Injector Amperage issue? (Bailey Modified Low-Z ECM)

[forcefed86]

Just had the ECU checked by Bob a few months back. Car has been running fine since.

Last weekend it started running rough. After a little trouble shooting I found the #1 injector was not firing. I'm getting full voltage at the plug. Noid light flickers just fine on the no.1 inj. lead. So I figure its an injector issue.

I pulled all injectors and set them up on my test rig. Pumped inj cleaner through them all and cycled them with 2amp 12v. All seemed to work fine. I re-installed them all the the car ran great.

Today (week later) the car runs rough. I went right to the #1 inj again, but it worked perfectly. Now the number 6 injector is doing the exact same thing! So I Ieft the injectors installed this time and brought my inj pulse setup over to the car. With my 2amp 12v power supply The #6 injector worked perfectly. Plugged it back into the engine harness and everything is ok again. Car drives/idles great.

I've confirmed I get bat voltage at the inj. leads. Noid light confirms they all pulse as they should.

Anyone have any ideas? The only thing I could think of is I'm not getting enough voltage at the injectors? The grounds are all ECU controlled correct? Not much I can do to help that. Can I wire in an "IGN ON" power source that I know is good to the main power going to the harness? Is this common? I recently had a HG fail as well, I think this may have caused it.










thanks!

 

[SHADOWII]

As far as I can remember, the ecm does provide the grds. But if this is intermittant, as it appears to be. It's more likely that the inj. problem may have caused the hg failure by leaning out one or more cylinders. I'm not familiar enough w/the wiring to guess where the probable cause originates, but I would contact Bob B. for suggestions. He would be able to narrow it down for you. It could be as simple as a loose grd.

 

[forcefed86]

As far as I can remember, the ecm does provide the grds. But if this is intermittant, as it appears to be. It's more likely that the inj. problem may have caused the hg failure by leaning out one or more cylinders. I'm not familiar enough w/the wiring to guess where the probable cause originates, but I would contact Bob B. for suggestions. He would be able to narrow it down for you. It could be as simple as a loose grd.

Thanks for the suggestion. I have a pretty beefy ground setup in this car. I really doubt thats the case. 99% sure the ECM controls the ground pulse to the inj anyway and I know the ECM/chassis/eng have good grounds. I will look into it though. Anyone know if e the ECM picks up the ground signal to pulse the injectors off a specific pin from the ecm?

The 12v to the inj's is a constant power source. I should be able to read the actual amperage being supplied. As soon as I know what that amperage is. Bob usually chimes in when he sees his name in a thread, I'm sure he'll drop in soon.

 

[RmvBfrFlght]

If these are low-Z injectors they will go to 2 amps on the peak, then hold at a 1/2 amp.

Standard hi-Z injectors vary in resistance. With the current being from 0.9 amp through 1.25 amp. This will also vary according to vehicle voltage.

Sounds like the injector harness and/or connectors are going out.

RemoveBeforeFlight

 

[TurboBob]

the ECM has several high-current ground pins, they all connect together inside the ECM, and all go to the engine ground. But if it were one of these, it would affect all the injectors.

Check the injector harness connector under the coilpack, check the injector harness connectors for corrosion. It is also possible that some of these connectors have lost spring tension in the pins due to heat and age.

Bob

 

[bison]

Check the pins at the ecu also. I've seen problems in that area. You can use a safety pin and apply a little pressure to bottom of each pin and bend it slightly so it's getting better contact at the ecu terminals. I commonly do this to the ignition module pins on cars that are old or have high mileage. The pins relax and the terminals corrode a little and connections become intermittent and you have problems like you described

 

[forcefed86]

Thanks all!
Just finished putting the car in winter storage. I'll do all of the above and test it out on the jack stands though. Can I "hotwire" the 12v "ign on" to all the injectors with a known good voltage source? Or will this cause problems?

 

[BEATAV8]

Can I "hotwire" the 12v "ign on" to all the injectors with a known good voltage source? Or will this cause problems?

racetronix sells an injector harness for that. has a "hotwire" with it.