617 weird behavior diagnoses - Page 8 - PeachParts Mercedes-Benz Forum

Lucas · #**106** 12-03-2014, 11:46 AM

Quote:

Originally Posted by leathermang

Mixing standards of measurement can cost millions of dollars and be very embarrassing.....

Well at least he can make left turns.

OM617YOTA · #**107** 12-03-2014, 12:09 PM

Quote:

Originally Posted by leathermang

Mixing standards of measurement can cost millions of dollars and be very embarrassing.....

CNN - NASA's metric confusion caused Mars orbiter loss - September 30, 1999

OK, 19mm then!

leathermang · #**108** 12-03-2014, 12:16 PM

My mistake..... I should have suggested which direction you go to.... at 65 I have no first hand impression of mm.....

mach4 · #**109** 12-03-2014, 02:17 PM

Quote:

Originally Posted by funola

Without measuring fuel pressure, you are shooting in the dark by stretching the spring. When I was working on my adjustable fuel pressure regulator valve and fuel pressure measurement kit, I did a test by adjusting the valve to zero pressure and the engine would not start.

I find this interesting....

Makes me want to add a fuel pressure function to my suite of engine monitoring system gauges.

What adapter did you use to tap into the banjo bolt for the gauge on your pressure measurement kit? Seems like a plain old NPT fitting to a nylon capillary tube would do the job. The current thinking is to use an oil pressure sender with a voltage divider as the input.

This would serve as an early warning system for both low pressure due to pressure relief valve problems and filter clogging. Adding a port on the pre-filter would allow diagnosis to determine which was the problem.

OM617YOTA · #**110** 12-03-2014, 03:45 PM

I REALLY like the idea of a fuel pressure gauge to monitor this stuff.

The high performance semi-truck diesel guys say that ALL diesel engines should have a vacuum/boost gauge, EGT, and.................fuel pressure gauge. Those three data streams are like a built in diagnostic suite that's constantly running. I am definitely seeing the wisdom of this. I've been running boost and EGT from the beginning, and if I'd had a fuel pressure gauge all along this issue would have been solved a long time ago.

A T and a couple hose barbs could plumb an oil pressure gauge into the line between the secondary filter and the IP pretty easily. I think this is going to get put on the short list, along with one of Greazzers overflow valves and that intermediate shaft. More swearing.

Thanks again everyone.

mach4 · #**111** 12-03-2014, 04:34 PM

Quote:

Originally Posted by OM617YOTA

I REALLY like the idea of a fuel pressure gauge to monitor this stuff.

The high performance semi-truck diesel guys say that ALL diesel engines should have a vacuum/boost gauge, EGT, and.................fuel pressure gauge. Those three data streams are like a built in diagnostic suite that's constantly running. I am definitely seeing the wisdom of this. I've been running boost and EGT from the beginning, and if I'd had a fuel pressure gauge all along this issue would have been solved a long time ago.

A T and a couple hose barbs could plumb an oil pressure gauge into the line between the secondary filter and the IP pretty easily. I think this is going to get put on the short list, along with one of Greazzers overflow valves and that intermediate shaft. More swearing.

Adding an oil pressure gauge is actually easier than T-ing into the supply line. If you drill and tap the banjo bolt for 1/8 NPT you can screw in a sender like the following directly into the system without affecting any fuel lines (less chance of leaks) The one shown was found on eBay and even comes with a 10.5psi visual warning indicator.

Since I'm planning on adding the sensor to my Gauges Project (Engine Instrumentation Project ) I'm looking at a sensor with a bit more resolution at the lower pressures. It will take literally one wire and two lines of code to add this functionality on the Arduino end and re-doing some of the screens in the display library code on the Android.

I'd also add voltage to your list as an early warning for alternator failure...don't ask me how I know.

I just checked the pressure relief spring on my spare engine and it was 21mm. Went ahead and stretched it to 27 so I wouldn't miss that at whatever time I need to install it.

OM617YOTA · #**112** 12-03-2014, 04:52 PM

Good stuff. I like that a lot better than a T in the line, and already have a 1/8" NPT tap.

I remember your alternator issues, and luckily I have a voltage gauge already!

mach4 · #**113** 12-03-2014, 05:22 PM

Based on funola's video of his fuel pressure gauge installation, it would appear that it might be necessary to to include some sort of a pressure damper ahead of the sender.

http://i31.photobucket.com/albums/c397/funola/20140523_133749.mp4

A quick search turned up a couple of interesting prospects.

First a unit from a Toyota that should be able to be sourced from a junk yard (you might have even had one on the original Toyota engine)

Also an aircraft damper that is probably a mega-buck

Those dampers probably have a diaphragm in them to keep fuel from displacing the air that is doing the dampening, but I don't see where air would be able to get in, so building one without a diaphragm would probably work just fine. A T connector would be all that is needed to install ahead of the sender.

OM617YOTA · #**114** 12-03-2014, 05:53 PM

I recognize the Toyota damper off the original engine, and have one just like it on my MR2. I bet you're right about the junk yard, almost a shame that all the old engine stuff was carted away a long time ago. Looks like they're only about $40 new online.

I'll get the replacement over flow valve spring in first, then worry about all this.

Thank you.

Lucas · #**115** 12-03-2014, 06:18 PM

That looks fun.

With a truck, depending on what your hauling, you might want tranny temp also.

OM617YOTA · #**116** 12-03-2014, 06:22 PM

It's the stock manual Toyota trans and an engine that's 25hp less and 1ft lb torque more than the stock motor, and being used to haul stock loads. On a full size truck hauling a large trailer with an automatic I'd 100% agree with you, pretty sure tranny temp will be fine in my application.

Lucas · #**117** 12-03-2014, 08:33 PM

I'm embarrassed of what I've done with a toyota 😂

My dads truck has a tranny temp on a manual. Always thought it was cool, but not needed. I just like gauges.

funola · #**118** 12-03-2014, 09:33 PM

Quote:

Originally Posted by mach4

I find this interesting....

Makes me want to add a fuel pressure function to my suite of engine monitoring system gauges.

What adapter did you use to tap into the banjo bolt for the gauge on your pressure measurement kit? Seems like a plain old NPT fitting to a nylon capillary tube would do the job. The current thinking is to use an oil pressure sender with a voltage divider as the input.

This would serve as an early warning system for both low pressure due to pressure relief valve problems and filter clogging. Adding a port on the pre-filter would allow diagnosis to determine which was the problem.

I have used both push lock and compression fittings. Either one will do. The push lock is more finicky. A liquid filled gauge will dampen the pulses some. You are not going to get a steady reading but that's ok. Just do an average of the reading with your eyeballs. I would not recommend a digital readout for this application.

barry12345 · #**119** 12-04-2014, 02:48 AM

The liquid filled 0-30 pound gauge will not stand up to the serious pulses generated in the injection pump in constant service. A damper of some sort has to be engineered into the circuit.

An inverted small container with trapped air in it may be enough. A diaphragm damper much better even. Those quick pulses are vicious in nature and transmit much faster than the gauge can totally respond to with a straight feed. So there is no real way to know the true amplitude or peak pressure.

They rupture the gauge internally all too soon in direct feed constant service is proven. Dampening also should really stabilize the gauge reading more as well. A very small orfice in the feed line may be all that is required as an alternative. Or perhaps in combination.

There is no need for instantainious readings anyways. I am guessing the small orfice in the feed tube the size of a pinhole should be adequate. It just would restrict the volume of fuel to the gauge at the high spike pressure intervals.

You just have to have something to keep the gauge functional. Or have a valve in the line to turn the gauge off and only use it periodically to check if old filters or a weakening or lift pump etc are going to cause trouble soon.

You really want a quick snapshot periodically at highway speed under load as well. This is where the fuel pressure test is most important. At idle as the factory manual suggests only is not a really good total test. Fuel flow then is minimal and can mask a serious falling off of pressure once the volume of fuel needed increases several fold at speed under load.

leathermang · #**120** 12-04-2014, 03:01 AM

Perhaps a mechanical gauge is not available which will give accurate readings... is there an electrical sending unit which would work well ?