Romping idle, "missing" under acceleration, low boost, poor mileage

[trevdalocal]

Howdy, truck has recently developed a slight romp at idle, doesn't seem to matter if oil is hot or cold, but occasionally it idles smoothly, usually when cold. Engine starts up quickly, about a half second of cranking and it lights, romps moderately for a few seconds, then cleans up to the slight romp.

Truck also feels like it's running on less than 8 cylinder under moderate acceleration, especially noticeable when you lug the engine down a bit. You can feel the "chugging" and hear it in the exhaust. Truck struggles to make 12PSI (according to ForScan) at WOT in 4th gear (ZF5 truck) at 2500-3000 RPM, and that's with the tow tune engaged on my DP F5 (I know, saving up for a PHP). Pretty gutless on stock. Downpipes don't look like they're leaking, firewall looks pretty clean.

Truck has 162k mi, and I believe the injectors are original. The injectors sounds pretty loud and crackly on tow tune, it quiets down a bit on "stock". I don't recall them being that loud before, but I could be imagining things. Fuel filter is less than 2k mi, same for the oil, 15W-40 Motorcraft with a Motorcraft filter. T500 HPOP easily holds 3000 WOT, 500-600 at idle. I am going to clean out the FPR screens this weekend.

All 8 buzz fine on a buzz test, and it passes a contribution test. Any ideas? I believe the Baro sensor is no good, as it shows 9.0PSI on ForScan, but from what I read, it shouldn't be causing these symptoms.

 

[ghohouston]

Oil in the i.c.p. sensor connector?

 

[Magnum PD]

How old is the CAM sensor?

 

[trevdalocal]

Oil in the i.c.p. sensor connector?

Dry as a whistle!

How old is the CAM sensor?

Age is unknown. I have a new Ford one, you think it would be worth it to swap it out?

I broke the plastic check valve trying to clean the FPR screen, and my T500 is weeping from the back plate again, so I've decided to bite the bullet and go efuel. Looking at the Strictly Diesel kit, seems to be well regarded here.

 

[Magnum PD]

I would try the ford cps

 

[trevdalocal]

I would try the ford cps

Gotcha. I'll slap it in while I'm doing the efuel and HPOP rear plate reseal (again) and post up the results!

 

[TSiZj]

I have a 96' F-350 and it sounds like we are having similar issues. My truck has exhaust and a edge tuner. I am going to try and clean my fpr screens this weekend. I haven't got a chance to log ICP or IPR duty cycle yet. Going to put in a new Ford CPS sensor I have also. My truck hesitates really bad at WOT also.

 

[dasboot]

Sounds like some of the same symptoms that I just recently developed. I'm looking a fuel pressure from the fuel pump maybe going bad.

 

[trevdalocal]

So... I started off by cleaning the FPR, and broke the little plastic piece. I decided to do a Strictly Diesel efuel setup if I was going to replace anything. Well, the Strictly kit requires you to pull the turbo to get the new fittings in. Pulling the factory turbo was such a pain, I decided to do a T4 kit... Cue Irate Diesel T4 kit, with 366SX-E. Just finished installing everything a few days ago. Ran into a few hiccups along the way, but great customer service from Strictly and Irate, got everything sorted in a timely manner. Downpipe needed to be rewelded at a *slightly* different angle, though that could very well be the truck's fault. If I ever do this again, I'll request the downpipe turbo flange come tacked on.

Truck runs like a scalded cat now. Still lopes a little at idle, not nearly as bad as it did with the old injectors, and doesn't miss when accelerating. Going to try swapping the unknown CPS for a new OEM one. Should've done UVCH and VC gaskets while I was in there, but I already spent way more than I had planned to, haha. The synchros in 3rd and 4th were pretty much gone and it sounded like the trans bearings were beginning to "whirr", but after a few hard pulls, it's pretty evident that I need a new trans. Called Midwest Trans and because of shipping costs, they suggested I try giving AutoZone a call, and gave me a part number. They're an AZ supplier, and indeed, although the base price of the trans is higher from AZ, the cheap volume rates they get for freight more than offsets it. Will be doing the trans next year.

Need to save up and do the second SD pump as fuel pressure does drop in the two hottest tunes. Plan to stud it and do valve springs and pushrods as well. Perhaps next year after the trans, and finances recover haha.

 

[jss]

Ok, I have a 97 with 400K on it and has never been touched......Recently upon start up, hot or cold doesn't matter, I get the world famous romp. It has an E40D in it and it'll shift into OD but not out of OD, with that said, if I put the truck in neutral and start it.....fires perfectly with no romping. Any ideas off the top of your heads? Has a new ICP and fixin to put in a new Ford CPS in a couple days. It's a stock truck, no chips.

 

[Patrick Feeley]

Try a new transmission range sensor . Cheers!

 

[trevdalocal]

Follow up to this since I'm still having issues.
Truck has some "good" PIS 250/200s, TE pump, new Ford CPS, Irate T4, Strictly Diesel efuel and regulated return, with a Hydra. It is a ZF5 truck. Just changed oil and the romping is back in a pretty serious way. On a hot start, once it catches and fires, the rpms are a little high, "hang" a tiny bit then come back down and romp. Idle fluctuates up and down a couple hundred RPM when engine is up to temp. When I let off the accelerator, the tach needle jumps a little, and you can feel the truck buck a little bit. Easily and clearly repeatable every time you let off the pedal. Other odd behavior I've noticed, on a moderate tune and a long hard pull in 4th, it felt like it hit a fuel cut, would've put me in the dashboard if I didn't have my seatbelt on.

Any ideas?

 

[trevdalocal]

Also should add, makes good boost. Need to check for boost leaks again, I feel like the damn Beans plenums are leaking again.