fire350tpi

Quick question, been noticing since i replaced my maf ( runs very good compared to before still a tiny miss but i can deal with it)
after 30ish cruising ses light pops up

Check codes when i get back 13,33,34,36

Do you think the o2 messing up would make the maf code pop up? ( brand new burn of relay and MAF if idling and reving etc, will produce no codes)

Vader

Test the power and signal at the MAF with the engine running, then monitor the MAF during shutdown/burnoff. I'd suspect your new MAF didn't solve the problem, and now you get to perform the diagnostics which should have been done before replacing it.

Is the MAF power relay good?

CKirocZ

Yes, the O2 sensor can cause the ECU to set MAF trouble codes. Test your MAF like Vader said and if it checks out OK, buy a new O2 sensor if you haven't already.
Oh, this may be a stupid question but, did you clear the codes from the computer after replacing the MAF?

fire350tpi

Ive done the diagnostics, before it was a bad MAF, threw a 36, i diagnosed it to be a bad maf from the troublechart it needed a new burn of relay.
It didnt help it so
I boughta reman maf, made it run so much better

I had used a snap on scan tool, dont have access to it now since out of shop ( summer wont be back till september)

Never measured the output of the maf during idle etc how is this done?

Vader

Backprobe the electrical connector for the MAF. A typical L98 should move enough air at a normal idle to generate a 900mV or so signal.

fire350tpi

Alright, ill try that

I believe blue is the output wire ill go check that



Another thing that accured to me is maybe i should just replace the o2, reset the computer and see if it sets a code

Its wierd because i can let it sit forever reving and such never throws anything,
Only when your cruising do's it

8Mike9

Did you clear the codes after the new MAF?

fire350tpi

yes i did, Ive reset the ecm a few time as well

Vader

Ground the meter at the black wire (terminal B) and positive at the green wire (terminal C) and meausre the voltage signal at idle.



You should read around 800-900mV on a 350 at a normal idle RPM:

fire350tpi

Was idling around 900

i got a .840-60 ish reading, flucuated a bit


im gonna reset the ecm and see if itll pop the codes up again, ( just checked codes 13, 33,34,36, 42

fire350tpi

Wasnt able to drive today, Probly tomorow


any other tests i can do?>

fire350tpi

Reset the ecm and took it for a ride was fine then code popped up


then i pulled over and checked them

13,33,34,35,42

All at the same time it seems, im thinking a new o2 would cure the problem( maybe est as well)

Vader

That MAF output is just about perfect. Nothing wrong with that piece of hardware.

You might want to verify good connections between the MAF and ECM, and keep an eye on the TPS signal. As long as you're checking, be sure the TPS has a full 5.0V reference voltage. May want to check ECM and engien grounds again, too.

Was that a typo, or did you actually get a "35" error code?

fire350tpi

typo, was a 36 as usual
----------
my question is there a System ground that is related between the 02 and maf systems or is it just coincidence the codes pop up at the same time

my tps is set at .56 and near 4.5volts WOT

i notice around the 2 volt range it goes to 0.00 so i think its a bad sensor

Would this make the codes pop up

fire350tpi

no ideas?

Vader

Boston - We have a problem...

If the TPS falls off to nothing part way through the sweep, it is probably failing. When the TPS signal falls off, the ECM will interpret the MAF flow at too high for that throttle angle (33). You at least need to resolve that TPS problem. That may clear up one or more codes, then you can procede.

fire350tpi

Alright, Ill see if i grab a new one soon bit tight on cash

fire350tpi

just bought new tps, installed and set to .54


Then tested it.... turns out it go's O.L at 3.9-4.0 ish volt


But thats only about wot, so.. better then the previous tps and its way to hot to be running back and forth lol

ill give it a test drive in about a hour

fire350tpi

been driving it lately, ive narrowed it down


ONLY when i get a code 24 do's everything pop up/go crazy

it was converted from an auto, but atm speedo/vss isnt working

So, code 24 is when its above 1700 in P with no throttle

and keeping that in mind, instead of let of the gas, i would push in the clutch etc

no codes popped up unless i slipped up by mistake



ALSO

have 175 bucks to spend on car, still has a vibration to it so im thinking, New performance plugs..gapped to .35 Accel 50k coil, and some taylor wires to get it all there and make it run smoother, then fix the vss/speedo when i get back into shop ( sept)