rraulston

Can you take a look at my dyno run and give me some ideas as to why my car goes pig rich instantly and stays there?? I have a new temp sensor, fuel pressure is good, injectors just rebuilt at RC Injector, brand new o2 sensor and I have a brand new AFM. Maybe a bad ecu???? It’s a 1983 944 all stock…Thanks Ray

blown 944

Did you see a lot of black smoke out the tail pipe? It doesn't look like the afrs leaned out even after you let off. Did it do this repeatedly?

rraulston

Yes, my bumper is covered with soot. This is a track car and i was informed by some other drivers I was emitting alot of black smoke. Rented a dyno to see if it was fuel or oil and fuel it was. The temp sensor tested "open" in the afm so I bought a new one. Car runs much better but still rich. There is no gradual change, it just falls right off. I did 2 pulls 5 minutes apart and same thing.....trying to research this "Closed/Open loop" stuff i'm reading.......I just hate throwing parts at cars and hoping to guess the right one after hundreds of dollars....

bsbiker

Go to www.frwilk.com. He built me a new computer for my 83 with a 89 2.7. He ca fix what ails ya.

Fara

To explain Open/Closed loop:

Open loop mode is used when the car is still not up to temp. It runs the engine on a fixed table of fuel/air ratios based on engine speed.

Closed loop is used when the car is up to temp. It runs the engine on a set of tables of fuel/air ratios based on engine speed, With a variable added to allow modification based on readings from the O2 (Lambda) sensor.

[Edit] The reason the car only runs in closed loop mode when hot, is that lambda sensors do not work when they are cold, also the engine is not at full efficiency until it reaches operating temps.

max_boost951

86 turbo here, and it was brought to my attention that I blow a lot of black too. I have a 4" no cat exhaust and a wide band o2 sensor for tuning purposes. Mine follows a similar line except when throttle is released AFR falls off

rraulston

so, what do I do next??

blown 944

Have you measured fuel pressure under load? It seems like it is drastically raising fuel pressure.

Also, you may try to run it without the tps hooked up and see if it gets any better. This will keep it out of the WOT maps (if that may be the problem)

I would also personally try another set of injectors. Borrow.

blown 944

If yours has the autothority chips this is somewhat normal. You could try turning your fqs to position 2

Rogue_Ant

Most APE chips I've seen have a much larger adjustment step than factory. Turning to position 2 on an APE chip will probably pull out 12.5% fuel... So if you try this, make sure to watch your AFRs!