sr20det Problem, stumped completely

[glacier985]

Okay, lets see. First off, car cuts out anywhere from 5500rpm to 6500rpm, somewhat random. So we figured the MAFS was maxing out. So a daughterboard was installed and a tune made for 555cc injectors and a q45 mafs was put on the chips. This fixed nothing (and the jumper was moved from CJ1 to CJ2). So more and more tunes were tried, nothing fixed anything. So daughterboard was removed and the car still ran, didnt cut out until 7k rpm, so we are like wtf??? So come to the next day and the car is cutting out a 5500-6500rpm again.

A new tune is tried for the stock MAFS and 555cc injectors, still the same. So we begin to suspect something else. The MAFS wiring, so with the car running the MAFS was disconnected, but to are amazement the car still ran the same. So now we are really, really confused. So my buddy, who owns the car begins to search for a cut wire, short, anything. But finds nothing, and decides to cut the MAFS wires at the ECU and yet the car still runs the same. Nothing seems to fix the problem. So the wires are reconnected and a new ground is install for the MAFS. This does nothing either, so now we come to this point, wtf if wrong with the car, it should not run at all with the MAFS disconnected and 555cc injectors with no tuning whatsoever.

Any Ideas??

[rogoman]

With the MAF disconnected, it should run in fail-safe mode. Something in the wiring is probably screwed up.

The MAF signal wires, pins 1 & 2, should be in a shielded jack from the ECU all the way to the MAF. If those wires are not shielded, EMF influence will cause negative affects.

Here's a test you can run for the MAF:

[5upra]

ahh...this sounds familar. I have had the same problem until a couple weeks ago when #3 cyl spark dumped on me. Now I am figuring out that I got some messed up stuff on that cyl. However you should check spark...does the car back fire at all when cutting in and out?

[matt_pound]

this is my car,

so if it's the sheilded wires that are they problemwhy did they all the sudden get messed up after 2 years of being in the carand if the wires somehow messed up inside that can make it go into fail safe?and how can i fix this

run new wires? what do i use to shield them?

and once fixed will it just come out of fail safe mode?

and i don't have a 4 pin mafs i have a 3 so is number 1 on the 4 the white wire like it is on the 3 pin
Modified by matt_pound at 2:05 AM 7/16/2006

[rogoman]

i don't have a 4 pin mafs i have a 3 so is number 1 on the 4 the white wire like it is on the 3 pin

Pins 1 & 2 are in the same position on a 3 pin MAF as well as on a 4 pin MAF.

[matt_pound]

ok, the car switches back and forth from normal to failsafe randomly
Modified by matt_pound at 3:18 PM 7/22/2006

[matt_pound]

i DO have continuity from the mafs all the way to the ecuand i have tried a different mafs

so now the only conclusion would have to be the ecu

unless anyone has any other ideas

[glacier985]

Some input from me now, not sure if this is the cause of the problem. But my theory is that the q45 MAFS wiring is different, but im still not sure and that screwed teh ECU up and so now it just jumps back and fourth.

[574-240sx]

What is the cars setup, whats done to it. Initially I would have said look at the coilpacks and ignitor. Sounds like its either a wiring problem or a ECU problem. I would with a known good ecu then go from there.