Clogged Fuel Injector

[Yomicron]

Here's the deal, my car is running rough. While it is running if you disconnect one of the fuel injectors the car runs much worse, this happens on all but one cylinder. On that one cylinder, there is no change between having it connectd or not, this would suggest that the injector is either clogged or broken, correct? Goning on the assumption that it is simply colgged, I ran through a tank full of premimum and a bottle of injector cleaner. Still no change, but I was told that I should run through 2 full tanks before I take more drastic measures.

Now, I was planning on going home for the 3 day weekend (~250mi each way) and thought it would be good to run some more injector cleaner through it. But my mom spoke with a mechanic and he said that it is not a good idea to drive a long distance if the injector is not working, because it would cause a buildup of heat and possibliy damage the cylinder.

I don't know much about cars, but the over heating thing doesn't make much since to me. It seems like it would lower the temperature, because there is nothing happening in that camber.

So, would the heating problem be due to the cylindar next to it being heated and the change of temperature between the two would cause damage? or what?

Do you think it would be safe to drive?



Thanks for your assistance.


EDIT: I forgot to add that I initially thought it was the spark plugs and went ahead and them, their wires and the distributor.

which lead to disconnecting the injectors one by one to see if they were causing the problem.

 

[radioouman]

Just replace the injector.... THey do go bad sometimes.

I don't think that heat is a big issue... It would be a problem if you didn't have any spark in that cylinder and you kept spraying gas into it. Then you might end up trying to compress liquid fuel eventually, and that would cause heat. But with no gas, I can't imagine that it would hurt anything.

 

[notfred]

Originally posted by: Yomicron
Here's the deal, my car is running rough. While it is running if you disconnect one of the fuel injectors the car runs much worse, this happens on all but one cylindar. On that one cylindar, there is no change between having it connectd or not, this would suggest that the injector is either clogged or broken, correct?

1) it's CYLINDER

2) Not neccesarily. If that cylinder isn't getting any spark, it won't fire regardless of whether or not there's fuel. If you were to go back and duplicate the same test, but discoonect spark plug wires instead of ful injectors, you should get the same results.

Goning on the assumption that it is simply colgged, I ran through a tank full of premimum and a bottle of injector cleaner. Still no change, but I was told that I should run through 2 full tanks before I take more drastic measures.

Injection cleaner doesn't really do a whole lot, not enough to un clog an injector. I suggest changing your spark plugs.

Now, I was planning on going home for the 3 day weekend (~250mi each way) and thought it would be good to run some more injector cleaner through it. But my mom spoke with a mechanic and he said that it is not a good idea to drive a long distance if the injector is not working, because it would cause a buildup of heat and possibliy damage the cylindar.

If, in fact, the injector is clogged, it will mean the cylinder won't fire, but it won't damage anything. No fuel = no combustion = no heat.
You will notice a loss of power, though.

I don't know much about cars, but the over heating thing doesn't make much since to me. It seems like it would lower the temperature, because there is nothing happening in that camber.

Yep.

So, would the heating problem be due to the cylindar next to it being heated and the change of temperature between the two would cause damage? or what?

I think the mechanic didn't understand the question that was asked to him, or he doesn't know what he's talking about.

Do you think it would be safe to drive?

Probably, but I'd try changing the spark plugs, wires, and distributor cap (if your car has a distributor) first.

Thanks for your assistance.

Welcome.

 

[d33pt]

it could also mean that you are getting no spark to that cylinder...i think that is more likely than the fuel injector... check the spark plug/wire

 

[Yomicron]

I forgot to add that I initially thought it was the spark plugs and went ahead and them, their wires and the distributor.

which lead to disconnecting the injectors one by one to see if they were causing the problem.

 

[notfred]

Originally posted by: Yomicron
I forgot to add that I initially thought it was the spark plugs and went ahead and them, their wires and the distributor.

which lead to disconnecting the injectors one by one to see if they were causing the problem.

Buy a new injector.

 

[Zenmervolt]

Originally posted by: notfred

Originally posted by: Yomicron
I forgot to add that I initially thought it was the spark plugs and went ahead and them, their wires and the distributor.

which lead to disconnecting the injectors one by one to see if they were causing the problem.

Buy a new injector.

Yup, new injector. Hopefully that will fix things, because if it's not the injector then it's either the wiring or the ECU. (Doubtful that it's the ECU though, usually if an ECU goes berzerk more than one injector stops firing.) And no, a dead ECU doesn't automatically kill the engine completely. Had the ECU on my 914 die and everything worked except two of the four injectors. The engine was even still smooth because of which two injectors failed.

ZV

 

[lightpants]

What kind of car? Do you have a DVOM handy? I could get you the specs to test it it you like.

 

Before you do anything else, check the compression on all the cylinders.

You need three things for an engine to run.

Fuel
Compression
Ignition

 

[XZeroII]

Time for a new car. Just drive this one into a river and get a new one.

 

[Yomicron]

Originally posted by: lightpants
What kind of car? Do you have a DVOM handy? I could get you the specs to test it it you like.

Its a '93 Toyota Corolla w/ 1.6L inline 4.

And yep, I've got my multimeter right here, what should I check?

 

[lightpants]

Injector resistance should be 13.8-14.2 ohms.
93 corolla sedan 1.6

 

[Yomicron]

Originally posted by: lightpants
Injector resistance should be 13.8-14.2 ohms.
93 corolla sedan 1.6

Hmmm.... I just measured it, it's 14ohms

This would suggest a clog or a bad signal wire right?


EIDT: I checked the resistance of the singnal wire from the terminals, it's 13.9 ohms. All those lecutres about load matching are coming back to me now....

 

[Zenmervolt]

You can try removing the injector and having it squirt into a bucket. Then you'll know for sure if it's firing or not, and you'll be able to check the spray pattern.

ZV

 

[GoodToGo]

Half of the car problems can be solved by windex or pee. Choice is yours.

 

[lightpants]

Make sure there is power to the injector. If yiou have a noid light you can check that, if not mmmmmmmm I believe there should be voltage on one of the terminals on the wiring harness side with the key on motor not running. The computer grounds the circut and that is what fires the injector. Dont do it with the motor running if you dont have some resistance beween the termanals you could damage the computer. in other words dont check acrossthe terminals with your dvom and try to start the car.

 

[Bignate603]

I could see how if it didn't fire there could be more stress across the engine because of the differences in thermal expansion. Since that cylinder would be cooler it would expand less. However, I don't know how much of an issue that would be because of the heat conduction through the block. If it's the last cylinder that the coolant runs by it would be even less because the heat from the other cylinders would warm the that last cylinder. If it's the first cylinder it runs past it wouldn't do this though. I think that the block would be strong enough to take some stress like that but I'm not a car guy, I just dabble in it a bit once and a while.

 

[Yomicron]

lightpants: there is no voltage on any of the wires with the key just in the ON position and I don't have a noid light...I suppose I could run some wire from the terminals to my meter to check for voltage while it is running without having to disconnect the injector...

Bignate603: I was thinking the same thing, I would think the block would transfer enough heat to avoid any problems. Perhaps I should call another mechanic and see what they have to say.

 

[ElFenix]

man... i wish i knew about cars...

 

[lightpants]

If there is too little gas going to one of the cylinders it will create a lean condition in that cylinder, it will run hotter and will damage the piston and require a rebuild. We have a car on the lift right now that had malfunctioning injectors and it cracked a piston. Major cash to fix. Not for this guy though, he is a good friend of my brothers and my brother is helping him fix it for free.
Two things:
Trust your mechanic!!
Make friends with my brother!

 

[Yomicron]

Originally posted by: lightpants
If there is too little gas going to one of the cylinders it will create a lean condition in that cylinder, it will run hotter and will damage the piston and require a rebuild. We have a car on the lift right now that had malfunctioning injectors and it cracked a piston. Major cash to fix. Not for this guy though, he is a good friend of my brothers and my brother is helping him fix it for free.
Two things:
Trust your mechanic!!
Make friends with my brother!

what if I temporarily disconnect the spark plug for that cylinder? would that keep it from being damaged until I can get it repaired?

 

[FrustratedUser]

Are you loosing coolant by any chance?
My engine was running rough sometimes and it turned out to be a broken intake manifold ----> coolant leaked into the intake.

I would also try to check the voltage going to the injector as proposed earlier in this thread. But I woulod use an oscilloscope instead of a DVM.

 

[lightpants]

It is bad for some ignition systems to fire without being grounded. So you could burn up a coil by doing that.

Jim <----former mechanic, dads on vacation so today I was watching the shop!

 

[Yomicron]

Originally posted by: FrustratedUser
Are you loosing coolant by any chance?

Nope

I would also try to check the voltage going to the injector as proposed earlier in this thread. But I woulod use an oscilloscope instead of a DVM.

I don't have an oscilloscope here at home. and I don't really feel like going to the university (of Arizona...yep, I'm in Tucson too) and checking one out.

 

[Yomicron]

Originally posted by: lightpants
It is bad for some ignition systems to fire without being grounded. So you could burn up a coil by doing that.

Jim <----former mechanic, dads on vacation so today I was watching the shop!

How would disconnecting the wire for that one sparkplug ungound the system? isn't it just a signal wire? wouldn't it be the same as if the spark plug was bad?

Its not that I don't believe you, I'm just trying to figure this all out, and if it would be possible to drive the car without causing more problems.