grksoccerkid91

iTrader: (4)

So, a few months ago my car decided to randomly start shutting off. It would shut off at red lights, pulling into driveways, or any other times. I didn't really do much aside from add a few ground wires and new clutch and it stopped doing that. The past week it shut off once or twice again, today, i realized it only idles rough and shuts off when my lights are OFF? I really don't get it.. The symptoms seem like a bad maf, bad idle, won't pass 2k rpms, but only when the lights are off and even then its once in a while.

My car is heavily modded so keep that in mind, the battery is in the trunk and has a 00 gauge wire going to the driver's side strut tower along with a 4 gauge wire going to the frame where the seat bolts into. I have a few ground wires in the engine bay, all 4 gauge, going from starter to frame, trans to frame, drivers side intake bracket (can't think of the sensor name) to firewall, passenger side intake to strut tower, and timing cover to frame. I'd assume my grounds are pretty good, the only one i'm missing i guess would be an extra ground on the alternator. I also have 00 gauge going to the battery from the engine bay.

I don't have any electrical mods, just a wideband which is actually disconnected, just a bad sensor in the downpipe. The car is running turboxs utec, oem gtr injectors and is turbod.

Originally this started happening on/off ever since i did the crank sensor i believe.

car is a 02 6spd and i also have a video, if you can't view it due to being on facebook let me know, i can upload it onto youtube.

http://www.facebook.com/photo.php?v=10200238096459721

Aviation005

Do your windows roll down quick and up quick?
It could be an alternator issue. When your lights are on, it kicks the alt into a higher output. Once the lights are off, it goes back to normal mode; this is probably not enough to run your ECU/engine. This is my best guess

i just saw you mention the crank sensor.. hmm maybe its bad? or has a short in the wire? I would swap it out and see what happens

grksoccerkid91

iTrader: (4)

My windows do roll down quickly, the lights somewhat dim when I hold them up and theyre already up. It's a new alternator so idk, but that was one of my guesses.

Does anyone know what controls the alternator output?

Aviation005

I believe its an internal voltage regulator..

if it is broke, it can very possible display all the symptoms you are having

louied9

the wont pass 2k was a MAF issue for me.. Hits the throttle wall. I too was stalling out and replace the IACV, ran great for a few weeks intermittent stalling but now she wont start.. might be a bad IACV. I was reading that there might be a bad ground wire in the MAF harness, good place to check the black wire. out of the MAF harness.


good luck , let us know what fixes it.

DennisMik

iTrader: (2)

Why don't you check the voltage to either rule out the alternator or point the finger at it? With the car off, the battery voltage should be around 12.5 volts. After you start the car the voltage should be around 14 volts if the alternator is OK. While the car is running, check the voltage at the battery and then again at the battery cables in the engine compartment. With good connections and such, the readings should be the same.

grksoccerkid91

iTrader: (4)

okay this has been driving me crazy.. i tested the alt and battery. the battery sits between 12.4-12.6 when off. when running, the battery was at 14.05-14.07 and up front it is at about 14.,08 - 14.09. i turned the lights off and the voltage went up to 14.13-14.15 and then the car shut off. I think it's safe to say the alternator is good then and the connections are good correct?

Next, crank sensor. I tried a crank sensor from a junkyard vq35 and the car ran basically the same low rpm but misfired up top and wouldn't pass 4k. i didn't really seem to have the same problem with the lights, but the rpm would dip down slowly.

who here has used autozone crank sensors? could this be a cause?

I've also looked into recalls, and there has been a recall for the crank sensor / wiring, my car falls under the dates, but would they accept it the way the car is? (all the mods)

Also, should there be a boot that covers the crank sensor? Mine seems to be missing. it may of fallen off in the process of the mods/trans swaps. (stock 6spd to specv 6spd)

According to my UTEC the MAF sits at around 1.10-1.50 i believe. This was just revving once in a while in my driveway. the "modified" map reading read about .3 lowere, but never below 1.05

This is driving me crazy!! What is another way to test the MAF and possibly check the wiring to the maf? I have noticed that because of how my intake sits the maf wiring has gotten stretched. all the wires are there and seem to be fine, just barely have any play.

sorry for the million questions, theres just so many little possibilities and it's driving me nuts.

DennisMik

iTrader: (2)

All the voltages you reported are what you would want to see. When you turned the headlights off, what kind of time delay was there before the engine turned off? I'm curious because the headlight/turn signal switch will lose ground internally when the switch contacts move. But I don't really see how this would cause the engine to shutdown.

Since the alternator does charge the battery, try this test. Unplug the 2 wire connector from the alternator so that it will not charge. Start the car and see that happens when you turn the lights on and off.

Aviation005

unplug your alternator harness then start it up and give it a try. if it works, replace the alt, the voltage reg is bad

rblower2012

iTrader: (1)

The not reving up past 2k sounds like your ecu is in limp mode, as for the light situation, good luck lol

grksoccerkid91

iTrader: (4)

I was talking to my bro in law about his old redline and his cat melted/clogged and caused back pressure and put the car in limp mode. I'm now struggling to pass 4k lmao. This has been driving me crazy, but I'm guessing when I swapped to an old crank sensor the car ran too rich (it backfired a few times) and maybe I clogged my resonator putting it in limp mode. It hits boost and goes slower now.

I'll try the alternator tomorrow. My old one is still ok. If that ones bad I can swap them.

The time varies. Sometimes its 5-10 seconds, sometimes a bit more, sometimes it just drops a couple hundred rpm and idles for a while but I shut it off and leave from anger lol.

Aviation005

your problem is either a short or bad connection at the crank sensor,or a bad sensor. maybe the sensor isnt mounted correctly?

we can determine this because once you switched sensors, the headlight issue went away. this links the problems and helps isolate the issue to one of those things.

maybe you have a bad MAF as well?

grksoccerkid91

iTrader: (4)

I plan on buying a new OEM crank sensor with next weeks check, hopefully a spare maf this weekend. I had to out the AutoZone crank sensor back since the OEM one couldn't pass 4k and sounded nasty lol. The crank sensor looks flush, however, should there be a boot around it or something?

For those who forgot, this is a 026spd

Nopike

iTrader: (2)

If your check engine light is not turning on you may consider your ignition switch as a possible cause. On a difficult problem like this I would try the cheap and easy stuff first.

grksoccerkid91

iTrader: (4)

The cel does turn on, I'm throwing p0031 and p0300 usually. I'm turbod with no cats and I had to extend the primary o2 sensor which is why I believe that code gets set. The misfire is from some cold starts. Possibly the crank, maf or o2.

I put a spare maf in the car that had a bad iat sensor. It still did the light thing but ran MUCH better. It had basically all its power back, but sometimes some oil passes through the turbo and gets my maf oily so its bad again -_- thinking about moving the maf.

I've thought about it and narrowed it down to the alternator or AutoZone crank. When I did those (both at same time) that's when this started. I tried doing ecu resets and I can reset it, but I haven't been able to adjust the idle.