14 AFR under 16 PSi out of nowhere

[thewird]

Last night while I was leaning out my AFR's in the vacuum cells. I noticed that when I do a full 16 PSi pull now, my AFR's go to 14!!! That is dangerously lean and I only let it run for like a second. Thinking that I may have edited the wrong cells by accident, today I loaded up the laptop and loaded the original map that was tuned before. Unfortunately its still doing the same thing...

Also, a bit after this test my air intake temps went to -25C and stayed that while for 10-15 minutes which made my vacuum AFR's rich and my 16 PSi loads roughly normal (~11 AFR). After about 10-15 minutes, it jumped back to normal (55C) and the 14 AFR problem under boost came back.

Ok, so theres a few things that I think this can possibly be. My air intake sensor obviosly needs to be replaced or wiring fixed. Now there is a possibility that the wideband sensor (Bosch) is almost dead and giving bad readings, however it can read rich AFR's still. I'm thinking since it only does it under boost and WOT, that it could be the fuel pump or fuel filter. Although when the air intake sensor died, I had proper AFR's so it might not be the pump so I'm leaning towards the filter. Also, could the TPS be a possibility? It might not be reading my full WOT position and therefore not putting enough fuel. It can also be the injectors but I'm hoping it isn't.

Has anyone ever had something similar or have other possibilities? I regularly track the track (almost every week) so I'm pushing it to the limits for prolonged periods often. Also the fact that I run 16 PSi at the track also pushes it even more.

thewird

[classicauto]

WHOA, crazy Marco!

Refresh my memory, you're not running a fuel pressure gauge correct?

I'd suggest fitting even a mechanical one so it can be watched on the dyno.

Given the fact that once the air temp sensor had a brain fart (and read -25) your AFR's under boost went back to normal, I would almost lean away from a pump/filter/injector issue a bit given that ONLY the change in air temp readings restored the proper fuel amount. If the filter were plugged up really well it probably wouldn't have been able to return given the fact that its clogged.

Is it also possible that during the first lean AFR situation that the air temp might have gone buggy? Did you notice it at the time?

Check out all the wiring and the sensor itself and go from there :)

EDIT: To me though, the most suspect part of the fuel system would be those 1300's as several people have had issues with them, but also, I don't know the age of your pump and filter. If anything, a fresh filter won't hurt...

[thewird]

The filter was replaced last year or the year before (can't remember). The pump was in the car when I bought it so I have no idea about its age.

I don't think the temp sensor was buggy at the time since I've been testing multiple times when its reading right (even tested it again today after finding a loose vacuum hose hoping it was that). It always goes lean under full boost but is fine at other times (as long as the temp sensor is reading ok). Once the temp sensor goes to -25 (which it did again today for 2-3 minutes), vaccum becomes rich and boost becomes ok again at roughly 11 afr.

What have you heard about the 1300's?

I guess its time I get a fuel pressure gauge too.

thewird

[classicauto]

Hmm, I'd absolutely check the wiring out on the temp sensor as well as the sensor elelment itself. If its goign to -25C at all, somethings wrong with it.

I've heard of reliability issues with the 1300's being that its a stock injector bored to nearly twice its size - it wasn't designed for that kind of flow. But that doesn't mean they're the issue. It would seem since they're operating "properly" as in, flowing proportional to the current readings (flow will go back up to an 11afr under boost when the air temp sensor is being whacky) then I wouldn't think they're a problem now.

Check that sensor out...

[charlies7]

Are you running a stock map sensor? I know the stock ones gets out of calibration around that point..Does the car still lean out if your only running.say 12-13 psi?

[thewird]

I'm running the 3bar map sensor. It still leans out at those levels if im doing WOT. If I'm not 70% throttle it wont lean out even if its 16 psi.

thewird

[classicauto]

very strange marco, how'd you make out?

[thewird]

Still doing it but I went to the track again and it runs fine. You might want to read the other forum where its been more updated ^_^. I'm gonna rewire the fuel pump according to Chuck's notes and then tune to 13 AFR and see how that goes.

thewird

[Phoenix7]

I don't have access to the other forum, any key details you found?

[JDK]

I don't have access to the other forum, any key details you found?

I'll get him to respond...:)

[thewird]

Well I found the problem to be the vacuum hose on the fuel pressure regulator was off. I put it on and everything started working properly again. After one track weekend it started doing it again, lean boost, and rich vacuum. This time it was the solenoid switch. So problem solved.

thewird

[cewrx7r1]

A fuel pressure gauge would have showed you the results of that as soon as it happened. Forgot to tie wrap?

[thewird]

There was a clamp on. Must have just gotten loose with all my tracking.

thewird