Now what...Poor idle, zilch over quarter-throttle - DFI and ECM - Third Generation F-Body Message Boards

dunesie · 06-30-2008, 11:40 PM

Ok,

I converted my '86 from carb to TPI. I have replaced the TPS and injectors. At first I had 26 lb. injectors and I replaced them with what the guy in Oceanside said was stock injectors but he also said they spec'd at 22 lb.

When I hook up my laptop to the ECM, I show no error codes but I do have the slow EECC (?) and rich flags. From start-up the I have to feather the throttle to get the engine to run, and when I put the transmission in gear I have to keep the throttle off zero to keep the engine running. If I go past about quarter throttle to half-throttle the engine bogs.

I am using WinALDL so I can log a data run if somebody can help me interpret the data. I am thinking I am still running injectors that are too big. If someone would help me out (I'm new to TPI and ECM data), what type of engine activity do you want recorded? Start-up and idle? An actual driving test? I really want to get this dialed in so I can get the car back on the road.

Thanks,

Duane

bigaggietrumpet · 07-01-2008, 12:23 AM

Well, I can't give you a lot of specifics regarding the ECM, but it sounds like you're overall way too rich, and I speculate it could be for a couple of reasons. Your fuel curve is probably not adjusted right to your new injectors, that has to be set in the ECM. It might also be something with the TPS, but seeing as you replaced that, I kinda doubt it. You're probably going to have to do some ECM programming in order to straighten this one out.

DENN_SHAH · 07-01-2008, 01:31 AM

hook up a fuel pressure gage to it & see what the pressure looks like.
it should be about 36~40 at idle with the vacuum line hooked up to the fuel pressure regulator. with the vacuum line unhooked it should be around 45 or so at idle.
what ever the pressure is at idle with the vacuum line off, it should be the same at under WOT when driving.

dunesie · 07-01-2008, 10:22 AM

The fuel pressure regulator is new and adjustable and is set to about 43 lbs. I will check the pressure tonight with the vacuum line detached. As for programming a new PROM for the MEMCAL, I think my best bet is to just pick up a new set of 19 lb. injectors for right now.

Is there anything in the raw data coming off the ECM that I can look for that will tell me how rich the engine is running? Will the O2 sensor reading give me an idea? The cost of another set of injectors doesn't bother me but the time to install them is a factor as I have way too many irons in the fire right now. I would like to verify that I am running way rich before I start the change-out.

Thanks,

Duane