T5 Cranks, but Won't Start

ProStreetDriver · Post by **ProStreetDriver** » 12 Jan 2013, 16:02

So I have a 1996 Volvo 850 Turbo, automatic. It isn't my daily driver yet, it's currently a project car right now. Car did run excellent when I first bought it, then started running real rough so I replaced the plugs on it and I believe I was getting an O2 sensor code (green square with a yellow upside down "Y" on the dash), then the car just stopped running. Checked the codes with a generic OBD2 code reader and it was showing a throttle position sensor fault.

-car is getting fuel at the rail and I can hear the pump working
-car isn't getting any spark
-tested the crank sensor with a reading of 280ohm
-coil wire wasn't great so I bought a set of new wires, only replaced the coil wire
-cleaned the crankshaft sensor
-tested the coil and it seems to be getting power, yet I hooked a spark plug directly up to the coil wire and turn over the car, still no spark. Yet when we grounded out the one side of the coil (blue wire), then the plug will spark but it's a very very weak yellow spark.

Is there any way to test that blue wire to determine if it's sending a signal when the car is turned out??? What reading should it have??? I also saw there was a way to test the camshaft sensor too, but from my understanding I have to penetrate the wire's insulation which I definitely don't want to do.

Any input would be greatly appreciated! Thanks in advance

Post by **Ozark Lee** » 12 Jan 2013, 18:05

I was getting an O2 sensor code (green square with a yellow upside down "Y" on the dash), then the car just stopped running.

That light is called the Lambda Light and it is the same thing as a Check Engine light in the US, it is more than an oxygen sensor light.

What specific code numbers did you get when you read the codes?

-car is getting fuel at the rail and I can hear the pump working

That makes no sense, if the pump is running you should have fuel pressure of some sort. Are you sure you aren't hearing the idle air control valve that is located beneath the throttle body? It is fairly loud and it has the same sort of motor running sound as the fuel pump. The place to listen for the fuel pump is behind the right rear seat.

I also saw there was a way to test the camshaft sensor too, but from my understanding I have to penetrate the wire's insulation which I definitely don't want to do.

You can back probe the connector to get the readings.

...Lee

ProStreetDriver · Post by **ProStreetDriver** » 13 Jan 2013, 09:25

The code was P0120.

Oh I meant I can hear the pump priming when I first turn the key on inside the car. Then after I depress the valve at the end of the rail, fuel squirts out.

Post by **Ozark Lee** » 13 Jan 2013, 09:56

I'm sorry, I misread your post and thought you said you didn't have fuel pressure. That's why I was scratching my ever balding head.

Did you replace the Throttle Position Sensor? A bad TPS can, in some cases, keep the car from starting.

When you put in your new spark plugs did you gap them? 0.028 is the spec and error to the tight side. Unless the replacement plug wires you bought were Bougicord brand you might as well box them back up and return them. Typical Auto Parts store plug wires (and really anything else in terms of sensors) can cause more problems than they cure.

...Lee

ProStreetDriver · Post by **ProStreetDriver** » 14 Jan 2013, 09:56

Nope I didn't replace the TPS... From what I've read with other people's problems, it'll only cause transmission shifting issues and that's it. Never a motor starting problem.

Nope I didn't gap the plugs either. I checked them to the old ones that were in the car and it was the same. The plugs are NGK platinum and the wires are also NGK too. So they are both brand name companies.

Post by **jblackburn** » 14 Jan 2013, 10:27

-tested the coil and it seems to be getting power, yet I hooked a spark plug directly up to the coil wire and turn over the car, still no spark. Yet when we grounded out the one side of the coil (blue wire), then the plug will spark but it's a very very weak yellow spark.

I believe you've got a bad cam position sensor. It and the crankshaft sensor send a signal to the ignition coil to fire.

Get the platinum plugs out of there - these cars hate them and will run like crap. Coppers or OEM Volvo plugs only.

Post by **Ozark Lee** » 14 Jan 2013, 11:53

ProStreetDriver wrote:Nope I didn't replace the TPS... From what I've read with other people's problems, it'll only cause transmission shifting issues and that's it. Never a motor starting problem.

If there are any other problems with the car, including rich or lean operation as told by the oxygen sensor, the throttle position sensor reading is the main substitute value for keeping the car running.

At the end of the day I think Justin is correct about the cam position sensor being bad but they are pricey and the throttle position sensor has already been identified as a problem.

Cam position sensor errors are a bit of a Catch 22. The camshaft position sensor error code won't post until the car is running and it can compare readings between the cam position and crank position but the car won't even start without a valid cam position sensor. The only way the cam position sensor code errors post is if the signal is getting intermittent interference but the car continues to run.

...Lee

ProStreetDriver · Post by **ProStreetDriver** » 01 Apr 2013, 10:27

So anyway, bumping up an old issue. Just want to keep everything together and I haven't had much time to look at the car before so the problem never got solved. Now that I sold my daily driver, this needs to be put on the road.

I was getting a transmission arrow error on the dash so I moved the shifter back and forth numerous times to clean the contacts in the switch, light still seems to stay on. I'm still getting the same P0120 code thrown by the car once I turn it over. If I clear the codes, the transmission light disappears, soon at I turn the car over, it comes back up. It'll also pop up if I hit the winter mode button and it doesn't make a difference if I have sport mode on or off. My reverse lights do work and the car also won't turn over in neutral(not sure if that's normal).

I bought an analog meter the other day... I tested the blue switching wire off the coil while the car is turning over and I'm only getting 0.19V (Not even 0.2V. Also tested the wire at the cam sensor unplugged with the key on, pin 2 is 2V and pin 3 is a full 12V. Then I left the cam sensor unplugged, turned the car over and I'm still receiving 0.19V at the blue switching coil wire. Is that normal??? Or it is just receiving a signal from the crank sensor???

Then I also picked up another coil from the wreckers to see if that was an issue, swapped them out and still not firing. But this other coil I picked up was slightly different, not sure why, but I do think it came off a non turbo'd model. Newish coil on left, original on right.

ProStreetDriver · Post by **ProStreetDriver** » 02 May 2013, 18:46

So I finally got in my new cam position sensor, replaced it and the car still won't start. Now it seems to have a new problem. Honestly I'm really hating this car... Soooo, moving along. I did previous tests with the cam sensor before with it plugged in with no signal from pin #1 while the car was turning over. With the key on and the sensor unplugged, pin #2 was reading about 5V and pin #3 was full battery voltage. Now pin #2 is reading 0.5V and pin #3 is at 2.42V. Haven't touched the car since I ordered the parts. Really need some input on this because this car is causing quite the headache for me.

Post by **mercuric** » 03 May 2013, 01:19

I think you need to remedy your TPS problem. Either way, your going to have to fix that to get the car properly working anyways. It's a fairly easy fix anyways.

I'm assuming you have an ohmmeter... Here's what to look for to test it.

precopster wrote:To test out of circuit with no connector:
a) Between pins 1 & 3 (from left to right) you should have 1K ohm throttle closed and 2.18K ohm throttle fully open
b) Between pins 2 & 3 (from left to right) you should have 2.49K ohm throttle closed and 1.30K ohm throttle fully open

That should help you confirm it's bad.

P0120 is actually a code generated by the transmission computer, and it puts your transmission computer in "emergency mode", hence the up arrow.

It corresponds to TCM DTC 2-1-3 and 2-2-3, signal too high or too low.

If the resistances of the TPS itself are good, continue with an actual voltage test:

Pin 1: Ground, brown/black stripe wire
Pin 2: source voltage from ECU, violet wire
Pin 3: Signal to ECU, orange/white stripe wire

Carefully backprobe the harness side of the connector, pins 1 and 3 (get it set up securely before you turn the ignition on)
Negative lead of meter to pin1, positive lead to pin3.
Should get about half a volt at idle, a little over 4 or so at full throttle, and a smooth voltage curve in between.

If you don't get voltage, make sure there is supply voltage between 1 and 2.
If you don't get supply voltage there, test between 2 and chassis ground.
If you get voltage between 2 and ground but not 1 and 2, the ground lead is the problem.
No voltage anywhere indicates the ECU is not feeding it, most likely a wiring issue.

Several board members have experienced no-start conditions due to TPS. May or may not be your starting problem, but resolving it is going to be necessary regardless.

It would also be wise to do an overall inspection for suspicious looking wiring, and inspect all your ground points, especially the main signal ground near the starter.