BLittle500 Posted January 19, 2009 Share Posted January 19, 2009 Hey guys, I'm new here, just had our diesel tech quit and had the work plopped into my lap (with me having no prior experience), yay! Anyway, we've had a relationship with a certain Excursion. The customer need injectors and a turbo at 200,000 miles so they decided to go with a Swamp's setup, not only for the price, but also some fuel economy. The only reason that the customer hasnt been jumping up and down about this truck is the fact that they are getting 25-27mpg now. So here's the problem, the truck runs fine. It just doesnt idle for crap after warm. When pulling up to a stop sign the truck surges, and almost sounds like its missing. Sometimes when your stopped it'll actually surge hard enough that it moves the truck. Like I said, it has aftermarket injectors, turbo, and a tune. I dont think its the tune because we've had about 5 chips in this thing with different tunes on it from Swamps, and finally the chip that is in it now has 6 different tunes trying to find one that doesnt surge, but it still does it on all of them. Just curious if anyone has ran into this before? Thanks in advance, Brandon Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 19, 2009 Share Posted January 19, 2009 I moved this topic to this forum because I don't think you have a tuner or aftermarket issue. For the 6.0L surging comes from two different sub systems and the symptoms and severity are different. The first and historically most common has to do with ICP, usually a bad ICP sensor or wiring related to the sensor (ICP sensor connectors are a common cause) - or something else causing a lack of control like IPR issues. If ICP values are erratic the engine will make adjustments to the IPR accordingly and since IPR control directly affects fuel delivery it causes engine surges. At idle these surges can be severe enough to cause the engine RPMs to raise, many times causing the vehicle to momentary accelerate. A second source of surging involves the VGT, the EGR valve and the EBP sensor on certain engines. A worn unison ring control slot, a sticking turbocharger or sticking EGR valve can all cause surging but here the surging is noticeable mostly while driving, acceleration and cruise. Basically, when the PCM does not see the desired back pressure it wants it starts to hunt by adjusting the turbo. I would suggest you start by looking at ICP and what the IPR are doing at idle when this happens. Do you know how to make recordings with IDS or the VDR if you have one? Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted January 19, 2009 Author Share Posted January 19, 2009 Keith, this is a 2001 Excursion with a 7.3 not a 6.0, I just wasn't sure if I should have put it in the mods or the 7.3 forum due to the mods, thanks for moving it though. As far as your suggestions go if they would still apply to the 7.3 (I dunno), I would be able to make recordings with either IDS or VDR, but I would probably just use the IDS because the issue is very consistent and very repeatable. Thanks again, Brandon Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 19, 2009 Share Posted January 19, 2009 Ahhh, no. My previous post would not apply as far as the turbo or EGR are concerned. I assumes this was a 6.0L - shame on me, you did not specify the year/model/engine - shame on you. I would still look at ICP & IPR... moving topic to 7.3... Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted January 19, 2009 Author Share Posted January 19, 2009 The topic is titled "2001 Excursion Issues" Anyway, I could still check out the ICP and IPR, correct? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 19, 2009 Share Posted January 19, 2009 Yep. 2001 Excursion eh? Have you ever heard the term flat-rate reading? Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted January 19, 2009 Author Share Posted January 19, 2009 Ahahahahaha Quote Link to comment Share on other sites More sharing options...
Mekanik Posted January 20, 2009 Share Posted January 20, 2009 Is this thing hitting on all 8 cylinders? Do you have any DTC's? Do you have access to a Performance Diag Worksheet? Have you tried changing the engine oil? What is your ICP and IPR reading at idle? Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted February 19, 2009 Author Share Posted February 19, 2009 Finally got this thing back in today, took it for a road test and it definatly idles rough when warm. Pulled the dipstick out to check oil, and it was covered in air bubbles. I'm going to change the oil and see where that gets me. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 19, 2009 Share Posted February 19, 2009 Look at Perdels when idling hot to identify which cylinders are weak. Cyls 1-7 should be under 1%, Cyl #8 can be 2-2.5%. If they are higher than that, you have injector problems. Good Luck! Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted February 19, 2009 Author Share Posted February 19, 2009 Changed oil, but it didnt seem to help at all. Remember I'm new at this stuff guys, so here's what I saw. ICP bounces around a little at idle between 450-530psi, IPR stays steady. When it really acts up the MFDES bounces all over the place, but it is calm when the truck isnt acting up (could this just be a result of the bucking, or a cause?) No continuous codes, no KOER codes, and nothing came up in a contribution test. Well, off to the diagnostic sheet! Brandon Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 20, 2009 Share Posted February 20, 2009 Changed oil, but it didn't seem to help at all. Remember I'm new at this stuff guys, so here's what I saw. ICP bounces around a little at idle between 450-530psi, IPR stays steady. This is probably OK. Is IPR in the 9-11% range at a hot idle? When it really acts up the MFDES bounces all over the place, but it is calm when the truck isn't acting up (could this just be a result of the bucking, or a cause?) Result, not cause. Will it act up at idle, or at higher RPM only? See if you can get it to act up at idle, and look hard at the Perdels. No continuous codes, no KOER codes, and nothing came up in a contribution test. Well, off to the diagnostic sheet! Brandon I'm not so sure the diag sheet's going to help a lot on this one, besides documenting your time to get paid. I'd try a cam sensor, as they have a tendency to do weird things occasionally. Do you have the cylinder shorting box/harness tool that interfaces with the 42 pin connector? MFDES is a PID representing fuel delivery to injectors. MFDES at a hot idle in neutral is usually 8-12, but if you have weak injectors it might be 15-18. This PID can be used to determine which injector or cylinder is not contributing to engine performance. Cancel each cylinder with the kill box while watching MFDES. The cylinders with the least amount of change when compared to your base number will be the weak ones. This is not a dead set test and should be run several times to verify its outcome. The MFDES number will move around substantially under normal operation. Run Contribution test in “Drive” if it’s an automatic. CAS GND- Difference in voltage between Fuel Pump Relay ground and PCM ground. Not a perfect way to check PCM ground, but worth looking at. Should read damn close to zero. Good Luck! Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted February 20, 2009 Author Share Posted February 20, 2009 I wont be back on this truck until Tuesday, 4 day weekend, yay! Bruce, I'd have to check for the cylinder shorting box, to be honest, I have no idea if we do have it or not. This thing only has a rough idle, that's the customers only concern. The MFDES only goes nuts when its idling rough, which like you said is just a result of the rough idle. I'll have to double check the IPR % at hot idle. I'll let you guys know what I find, Thanks again, Brandon Quote Link to comment Share on other sites More sharing options...
SteveS Posted March 16, 2009 Share Posted March 16, 2009 Look at Perdels when idling hot to identify which cylinders are weak. Cyls 1-7 should be under 1%, Cyl #8 can be 2-2.5%.Have you seen this hold true with the new CPS? It seems to me that nearly all the trucks with the late CPS are setting Cylinder Contribution codes for #8 and the PER DEL on #8 is usually 4% and higher. I think that the idle is noticably rougher with the gray sensor than the black sensor. What say you? Quote Link to comment Share on other sites More sharing options...
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