Finding out if you have a bad injector

ericem · Post by **ericem** » Wed Dec 31, 2008 4:37 am

Someone was suggesting on USMB that my fuel economy issue could be related to a injector that is stuck open. If that is the case how can I find out which one it is? Also I noticed that 1/2 throttle seems noticeably faster then full throttle. Especially when launching from completely stopped. Any idea's guys? Thanks. Car has 323,000km now so I do indeed plan on checking out the compression.

BXSS · Post by **BXSS** » Wed Dec 31, 2008 2:46 pm

Coolant temp sensors, O2 sensors, Knock sensors can all cause poor fuel economy.

I wonder if the car would even run well with an injector stuck open.
I'd think it would bog / blow out clouds of black smoke.

glennda5id · Post by **glennda5id** » Wed Dec 31, 2008 6:09 pm

If you think you have a leaky injector the only good way to tell is to hook up a fuel pressure gauge and see how fast the pressure bleeds off once you stop the car. I think the car would be running very rich if that was the case though.

Since our cars don't have a fuel pressure valve you would need to get a kit like this:

http://www.harborfreight.com/cpi/ctaf/d ... mber=92699

and install it in-line between the fuel filter and the fuel rail.

ericem · Post by **ericem** » Wed Dec 31, 2008 9:52 pm

Already replaced my 02 sensor, knock sensor, ECU temp sensor all OEM parts brand new. I will look into the fuel pressure guage thanks.

douglas vincent · Post by **douglas vincent** » Wed Dec 31, 2008 10:37 pm

Simply have the car idling and pull off the injector clips, one at a time. If you have a leaky injector, nothing will happen when you pull the clip on the leaky injector! It will continue to idle just as before....

kimokalihi · Post by **kimokalihi** » Wed Dec 31, 2008 10:57 pm

Does your exhaust smell really rich like unburnt fuel?

ericem · Post by **ericem** » Thu Jan 01, 2009 3:20 am

Yes it does actually. Especially when cold.

Post by **Legacy777** » Fri Jan 02, 2009 5:13 am

ericem wrote:Yes it does actually. Especially when cold.

That's kind of normal, and the point of cold start fuel enrichment.

log1call · Post by **log1call** » Fri Jan 02, 2009 11:20 pm

Get a long screwdriver to your ear and listen to each injector in turn. They should make a nice crisp click noise if they are shutting nicely and probably no noise or a dull bump at best if they are stuck open. Even if they are shutting though they may still be leaking or atomising badly due to deposits under the seats. In my opinion, the surest way to check them is to pull them out and test them visualy for spray shape, atomisation, clean start and stop and no drip build up, ie. a slight leak.

ericem · Post by **ericem** » Sat Jan 03, 2009 12:29 am

I unplugged one by one at idle. I found one of the amount of shiver made with one of the passenger side injectors was no significant. I can still rev the engine normally btw, just a bit of shiver at idle really. I am thinking ill just put a tank of good quality injection cleaner(I was using this red crap which is thick IMO not very watery) and 91 octane like $10 worth on the same tank.

Think that will clear it out? If after this there is no difference I guess I will need to look into new injectors. The car does have 322,000km now (over 200k miles) so I figure they would be someone warn out right?

Main reason why I want to fix this is fuel economy is pretty horrible. For a N/A and driving with little to no full throttle getting under 20mpg sucks. Only getting like 300km now before the light comes on. Usually it is 400km range but I believe it could be better.

93Leg-c · Post by **93Leg-c** » Thu Jan 08, 2009 4:46 am

Have you run a compression and/or leakdown test on all cylinders? I had a low compression reading on one of my cylinders and I was getting 18-20 mpg (NA engine).

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Finding out if you have a bad injector

Finding out if you have a bad injector