Any point?

[Twizzler09]

I'm getting ready to replace the injectors on my '96 OHV, and was wondering if theres any point in going to a bigger injector? I dont have any current engine mods or anything besides exhaust. Thats not enough to justify bigger injectors, is it?

 

[MAKG]

If you needed bigger injectors, you would have blown up your engine by now. Lean mixtures are baaaad.

You MIGHT need it if you have a BIG turbocharger. All it can do now is screw up adaptivity.

 

[Twizzler09]

Didn't think there'd be much point in it right now. Even after I finish the future mods (Pacesetter headers, jet programmer) still wont be nessecary.

An after thought, should I replace the stock injectors with Genuine Ford injectors or go aftermarket (probably cheaper)?

 

[AllanD]

I'll ask what some think is my favorite question

Why do you think you need to do that?

"93-up use disc pintle injectors.
I mention that because the old stem pintle injectors were usually
good for 200K miles or more.
the Disc pintle injectors in your 96 almost cerainly have another 250k miles in them...

I say buy two large cans of Chevron Techron injector cleaner.
(this stuff was a magic bullet for the Bosch CIS injection)
Run your tank down under 1/4 tank preferably about a 1/8tank
and pour in the first bottle. (keep a gas can in your bed)
Run as far as you can stand before you buy gas but add
the second bottle first.

Most of the time this cleans out the injectors beautifully.

Injectors aren't cheap.

AD

 

[MAKG]

And a bit more to the point, injectors do occasionally plug, but most complaints of plugged injectors end up being emissions or electrical problems.

People treat injectors like carburetors. They are LIGHT YEARS ahead of carburetors. You don't need to rebuild them EVER. Well, hardly ever.

I'm still running original injectors on my Prizm. 280,000 miles, and it still gets 35 MPG on the highway (40 if I try).

 

[Yellowsplash]

 

[Twizzler09]

Well, at this point I'm only guessing. But I'm still trying to diagnose the mis-fire in my truck. I ran out of ideas long ago, and short of an engine rebuild, I'm running out of options.

I *thought* the slight miss was caused by a faulty O2 sensor on the driver side manifold. Replaced the sensor, it runs better but still not like it should.

The only symptoms I can give you, is that the engine is misfiring, but the computer doesnt even know it, its not kicking a misfire code. Runs a bit rough at idle, and smooths out after I give it some juice, but you can still hear it. It used to be that I could fill the gas tank, and it would quit misfiring until it hit around 1/2 tank, but that doesn't work anymore.

The only thing I can think of that I haven't tried yet is the injectors or the fuel pump. Neither of which makes sense. But as I said, only stabbing in the dark at this point.

 

[derekj]

Put a 4 gas analyzer on the truck to see if you have a lean misfire or a rich misfire. That might give you a better idea of what is causing your miss. Try doing an injector balance test as well to help in narrowing down the problem.

Derek

 

[almostclueless]

It ran just fine with original sized injectors.

Have you done compression tests, leakdown tests, and put a vacuum guage on it?


Maybe you should let a Ford shop diagnose it?

 

[Twizzler09]

The Ford garage here in town wants mega cash to diagnose it. Not sure I can afford to hand it over to anyone either, as this is my only vehicle and I still need to get to work.

I've done a vac-test already and vacuum checks out just fine. I'd have to take my truck to work with me someday for compression and leakdown tests. I'm almost certain that compression is going to vary greatly from one cylinder to the next due to miles (207,967...it'll turn 208k before the end of the month).

Derekj, 4 gas analyzer? And explain an injector balance test. I've never heard of either one. I do smell something that smells rather like gasoline in the exhaust if I sit still long enough or if I'm standing outside of the truck. Rich?

 

[derekj]

A 4 gas machine is used for smog testing. It gives you a read out of what is coming out of the tailpipe as far as emissions. High hydrocarbon readings would mean raw fuel coming out of the tail pipe. An injector balance test can help you narrow down your problem to one cylinder. With the vehicle running disconnect one injector at a time and see if you can feel a difference in the idle while it is unplugged. If you unplug one and don't notice a difference in the idle then you have found your bad cylinder. Some scan tools have an injector balance test built into the scanner which makes the test a little easier. If you have high hydrocarbons at idle (say 600ppm) and you unplug an injector that is not closing all the way you will see a large drop in your hc's. Unplugging an injector that is ok will only show a small drop in hc's. If you can find a shop that can do this for you it could be a quick way of telling if your misfire is from a bad injector before replacing them all.

Derek

 

[Twizzler09]

Thanks for the info

I got some time off Sunday/Monday, hopefully get some results coming in, and then a better idea of what needs fixing.