I did an intake R&R last week and things turned out really nice. The car ran great over the last week until yesterday when i pulled into the exit lane on the hiway and turned the corner onto the road to my house. As soon as i accelerated out of the corner the car developed a miss and i suspect it is now on 7 cylinders. Am I correct in thinking it's a leaking injector? I am thinking so because the motor seems to clear out above 3000ish RPM and pulls somewhat normal at that point as the demand for fuel reaches what is already provided by the leaker. Anyway...

1. 86.5 my
2. intake restoration/idle&full load switch set last week
3. I had to turn idle adjustment screw all the way in to get car to idle correctly after R&R.
4. checked all connections, everything is tight, no false air.

NOW

1. Missing/stumble and rich smoke at idle.
2. Engine clears and runs BETTER but not optimum above 3000ish RPM.


I should also add that i installed the injector seal/pintle cap kits from DR to a used set of injectors that i bought a few months ago. I installed the other injectors to use while mine are sent to Witchhunter for cleaning. The more i think about it, i come to the conclusion that one of those old injectors has $hit the bed.

 

I was just reading on the witchhunter site that leaving injectors in storage can cause the internals to corrode, stick, and leak. That's hopefully what has happened, that backup set of injectors sat in my garage in ziplock bags for 8 months or so.

 

Hello Ben
You need to warm the engine to normal temp, disconnect the O2 sensor from the LH ECU, and then adjust the idle mixture pot to 0.6% measured on the test pipes (before the cats) as per the workshop manual.

 

Could be getting false air from one of the many sources that you just worked on. Might want to recheck all of the air related hoses, clamps, etc.

 

What do i measure the mixture with?

 

Ok, I have a copy of the service manual EZF/LH Test plan and it appears that i need a CO tester to accomplish the procedure, Where would i be able to get one?

 

Leaky injectors cause starting problems from loss of fuel pressure and flooding once the car is stopped for a while and attempts are made to restart it. Look elsewhere. Not saying you don't have bad injector(s), but the symptoms don't fit a leaky one.

If you think you are running on 7 cylinders then there will be one cylinder that will not show any response when you pull its spark plug cap. All the others will show a slight drop in RPM and more roughness to the idle. A dead cylinder could be due to a failed injector or a bad plug/plug wire.

However, the fact that you had to put the idle screw in all the way to get the car to idle and it is running rich at idle points elsewhere, as others are indicating.

 

I agree with what was said so far. I went out this morning after reading the LH/EZF test plan and started monkeying with the MAF idle mixture. With the car up to Temp, I disconnected the O2 sensor as per instructions, marked the setting of the idle mixture adjustment, and turned the idle mixture adjustment 1/4 CCW. After repeating this 6 times, with subsquent idle adjustments on the throttle body, and a button up/test drive, i was able to get the car to idle smoothly and stop missing. Since i don't have a CO tester is it possible to disconnect the O2 sensor and monitior the feedback from that for a specific voltage as i adjust the MAF mixture? Who has a Co tester?

I am pretty confident that getting the mixture spot on will solve the symptoms because each time i adjusted the mixture the car ran a little better. What i can't figure out is why did the car run fine but with a slightly higher idle everyday this week and then all of a sudden this crap?

 

John Deere has a CO tester that we use for checking confined spaces before entry but i doubt i can just roll up to the guard house and say "let me use the CO tester to adjust my fuel injection" LOL.

 

You couold try monitoring the disconnected O2 sensor output voltage, it have a very abrupt transition around 14.7:1 air fuel ratio (stoich) . Either side of stoich it will sit at nearly 0v (too weak, turn pot clockwise) or around 1v (too rich, adjust pot anticlockwise.

It will be almost impossible to get it in between, but get as close as you can.

 

So if i understand correctly, i am looking for a feedback of 1vdc at Stoich from the O2 sensor? The sensor will read close to 0vdc either side of stoich? And it's a fairly narrow range on the mixture pot where 1V will be read on the O2 sensor?

 

Sorry, my typo. :-(

ONE side of stoich it will sit at nearly 0v (too weak, turn pot clockwise) or around 1v (too rich, adjust pot anticlockwise.

 

okay got it.. between 0vdc (lean) and 1vdc (rich)

 

Thanks guys, it was that the CO level needed to be readjusted after the intake R&R. Guess we can close this one.

 

OK, good. I like happy endings :-)