running rich, required fuel way off
 

i installed the megasquirt, and my wideband over the weekend, and i'm a little bit concerned.

i had problems getting the car started initially and was told by :brain: to adjust the required fuel since he thought it was lean. it turned out that the car was only running on two cylinders.... thats fixed

i knew that it was running rich, but when i started it the afr gauge was pegged at 10. since i had adjusted the required fuel before, i redid the req fuel calculator in TS, and got 12.7. burnt that to the ECU and the AFR went to 10.2-3. I kept adjusting the fuel and got all the way down to req fuel= 7.5. It idled with a AFR in the high 13's, low 14's like that. That req fuel number seems REALLY low for stock injectors to me. I'm thinking i might have a leaky injector, or maybe one is stuck open. I held a piece of rubber hose to each one and heard them clicking pretty clearly, but they do have over 160k on them afaik.

i have a newly cleaned and flow tested set of 550cc injectors, would it be a good idea to throw them in and see if thats the problem?

i'm going to attach my MSQ as well. the Req fuel is around 8 atm

I think you may have mistaken the required fuel (general statement) for the Req_Fuel (constant)?

What he was likely referring to is that you need to tune the fuel tables. It's not going to be perfect right off the bat. You've tackled the first part: starting the car. Now it's time to tune tune tune. Adjust the Fuel VE Table (not the Req_Fuel) to fix your idle AFR's. Also, I'm assuming you're starting on a cold engine. First start, you'll need to baby the VE Table until the car is warm and no warm-up enrichments are activated. On first start just adjust that table until the car is warm, then zone it into your target AFR. You can adjust the warm up enrichments later if needed.

If you're autotuning using Tunerstudio, you may also want to consider filtering out the idle cells once you have those where you want so they don't change while you're street tuning.

If you're running stock injectors, try 13.2 for required fuel.

put the reg fuel back at what you got for stock injectors and adjust the fuel ve table and see if you can get it to idle near stoich

the req_fuel should be considered abritrary; it's a multipler that's it. it's purpose is to keep the VE fuel table values within scale.

(if you want to reduce fuleing across your entire fuel map 50%, lower the req_fuel value 50%)

If you're too rich at a req_fuel of 8, lower the Req_fuel value, or start lowering the values in your fuel map. The value should have been reduced in proportion to the injector size change.

That being said, if I was running 550, my req_fuel would be ~5.9.

if i'm way off base here, please explain why...

the fuel map im using is for a stock 1.8 (which is what i have). it seems to me that if it's pig rich at idle, it's going to be super rich everywhere. thats why i was trying to get the idle AFR close via the req fuel number. if i just adjust the cells in the map where it's idling, i'm afraid it will still be rich everywhere else. I dont even want to drive it with the AFR's in the 10's.

btw i think brain misunderstood my OP. I'm still using the stock 1.6 240cc injectors right now.

READ: http://www.megamanual.com/v22manual/mtune.htm#ve

Come back with answers :) ....and follow techsalvager's advice. Don't assume the car is ready to drive as is with no tuning. You have to tune it! Set your AFR targets, warm the engine up, then start the autotune and drive.

thats great and all, but it doesnt help me determine whether or not i have a problem with my fuel system.

i'm afraid i have an injector leaking badly, or stuck open, therefore throwing off my AFR on the gauge. if this were the case, it might show ten, when three of the four cylinders are actually stoich, or lean.

It is great isn't it? At least make an effort to tune the car before speculating that you've got a mechanical problem. Have you even warmed the car up beyond warm up enrichments? If not, then yes, 10:1 is perfectly normal on an untuned engine running on a base map.

i ran it for quite a while playing with the req fuel, but never looked at the coolant temp. i'll try again and make sure it gets warm.

Do you understand why you should leave req_fuel alone?

not really no. all req fuel does is scale the whole fuel map. if it's rich all over, why cant you adjust the req fuel, then just fine tune the VE table? that seems easier than hitting every single cell in the VE table

Put req_fuel back to where it was. 13 IIRC.

if it's too rich, highlight the entire fuel map and lower the values. Car should be running in the high 12s during warmup.

I also forgot to mention, next time you do this tuning "DATALOG" it

Alright, thanks for the help guys.