Maf Trouble

[teddy]

To make a long story short, ....

My car dies at idle. I unplug the maf, it idles great, but I obviously can't rev over 2500. I plug the maf back in, and the car dies. But if I give it some throttle, I can rev freely anywhere.

Engine is a ca18 with a t3/t04e, stock maf, stock injectors, walbro pump, afpr, etc.

I've been trying to solve the problem for 3 weeks. It's the only thing that's keeping me from finally getting to drive the car. Help is much appreciated.

[vancouverbc]

is the ecu giving the code for malfunctioning maf? make sure the maf ground is good and maf is clean.

[teddy]

no codes. I cleaned out the maf not too long ago, but I guess I could always pick up some electrical cleaner and go at it.

[vancouverbc]

I'd make sure the ground is good.

[teddy]

Went out to check the codes again. First time, I got code 13, which is maf error. Checked the codes 3 more times to make sure, and flashed 55, which is no faults all three times.

Checked the ground, it's fine. Monitored the maf in and out voltages through my e-manage and they seemed normal too.

[vancouverbc]

the black wire should have .2v or less to ground. If you search in online mechanic, you will find a lot on the maf.

[teddy]

Well now I'm really stumped. Checked out all of the wiring. I'm getting the reg reading on the power wire, signal wire is just where it's supposed to be, and the ground is fine. I even added another ground on to that one and the car still stalls out bad. I used electrical cleaner on the connections and maf sensor itself. The car idles decent for about 3 seconds before it fell flat on it's face.

Any other ideas on this? Possibly the ecu circuitry is fried? Or could this be caused by a massive vacuum leak?

[corn322]

teddy, can you drive the car at all? I've been driving like this for about a month now. I managed to get it to almost idle when warm. It would hover around 550, and if I'd tap the gas sometimes it would stick at 700 for a while.

I put a new(er) intake manifold on today, and I seemed to make the problem worse.I pulled the cover off of the MAF connector, and my white wire was barely hanging on. My dad soldered the wire back to the connector, but had no affect.

[teddy]

I can't drive the car at all. It stalls in neutral and every other gear. If I keep on the throttle, yes, but it's hard to keep the car going if the rpm's dip below 1000. I just put all new Tbolt clamps on the i/c piping but it didn't seem to make much difference.

I'm wondering now if maybe my TPS is acting funny or my maf in general is bad, even though I can rev freely on it.

[corn322]

Any progress on your car, teddy?

I spent all day fiddling around with my car, and at one point it just started working correctly, so I left it as is. I wish I knew what it was that made it unhappy.

[teddy]

No dice yet. I checked the voltages on the TPS and they are within FSM specs. I tried screwing with the iacv hoses and that didn't make any difference. I still haven't thrown in a new maf yet bc I haven't had a chance, so hopefully that will fix my woes. My bov is vented, which I know doesn't help the situation, but the tension on the spring is all the way down, and I'm only trying to get the car to sit at idle. I don't think that would make much difference.

[rsmithdrift]

That sounds exactly like my old Z cars problem... It would run fine for a few weeks when I put dielectric gel in the connector and finally I just gave in and sliced in a new female connector.....solved 75% of the problem.....it still showed up once in a blue moon......

Also when my car wouldn't idle properly it would stumble at horribly to the point that the car wouldn't go anywhere and would finally die. And the more throttle you gave it the faster it would die. Very odd.

[teddy]

New update. Put in a working maf....and what do you ya know, it STILL dies. And now, when I unplug the maf plug, it dies then too. I tried using my hand to cover up the bov in case it was leaking, and that was nada. Tried the TPS sensor, adjusted the timing, sprayed carb cleaner in the throttle body, opened up the ecu to check for burn marks, unplugged the e-manage, tightened down all my clamps. I even used a new female connector for the maf wiring. I'm completely burnt out on this and have no idea. All the gaskets on the intake manifold have been sealed with rtv.

If the timing was screwed up, would it cause the car to stall? It really just feels like its getting too much fuel and is bogging to the point of dying. Because I can get it to idle for like 5-6 seconds now before it dies. I turned down the fuel pressure, but it didn't seem to do much.

[corn322]

Yeah, I imagine that if the timing was way off the car would not like to run.

[rsmithdrift]

When I fist got my Z the timing belt was off 4 notches on the right cam...So you couldn't tell because the dist is on the left cam (SOHC VG30).......Argg!!

So my idle was lopey as hell and it would have tons of touque down low and sound like bad valves at 3k rpm......if your timing was off the car would either have NO power down low or NO power up high......and wouldn't stall so much as lope very badly.

Anyways

[vancouverbc]

" I tried screwing with the iacv hoses and that didn't make any difference. "

if you squeeze the hose delivering air to iacv, it should make a difference. if it doesnt make difference, it suggests iacv is not working. you can do this test with air regulator as well.

the car idles fine in fail-safe mode. that is probably the key. online mechanic probably knows.

[vancouverbc]

Have you tested the fuel injectors?

[teddy]

All are working, but it's a possibility that one may be stuck open. I also just found out yesterday, that even with my stabilized fuel from last year and the 3 new gallons of 95 I dumped in last week, the gas is still smelling pretty rank. I think that may have something to do with the problem.