peak-n-holds

[Mike Pitts]

Sorry about the non-descript question. 

More specifically:

I have the stock ECM in my Buick GN which still has 
the stock saturation type injector drivers installed. 

I am however running 55# low-impedence injectors. 
I know that this is not supposed to work, but it 
has been working...so far.

I have some peak-n-hold drivers (4A) that I would 
like to install into the ECM to make it right for 
the injectors.

I am curious if doing this is going to change the 
fuel output of the injector compared to what it is 
right now with the saturation type drivers.  

My understanding is that the "peak" part of the 
peak-n-hold might cause the pintle to open slightly 
quicker. If so, I would guess the total open time 
would be slightly longer, allowing more fuel to enter 
for a given pulsewidth.

Thanks,
-Mike

-----Original Message-----
From: owner-gmecm at efi332.eng.ohio-state.edu
[mailto:owner-gmecm at efi332.eng.ohio-state.edu]On Behalf Of jsg at donet.com
Sent: Thursday, March 18, 1999 4:01 PM
To: gmecm at efi332.eng.ohio-state.edu
Subject: Re: peak-n-holds 




   In message <E299274A3F18D211B9E700600805A01D0100BFB8 at crash>, you write:
 
| Has anyone ever taken fuel delivery measurement differences 
| between peak-n-hold and saturated drivers, for the same 
| injector at the same PW and fuel pressure? 

Same injector? If you have a low impedance injector, you don't want to
use a saturation driver. You can detect an electrical insulation
burning smell with full power on for as little as a second. If you have a
high impedance injector, it is designed for full voltage (or full
current). So... if you have low-z injectors, you need pnh drivers... if 
you have high-z injectors, I don't see a need for not using a
saturation driver nor a performance difference if one is used.

| My thinking is that the P-n-H drivers may open the injector 
| a little quicker, therefore delivering slightly more fuel 
| for a given PW.  

Using a high-z injector with a higher source voltage (like 30-40V)
to give an initial current greater than 12V/Z_{injector}
may make a difference, but that would require a setup power
supply. Is that what you want to try?

john