Would injector problems show up on an Engine Dyno? ---

[Paul Workman]

Originally Posted by alwayscode390

My idle is great actually.

I will search on the ohm out injector process too.

I appreciate it ---

After a shop gave me back my 95 LT1 Vette, with a note that said, "No problem found", I bought an AutoXray scanner.

The scanner was able to report status of 42 different items, but the one thar really pulled off the fix was the "event" capability. I drove the car in the manner where the problem usually occured, and when it did, I pushed the button resulting in several seconds of data before and after the "event" was triggered. This allowed me to find an intermittent problem (with an O2 sensor, in that case). Since then, that scanner has paid for itself many times over - not just on the LT1 Vette, but once or twice on the ZR-1 as well (diagosed some connector problems for me!).

I keep the scanner in my "cubby" storage box behind the passenger seat...Just in case!

P.

[alwayscode390]

Awesome!

I drove the car this morning. I got it to "shudder" in the same problem spot but ONLY when I am not in the throttle enough.

It seems like its dumping a lot of fuel when the secondaries open, and if I don't have the throttle open enough or the rpms climbing quick enough it cant burn all the gas... and it shudders from it being too rich for that second.

As long as I am driving it aggressively enough there isn't a single issue.

Now, I have noticed irratic starting behaviors ... BUT the weather here has been so up and down (70 one day , 30 the next ... seriously) I am not sure if its connected to the temperature , or if its another clue to an injector issue.

When its cold outside it seems to take 5 seconds to start ... when its hot outside it starts the instant I turn the key which freaks me out because it takes 2 seconds for the oil pressure to rise when that happens, and its running with 0 pressure in that time frame.

Just figured I would throw that out there in case it points to another issue or confirms anything ---

[vilant]

You will need a voltmeter (never seen one without an ohm test on it) to ohm out your injectors. Here's a post that someone gave me when I needed to do mine. Great post, made it easy http://www.zr1.net/forum/showthread....7299#post17299

[alwayscode390]

Now that's what I am talking about. Thanks a lot Joe! Sometimes I need that motivation to get to work ---

[Hib Halverson]

An injector problem likely would show up on the dyno if you were taking air/fuel data

That said, injectors don't "stick" until "enough pressure from 1/2 to WOT pulls them open. "

First of all, at WOT there is no pressure other than atmospheric in the intake manifold so there's no "pressure" to "pull them open".

My guess is is there is a hesitation it's some problem with port throttles. Either they are slow to open or they're late to open on one side...something like that.

It's also possible the mixing and matching of injectors is a problem.

Never thought I'd see the day when someone would mix/match 15 stock injectors with one aftermarket unit. But then...fact is always stranger than fiction.

[alwayscode390]

OK, thanks.

I was given 15 stock injectors and 1 new aftermarket in a bag ... Im worried they re-used one of the original ones for some reason. ---

[Paul Workman]

Originally Posted by alwayscode390

OK, thanks.

I was given 15 stock injectors and 1 new aftermarket in a bag ... Im worried they re-used one of the original ones for some reason. ---

I'd be concerned if the 15 were NOS injectors built before 93. I can tell you from personal pain that NOS injectors before 93 are good for something less than 3 years before they start going south (on 10% ethanol).

Hope you didn't already install them if they're the older injectors... Are they, do you know?

p.

[alwayscode390]

The 1 new secondary injector I got is a yellow/red Ford aftermarket.

The 15 others were black/gray OEM.

I hope they bought 1 too many injectors , but its looking like they either forgot to use the 1 Ford leftover , or it had issues so they reused the 1 best OEM.

Just checking ... but you cant see what injectors are installed until the plenum is taken off, right? ---