Quick AEginuity question

azkcr · Apr 1, 2013

Yep, another thread that I posted on the org and haven't gotten any help with yet.

Hi,
we have a 1999 7.3l that is TERRIBLE to start in the mornings even when plugged in.
I know that there are a few injectors that are not functioning until it has been started and run for a bit.
When you first start it, the autoenginuity says that #3,5,8 have a high/low issue.
Once it runs and starts to smooth out, all the injectors are fine in the Contribution Test.
Is there an electrical issue or do I have 3 failing injectors???????

Thanks,
-Ben

golfer · Apr 1, 2013

Contribution tests are NOT injector tests...

read this diagnostic.

http://swampsdiesel.com/files/7.3LInjectorDiagnostic.pdf

azkcr · Apr 1, 2013

Aaaah...
Thank you much sir ^^^^

So the only/best way to diagnose each injector is for listening to the buzz test...
When cold? Hot? After it's ran for an hour? Before it's been started??

DocBar · Apr 2, 2013

You should also check your glow plugs and the GPR (glow plug relay).

azkcr · Apr 2, 2013

Checked GPs after replacing GPR with a Stancor unit. They're definitely hot

ToMang07 · Apr 2, 2013

Definitely do the injector buzz test BEFORE you start run it, preferably when the engine is cold, after sitting overnight.

Most of the time the #3 and/or #8 fail on the CCT due to the CPS. So that is a very unreliable test.

Any chance of a start video Ben?

And how is the blow-by when it's warmed up?

rustbucket · Apr 2, 2013

Hows compression on those cylinders when cold.

azkcr · Apr 2, 2013

I'm a road warrior today delivering equipment, but I'll definitely try to get a video of it this afternoon.
IF it'll start, big if, then I'll get a cold start video. Even plugged in, it's terrible.

Haven' done a compression test yet, and it's got a CCV reroute and it hazes just a smidge.

But, it has been sprayed. We have 90+ mechanics that work here that "know how to get'r runnin'...."

azkcr · Apr 2, 2013

Running 5w-40 syn and RevX (I know it doesn't help 7.3s as much).
Kinda at a loss here... They all buzz, not all are strong. But they buzz

rustbucket · Apr 2, 2013

I would do a compression test. My truck had the same issue when i got it from an auction. Four cylinders where polished glass smooth. We had to pull start it but once it was warmed up it would start and run desent.

PSDEng · Apr 2, 2013

Great, they all buzz, all of your injectors are plugged in. Did you read the entire tech article that Dave posted?

"Cylinder contribution tests(CCT) & rotational velocity tests are not "injector" specific tests. A buzz test is as close to an injector specific test...but...an injector buzz test, merely checks the electrical continuity to/from each inj to the IDM. Basically...if all 8 injs 'buzz'...then that merely meansthat they are plugged in. No determination can be made about whether the injectors are good or bad..or somewhere in-between.
The consistency (in tone) of the buzz test (audibly)should be considered and paid attention to when a buzz test is performed ...since any difference in sound can indicate problems (or just normal wear issues) related to the movement of the poppet valve, when it is pulled up by the (energized) solenoid."

Arisley · Apr 2, 2013

How many miles on the truck. Just a WAG here, but I would bet on time for a set of injectors.

ToMang07 · Apr 2, 2013

Arisley said:
How many miles on the truck. Just a WAG here, but I would bet on time for a set of injectors.

My guess is injectors or compression problem.

Arisley · Apr 2, 2013

True, and a compression test would either confirm or eliminate a compression issue.

crowz · Apr 2, 2013

If you have injectors not firing cold and it smooths out warmed up its easy to figure out if its the injectors.

Plug the block heater in. If it runs fine the next morning the injectors are shot.

Trust me, I spent a few years with mine tethered before replacing mine

My avatar used to be a pic of it with the block heater plugged in.

As for figuring out which ones are bad, good luck. I buzzed tested, contribution tested, pixie dust tested, etc for years. Never did find a reliable way to figure out which ones it was. Just replace them and be happy is my advice if the block heater cures it. Set of swamps injectors fixed mine right up and has been perfect for years now.

JLDickmon · Apr 2, 2013

who's "Crowz?"

azkcr · Apr 2, 2013

PSDEng said:
Great, they all buzz, all of your injectors are plugged in. Did you read the entire tech article that Dave posted?

"Cylinder contribution tests(CCT) & rotational velocity tests are not "injector" specific tests. A buzz test is as close to an injector specific test...but...an injector buzz test, merely checks the electrical continuity to/from each inj to the IDM. Basically...if all 8 injs 'buzz'...then that merely meansthat they are plugged in. No determination can be made about whether the injectors are good or bad..or somewhere in-between.
The consistency (in tone) of the buzz test (audibly)should be considered and paid attention to when a buzz test is performed ...since any difference in sound can indicate problems (or just normal wear issues) related to the movement of the poppet valve, when it is pulled up by the (energized) solenoid."

Yes, did you not read the entire thread???
I said that they all buzz but meant that some are stronger than others and if that is how you diagnose specific injectors.
:edit: Or did I??? lol

azkcr · Apr 2, 2013

It's hard keeping track of what info I've given on here and what I've given on the org about it.
Because we have 3 PSDs down right now and I first tried over at the org and it seams that they aren't as busy as they were a year ago.

Some injectors buzz stronger than others, some have been replaced with OEM sticks, some have been O'Reilly specials, some are original.

My entire problem is that I was thrown into this entire fleet and no one knew/knows how a PSD works or what to do/not do.

It's not even the same motor that came with the truck

wned:

I will be doing a compression test soon. My main question is how do you find out which injectors are bad?? (If there is a way)
BC like I said, some are new, some are crap... :slap: