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Discussion Starter #1
I have a F150. In the last week, it has lost all power when going from a full stop. I takes 15 seconds or so just to get above 10mph. Once the revs kick in, then it seems to have full power, but when the transmission shifts and the rpms drop, so does my power.

Here are more details:
F150, 4.2 liter V-6, automatic transmission
Truck is 2003 with 220,000 miles on it
Engine is a Jasper put in about 25,000 miles ago
Transmission was rebuilt about 45,000 miles ago

-For the last few years, there was a nagging "sounds like a heat shield" rattling sound under the floor boards, but I could never find it. It disappeared when driving, it only happened at low rpms.
-9 months ago, it started pinging like crazy. I shifted to 93 octane fuel and the pinging stopped.
-2 weeks ago, the crankshaft position sensor went out. I replaced it.
-Yesterday I removed 2 pre-cats and 2 cats and replaced with straight pipe, thinking that I had a clogged exhaust system. The guy doing the welding remarked how hot the cats were when I drove up on the lift. It helped somewhat, but not entirely. I'm still running original piping from exhaust manifolds to the new sections. Downstream of the new sections I have the original muffler.
-I put a multi-meter on the mass airflow sensor wiring and it performs as it should. Good +12v power, good ground, expected sensor voltage, expecting increase in voltage as rpms increase.
-When the transmission is in park, the engine revs GREAT. It has good response and increases rpms in proportion to me opening the throttle. The problem is when I put it into drive and put a load on the engine. When in drive, the engine rpms don't increase, even if I floorboard it. Eventually rpms increase and tires start to roll.

Thoughts?
 

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Discussion Starter #2
Update: A few hours after my original post, I dropped by the auto parts store and pinged the counter help if they had any ideas. One guy thought it was poor fuel supply. I got a new Motorcraft filter and also replaced the air filter while I was at it. No change, still no power from a dead stop, but expected get-up-and-go once I'm around 15mph.
 

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Discussion Starter #4
Thank you very much for reading my post, @Grabber70Mach !

Yes, it comes equipped with an IAC valve. When at idle, I get a small, but audible pulse in RPMs, i'm guessing maybe about from 800 - 900 rpms or something along that line. It isn't like it's a 1000 rpm swing.

I had a honda v6 where the IAC valve went out. It varied a LOT. On my F150, just a little, but not "none."
 
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Discussion Starter #5
Update: I just checked my throttle position sensor. It checks good with a multimeter: 0.96v with key on, engine off with throttle closed. Nice gradual swing from 0.96 up to 4.96v going to wide open throttle, same back down. I don't think it is the TPS.
 

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Can you put a fuel pressure gauge on it and take it for a drive? On a hose and tape it to the windshield.
 

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My first guess would be that it needs a throttle body cleaning.
Second guess would be IAC valve.
Third guess, stuck open EGR valve.

Have you checked the trouble codes?
 

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Discussion Starter #8
@Matter - I haven't considered doing a fuel pressure check while at speed. I didn't think it was a fuel pressure issue because I have lots of power at high rpms. It seems to get plenty of fuel when demanding a lot. I think it would be odd to be able to deliver a lot of fuel at high rpms, but little fuel at low rpms.

@MrFlash - I have some carb cleaner and will spray down the mouth of the throttle bottle, wiping it out with a clean cloth. When I took off the inlet, I didn't notice much build-up. I'll look up IAC valve multimeter check procedure and report back results tomorrow. I'll also search out the EGR valve and do what I can to check operation.

No trouble codes! No check engine light, not service engine soon light, nothing. I wish that I DID! It would make it so much easier!
 

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Discussion Starter #9
Update: I raised the rear wheels and rev'd the engine while in drive. The engine rpms increased as one would expect, and the speedometer showed wheels were turning ~40mph. It did that several times. Then I lowered the wheels, put it in drive and hit the accelerator and I couldn't go much more than a few mph. No change that before except that it shows it isn't "when in drive", it is "when in drive AND under load." It revs fine when in park.
 

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Discussion Starter #10
@MrFlash - Thank you so much for suggesting the EGR valve. Here's something that I found when looking for EGR valve verification procedures:

Common Symptoms Of A Bad EGR Valve
The following are the most common symptoms that a Ford (or Mercury or Lincoln) car or truck will usually experience when there's a fault in the EGR system:

  1. Car or truck runs fine, but the check engine light (CEL) is on with an EGR Valve Fault Code:
    1. P0401 EGR System Flow Insufficient.
    2. P01406 EGR Valve Pintle Position.
  2. Rough Idle.
  3. Really bad gas mileage.
  4. Lack of power as you accelerate the vehicle down the road.
  5. Car (or truck or mini-van) seems to run ok above 30 miles and hour but once you come to an idle, the engine barely stays running and/or idles rough. Once you take off again, it runs OK.
That reads EXACTLY like my issue. More to follow!
 

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Sometimes a weak fuel pump can show problems under heavy load as accelerating and be ok at higher rpm's as there can be actually less fuel demand. I don't necessarily think that is what you have, but it is easy to eliminate as a source and just something to keep in your back pocket...
You might try a long or steep hill to simulate load and see what happens.
 

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65 Fastback 289 4 spd, 65 convertible 5.0L 5 spd. 3.73 8.8
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I have a F150. In the last week, it has lost all power when going from a full stop. I takes 15 seconds or so just to get above 10mph. Once the revs kick in, then it seems to have full power, but when the transmission shifts and the rpms drop, so does my power.

Here are more details:
F150, 4.2 liter V-6, automatic transmission
Truck is 2003 with 220,000 miles on it
Engine is a Jasper put in about 25,000 miles ago
Transmission was rebuilt about 45,000 miles ago

-For the last few years, there was a nagging "sounds like a heat shield" rattling sound under the floor boards, but I could never find it. It disappeared when driving, it only happened at low rpms.
-9 months ago, it started pinging like crazy. I shifted to 93 octane fuel and the pinging stopped.
-2 weeks ago, the crankshaft position sensor went out. I replaced it.
-Yesterday I removed 2 pre-cats and 2 cats and replaced with straight pipe, thinking that I had a clogged exhaust system. The guy doing the welding remarked how hot the cats were when I drove up on the lift. It helped somewhat, but not entirely. I'm still running original piping from exhaust manifolds to the new sections. Downstream of the new sections I have the original muffler.
-I put a multi-meter on the mass airflow sensor wiring and it performs as it should. Good +12v power, good ground, expected sensor voltage, expecting increase in voltage as rpms increase.
-When the transmission is in park, the engine revs GREAT. It has good response and increases rpms in proportion to me opening the throttle. The problem is when I put it into drive and put a load on the engine. When in drive, the engine rpms don't increase, even if I floorboard it. Eventually rpms increase and tires start to roll.

Thoughts?
It will not be an IAC valve, It could be a bad fuel pump, ck your psi 35 and volume (1 quart) in 20 sec. I have also seen MAF that read just low enough that you overlook them. I use my snap on Scope to verify, or you could switch it with someone else.
 

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Years ago, I had an 81 Camaro I bought new. Couple years later I had a major power loss. Foot to the floor couldn't get it over ~ 30 mph. Turned out plugged catalytic convert. It had failed and plugged. Dealer replaced it. All was normal.
Perhaps not your issue but one that happen to me.
 

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Discussion Starter #15
@sixtysevenGTconv - That's EXACTLY what I was thinking! Especially with the mysterious "somewhere under my feet" rattle. Last Friday I went to a muffler shop and had them remove the cats. No change.

@Wiseguy59 - Sadly yes. Read on:

This is probably the second-to-the-last update on this thread. After reading more internet stuff, I became more sure than ever that it was a something wrong in the EGR system. To avoid buying a $65 mighty vac to test a $50 EGR valve, I decided to just buy the valve and replace with fingers crossed.

I drove to an appointment this morning and on the way, same issues presented itself only even worse. I couldn't get above 45 mph and FINALLY the "Service Engine Soon" light came on. A relief! I passed by an O'Reilly's and asked them to pull the code. "Our machine is broke. I can't." (Nevermind the fact that they sell the danm things.) So I continued to limp homeward to go to the next O'Reilly's to read the code and probably buy the valve.

On the way, I lost all power, sputtered at 5mph on the interstate shoulder and eventually it died. Battery light on, overheated, lit up like a Christmas tree. Underhood, the drive belt was shredded. (Huh?)

I got a new EGR valve and belt and went back with a trunkful of tools. I replaced the EGR valve, cleaned the throttle body with car cleaner, went to put on the belt and noticed that the crank pulley didn't align with all of the other belts. I reached down and pulled the crankshaft pulley straight off. The crankshaft pulley bolt head sheared off, leaving the shank in the crankshaft. Closer inspection shows the bolt head failed a long time ago and the failure face fatigued very slowly. The keyway should be 1/4" wide and 2" long. But at 1" from the end, it becomes 1/2" wide.

Bottom line seems to be that the crankshaft pulley bolt wasn't put on properly at rebuild 30 months ago. Either it was too loose (so that it didn't seat, stretch the threads, and backed out) or too tight (so that it sheared the head). The belt tension kept the pulley in place but over time, it worked its way off of the crank/key making it wobble.

Bad timing caused the pinging, I thought I had a bad crankshaft position sensor (it was wobbling), no power (I thought I had an exhaust blockage). Maybe bad EGR valve, but with every possible code thrown when the pulley fell off, overheated, no crankshaft position sensing, I have no idea.

I had it towed to the shop that installed the new engine 30 months ago. Jasper won't warrant it because they say it isn't the engine. (I have to agree with them.) I'm hoping the shop will warrant the work as bad engine installation. I hope to post the final update to this saga in the next day or so to close the loop.

Thanks to all for your suggestions, mechanical insights, and willingness to help a fellow Mustang owner out.

(I'll post photos tomorrow. Not a pretty sight.)
 

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Discussion Starter #17
In fairness, I can't blame Jasper if the problem was that the crank pulley/harmonic balancer wasn't properly attached to the crankshaft. That's an engine installation problem, not an engine build problem.

In my Chilton book, it says to torque the bolt up to 65 ft-lbs, then back off, then torque to spec in stages. I worry that the installer took a short cut when performing this multi-step approach. I imagine some guy at 5pm on a Friday afternoon grabbing an air impact gun and firing that sucker up. 🧨 ⚰
 

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Discussion Starter #18
As promised, here is the wrap-up:

For $450, the shop extracted the crankshaft pulley bolt and installed a $200 one-piece one along with a Ford bolt and washer. It still had the check engine light on along with a printout showing me it is throttle position sensor failure.

To put it mildly, I was "very angry". After buying a new engine, having it installed, and taking it back for the bolt failure, they didn't even fix the TPS?

I drove home the 25 miles. Throttle response was sluggish. I stopped by an auto parts store and bought a new TPS. Once home, I replaced the TPS and cleared the code. Driving from workshop to garage, it didn't throw a code so I'm hopeful that this issue is behind me. No idea when the TPS failed, maybe it was two days ago at failure, maybe 2 weeks ago, or even longer.

For now, case closed.
 
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