Voices in my head.

775 Views 5 Replies 4 Participants Last post by ghnl, Apr 2, 2011

Alfa Seltzer

Discussion Starter · Apr 1, 2011 (Edited)

Poked around my '86 Veloce with a screwdriver-as-stethoscope. I decided to listen to the injectors just for fun. #1 and #4 go on and off with a very distinct CLICK-CLICK-CLICK but my #2 sounds more like its just rattling and #3 clicks but nowhere near as loud as the #1/#4.

Time to grab a noid light set from AutoZoo?

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Tifosi

· #2 · Apr 1, 2011 (Edited)

To see if the injectors are working?
Look at the spark plugs for free.

To see if the injectors are working properly, they need to go someplace like OK Injectors for testing/inspection and if desired, servicing.

Or you can play that game with the jars with measurements on the sides where you take the rail off and spray them into said jars to check volume over x amount of time, then get a pressure gauge to check pressure in the rail.

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racer1958

· #3 · Apr 1, 2011

You might also want to hit the exhaust manifold with an infrared heat gun. Try to pick the temp as close to the head as possible, this will give you an indication of variances in exh temp and therefore mixture. Mid RPM @ 2 minutes will give you an indication of EGT.
If you have a weak-dead cylinder it will show, you are looking for even numbers across all four cylinders.
Harbor Freight has the gun for $40.00 and is a great diagnostic tool.

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Alfa Seltzer

Discussion Starter · #4 · Apr 2, 2011 (Edited)

Yesterday it was idling all funky and missing at idle. It's been doing that occassionally.

Turned it on today and it started, idled and ran just fine. Drove it 60 miles without any issues. #2 injector sounds perfectly normal now and while the #3 is still a little quieter than the rest it is definitely clicking.

Racer1958, I've actually got a pocket IR thermometer. Keep it in the car to check the brake temps and to make sure the temp gauge on the dash isn't completely off. If it happens again I'll shoot the headers and see how it does.

Tifosi, I'd like to double check that the injectors are getting proper signal/power from the ECM before shipping my rail cross country. On the other hand I guess if they're making any noise then they've got power.

I pulled the plugs two weeks ago and found that the #1 was nice and tan but the rest were white as a ghost. Found and fixed a leaky fuel line and a bad vacuum connection on the intake accordion to throttle body coupler.

I'm gonna run outside real quick and pull them to see if that fixed the lean condition.

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Tifosi

· #5 · Apr 2, 2011 (Edited)

Alfa Seltzer said:
I pulled the plugs two weeks ago and found that the #1 was nice and tan but the rest were white as a ghost.

Point of note:
In the L-jet and other EFI setups, if everything is in good working order plugs looking bone white/brand new to a very light tan is the norm.
Tans and browns, blacks, spalling and other residue indicate issues not neccisarily related to the A/F mixture.
(plug reads are vastly different than what a carb'd engine will produce)

ie: the plugs either look right, or they look wrong for whatever reason, there isn't really any in between on them in EFI.

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ghnl

· #6 · Apr 2, 2011

I mostly agree with Darren. Except that the computer tries to keep the average mixture at ideal. If one cylinder is off (air/vacuum leak, faulty ignition, faulty injector, etc) the computer will try to adjust the other cylinders to compensate. Keep in mind it squirts all the injectors together (not sequentially like spark plugs). It cannot adjust any one cylinder - it averages them all together based on the signals from the (one) O2 sensor.

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