Author Topic: car cranks but no start? help plz (Read 5099 times)

318bud · « **on:** December 27, 2011, 06:43:23 PM »

one morning i wake up and the car just keeps cranking but not turning over?

Its really got me puzzled cuz it was driving the night before lol

I just did the stomp test and its 1444 which means theres no fault codes.

anybody have any idea what coulda happened to my car overnight?
spark plugs or fuel injectors?

And also, the brake pedal will barely press in. no idea why

any help is appreciated

DesktopDave · « **Reply #1 on:** December 27, 2011, 09:49:58 PM »

If you have a digital multi-meter handy, check the resistance on your crank position sensor pins 1 & 2. It should be around 640 ohms. The other readings (pins 1 & 3 and 2 & 3) should be very high, like 30k ohms.

If the computer isn't seeing a pulse off the trigger wheel it won't start the fuel pump. You'll get a 1444 reading in that situation. You can test this by pulling the fuel pump relay and using a short bit of wire to jump sockets 30 and 87. If the pump starts up, chances are really good it's a bad crank sensor.

As for your brake pedal, might just be that the booster has lost vacuum. That's normal. It'll loosen up as soon as the motor starts & sucks the air out of it again.

318bud · « **Reply #2 on:** December 29, 2011, 09:27:39 AM »

replaced my spark plugs and no luck. Im gonna pull the trigger on a new crank sensor for $80.

My fuel pump and filter were replaced about a year and half ago so im thinking thats not it

318bud · « **Reply #3 on:** December 29, 2011, 09:28:43 AM »

i dont own a digital multimeter btw

DesktopDave · « **Reply #4 on:** December 29, 2011, 11:26:53 AM »

Replacing the crank sensor is a good idea, but a decent meter is cheaper than $80...IMHO better than throwing parts at the car until it runs...

I don't want to sound like a know-it-all PITA (though I am

) but a decent meter will save you a fortune with old German junk. I bought a few of the surprisingly adequate $4 ones at Harbor Freight just to have them in the car all the time. I also have a binder with copies of the ETM.

I never leave home without those. And the usual stuff...jumper cables, ratchet/tow strap, inflated spare tire, spare fuses, relays, bulbs, and a fire extinguisher...the usual junk.

318bud · « **Reply #5 on:** December 29, 2011, 11:58:15 AM »

So a $4 one from harbor freight will do? lol i just figured putting new parts on the car wont hurt anyway. When the part will probally go eventually :rolleyes:

i just dont see what else it can be, ruled out fuel pump and plugs and dme is fine so :confused:

DesktopDave · « **Reply #6 on:** December 29, 2011, 12:05:15 PM »

Yep, the $4 DMM is much better than nothing. If it saves you one part you're ahead of the game. I even use mine to test AA batteries ('cause I'm an incredible cheapskate) you'd be surprised how many of them end up being good. With all the kid's toys around here I'm perpetually running out of batteries.

BTW, could be a flaky fuel pump relay or loose pump connector as well.

New parts for these cars really add up. They're cheap enough but eventually you'll have more money in parts than the car is worth.

318bud · « **Reply #7 on:** December 29, 2011, 01:52:21 PM »

okay ill go buy one when i get off from work before i put the money down on a crank sensor.
Ill check the readings on pin 1 & 2 like you said. Are you talking bout the pins in the circular unit on the left of the engine? where i reset the oil lights

DesktopDave · « **Reply #8 on:** December 29, 2011, 05:01:43 PM »

Nope. The crank sensor plugs into the front of the wiring plenum under the intake manifold. That's also where the cam sensor plugs in. Don't mix them up...the plugs are identical. The crank sensor goes to the bottom plug on the plenum.

Pins 1 & 2 on the sensor plug should have about 640 ohms, give or take. Pins 1 & 3 and 2 & 3 should be very high, likely it'll max out the meter...more than 10k ohms.

One more warning...if you're doing continuity or resistance tests like this (set to ohms, it's the omega sign or a broken "0"), don't test out any wires that go to the DME (ECU/computer) or other delicate electronics like the instrument cluster. It can damage the DME. You should only do voltage tests off the computer unless the ETM specifically tells you otherwise. Any continuity or resistance tests have to be done on the DME connector plug, not the computer's pins.

318bud · « **Reply #9 on:** December 29, 2011, 09:33:11 PM »

i tested the crank sensor voltage and it was really low so went and ordered the crankshaft sensor. If it doesnt fix the problem what else could it be? im hoping i could return it if it doesnt fix the problem tho

amd thanks for the tip ill remember that

ok so the pins are on the end of the sensor wire, that plugs in, under the intake.

i tested the voltage of the actual metal sensor plug

DesktopDave · « **Reply #10 on:** December 30, 2011, 09:32:29 PM »

Voltage? Are you sure? What's the number you saw? If you tested voltage to those pins it'd be something unbelievably low. That doesn't mean it's a bad sensor though.

You should have tested the crank sensor resistance, in ohms. Set the meter to ohms and test pins 1 & 2 on the sensor's wire.

318bud · « **Reply #11 on:** January 02, 2012, 09:21:25 PM »

Thanks a lot Dave. Do you know what can cause a rough startup. It always bounces for like 10 to 20secs, even stalls sometimes. Bad Icv or vacuum leak? I tried cleaning Icv and replaced MAF but no luck so far

DesktopDave · « **Reply #12 on:** January 02, 2012, 10:19:43 PM »

Did you get it running? That's some progress.

I'd test the temp sensors. If they're not right the car will run badly until it warms up. There are three - one inside the AFM (MAFs are newer tech) and two on the side of the head. The one closest to the front is for the DME, that's the one I'd test. Resistance must be high when it's cold and drop off gradually as it heats up. At 60degF it should be something like 2700 ohms (or 2.7 K-ohms). At 180degF it should be only 300-ish ohms. Colder temps should be even higher, but anything really high is suspicious.

I can't recall what pins the intake sensor is, but it's on the site somewhere. Similar values as well.

The ICV is a PITA on our cars. I haven't found a good way to clean them yet. I usually spray the inner valve with penetrating oil like PB Blaster then some TB cleaner to clear it out. While you have the meter out, test the resistance on the coil pins. You should see low resistance...8 ohms give or take 2.

318bud · « **Reply #13 on:** January 04, 2012, 11:21:48 AM »

yup. i did get it running
lol it was all because the tiny vacuum hose in front was disconnected haha.

at least i didnt spend any money

and thanks man, never even thought that it could be the temp. sensors. the bouncing is just so annoying at start-up. but idle is perfect afterwards.

the car will sometimes even stall while bouncing. but starts right back up(easily if giving it gas)

sucks because i spent $50 on a MAF and i thought it would fix the problem. Always thought the ICV was good because idle is fine after startup, but i will test it. Im just glad its pretty easy to get to on this car lol

d.hitchcock · « **Reply #14 on:** January 04, 2012, 12:28:32 PM »

Accursed vacuum leaks!