Who here is running a MAF with stock injectors??

If so, what psi are you running?

Done duty cycle tests or a/f printouts???

 

With a MAF, at 3bar FP you will be maxing out the stock injectors (at 16-18psi) with the stock turbo.
The duty cycle is 100%

 

Does the MAF lower the amount of boost you can run with the stock injectors or is 16-18psi the upper limit with the stock AFM as well? I don't completely follow.

 

I was maxing out my stock injectors with my MAF and 2.5 bar fuel pressure at 15 psi.

Chips from Vitesse, 55# injectors, 3 bar fuel pressure ought to eliminate this problem

 

Autothority Stage II MAF with chips 14psi LBE Stock everything else.
Never had a lean situation(then again I am on narrowband
Go to 80 percent duty usage on the upper band with stock injectors.

I know this is not the optimum setup...but have not had the money to invest in the tools to do the job right.

 

What is the contributiing factor to the duty cycle of injectors?

Is it the VE, hp, boost, cfm????

 

The injector duty cycle is dierectly related to airflow or CFM however, at any point in the engines operating envelope it is a combination of things, rpm which gives airflow as measured by the AFM or MAF. The airflow at any given rpm depends on the boost being made. If the manifold pressure is exactly atmosphere at a given rpm then the airflow would be x. At the same rpm and at 14.5 psi of boost(1 bar), the airflow will be approximately twice the value of X. So the computer brain measures these and sends a signal based on either a programmed value in the chip , when operating in open loop, or when operating in closed loop at say partial throttle it reads the O2 sensor output and adjusts the fuel injector open time from 0 to 100% depending on the airflow. If the specific injector is operating at the 100% level it is flowing all it can flow at a given fuel pressure.

 

Do setups such as Vitesse Piggyback monitor/log injector duty cycle. If not, what's a good way to monitor duty cycle?

Crap, I feel the need to highjack a bit. What's a good way to monitor fuel pressure on WOT (and other condition) runs?

Oh, oh! and can piggyback systems log EGT's?

/hijack

 

I think the SMT6 can monitor a couple of aux inputs.

I know the Zetronix Wideband can monitor EGT's as well as boost and a/f

 

Bosch do not recommend running more than 75% duty cycle...

 

In its last evolution my car ran an Autothority MAF, TiAL WG and custom chips at 1.01bar on an otherwise stock engine. I don't know the duty cycle as it was only like that for a few weeks before I broke it (not a fuelling issue) but it was capped to that sort of boost to keep within the capacity of the standard injectors. It was still a lot fatser than stock and very smooth with little latency. It is a '90 UK car so had a K26/8.

 

My car with Vitesse chips, Lindsey DP wastegate, EBC, and testpipe is at the limit of the stock injectors at 16-17psi. That's with stock AFM and stock K26/8.