deezul Posted October 14, 2010 Share Posted October 14, 2010 A 2007 Econoline Cube came in with transmission concerns and rough running when cold. Injectors 1 + 7 were dead on power balance when cold, slowly come around and then operated properly after 5-7 mins of idling. Performed fuel pressure tests, cylinder contribution tests and then replaced the two injectors. Re-assembled unit and now idles at 850 rpm...Unfortunately I never made note of any elevated idle concern prior to replacing injectors. Have checked for stationary elevated idle controller - wires have not been touched, remain blunt cut. Have verified EOT, ECT, APP, MAP, BARO, EBP, TR sensor, Alternator Output, ICP (bias/operation) and IPR without any issues present. Verified leaks at d-rings, none present. On road test load PID very erratic at times, truck cuts in and out, falls on its face, no other pids showing concern. When initially started the truck will idle at 650rpm with a commanded idle of 650 rpm, idle time can vary from 2 seconds - 20 seconds then "kick" into high idle. Truck can be commanded down to 650rpm and ICP and IPR switch accordingly. When rpm command released truck idles back up to 850rpm. When manually comanding the IPR, ICP and RPM change accordingly. Have disconnected ICP and RPM still remains at 850rpm. Tranny codes are present but no codes present for engine. Any help would be great, thanks! Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted October 14, 2010 Share Posted October 14, 2010 The only time I've seen elevated idle on a PSD was from excessively high ICP pressures but I may not suspect that on this truck. Thinking out loud: What's going on with VBAT? Is this an ambulance? Does it have a Load Controller for electrical loads that might be sensing low VBAT and kicking the idle up to compensate? Single or dual alternators? The tranny uses the load PID to determine shift points, IIRC. Fuel pressure OK under load? I might look at Sync/Ficm Sync and graph them in IDS with a bar graph. usually Ficm Sync changes just before Sync during cranking. Maybe check the CMP to see if there is rust under it, that might explain both of your problems. I have voltage pinouts for the TCM connector on the PCM if you need them, they are not in the PCED. For the record, I neither have grey (sp) hair or am a Rotorhead... Quote Link to comment Share on other sites More sharing options...
deezul Posted October 15, 2010 Author Share Posted October 15, 2010 I have monitored VBAT and it seems to be operating correctly. Even when the high idle kicks in VBAT doesn't really change, remains at a relatively constant 13.6-13.8volts. It's not an ex-ambulance and is a single alternator system. I will perform the rest of the suggested tests tomorrow, thanks for the help! Quote Link to comment Share on other sites More sharing options...
Spdracer Posted October 15, 2010 Share Posted October 15, 2010 I had an 03 6.0 once that the truck idled high...around 900rpm all the time and it was the ICP sensor. It showed the correct pressure and the IPR was around 24%. It ran smooth, just idled higher than desired. Quote Link to comment Share on other sites More sharing options...
deezul Posted October 15, 2010 Author Share Posted October 15, 2010 Started the unit this morning after sub zero over night soak. Truck started with no issues but idled at 748rpm instead of 850rpm...Idle slowly came down .5rpm/sec. ICP_DES and ICP remained at 875psi, IPR @ 30.7%. Commanded RPM to 500. ICP_DES and ICP @ 690PSI and IPR @ 27.3%. ICP Pressures too high for RPM, IPR too high for RPM. Performed road test - After road test unit returned to 850rpm idle... Have replaced IPR and ICP already... Checked Vbatt again, no issues. Fuel Pressure is 48psi under heavy accel..Sync and FICM sync are properly operating as well...I am going to check tomorrow for rust under cam sensor, the o-ring is leaking anyways.... Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 15, 2010 Share Posted October 15, 2010 I had an 03 6.0 once that the truck idled high...around 900rpm all the time and it was the ICP sensor. It showed the correct pressure and the IPR was around 24%. It ran smooth, just idled higher than desired. I know he said he replaced the ICP and the IPR.. I have come across maybe a handful of 6.0L and 7.3L engines doing this that indeed had bad ICP sensors. Most had normal KOEO voltage readings and I think one had an erratic signal that I could see. Now, the last truck I worked on that had a high idle concern, a 7.3L, turned out to have a bad PCM. I discovered that unplugging the ICP sensor corrected the condition so I looked at it deeper. I installed the breakout box and monitored ICP voltage with data logger and mu DVOM. The readings were different... this was on a reman PCM I had just installed. A second PCM fixed it. The post is here ---> Lying PCM Quote Link to comment Share on other sites More sharing options...
mchan68 Posted October 15, 2010 Share Posted October 15, 2010 I don't know if this helps, but I believe hot idle ICP and IPR data should be around 580 psi (both desired and actual) and 22 to 24%. Sounds almost like you may have a harness issue if you've already replaced the ICP and IPR. Quote Link to comment Share on other sites More sharing options...
deezul Posted October 15, 2010 Author Share Posted October 15, 2010 Thanks for posting the link to the "Lying PCM" thread... Tech line advised me to replace the PCM, I have ordered one but I have that gut feeling that it won't fix this issue. It's not like I haven't been burned by tech line advising this before.... Quote Link to comment Share on other sites More sharing options...
GregKneupper Posted October 15, 2010 Share Posted October 15, 2010 This is probably really far fetched but have you checked the ap pids. I have seen accelerator pedals stick on a few 6.4 liters cause a high idle concern. I have never seen one stick on a 6.0 but anything is possible. Try pulling up on the pedal and see if the idle drops. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 16, 2010 Share Posted October 16, 2010 This is probably really far fetched but have you checked the ap pids. I have seen accelerator pedals stick on a few 6.4 liters cause a high idle concern. I have never seen one stick on a 6.0 but anything is possible. Try pulling up on the pedal and see if the idle drops. Yes! We had a 6.4L truck do that too and like you have never seen it on a 6.0L truck. Worth checking though. Quote Link to comment Share on other sites More sharing options...
Aaron Posted October 18, 2010 Share Posted October 18, 2010 My personal truck has done that a couple times (sticking pedal). Returns to base idle if you give the pedal a light tap with your foot. More often than not when it's cold out. As for the fast idle concern... I read the thread over again quickly... what's the RPM_DES pid when the concern is happening? Quote Link to comment Share on other sites More sharing options...
deezul Posted October 18, 2010 Author Share Posted October 18, 2010 I did verify my App Pids and everything checks out fine, even against a like unit... Aaron: The RPM_DES pid is usually at 850rpm, except for that one cold start where it was 748rpm but RPM_DES and actual RPM are always relatively close... Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 18, 2010 Share Posted October 18, 2010 That is a key piece of information. This tells you that the PCM is commanding the RPM to that speed based on "some" parameter. if you view chart 5 on the diagnosis by symptom there are some things to check and these are my favorites based on what we know about this truck: [*]Biased ICP [*]Accelerator pedal [*]Biased/faulty EOT sensor [*]Engine not reaching normal operating temperature. [*]Power take-off (PTO), auxiliary idle control, and charge protect devices Quote Link to comment Share on other sites More sharing options...
Spdracer Posted October 19, 2010 Share Posted October 19, 2010 IMO, You cannot always go with ICP pressure in IDS. It could be a subsituted value. I trust the voltage PID more than anything. I assume the engine oil is in decent shape? I think your IPR command is a little high so maybe it compensating for an ICP issue that the PCM thinks is there that isn't. It sure sounds like an ICP sensor/wiring issue. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted October 19, 2010 Share Posted October 19, 2010 IMO, You cannot always go with ICP pressure in IDS. It could be a subsituted value. I trust the voltage PID more than anything.[/b] I assume the engine oil is in decent shape? I think your IPR command is a little high so maybe it compensating for an ICP issue that the PCM thinks is there that isn't. It sure sounds like an ICP sensor/wiring issue. +1 in a big way. If I were fighting this I might even double check the ICPV manually at the sensor or PCM connector. Didn't Keiff have one where the IDS lied about ICPV? I'd also check/clean basic electrical such as PCM powers and ground levels, sensor return ground vs B-, ACV output of the alternator, disconnect the alt and see if your problem is still present. I'd do a full electrical test (my 12 minute test sheet is somewhere on this forum) and check charging amperage- it should spike up to 40-100 initially but settle down under 10 amps within a minute or two after starting. I've had bad batteries cause freaky problems I could not explain logically. Weird stuff like this can easily be dirty power. (bad grounds, excessive ACV, ground loops, etc) ACV should be .02-.05 measured idling, the old industry spec of .5VAC is as old as Grumpy, and therefore worthless. If you have a BOB this is the time to get it out and use it, battery negatives should be .05DC or less. Good Luck! Quote Link to comment Share on other sites More sharing options...
deezul Posted October 19, 2010 Author Share Posted October 19, 2010 Thank you very much for your info and help! I'm the only diesel tech for our three dealerships so I get spread pretty thin...I haven't had a chance to get back on this unit for the last few days...You've given me some good leads to check into, hopefully I can get this thing fixed and out of my hair... Quote Link to comment Share on other sites More sharing options...
deezul Posted October 19, 2010 Author Share Posted October 19, 2010 That is a key piece of information. This tells you that the PCM is commanding the RPM to that speed based on "some" parameter. if you view chart 5 on the diagnosis by symptom there are some things to check and these are my favorites based on what we know about this truck: [*]Biased ICP [*]Accelerator pedal [*]Biased/faulty EOT sensor [*]Engine not reaching normal operating temperature. [*]Power take-off (PTO), auxiliary idle control, and charge protect devices I had checked for any of these conditions/issues but will check again.... Quote Link to comment Share on other sites More sharing options...
deezul Posted October 22, 2010 Author Share Posted October 22, 2010 Re-verified my diag, performed all suggested diag and still came up relatively empty handed, replaced PCM and issue is now resolved! Thanks for all your help guys!!! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.