Gutless and code P0193

[tolsen 630]

Mender ought to offer advice since not long since he checked his rail pressure sensor. 

I’ll check on mine tomorrow morning weather permitting. 

[Toxophilite 29]

Hmm at this point I'm mostly hampered by not knowing for certain what the pinout is for the pressure sensor.

 

ON some things I find on the internet it has the supply on the left(blue), signal in the middle(yellow) and ground on the right(white)

 

On other ones it has the ground in the middle and the signal on the right.

 

If I do the tests with the plug unplugged I get the 5V supply on the blue wire and the yellow and

12.38 volts battery voltage on the same two wires

Both wires also have continuity to chassis and engine block ground.

 

With the switch plugged in and the ignition on (but the engine off) both the blue and the yellow wires have 5 volts on them while the white reads nothing

As well the white wire does NOT have continuity to ground

Something is amiss but until I know for sure the pinout of the plug it is hard to determine what.

 

 

[mender 42]

From earlier:

"Update: fuel pump runs and pressure on low side is 2.1 bar just before the clear lines by the fuel rail. Drops to 1.9 bar while cranking. No start but again, puffs of atomized diesel coming out of the exhaust. Checked high side fuel pressure sensor, has 5.012 volts supply and good ground, sensor voltage is 0.035 volts when fuel pump is on. Sensor reading goes to -0.086 volts while cranking, supply voltage drops to 4.868 volts while cranking. A little math shows the voltage difference when on and then again while cranking is roughly the same at about 4.96 volts. How would a faulty pressure sensor affect starting/running?"

 

Next step:

"Changed the fuel rail to get different pressure regulator and pressure sensor. Old rail was full of fuel so the prior regulator might not have been the issue, and fuel was getting through the high pressure pump.

Result: now reads 0.525 volts with key on, engine off so reading the pressure from the feed pump. Reading goes to 1.3v range when cranking and there was more activity from the engine. Fired one cylinder once within first rev, then sporadic firing. Not enough to get anywhere near starting but encouraging."

 

My problem was solved by replacing the nozzles on my injectors. They were clogged/rusted badly enough that there wasn't enough fuel to start the engine. With an ether assist it did run but quit after about ten seconds when the alternator started charging; the extra load was enough to drag the engine down and make it quit.

 

But at least you have the results of my fuel rail testing.

Edited February 24, 2019 by mender

[mender 42]

On 2/22/2019 at 11:08 AM, tolsen said:

You can read signal from rail pressure sensor with a multimeter.

Tolsen's diagram is correct for the expected voltages. I'll see if I can confirm the locations and wire colours for you tomorrow. -27 C predicted in the morning.

Edited February 24, 2019 by mender

[Toxophilite 29]

Yikes, you're having real winter! Much respect. You should see people cower and complain when we get a bit of snow here. i just think "What fun"

 

My car runs but without much poop , I have the engine light and the code in the thread title which points at the fuel rail sensor one way or another.

If you can check the wire colours and what they refer to, going into the sensor I'd really appreciate it

Thanks

[tolsen 630]

+20C and sunny here for a change in balmy Banchory situated at 57.0539° north and 2.4910° west.  A perfect day for a walk, a cycle ride or simply tinkering with a seventeen year old Smart car.

 

 

 

[tolsen 630]

Smart 450 Common Rail Pressure Sensor Pin Out:

 

Pin 1 - Grey, signal ground.

Pin 2 - Yellow, signal.

Pin 3 - Blue, 5 V supply.

 

Measured on my 2002 Smart 450 Cabrio Cdi:

 

Ignition on engine off.

Pins 1 - 2: 0.5 V.

Pins 1 - 3: 5.0 V.

Pins 2 - 3: 4.5 V.

 

Ignition on engine at idle.

Pins 1 - 2: 1.1 V.

Pins 1 - 3: 5.0 V.

Pins 2 - 3: 3.9 V.

 

I also checked signal voltage at snap acceleration and confirmed voltage went well above 2 V but to quick to make any accurate reading with a multimeter.  Signal voltage at steady 2000 RPM no load was 1.4 V.

 

Engine will run with sensor disconnected.  Unsure for how long though and whether on reduced power.

 

 

 

[Toxophilite 29]

Thanks, to confirm this:

If you are looking from the back of the car,

Are you counting starting from the wire/pin closest to the back of the car?

I didn't see any number ing on mine, though perhaps I didn't look close enough

 

One thing that confuses me is , why does your signal ground voltage change when you accelerate

Everything I've read says it's the signal voltage that should change?

 

[tolsen 630]

Each pin is marked on connector.  Signal voltage is of course relative to signal ground,

[tolsen 630]

And pin 1 has grey cable attached, pin 2 yellow cable and pin 3 blue cable.  Cannot be any clearer in my humble opinion.

[Toxophilite 29]

Thanks I will get a light (  I believe my glasses prescription has changed) and look for the numbers which I will admit to not having looked for before.

 

Though I like winter I am envious of your balmy 20 degrees!

 

[Toxophilite 29]

Does your signal ground have continuity to the engine block?

Edited February 24, 2019 by Toxophilite

[Toxophilite 29]

Okay I found the numbers. They're on the underside of my plug, right where the wires enter the plug. I hadn't been looking at the underside. I normally don't spend a lot of time fixing cars if I can help it so many things that may seem obvious to some aren't to me. Even my mechanical engineer father who repaired and maintained his own airplanes said about the car "It must be Smart, I can't figure it out!"

 

Still I'm not getting any voltages between the ground and the signal wire, nor between the ground and well, engine ground. And the signal wire maintains a steady 5V to engine/chassis ground.

My method of tapping into the wiring while plugged in might not be ideal, likely there is a far better way that hasn't been made obvious to me yet . 

 I see that on the pretty well inaccessible bottom of the plug there are two ports that allow access to pins 1 and 3...if one had probes shaped like fishhooks, which could be done. Nothing that obviously allows access to the signal ground connection when the plug is plugged in 

 

I think I asked before but maybe it got lost.

 

How are other more experienced people measuring the 3 pins when the plug is plugged in? (oh and I don't have a wiring diagram either so I can't trace the lines to their source at this point.)

 

 

Also testing my signal ground with the plug unplugged I get no batttery voltage on the signal ground wire. (when testing between battery positive and the signal ground) Where would I find the other end of the signal ground wire if I wished to attempt to bypass it in case I have a bad signal ground?

 

 

 

[Toxophilite 29]

So I got tired of fussing, unhooked battery for 30 seconds, and alligator clipped sensor ground to engine block, cleared codes and went for a test drive. Bingo, Car ran great, no engine light, no codes (tested twice as I went to store and back , tested at the store and when I got home.

 

So my next stupid question is, where is the ECU(apparently also called the ECM) so I can track down the other end of the sensor ground and clean it and or fix it there rather than having an alligator clip on the engine. which isn't really reliable in the long run.

[mender 42]

It's on the side of the air cleaner. It uses the intake air for cooling. 

 

 I was going to mention the possibility of a bad engine ground and using a temporary jumper to test. Find the proper ground, clean it or tighten the fasteners and you should be good. Or if it's too awkward at the moment, make your jumper more permanent with at least a 10 gauge wire bolted to the car and engine. 

 

Do the engine ground first, it's a common fault for a lot of cars and should be at the top of the list to check for any electrical or electronic issues. I should have said so earlier, sorry.

Edited February 24, 2019 by mender

[tolsen 630]

2 hours ago, Toxophilite said:

Does your signal ground have continuity to the engine block?

No. Signal ground is not same as battery ground.  

[Toxophilite 29]

The engine ground is the braided copper unit going from chassis to the EGR mount yes?

I have good continuity between the engine block and the chassis, testing from two different ground strap points on the chassis.

 

This leads me to believe I should examine the connector for the ECU. I think the sensor goes in on the lower of what seems to be two connnectors

 

[Toxophilite 29]

15 minutes ago, tolsen said:

No. Signal ground is not same as battery ground.  

One of the tests I was told to run is to test the signal ground with the plug unhooked by measuring between the signal ground on the plug and the positive terminal of the battery.

 

Strange, with the signal ground clipped to the engine block my engine light goes out, The codes, when cleared don't seem to be coming back and the car is running properly.

[tolsen 630]

I think we need a wiring diagram. Perhaps someone can research and post diagram if one exists. 

[Sydney 218]

If you are looking for ground point for the ECU and various other sensors, look in the engine bay above the intercooler. There is a group of ground wires (brown) that are all clipped together and mounted to the chassis with a 10mil nut. (you might find one corroded off). It seems to be a problem area with a lot of cars. 

[Toxophilite 29]

Thanks!

As I'm new to smart cars I will now look up the intercooler location

[Sydney 218]

The intercooler is the small looking radiator in the engine bay with a fan mounted on it. Look just above it under the lip where the engine cover lays. You will see the ground wires. The 10mil nut faces down so a wrench is your best bet to remove it.

 

[Toxophilite 29]

Thanks I found it a couple hours ago and it looked quite clean and it seemed to have continuity to ground. as it was late in the day and I am working in a parking lot I might take it off and have a better look tomorrow. 

[montypeel 1]

On 2/24/2019 at 7:39 AM, tolsen said:

Smart 450 Common Rail Pressure Sensor Pin Out:

 

Pin 1 - Grey, signal ground.

Pin 2 - Yellow, signal.

Pin 3 - Blue, 5 V supply.

 

Measured on my 2002 Smart 450 Cabrio Cdi:

 

Ignition on engine off.

Pins 1 - 2: 0.5 V.

Pins 1 - 3: 5.0 V.

Pins 2 - 3: 4.5 V.

 

Ignition on engine at idle.

Pins 1 - 2: 1.1 V.

Pins 1 - 3: 5.0 V.

Pins 2 - 3: 3.9 V.

 

I also checked signal voltage at snap acceleration and confirmed voltage went well above 2 V but to quick to make any accurate reading with a multimeter.  Signal voltage at steady 2000 RPM no load was 1.4 V.

 

Engine will run with sensor disconnected.  Unsure for how long though and whether on reduced power.

 

 

 

I know this is an older post but I was hoping people more experience can help me. I have a 2006 Smart 450. I got it for next to nothing as it wasn't running. I had to replace SAM, ecu and speedo (original ecu burned a hole through the curcuit board. was diagnosed as a ecu failure by previous owner mechanic). I've gotten it running now but i'm having a problem with the SAM and the fuel rail pressure sensor. when i measure voltage between 1 -2 i get 4.95v with ignition on/ engine off and same for idle. I have some unrelated SAM issues but im going to get the old sam flashed from the on that works with this ecu/speedo once i get the engine running properly. 

 

my question is how can i test my rail sensor without replacement as I cant find one to save my life for a price worth taking the risk. ive checked junk yards but the one where i was getting my parts someone already cut the fuel rail off... any other ideas on what would cause a high reading all the time?

 

[Willys 747]

I would ask Tolson or try to find out , IF his older CDI is the same as the 2005-2006 Canadian CDI we have....just to be sure...?
England for a better location or lets say Great Britain seeing as Scotland is a part of that for now anyway...lol.  They got many different Smarts we never were allowed to have....and well before the years they shipped them to us.
So, I would ask before accepting his numbers as equal to ours...?