I got to drive the Diesel truck (in signature) earlier this week - rough running. Wife has had it out weekly and hadn't mentioned anything. Only issue I knew about was a minor rpm drop, at a fast idle, when cold (idle to ~ 1300, rpm drops to 1100, sometimes for only a second, sometimes for several seconds). Driving down the road, the engine will exhibit an intermittent miss condition at various rpms that are all very short durations. Frequency between these 'miss events' can go from a couple seconds to maybe as long as twenty-five seconds. AT highway speed, a few miss events induced the kickdown from OD so I left that off. Going down the road, the EGT gauge reading was normal as was boost during acceleration (up to 6 psi - yes I have a light foot).

Anyhow, when we got back, I got out the computer (running the AE w/ version 9 s/w) and no trouble codes. Since the engine was warm I ran thru the computer side of the Ford Diesel Engine Diagnostic guide (worksheet) and did the computer based tests, in recommended order. KOEO demand test passed and the KOEO injector electrical self test passed. Then did the KOER demand test which passed. I skipped the CIP test as holding the engine @ 3400 rpm for a few minutes scares the He!! out of me. Then ran the CCT test which passed.

I then collected the data from the ICP, the IPR, the RPM and EOT sensors for several minutes and readings were consistent with values found in other posts and reference materials (numbers at home, not readily available).

I'm at a bit of a loss for the next steps.

I rebuilt the fuel bowl late last spring - normal neglected multi-owner situation - so it was rebuilt with new o-rings and then the heater - WIF sensors were deleted due to leaks. Fuel pressure (idle) was at a nominal 60 PSI so I deferred the shim mod. Filter has about 10K miles on it and the bowl had no water in the drain (that was checked right after xmas). And the lift pump was changed back in the fall so it has about 10K miles on it.

Starts right up since the two new batteries went in at the beginning of the month. Alternator output checked and within spec (14.2 v) and nominal current going into the batteries is about 30amps after the glow plugs shut off. Glow plugs are presumed ok as the initial key on current draw is ~ 160 amps (temp dependent) and it drops down with time. Voltmeter indicates they turn off after the nominal two minutes when at first start for the day.

Anyhow, all recommendations appreciated.

 

What type or high idle controller do you have? I ask because I have had to replace a couple Ford high idle controllers for this problem. I don't remember if they were doing it on the road though. If you have one unplug it and see if the problem continues.

If you have the DIY high idle mod like me then the high pressure oil pressure can cause it but it's not a problem really. With mine I can have it set at 1300 when it's warmed up but the next morning when it's 10 degrees out it will just go to 900 which is cold idle anyway on it. as the oil warms up a bit so does the idle. It's just the war it is wired, there is no regard for oil temp on the DIY mod. The Ford apcm does take it into account though.

Only other thing I can think off offhand is look for water or corrosion at the IDM connector. Maybe even take it out and open it to look at the board for corrosion. Check all the connectors for water or corrosion or burned pins.

 

RR:
No AIC installer yet, this is with the foot. The variation at idle doesn't bug me nearly as much as the one going down the road. I've got the DIY AIC but haven't done the install yet - no garage here.

Since you mentioned connectors, I went thru some of my notes and found one from the initial bowl inspection that said the IPR connector (?) appeared to have been 'repaired' by one of the PO's. (Small two pin connector, with a retaining bail, that plugs into the HPOP with the leads in the loom leading to the connector on the pass. side of the fuel bowl.

I'll add 'thorough connector inspection for the IDM leads' to "verify adequate fuel pressure going down road" on the next to do list.

- additional data - CPS replaced with Ford Part as preventive maintenance action just over a year ago.

 

Sure are allot of folks with similar issues of late. Either idle issues or losing power / miss / stalling. The folks with autos are experiencing the same symptoms as yours. Perplexing to say the least. With all the different symptoms and the random timing of the events. I'd take a quick look at the PCM. Maybe pull it and check it out and inspect it. Maybe its getting wet somehow. Just a shot in the dark.

 

Do you still have your old CPS? Maybe you can swap it back in to see what happens also. That is the second most commonly bad new part I have ever gotten. Next to VW ignition coils. No idea why.

Also I can say with a certainty that if you see crimp connectors anywhere on the engine harness then it will cause problems. Especially on ICP and ind injection circuits. Any wire repairs should be soldered. You could also start with that to eliminate the obvious.

Can you watch the datastream on it now? I know with my scanner I can set it up in different ways to catch glitches. have it trigger an event log at certain parameters for whatever sensor I'm looking at. You could watch the CPS readout for glitches as well as the RPM reading. ICP duty cycle at idle should be fairly stable unless something is making it not stable. Like a loose nut on the back of the solenoid, air gap on the cps too great or too close, loose wire connectors or oil or water in the connectors. Lots of things could make it weird. If you see RPM just dropping out then really look hard at the cps or just swap it back to the old one.

 

LOL Ah the memories. VW coils. I remember those days fondly. Simpler times.

 

no kidding. I often miss my first car just because of simpler times. A 65 mustang with the 200 straight 6. No air, No power brakes, no cruise control, no power steering, no nothing!

 

Pete:

I must be geezing as I spent a few hours last night searching just this board and I found many that were what I'd call "much worse off" that what i have - would you point me to a couple threads?

RR:
best i can tell, the harness parts appear original. Last connector I separated had factory crimped pins at the end of the wire....you aren't suggesting the need to rework the entire harness are you?

On the data stream, I can see a handful of PIDs at a given time. From what I remember, the AE logging/display system runs with a nominal 1 Hz sample rate and i haven't found any '****' to adjust it. It surely doesn't appear to be designed for catching those brief intermittent glitches.

Also, on the CPS, I have the original to me as well as a second new factory part as athe glove box spare. My cousin lost one on his 99 and lost a full week running down the parts - if it costs less than a two, its a good spare to have if it keeps the engine from running..

 

I just meant like butt connectors, wires twisted and taped, bullet connectors, anything the factory didn't do. Those weather pac connectors they used work great as long as moisture is kept out of them but I usually solder new ones when I put them on. Just look for anything rigged. It's not good.

I've got an old star scanner and a really nice mac multimeter with a breakout box. It's a graphing meter so it helps a lot. I don't use the breakout box much but when I need it it's a life saver.

 

Might want to clean up the area around the go pedal and the TPS.

Just to throw it out there what color is your MAP sensor. Black or gray? I think the gray is the good / upgraded one. RR will correct me if I'm mistaken. Since it's a 96 it may have the gray one from the factory. Since this issue seems to occur with either tranny I thought it worth a look. May be way off base. But what the heck.

 

you're right. gray is good. black ones and aftermarket ones bad.

 

No chip involved is there?

 

Raining all night when I got home yesterday so I didn't even pop the hood.

No chip - at least not anything visible and the PO said he didn't install anything.

MAP sensor - can't remember. last time I touched it was when the gauges went in last year. I'll add that to the list (color) and also do the sniff on it's output with the AE.

tnx, again, for the ideas. Noted diesel has gone up $0.20/gal this week, so far...

 

Diesel at out cheapest station in town just went from 3.19 to 3.59 in a week. This IS getting ridiculous! Bio is still sitting at 2.73 for me and I'm mixing it half and half. I might as well just go straight bio with these prices! I hope you get it figured out soon because anything less than perfect wastes fuel on these engines.

 

No doubt about that!

Only good part is that the crew cab is not required as a daily driver, for a few more months anyhow.