I've had two problems - rough engine and some kind of memory problem with the PCM. The OBDII codes get erased very quickly when the engine light goes out. If I catch a reading with the light on, I can generally get the codes, otherwise it just tells me no codes are present. Do I need a new PCM?

Regarding the engine - if I don't plug the block heater in, I get a fair amount of white smoke and very rough idle until operating temps. If I try to get the RPMs up over 1k for more than 5-10 seconds, engine stalls out / shuts down. Happens very abruptly. Near operating temps I can drive the truck, but even so if I get over 2k RPMs the engine will try to stall out - generally if I give it alot of fuel it will overcome the stall and keep going (with the engine light tripped).

Vehicle is at 126k miles with factory injectors, so I'm going to start by swapping out a set of 8 rebuilt injectors, new glowplugs, glowplug relay, valve cover gasket and at least the under valve wire harness.

I've read through the stickied post on white smoke / cold starts. Are there any special tools that I should get for this job? Torque wrench that goes down to 14 in/lb, as well as a deep, thin-walled 13mm socket for glowplugs, and then a short 10mm(?) socket for valve cover was recommended in that thread. Anything else?

Thanks in advance for any help.

 

I wouldn't be so quick on the injectors... 126k miles isn't a lot per se... What kind of code reader are you using? Once the CEL comes on, the code should be stored. You should be able to retrieve it regardless of whether the light goes out or not...

And just to be clear, you got your sizes mixed up for the sockets... It's 10mm thin walled for the glow plugs and 13mm for the valve cover bolts...

More than likely your PCM is fine..

 

Glow plugs are 10mm.. also get a short length of rubber fuel line. Loosen glow plugs with socket. Remove socket. Shove fuel line onto plug to remove.

 

Valve covers are 13mm.

Glow plugs are 10mm.

Injector hold down bolts are 8mm.

 

Welcome to FTE!

Swapping parts on these trucks gets expensive... fast.

I agree with what others have said about it probably not being the injectors. Your white smoke, rough running at start-up are typical signs of glow plugs not working properly. You may want to check the GP's & harness connections with a good digital meter to see if they are the problem before changing them out.
What's your fuel pressure? Your cutting out/stalling issue may be fuel related. Easy to check using the schrader valve at the fuel bowl.

 

Yeah and this probably goes without saying, but you only have to remove the bottom injector hold down bolt, then you can slide the hold down up and pull the injector out with the hold down on it.

I agree that it sounds like you have an issue other than injectors. I am guessing it to be a HPO issue of some sort. You need to use a high quality scanner and see what those codes are. I have never heard of a PCM that loses it's codes if not retrieved immediately. My guess is that the codes is for a HPO issue or a bad CPS. Have you changed the CPS to a new one from Ford or International? I would sure start there if that hasn't been done. It's a $30 part and only takes a couple minutes to change. It would sure be a lot easier than swapping injectors.

 

Generally my scanner shows no error codes, sometimes even when the CEL is on. I took it to a Ford dealer assuming they had better scanning equipment, and their tech was getting similar results. If he was quick he could get codes, but otherwise lost them. Here's the service record from this past winter and the codes he's received.

First visit (around October):
1. Barometric sensor (which he replaced)
2. Exhaust back pressure (which he replaced) - also cleaned the tube related to this sensor and put in a new connector for it
3. Transmission / Solenoid set error (didn't do anything with - but trans runs smooth)
4. Memory Error
5. Keep Alive Memory
6. Waste gate for Turbo is broken (tech didn't think this would be a big deal)

Second visit (around January):
Cam position sensor error (replaced)
Mass air flow sensor (replaced)
Errors on Injectors 1, 4, 8 (didn't replace - assume he got a code for this)


The tech's best recommendation was to replace injectors 1, 4, 8 because of the error codes relating to them. Their dealer was charging alot for just the 3, so I figured I'd look around online and found a set of 8 rebuilt and bench flow-tested injectors for about $1100 (after sending back my cores), which seemed reasonable. So I figured I'd try to do the job myself (I can return the injectors for a refund if necessary, but figured with the dealer reporting errors on 3 of the 8, I might as well replace the set).

Reading the forums here made it clear that if I did indeed remove the valve covers, replacing GPs, GPR, and at least checking if not replacing the wire harnesses and gaskets is a good idea as well. So I'd ordered a set of rebuilt injectors from Swamps and was about to order 2 gaskets, under cover harness and 8 glowplugs from a site linked in the sticky cold start thread (forget the name... but they were a shop here in the US that had good prices and claimed that their GPs didn't expand in the cylinder head - so sounded like a good place to purchase from).

Regarding some of your questions - yesterday I put a scanner on the OBDII connector and received no error codes, despite having the CEL go on yesterday, and having 20 minutes of rough idling from forgetting to plug in the block heater. I'll try and put a voltmeter on the valve cover wire harness later today and get an ohm reading on the GPs, and a voltage reading on the GPR when ignition is off versus right after ignition power-on, and post back with my readings.

 

I'm not familiar with that valve - how exactly do you get a fuel pressure reading from it? Unfortunately I'm a novice when it comes to this engine. I'm limited to some general maintenance and easy repairs: replace batteries, starter, alternator, starter solenoid and simple things like that on the exterior of the engine, but haven't done anything related to fuel or combustion, so detailed instructions or links to pictures / video that might be floating around (or a good repair manual for this engine) would be a great help.

Thanks in advance guys.

 

This is a 7.3 your working on?

 

Just using a cheap scanner at the moment: U380 OBDII Scanner from UIF Technology. Amazon has some details at this link.

I figured the Ford dealership would have a much better scanner, and if they were having trouble getting codes (check my above post), I assumed I would have similar problems despite high cost equipment. Could be an incorrect assumption of course - maybe you guys would know better on the scanner problem. As I listed above, the dealer's tech did identify a Memory Error, and a Keep Alive Memory error.

 

In general, you have to have a pretty high quality scanner (Snap On, AutoEnginuty,) or an Aeroforce scangauge to read these trucks. Most of the lower quality readers won't communicate with the PCM and you won't get any codes. If your CEL is on, THERE ARE CODES stored in the PCM. If you;re not getting them out, it is because your reader isn't speaking PSD.

What year truck is this? Either you have a super duty truck (99 and up) or your dealer doesn't know what they're doing (this is what I am betting on). It sounds like they are just reading the book and swapping parts to me. The OBS Powerstroke trucks (94-97) don't have a wastegated turbo. There is no wastegate. There is an Exhaust Back Pressure Valve (EBPV) and it won't present a problem unless it is closing when it shouldn't be in which case you can just unplug it and it should be fine.

Memory Error, KAM (Keep Alive Memory) can be set because of having the batteries unhooked. Those really don't mean anything either.

There is no Mass air Sensor on a PSD either. There is a MAP (Manifold Absolute Pressure) sensor. Maybe that is what they replaced?

You have to be really careful where you take these trucks to have them diagnosed. If the tech hasn't been around these a lot, they don't really know what they're doing. They will just read the service manuals, follow the procedures, and change parts until the problems go away, which is generally a pretty expensive proposition.

 

Yep, 1997 7.3L Powerstroke. The vehicle itself is somewhat of a hybrid - (purchased it that way; didn't do it myself). Its a 1992 F-250 cab hooked up to an F-350 7.3L Diesel, transmission, front and rear differential. So, basically the engine, suspension, transmission and drive of the '97 F-350 7.3L diesel (although the PCM has a late model '96 code), with the cab of the '92 F-250. I mention this because there might always be some latent issue with wiring / hookups, although the truck ran pretty smooth all last summer and early autumn before ambient temperatures started dropping.

 

Alright, so let's back up a couple steps. Let's start by assuming that the PCM is alright and the code issues you're having are because the scanner you're using may not be communicating with the PCM. This could be verified easily by unplugging the electrical connector on the MAP sensor. It is located on the passenger side of the firewall and is a gray sensor with a tube attached to it that leads to the intake plenum on the passenger side. With that sensor's electrical connection unplugged yous hould be able to start the truck up and it should set a CEL. If it does, try and scan the PCM. If you don't get a code, it is your scanner and not the PCM.

If we can remove the PCM from the equation, it narrows your symptoms to the smoking at startup and the cutting out. Using a test light check for voltage at both sides of the GPR (Glow Plug Relay). When you turn the key from "off" to the "run" position it should click in and have voltage on both large terminals. If it does not, you may just have a bad GPR, or a wiring issue between it and the PCM. With the GPR Working correctly, when you should get battery voltage at both of the large terminals and one of the small terminals. The other small terminal should have continuity to ground, so if you connected your test light to battery voltage (say the always hot terminal of the GPR) then touched the grounded small terminal, when the key is turned to "run" the light should light up. Assuming this all checks out, I would also suggest testing the GP's themselves with either a Digital Volt Ohm Meter (DVOM) or a test light. We can go over that process later on if necessary.

Does the truck still stumble and cut out as described above since the new CPS has been installed?

 

Thanks for the example scanners. If I found the ones you were referring to, they all seem to be 250 or more. I've found these links:

AeroForce Interceptor $250
SnapOn CanOBD2 has this one for $280
AutoEnginuity Scanner / Diagnostic - is $250 also. Although the Ford Expansion software is another $200 (is that just for the 99 - 03 powerstroke? though).

I like the idea of the real-time guage and code reader in one, but 250 is a bit steep (didn't see any discount codes on a quick google search). Will the Interceptor talk with the OBS powerstroke PCM the way you referred to above?

Any idea if the ScanGuage II at $160 or this ScanGuage E for $95 will do the same? If not, I'll have to look into the Interceptor.

Thanks again.

 

Yes. The cut-out is a recent phenomenon that occurred only after the CPS was replaced actually. The CPS was replaced around January of this year, and I started getting the cut-out since maybe mid March if I remember correctly. The engine stumbling has been pretty consistent since early last fall, except for a two-week period after the first trip to the dealer in late October, when the barometric sensor was replaced and exhaust back pressure (valve?) was replaced or cleaned, or whatever they did. After that repair that truck started up great and ran perfect when hot or cold, with block heater plugged in or not. But it lasted only 2 weeks before the engine stumbling began occurring again, and it hasn't really improved significantly since.

I'll get back with the GPR and GP voltage readings this afternoon, and will look into that MAP sensor diagnostic idea and see if I can do that.