98 4.0 SOHC Hard Start Rough Idle/Rev

[2000StreetRod]

use your powerflash

. . . I have an SCT3 programmer the only codes its throws are lean code bank 1 and 2 and O2 heater sensor code. . .

I suggest again that you use your scan tool to determine what's going on with the engine. It only takes about 10 minutes to set up a parameter identification (PID) file and it can be saved for future reuse or altering. Then you can datalog to your laptop hard disk and then view the PIDs as they change at your leisure.

Some things to check are engine coolant temperature, intake air temperature, RPM, short and long term fuel trims, throttle position, air flow, and ignition timing.

 

[feedthezombie]

how do i set up the file, If there is a how-to guide somewhere that would be great.

I'm going to hook up my SCT to the laptop and check on their website to see if i can figure it out on my own. I will post if i come up with anything.

 

[mountaineer99]

1999 mountaineer 4.0l hard starting won't idle

I had a problem with my 1999 mountaineer where it was hard to start and when I gotit to start the idle was all over the place. It acted like a vacuum leak which I could not find. I read an article about the intake gaskets going bad on all the 4.0lengines so I took the intake off and replaced the two sets of rubber gaskets and the problem went was gone. I am sure there is posts on the intake gaskets being a problem. My engine is stock but it sounds like the same problem.

 

[feedthezombie]

OK well i figured out how to do the PID and log, i did a test run but forgot to select save.

Going to try to have the wife shoot a video while i do the log so it can put site/sound with the data.

With this original attempt i managed to get the truck started without using any carb cleaner which was nice.


mountaineer99:

The gaskets that are on there are in excellent shape replaced about 30k miles ago. I'm not opposed to giving it a try, i have done several tests where i get the truck to stablize and idle then spray carb cleaner around all the gasket surfaces and vac connections, nothing has turned up as a suspect.

With your explorer would it still run even with the leak, or did it behave like mine where it was hard to start, rough idle and no power? I mean mine is so bad you can't pull a hill without it choking and stalling.

 

[feedthezombie]

ok here we go, i saved the log as CSV and the timeline should fit fairly close to what the video shows, theres several stalls and starts and a back up attempt.

any help is much appreciated.

DATA LOG
http://downloads.bustedfingermotorsports.com/datalog1.csv


On the hill pull i had to constantly feather the throttle back and forth to keep the vehicle from stalling. Also during any stationary rev during the video was never above 2k despite it sounding loud (open exhaust).

VIDEO

 

[2000StreetRod]

closed loop?

I've started looking at your first datalog. The long term fuel trims stay almost constant (1.00 to 1.02) for the entire period. The short term fuel trims do not cycle between slightly rich and slighty lean and they do not change as the throttle or rpm change. The fuel trims should be changing. I suspect your PCM is not switching to closed loop and is ignoring the pre-catalytic O2 sensors outputs.

Also, there is not good correlation between the throttle position and the engine rpm. During the first 25 seconds the engine speed slowly increases and then decreases for a very slight throttle position change. The desired engine rpm remains fairly constant so the change is not due to the PCM commanding the IAC valve to open and close. Did you perform the TPS test procedure?

Other than the open exhaust, is the engine in a stock configuration? Was this datalog for the restored stock PCM load?

If you perform another datalog please add vehicle speed so I can tell when the vehicle is moving.

 

[feedthezombie]

Thank you guys so much for the help!!!!!


I knew it wouldn't go very far so i didn't think to add the speed into the equation i will grab a shorter one tomorrow.

I haven't tested the TPS you think that could be a cause? It and the MAF wiring is on my list to try but i ran short on time today.

What does the short term and long term fuel trims mean? Can that help point in any direction of where my problem may lay?

Yes i did a return to stock flash, so stock map no stored info etc.. There are no rear O2 sensors but the upstream one's are brand new Bosch sensors, could they be a problem?

 

[2000StreetRod]

procedures

What are the current diagnostic trouble codes?

. . . I haven't tested the TPS you think that could be a cause? It and the MAF wiring is on my list to try but i ran short on time today.

Ford Explorer - Ranger TPS Test Procedure

MAF Sensor Test Procedure

Was the new MAF sensor you installed the standard 55 mm diameter or an oversized?

Does the engine run any different with the MAF sensor disconnected?

What does the short term and long term fuel trims mean? Can that help point in any direction of where my problem may lay?

The PCM adjusts the fuel trims to maintain the optimum air/fuel ratio. When the short term fuel limits are reached the PCM changes the long term fuel limits. If the PCM cannot achieve the optimum A/F ratio within the combined fuel trim limits it sets a diagnostic trouble code (too rich or too lean). Your long term fuel trims are neutral (1.00). Your short term fuel limits are initially 30% from neutral (saved from previous engine run). They start changing at 62 seconds indicating your O2 sensor heaters may not be working. My PCM goes into closed loop within 20 seconds.

Yes i did a return to stock flash, so stock map no stored info etc.. There are no rear O2 sensors but the upstream one's are brand new Bosch sensors, could they be a problem?

You mentioned that your vehicle set unused for a year or so and you added cans of Heet. As I recall Heet is to remove water vapor from fuel. I doubt it restores the combustibility of old fuel. If you didn't add fuel stabilizer a year ago your fuel may be turned to lacquer. I suggest you check your fuel pressure:
Ford Explorer Ranger Fuel pressure test procedure

When fuel is released thru the Schrader valve is it redish colored and does it smell fresh or does it have a yellow tint and smell like lacquer? Your symptoms are similar to bad fuel or low fuel pressure. If the fuel does not smell fresh I suggest removing the fuel filter, draining the fuel tank, checking for rust, installing a new fuel filter, and adding a bottle of Techron fuel injector cleaner to half a tank of fresh fuel. If there is rust in the fuel from the tank you may have to remove the tank and clean or replace it.

 

[2000StreetRod]

fuel injectors

You mentioned that you replaced the fuel injectors. Did you replace them with the standard 19 lb/hr injectors?

 

[2000StreetRod]

restarts?

There are several instances when the datalog shows the engine rpm to be zero: 63, 90, 113, 116, 155, 188, 191, and 229 seconds. Did the engine quit and then get restarted at these times? If not, then the crankshaft position sensor could be intermittently malfunctioning or there was a data loss between the OBDII port and the PowerFlash. However, there is continuous ECT and IAT data at those times indicating there was no data loss problem.

 

[feedthezombie]

There are several instances when the datalog shows the engine rpm to be zero: 63, 90, 113, 116, 155, 188, 191, and 229 seconds. Did the engine quit and then get restarted at these times? If not, then the crankshaft position sensor could be intermittently malfunctioning or there was a data loss between the OBDII port and the PowerFlash. However, there is continuous ECT and IAT data at those times indicating there was no data loss problem.

I'm going to try to grab these in order here, thank you so much for the information. I'm going to go do the MAF and TPS test this afternoon as well as another data log with speed and a little shorter so its easier to read.

And yes it died a few times and had to be restarted so thats why the RPM's dropped off. It typically won't run for very long unless you use carb cleaner to get it started then massage the throttle to get it to stabilize and once it stabilizes it does alright for idle but once its up to temp if you turn it off, it won't restart. It will spin and not even hit......

The trouble codes that are present right now after the run yesterday are as follows:

P0743
P0760
P0765
P0141
P0161
P1401

The shift solenoids have been present even when the vehicle ran with previous motor. The DCCP or whatever isn't there the SCT tune normally takes care of it as well as the rear O2's for me.


About the MAF it was nothing special just a standard replacement from Advance auto everything bolted back up with nothing seeming to be different, but the problem was there before swapping out with the new MAF.

The fuel injectors were both from 4.0 SOHC, the set that was originally installed came off the running engine that had low oil pressure. I swapped them and all of the sensors off the old motor onto the new LKQ engine despite it already having them (just to make sure since i knew the other engine ran without any problems). Once i started having issues i tested both sets of injectors and just for the sake of trying swapped in the LKQ injectors onto the new LKQ motor.

Fuel pressure is good it has an aftermarket FPR just like the previous engine, it also has a 255lph fuel pump and new screen that was installed last year on the old engine.

The truck has sat since October 2011, i installed a new crank in the old engine since it had major bearing failure and re-installed it in Feb/March of 2012. The engine started and ran perfectly fine revved nice and smooth truck could be moved freely but the oil pressure was 10-15 psi so i didn't want to drive it and ruin the new crankshaft. So i purchased a used engine with 75k from LKQ and installed it around April, i also upgraded transfer cases around that time and had some other work to finish on the truck like rebuilding the LSD etc.. So it didn't do a test start until May. So when it had issues i checked the fuel it looked orangish to me, i changed the fuel filter and so forth but here is a picture of some that i pumped out just to look at.

 

[feedthezombie]

OK did the MAF and TPS test and here are the results.

TPS

.897v closed 4.65v WOT
VREF 5.05v

MAF

KOEO 9.6mv
RPM range 500-800 i read .854v-1.02v (this was hard to do until the engine happened to calm down and idle somewhat normally, at which point RPM's were around 850 and voltage read 1.00-1.02v)

I also checked the feed voltage (red wire) and it had 11.98 volts (both with the existing ground in the harness and to battery ground.)

I unplugged the MAF without resetting the ECU from yesterdays log, and started the vehicle. It actually started up more easily and seemed to stabilize although RPM's kept rising and falling, rising and falling it wasn't perfect by no means but with the MAF connected it took forever to get the engine to stabilize and i ended up using some carb cleaner to get the engine to idle so i could do my final MAF reading.



This datalog is super short i thought the device would store a couple of logs so the previous 2 were apparently overwritten. They showed the initial fight to start the truck up pre carb cleaner and post carb cleaner.

This log was done after the truck started to warm up and actually run almost decent i backed it up and down the driveway 3 or 4 times and it did fairly well (no power) as long as you kept the throttle very very mild, if you went half throttle the engine would start to stall. But on the last trip the engine just hit a wall sounded horrible like all the cylinders were just misfiring so this log is from that situation where i parked it and could keep the engine alive by holding it part throttle.

Another note on this is i obviously reset the ECU and CEL prior to doing the new logs and there was NO CEL's present at the end of this event which was strange.

http://downloads.bustedfingermotorsports.com/datalog00.csv

 

[2000StreetRod]

old fuel

. . . here is a picture of some that i pumped out just to look at.

I don't see any signs of rust but the fuel looks old to me. That may explain why the engine starts easily on starting fluid but not on fuel. I suggest that you drain the tank (save it in a container if you think it might be useable mixed with fresh fuel) and put in several gallons of fresh fuel with a can of Techron injector cleaner. You can disconnect a fuel line somewhere, fit a hose to it, and use the fuel pump to empty the tank. You can remove the fuel pump relay and insert a jumper instead of turning the ignition key on multiple times.

 

[feedthezombie]

I don't see any signs of rust but the fuel looks old to me. That may explain why the engine starts easily on starting fluid but not on fuel. I suggest that you drain the tank (save it in a container if you think it might be useable mixed with fresh fuel) and put in several gallons of fresh fuel with a can of Techron injector cleaner. You can disconnect a fuel line somewhere, fit a hose to it, and use the fuel pump to empty the tank. You can remove the fuel pump relay and insert a jumper instead of turning the ignition key on multiple times.

yeah it looked old to me and smelled "stale" if that makes sense. Its a cheap thing to try since i've tried everything else. I will pump it out tomorrow and put 5 gallons of fresh juice in it and a treatment then give it another try.

Can you tell anything from the log that i should be looking for wiring/sensor wise? I found it strange that the engine didn't throw any CEL's this time around. Just looking for anything else i may look at while i'm working on it tomorrow.

Thanks again!

 

[2000StreetRod]

2nd datalog

Your thermostat, ECT sensor, IAT sensor, and CKP sensor appear to be functional. Your long term fuel trims track each other but are not stable. Your short term fuel trims are opposite each other. Are the O2 sensors connected to the correct banks? Bank 1 is passenger (right) side and Bank 2 is driver (left) side. To verify, I suggest disconnecting the driver side (usually the most accessible) and see if the PCM reports: P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
If the PCM reports: P0135 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) then the O2 sensors are swap connected.

 

[feedthezombie]

Well i pumped the old gas out today, threw in a can of techron and added 6 gallons of fresh gas. The problem is still there overall, it seems to idle more easily now but there is still a problem. I didn't have to spray carb cleaner to get it to idle, i just had to work with the throttle a little then it evened out on its own and was ok. But the same issues are there.

I did try a few things just out of curiosity sake while the engine was idling i revved it by hand it would stumble and buck and just all around sounds horrible. I unplugged the MAF expecting the engine to slowly die but instead no change, i gave it a rev like i did before and it revved more easily and seemed to be a little smoother. I don't believe it is a MAF sensor problem because this one is brand new and the problem was present with the other MAF that wasn't bad i just replaced it to "try". Is there somewhere else i should be looking? The signals feeding and coming from the MAF seem to be ok (the test i done earlier) could it be a PCM problem?

I'm going to let it cool down and try to unplug the drivers O2 just to see if the wiring may be reversed off the back side.

I'm still at a loss for a good solid lead on where the problem lays with this damn thing. Im thinking about pulling the engine harness off stripping the looms and going through all the wires to make sure they are all ok then re-loom and connect back. I also bought a new tube of dielectric grease, plan to check all the pins on both large connectors on the engine harness ends and grease them before putting it back as well.

After that i don't know where else to turn besides PCM??

 

[2000StreetRod]

O2 sensor wiring

The driver side O2 sensor should have a red/black wire and a yellow/light blue wire connected to it. The passenger side O2 sensor should have a red/white wire and a gray/light blue wire going to it. I suspect you have them reversed.

 

[feedthezombie]

The driver side O2 sensor should have a red/black wire and a yellow/light blue wire connected to it. The passenger side O2 sensor should have a red/white wire and a gray/light blue wire going to it. I suspect you have them reversed.

if they are reversed is it something that could cause such a dramatic affect?


I did plug wires one time and the diagram i followed showed 4-5-6 on the coil pack instead of 4-6-5 and i ran it with 2 wires switched "briefly" and it still had more power and stability than it does now.

does the MAF sensor being disconnected and the engine running better tell us anything or is that what has helped point you to the reversed O2's?


I will check tomorrow about the O2's and switch them if they are backwards, reset the ECU and try try again. I hope it is something that stupid simple, be nice to finally have it running.

Thanks again for all the help

 

[2000StreetRod]

If the O2 sensors are reversed, when the PCM goes to closed loop it will incorrectly adjust the air/fuel ratios because the wrong sensors are being used. The eventual effect is usually lean condition code on one bank and rich condition code on the other bank. The incorrect fuel trims are stored in non-volatile memory for the next engine start. The fuel trims are normally not adjusted after engine start until the TPS is moved from closed throttle to part throttle. I'm aware of several members who have experienced reversed O2 sensors after removing and then installing an engine. One member had it done by a mechanic at an auto repair shop. It took me a while to diagnose.

The PCM may stay in open loop if it detects the MAF sensor is disconnected. It would revert to relying on the TPS for establishing A/F ratios but has no way to determine engine load.

 

[feedthezombie]

Well i swapped the connectors on the O2's... it didn't make any difference, i actually believe they were in the right spot but the pass side connector i didn't see a yellow/ltblu wire in but the drivers had a red/black and a yel/ltblu so i switched them anyway just to see.

Here is a datalog this was probably a minute after i started it up once i got the idle to stabilize. The only CEL's were sensor 2 heater circuits for the rear O2's and the shift solenoid ones that are always there.

DATA LOG
http://downloads.bustedfingermotorsports.com/datalog_00005.csv

Im going to strip the upper and lower manifolds off and pull the engine wiring harness and go through it see if any wires are broken, any pins in connectors are pushed back and go from there i guess.