Injectors in----Idle down ???

[cdrider]

OK, Heres my unexpected problem:

I installed a set of Bully Dog 50 hp injectors in the 93. I bled the lines and it started right up but the idle seems lower and it has a definite roughness that is noticeable until I rev it to probably 1500 rpm(don't have a tach). This is in neutral/no ac. In drive with ac on its really rough. I took it out for a 10--15 mile run to make sure the air was out but it didn't help any.

The stock injectors I pulled out gave a VERY smooth idle even in gear with ac on.

It seems(from the posts) like most guys see the opposite---an increase in idle when they upgrade injectors.

What should I be looking for---bad injector? ---could there still be air trapped in a line? I sprayed it of with brake cleaner and there are no leaks.

Any ideas appreciated.

 

[dpuckett]

I would hazard a guess that the pop pressure of the new injectors is higher, giving you a net retard in dynamic timing. THAT will lower your idle, and make it run rough as a cob. Try advancing your timing (AFC housing TOWARD the head) about 1/16" inch on the pump flange vs the gear housing, and see if that helps. Did you get any whit smoke with the increased roughness? Last timing advance I did (TO 1. 7mm when I was @7500ft) gave me another 50 or so RPM, but i have no tach either, at least not hooked up.



PS- I may be interested in your stock injectors later this summer if the spray pattern is good and pop pressures are even. Getting a new head sometime this summer, and doubt I'll be able to afford new EDMs at the same time.



Daniel

 

[BushWakr - RIP]

It is common to find your idle down a tad with uprated nozzles... don't be too concerned.

Follow Dan's tips, including increasing the timing.

Your idle should be around 800-850 RPM with no accessories on.

With AC on high and in gear (for an auto) your idle should rest around 750-775RPM.



pastor bob... .

 

[bgilbert]

Yes uprate injectors will lower idle. . Time for timing or fuel or governor screw adjustments. Fuel and governor screw alone will increase idle, so you might not have to adjust your idle with the low idle screw. Wait til you do these if any adjustments before you play with low idle screw.

 

[JLEONARD]

Gee, when I installed my Bully Dog +50 injectors, the idle stayed the same... except for being smoother.

Power increase was awsum... really turned on in low to mid range.

Now "adjusting" the fuel screw... well, that raised the idle "a tad".



Jay