at hot idle. Just do it manually.

You need to keep it running enough to get hot. Then you can see what you have.

I dropped a pair of side cutters in my fan oneday....4 or 5 broken fins later, I found it .....

[yarin]

datalog is not too bad...

You are still in warm up mode. That could be some of your rough idle problem. are you using the stock AAR valve? Autotune won't do a great job at hot idle. Just do it manually.

You need to keep it running enough to get hot. Then you can see what you have.

I dropped a pair of side cutters in my fan oneday....4 or 5 broken fins later, I found it .....

I made it out of warmup, my other CHT read almost 275F. i am using the stock fast idle solenoid but i have it capped off. For some reason or another i cant get the engine idling below 2500rpm. i'll look into it again tonight, i've never used this throttle body before, but i do have every single opening plugged.

i'll PM ya later to settle the injectors. thank you so much! back to work...

[Tobra]

I knocked a vacuum line off and got the real fast idle, does the MS run vacuum or mechanical advance? How does that oil smell, like diesel maybe?