hosrom_951

Title says all basically, any sounds/noises or symptoms when they go bad? car does NOT smoke under/off boost, idle cruise etc.....

evil 944t

Then whats the problem? Why do you think you have bad injectors?

hosrom_951

Pretty hard to explain, i'll try to make things simple.

We all know how are car's sound right? i mean, you work on the car and know when it sounds good. Under mild to hard acceleration, the engine sounds great. But recently, while decellerating, the injectors appear to be firing louder. On idle, it sounds fine, just when decellerating.

I listened VERY closely to the cylinder head suspecting maybe a lifter is starting to fail or something while the car was on idle, and reved it up some. But sounds fine, the injectors sound fine (i also heard that the injectors in our cars are supposed to be somewhat noisy to a point, is this true?) it is just when i accelerate, let off the trottle and i notice the injectors are firing louder.

Now thinking about it, could this somehow indicate another problem???

Jfrahm

I suppose the fuel pressure might change the sound of the injectors but that would be a subtle effect.

hosrom_951

Recently new FPR and FPD, car starts up fine when cold/warm etc.........all signs of a healthy system.

Just, sounds difference when i let off the throttle when still in gear. Make you think that maybe a lifter is failing...tick, tick, tick, tick..........nothing like that on idle/cruising or accelerating......

evil 944t

Maybe you have a bad CV joint(axle). I actually CAN NOT hear my injectors while driving.

You must have great hearing. hee hee

Dal Heger

The injectors are actually shut off during deceleration. The TPS will actually turn off the injectors when the throttle is closed and the injectors don't come back on until the engine speed gets to 1200 rpm (or thereabouts). So, no it's not your injectors.

Injectors are REALLY REALLY simple parts. There is only one moving part, the pintle, or little rod that acts as a valve to control the flow of fuel. The pintle is controlled by a coil that uses magnetic induction to open it. The only thing that can go wrong with an injector is that the coil can get burned out (very low probability) or that the injector can get gummed up with junk, in which case you take it off, take it to the nearest diesel repair company and get them to clean it (at about $25/injector) using the ASNU process. They replace the little fuel filter screen at the top of the injector and and replace the pintle cap and o-rings. Usually it's done in a few hours (depending on the shop).

Dal.

hosrom_951

I see, my injectors were cleaned out and re-sealed at the local Bosch Service Centre here for ~$55 for all 4 , but that was a couple of years ago....I may have to clean them out again.

Matt H

Could be that giant 4" exhaust is causing you to go deaf!
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evil 944t

Maybe, I could 'nt hear a firetruck if it smashed into the side of my car, full lights and sirens..

Hosrom, If you think they are loud, it could be you need a new fuel dampner. Thats a guess, I never heard of them going bad but, that is one of the reasons why it is there.

hosrom_951

The fuel damper and regulator were replaced a couple of months back.

I read that a faulty fuel damper causes a fuel smell to mix with the oil (sniff your oil dipstick), again, this is not the case........

Anyway, how often does one need to add 'fuel injector cleaner' to the fuel tank to keep the injectors clean? every 10,000miles or so?

evil 944t

I guess that would depend on the quality of fuel you use.

Why would a bad damper cause a smell in your oil? That does'nt make sense.

The fuel system is totally seperate. The damper keeps the heavy pulses down and helps keep a supply of fuel in the rail. IT also keeps the noise down.

hosrom_951

I use 98RON Super Unleaded ( 93 US Octane)

This is what i got regarding the fuel damper regarding fuel-smell-oil thing:

"Located on the fuel rail. Fuel dampner. It does go bad, but you will never know about it. Intermitten "rich" condition associated with excessive fuel consumption. Also responcible for the smell of fuel in your motor oil (sniff your dipstick) Broken diafragm dilutes oil with fuel in the crank case, making your engine loose oil pressure."

I got that same response from several rennlisters here a while back, along with those remarks. I did have a fuel smell in my oil, replaced the damper and the smell is gone. Anyway.........

evil 944t

Is that whole last 2 paragraphs a quote?

Hey, maybe I'm wrong but I don't see it..I guess thats something above and beyond me..I still don't see how it could mix with your crankcase oil. Your car WILL RUN WITHOUT the damper.

I spoke to a fuel injector place(who will remain nameless) and the damper keeps the injectors that are'nt firing full of fuel. During a pulse from injectors opening,the damper keeps more fuel in fuel rail.
If it did'nt you will have a lean situation in those cylinders. They have done lots of dyno work to prove it.

but thats my 2cents

hosrom_951

I should have been more specific, yes the paragraph was quoted, i will edit it right now, here are also some previous posts regarding what would cause fuel smell in oil:

https://rennlist.com/forums/showthre...ighlight=smell
https://rennlist.com/forums/944-turbo-and-turbo-s-forum/145010-heat.html (this was unnrelated but i asked the question regarding fuel and oil)

I also could be mistaken about this, but that is how i solved my problem with the fuel in oil thing. Other may/may not have solved this problem by replacing the FPD.