So I've been battling a rough and lean idle and knocking in WOT (due to lean condition I think). So This weekend I checked the fuel pressure and injectors. The fuel pressure was between 38-40 PSI at idle with the vacuum line on, and 45 PSI with the line off. So I think that is in spec.

Then I did a power balance test on the injectors, but I didn't realize you also have to disconnect the ESC when you do it (I did unhook the IAC), so I didn't see the RPM drop like I was supposed to. But I did notice something interesting on the BLMs. When I disconnected #1, the BLMs shot up to 160, which makes sense. However, all of the passenger side injectors caused no change in the BLM when individually disconnected. On the drivers side, 2 of the injectors caused the 160 BLM, one cause a 136, and the last a 140.

(Note that I normally get between 124-128 BLM at idle, but only because I've jacked up the fuel in the tune, it will run almost to 160 on a normal 6E table from AUJM).

All injectors are energizing as I can feel them switching. So does this conclude that my injectors from '87 are indeed ready for replacement? Or do I need to rerun the balance test without the ESC? There really wasn't much change at all in the sound or temperament of the motor when I was doing all this either.

 

checking ohm on all injectors will give you more info...should not be less than 11ohm. If they are then you need another set if injectors.

 

Yeah I meant to do that but I was out of town and didn't bring the meters. But that will only give me the state of the coils correct? They could still be clogged? They look like they've seen better days, some are pretty rusty.

 

Yes, that is correct, but if the coils are bad then that's it, end of story, you will need new injectors. Can they be clogged? absolutley. Start with the easy stuff first. Post your findings.

 

Gotcha, I was just making sure. I'm hoping to do another power balance test (correctly) and an ohm test either tonight or tomorrow. Got my eye on a set of those 27lbs Bosch III's, assuming mine are bad...

 

just let us know what you need...we will be happy to help!

 

Looks like the coils are fine, everything was between 16.7 and 16.9 ohms. I guess I'll have to do another power balance test.

 

Ok so I redid the balance test with the ESC and the IAC unplugged. The BLM's reacted the same. Here's the RPMs:

Base idle: 600-650 it was very lopey

Drivers:
All - 650-700 rpm (RPMs went up ????)

Pass:
1 - Pretty much stalled but came back up 500-600 all over.
2 - 600-625 (no change)
3 - 600-625 (no change)
4 - 500-625

Soooo, my guess is that they are bad given the discrepancy of behavior between each one. I guess I don't feel completely convinced since I haven't worked with injectors too much. Opinions?

 

why are you getting such big injectors? Car may run worse with those.I would not go over 24lb/hr. I would use the stock ones and bump up the fuel pressure if you want more power.

 

I have a burner so I'll adjust the injector constants. I will be building this car up in the future so it seems like a good idea to me. I've read of people using larger injectors on stock cars just fine, so I think with the proper tuning I'll be ok.

Well I went ahead and ordered new injectors and an AFPR. I'm still not completely convinced that they will fully solve my issues, but I think they are a contributing factor. It still bothers me that my BLMs don't respond to the passenger side injectors being unplugged, especially when one practically stalled the engine. The PO had Meinike fab up a custom exhaust which is a bit funky looking, could the O2 sensor not be getting a reading from the passenger cylinders?