Slow crank after possible overheat

[Luke_IDI]

It may be biodiesel.

Wait to start light comes on when key is cycled, goes out after about one second.

 

[Rdnck84_03]

With the fact that it comes on is a good thing, that means the pcm is atleast doing something. I believe it determines glow plug time from an oil temp sensor, not 100% on that though.

With A/E you should also be able to monitor how long the pcm is commanding the glow plugs and if the relay is energized. Or atleast my snap-on does.

James

 

[trackspeeder]

With the fact that it comes on is a good thing, that means the pcm is atleast doing something. I believe it determines glow plug time from an oil temp sensor, not 100% on that though.

With A/E you should also be able to monitor how long the pcm is commanding the glow plugs and if the relay is energized. Or atleast my snap-on does.

James

Yes, the pcm does use the oil temp sensor to control the glow plugs.

 

[Luke_IDI]

I hear some clicks when turning the key on (relays etc.) and the fuel pump runs. It may just have a bad glow plug relay. Again, nothing about the history of this truck is known….So we have no idea how many failures have been building up over years of bad maintenance, and how each may be contributing to the total picture. Next time I work on it I will pull the air filter housing and check whether it’s getting voltage. That being said, I’m not too worried about glow plug operation as it’s 100 degrees here right now. My friend’s van I pulled the known good starter out of fired up immediately without waiting for the glow plugs. I mainly want to be sure the PCM is booting up and doing what it should do, which it seems it is. Maybe a bad oil temp sensor failing high and telling the computer oil temp is above the cutoff temp (140 degrees from what I have read).

Thanks for all the replies thus far folks, and for keeping this thread going. I have ordered a laptop and a FORScan-recommended adapter, so connection woes should be sorted out sometime next week. I have to go a few hours away from the truck for a few days to work on the old Ford service truck I am outfitting (300 gas-powered at the moment, though maybe an IDI one day), so stay tuned for high pressure oil system data results….

 

[greenskeeper]

since the valve covers are off, crank it over and look for oil coming from each injector spout. If there is oil flowing from all 8 injectors then you can eliminate the HPOP, IDM, and electrical side of the no start problem.

Next, jump the large terminals on the glow plug relay for at least 15 seconds prior to starting (a jumper cable clamp works good for this) and then try starting the engine.

 

[Rdnck84_03]

That is good advice, I must have missed the valve covers already being off part.

James

 

[Luke_IDI]

since the valve covers are off, crank it over and look for oil coming from each injector spout. If there is oil flowing from all 8 injectors then you can eliminate the HPOP, IDM, and electrical side of the no start problem.

Next, jump the large terminals on the glow plug relay for at least 15 seconds prior to starting (a jumper cable clamp works good for this) and then try starting the engine.

About how much oil should I see coming out of the injectors while cranking?

 

[Rdnck84_03]

Not really sure on an amount, but it should spurt some each time the injector fires.

James

 

[Luke_IDI]

Ok, back at the truck. Hooked up FORScan and have obtained some ICP and IPR % readings. Cranking, IPR % goes to approximately 60%. ICP builds steadily over a few seconds, maxing out around 26,000 kPa, equal to about 3700 psi. This seems like plenty enough to fire, in fact it seems excessive. I am not seeing oil coming out of the injectors while cranking, however. Could an IPR valve stuck open (supplying maximum ICP) cause this?

 

[Luke_IDI]

KOEO Output state self test finds p0198 (oil temp sensor circuit high), p0380 (glow plug circuit), p0603 (batteries disconnected), p0470 (exhaust back pressure circuit malfunction).

I wonder if this oil temp circuit failure would have triggered the oil warning light when it occurred?

 

[Luke_IDI]

I understand from some more reading on the forums that the ICP the PCM reports may be an inferred value if the ICP voltage does not reasonably correspond to the desired ICP.

I decided to back probe the wires at the ICP sensor to get actual voltage with the engine sitting and while cranking. I believe the black with white stripe wire is ground, while the gray with pink stripe (?) wire is 5v reference, and the blue with green stripe is signal. Blue with green stripe reads about 4.6v KOEO. This value does not change while cranking.

According to a graph I found online, 4.6v would give a reading of over 3500 psi. Obviously incorrect. And this does not change when cranking. So we obviously have a failed ICP sensor. There is also oil in the connector.

However, from what I have read, if the ICP sensor has failed, the truck should start if the ICP sensor is unplugged, if the ICP sensor is the only issue. With the ICP plugged in or not, I still do not see any oil “spitting” out of the injectors.

My next step is either to replace the ICP and see where that leaves me, or hook up a hydraulic gauge in its place to get a mechanical ICP reading.

I did hook up a test light to one of the injector harnesses to verify that the PCM is controlling the injectors while cranking, as well as doing an injector buzz test. All the injectors sound about the same.

 

[Rdnck84_03]

I would honestly check the oil pressure in the head with a manual gauge if at all possible.

I don't remember what all you said you looked at when you first started trying to diagnose. Did you saw you had the fuel filter out? If so was the fuel black?

James

 

[Luke_IDI]

I would honestly check the oil pressure in the head with a manual gauge if at all possible.

I don't remember what all you said you looked at when you first started trying to diagnose. Did you saw you had the fuel filter out? If so was the fuel black?

James

Fuel filter has not been out. Black fuel would suggest oil in the fuel, and thus badly blown injector o-rings?

I am trying to get my hands on a hydraulic gauge and adapter (m12 x 1.5 I believe).

My main question at the moment is, does the climbing ICP reading (increasing to 3500 psi) indicate real ICP pressure? Or is it possible for that to be an inferred reading and oil pressure actually low?

I do believe the sensor is bad as well, and that’s why the PCM reports the climbing inferred reading. I may make a separate thread to clarify this issue, then back here to continue the diagnostic saga!

 

[Rdnck84_03]

Yes the black fuel filter would indicate a blown center injector o-ring. Could also watch around the base of injector for oil coming up around any of them.

I may be wrong on this but I didn't think this system was capable of building that kind of pressure at cranking speed.

 

[Luke_IDI]

Yes the black fuel filter would indicate a blown center injector o-ring. Could also watch around the base of injector for oil coming up around any of them.

I may be wrong on this but I didn't think this system was capable of building that kind of pressure at cranking speed.

I wouldn’t think it would be possible to build 3500 psi from 150 rpm either, but I’m not too familiar with the system. Somehow I am having a heck of a time finding an answer to the question of why my ICP signal reading would climb like that. Especially given my seeming lack of a sensor reading at the connector itself. I agree with your earlier post, I think it’s time to collect the materials to get a manual gauge reading and put this uncertainty to rest.