Ridiculous drop in power...

[Sandstone VR-4]

Where to start??? Lots going on with my wife's Explorer over the past few months ('04, 4.0l).

It started with a bunch of misfire codes. So, I replaced plugs (Autolite Platinum - gapped to .054) and wires (AC Delco).

Still no fix, so I replaced the crank position sensor. While making sure everything looked right after the install, I noticed that the balancer had a wicked wobble going on. Turns out that where the balancer slips onto the end of the crank had cracked in half! http://www.explorerforum.com/forums/showthread.php?t=389275

Anyways... got a new style balancer on there and the Explorer has been running well up until about 4 days ago. She threw a P0316 code, so I went straight to the pulley. Turns out that the crankshaft pulley bolt had somehow begun to back out, causing the new pulley to wobble enough to throw the misfire code. Not sure how it backed out, but bolt has been re-torqued.

I re-set the SES light and it has not come back on. However, I am experiencing a crazy drop in power. From a stop, there is NO pickup until you hit about 15-20 mph, at which point it begins to respond. But there is no power until that point... like, "you better not try and pull out into traffic" power.

Any ideas? I'm dumbfounded. Since the engine light hasn't come back on, I don't have any codes to be pulled.

Could it be a problem with the wires or plugs? What potential damage could have been done by these pulleys that could cause these symptoms?

I appreciate any info you all may be able to provide!

Thank you!

 

[2000StreetRod]

P0316

P0316 Misfire Detected On Startup (First 1000 Revolutions)

Did you replace the crankshaft position (CKP) sensor again after replacing the harmonic balancer? If not, did you at least reposition the CKP sensor to achieve the correct clearance? Did you install a new balancer retaining bolt? The bolt is torque-to-yield and should not be reused. When the balancer retaining bolt worked loose did the balancer wobble enough to damage the crankshaft position sensor?

I suggest checking the balancer for any wobble and if none repositioning the CKP sensor for the proper clearance or if it looks damaged replace it again. If the new balancer still wobbles I would begin to wonder if the crankshaft is bent.

 

[Sandstone VR-4]

P0316 Misfire Detected On Startup (First 1000 Revolutions)

Did you replace the crankshaft position (CKP) sensor again after replacing the harmonic balancer? If not, did you at least reposition the CKP sensor to achieve the correct clearance? Did you install a new balancer retaining bolt? The bolt is torque-to-yield and should not be reused. When the balancer retaining bolt worked loose did the balancer wobble enough to damage the crankshaft position sensor?

I suggest checking the balancer for any wobble and if none repositioning the CKP sensor for the proper clearance or if it looks damaged replace it again. If the new balancer still wobbles I would begin to wonder if the crankshaft is bent.

Thanks for the response! I did replace the bolt when I installed the new pulley. Even used some loctite, so I'm perplexed about how it could have backed out.

There is a very slight wobble to the pulley now, so I have been fearing the worst. Will try to re-position the CKP tomorrow to see if that helps at all.

Any other ideas/things to check? Again.. there is no SES light, so no current codes to check.

 

[Sandstone VR-4]

Ok... so had a chance to pull the CKP and there is evidence that the wobble of the pulley may have caused superficial contact. There are rub marks on the sensor, but they are so minor that they appear almost like sandpaper scuffs. Nothing "damaged" that I can tell.

I started thinking of the symptoms, as they really appear to be primarily from a stop. Once the car picks up to about 15 mph, it drives nearly normal. If starting from a stop (in Drive OR Reverse), I can depress the pedal almost to the floor with the Explorer *barely* moving under it's own power til it reaches the afore mentioned 15 mph. The engine isn't reving while the pedal is depressed, so I'm wondering if this could be throttle by wire problem?

Any sensors or relays that might cause a symptom like these?

Any additional ideas? I'm willing to try and troubleshoot anything I can to get this thing running well again.

Thank you!

 

[2000StreetRod]

rub marks

Ok... so had a chance to pull the CKP and there is evidence that the wobble of the pulley may have caused superficial contact. There are rub marks on the sensor, but they are so minor that they appear almost like sandpaper scuffs. Nothing "damaged" that I can tell.

I think a new CKP sensor comes with calibrated spacers that are intended to be rubbed off as soon as the engine is started.

I started thinking of the symptoms, as they really appear to be primarily from a stop. Once the car picks up to about 15 mph, it drives nearly normal. If starting from a stop (in Drive OR Reverse), I can depress the pedal almost to the floor with the Explorer *barely* moving under it's own power til it reaches the afore mentioned 15 mph. The engine isn't reving while the pedal is depressed, so I'm wondering if this could be throttle by wire problem? . . .

Unfortunately, I have no experience or knowledge of the throttle by wire system. Does the transmission downshift at WOT?

 

[Sandstone VR-4]

I think a new CKP sensor comes with calibrated spacers that are intended to be rubbed off as soon as the engine is started.



Unfortunately, I have no experience or knowledge of the throttle by wire system. Does the transmission downshift at WOT?

At speed, the transmission downshifts. However, from a dead stop I can depress the gas pedal and the car inches along like battery powered toy until I get up to about 15 mph. At that point, revs climb and throttle responds almost normally.

Wife just texted me that the SES light has come back on, so sending her to get codes pulled. May have more info in a bit...

 

[TBMounty50]

Maybe trans is not starting out in first gear.

 

[Sandstone VR-4]

Maybe trans is not starting out in first gear.

Thought about that, but there is also heistation in the upper RPMs and a rough idle.

Wife just texted me saying that they pulled a P0300. Guy at Autozone recommended new plugs and wires, but wife didn't realize that I had just replaced them less than 1500 miles ago. COuld it be the plugs and wires I used? AC Delco wires and Autolite Platinums.

She also said that on the way home from Autozone, SES started flashing and temps shot up. Originally, only for a second, but ran hot all the way home (about 2 miles)...

 

[2000StreetRod]

manual selection of low

Maybe trans is not starting out in first gear.

Good point. Have you tried starting out in manually selected low to see if the accleration is significantly different?

 

[2000StreetRod]

random misfire

Thought about that, but there is also heistation in the upper RPMs and a rough idle.

Wife just texted me saying that they pulled a P0300. Guy at Autozone recommended new plugs and wires, but wife didn't realize that I had just replaced them less than 1500 miles ago. COuld it be the plugs and wires I used? AC Delco wires and Autolite Platinums.

She also said that on the way home from Autozone, SES started flashing and temps shot up. Originally, only for a second, but ran hot all the way home (about 2 miles)...

P0300 Random/Multiple Cylinder Misfire Detected

Based on posts from forum V8 owners, the V8s seem to be more picky about spark plug type and gap.

 

[Sandstone VR-4]

P0300 Random/Multiple Cylinder Misfire Detected

Based on posts from forum V8 owners, the V8s seem to be more picky about spark plug type and gap.

Mine's a 4.0l.

Any idea the temp issue? Could a faulty thermostat cause a p0300? Seems unlikely to me, but who knows...

I appreciate all the ideas so far! I've about had it with this thing... ready to find "the fix".

 

[Sandstone VR-4]

Need to add that the temp issue was accompanied by the "Hi Temp / Low Oil" warning light. It was on for about a minute and then went off. I just got home and checked coolant levels. Looks good and is full of coolant.

 

[Dave8338]

Any chance a bad/ failing thermostat is causing the truck to run in "limp mode" ? What happens if you leave it in park and cycle the accelerator through just off idle to say 4000 RPM ?

 

[Sandstone VR-4]

Any chance a bad/ failing thermostat is causing the truck to run in "limp mode" ? What happens if you leave it in park and cycle the accelerator through just off idle to say 4000 RPM ?

When in park, the thing revs fine. Really bizarre and driving me nuts!

 

[Dave8338]

Is it equipped with traction control ?

 

[Ickey09]

Check to make sure spark plugs have not backed out....? Have your replaced the coil? Maybe dirt tpc? Checked fuel filter? I replaced the spark plug wires a little bit ago to find out one became burnt and melt by the header, check for ark in a dark garage. Last thing I can think of would be the balance is damaged some how?

 

[Sandstone VR-4]

Is it equipped with traction control ?

Nope. No traction control.

 

[Sandstone VR-4]

Good point. Have you tried starting out in manually selected low to see if the accleration is significantly different?

Tried this and there is no improvement in acceleration. It may actually be worse, as I can depress the pedal and the car doesn't rev and baaarely begins to move.

 

[2000StreetRod]

determine start out gear

For the 5R55E when starting out in "D" the transmission should be in 1st gear and will quickly upshift to 2nd speed (1st & overdrive). When starting out in "1" the transmission should be in 1st gear and not upshift. When staring out in "2" the transmission should be in 3rd speed (2nd gear) and not upshift. I don't know if the 5R55S performs similarly. The graph below shows my engine speed vs transmission speed with a 3.73:1 axle ratio.

I suggest that you confirm the vehicle is starting out in first gear and not 3rd speed.

I thought that the PCM could detect a throttle-by-wire problem and generate an associated DTC.

 

[Dave8338]

After verifying the above graph, if you determine that the trans is shifting at those numbers (R&P ratio won't matter) and you are within range, I would HIGHLY suspect the throttle pedal assembly as being faulty. Had it happen on a F-350 several years ago and it sounds very similar to what you are describing.