Crazy injector... Cant decide if its bad or not!

[elwesso]

I will flaunt that Ive likely had one of the best Q45 experiences out of anyone over the last 5 years or so... No issues other than a bad fuel pump, and everything else I replaced were wear items like suspension, etc.. Got lucky that had a T3 engine swap so all the right stuff was done...

So probably 3 weeks ago, I drove about 30-45 mins away to help a friend, and on the way back i noticed the car was idling rough, CEL was on, and lost a little power... My first thoughts were that an injector was bad.. So when I got home, I checked my injectors and sure enough, #5 was bad...

#5 injector ohmed out around 120 ohms or whatever, was clearly out of spec.. Called up deatschwerks, ordered a new injector and everything is dandy.

Fast forward to this monday, i have not driven the car in almost a month because I was waiting for a good time to change the injector. I was in a pinch and I had to drive the car. Started it up, and from running rich was a bit hard to start and once it got going, lots of smoke from unburnt fuel..

Once it was going, it was running great, like nothing had ever happened... Drove it and everything was fine. So today, I got curious and tried it again... Started up a little rough, but its running great now...

The weird part: I ohmed the injectors again after driving a few mins, and all 8 were back in spec... They were all within .1 ohm of each other, just under 12 ohms... So i went and drove it for about 25 mins, city and highway, thinking maybe something was funny when it got up to operating temp... Still runs great... But when hot it ohms around 90ohms, but still runs smooth..

So this weekend Ill be replacing the injector... Just kind of strange how injectors act sometimes.

[JOSHIE88]

my car has done that a couple timesi give it a couple days to make up its mind if it wants to fix its self or if i have to do it lol

[Q45tech]

If you xray the injector you will see the EXPANSION cold vs hot and how the coil wires pull away from the crimp to terminal.I have seen some where the diameter of the coil wire gets reduced [resistance goes up] from caustic/corrosion action of components in fuel.

[Trumpkin]

I think the big thing here is when did you ohm it? Right after you got home? still warm? Take it on a 2 or 3 hour roll and I bet it would act up. It eventually will again. You are smart to do it though.

[elwesso]

I think the big thing here is when did you ohm it? Right after you got home? still warm? Take it on a 2 or 3 hour roll and I bet it would act up. It eventually will again. You are smart to do it though.

i drove the car yesterday for 2 hours on the highway straight, and still operates fine. Starts a little hard, it seems like the injector might be bleeding down a little. When it gets going its fine but when you first start it, it seems like its running super rich and then clears itself out...

Im going to roll with it for the time being and carefully monitor the situation...

[Q45denver]

Sounds like there might be some contaminants/deposits causing the injector nozzle to remain open. If so, I would be concerned about possible hydro-locking. I would not recommend running it until fixed.

[Trumpkin]

either way its bad and should be changed. Come on Wes! Do it before it gets really cold up there!

[elwesso]

unfortunately im not going to be able to attend to it right away, as I do not have a new set of plenum gaskets and what not...

[illtww]

Elwesso..

Can you check your q45.org E-mail address?

[ericthered]

The weird part: I ohmed the injectors again after driving a few mins, and all 8 were back in spec... They were all within .1 ohm of each other, just under 12 ohms... So i went and drove it for about 25 mins, city and highway, thinking maybe something was funny when it got up to operating temp... Still runs great... But when hot it ohms around 90ohms, but still runs smooth..

So this weekend Ill be replacing the injector... Just kind of strange how injectors act sometimes.

I went through this a few years agohttp://forums.nicoclub.com/zerothread?id=106668

The injector is at its hottest 5-10 minutes after the car is turned off with the hood shut. Fuel injectors are cooled by flowing fuel and the fuel rail when the car is running. Once off, the temp goes up.

In the above thread I mentioned that one injector only had its resistance go up a little when hot. That injector totally failed 1 1/2 years later, and no others since then.

[Q45tech]

Why it is best to look at current waveform of all 8 injectors simulataneously at injector fuse While engine is running. You can see the ramp shape and peak current along with the point when the pintle acutally LIFTS.

http://www.picoauto.com/current-clamp-small.html

After all this test equipment can be used forever in any vehicle you have including all electric or nuclear. Everything flows current and it needs to be visualized.

http://www.autonerdz.com/events.html