My car is running really rich at WOT. At the dyno, my A/F ratio was 11.8. At idle it is around 14.7. As soon as he punched it, it droped to about 11.2 and slowly rose to 12.0 at the end of the run. Does anyone have any ideas? My mods in my sig. I tried adjusting the AFPR but it didn't really do much as far as the A/F ratio. I had a big effect on my torque though. I was thinking of a leaking injector but would that cause it to run rich at idle also? Thanks guys.

 

Exactly how close do you expect a stock chip on a 18 year old car to be. 12:1 isn't the end of the world.

But yes, old injectors can always be suspect. I had a set cleaned and flowmatched for my car just for general principle. MPFI kinda needs consistent fueling.

But if you really want to get a tune on, you have to be in the chip. Which is a hassle with the 85 dinosaur ecm.

 

It's not the 12.0 that bothers me as much as the 11.2. When you punch it, you can smell the gas and this is with the car warmed up. Even with the stock chip I expect it to be closer that 11.2.

 

Apparently your ECM and engine have other ideas?

 

:lala: :lala: Gee thanks, you have been a lot of help.

 

 

Also, you haven't said what your injectors size is (original stock)? How much have you cranked up the fuel pressure also? If you just cranked up the fuel pressure without modifying the eprom, you probably found your problem.

Virtually all calibrations I've seen for stock General Motors' cars tends to error on the side of richness. The last thing a bascially stock engine needs is more fuel. Cranking up the fuel pressure not only can cause over fueling in WOT but also affect the "Accelerator Enrichment" aka (EFI pump shot), that's why you are dropping so much when you first boot it.

Ed's right, the ECM and eprom (calibration) are not happy right now. Also, Ed's comment on "old injectors" is valid too. You may have a couple of things working against you.