Sounds like a bad tps.

You replace them, not clean them.

They are junk brand new, removing to clean will just make matters worse.

If you're not getting a CEL, that's more than likely the issue.

$20 something from Steve @ Tousley.

- Drew

 

What is the thought process for the TPS going bad?

... that the Computer doesnt see that the Butterfly is open therefor cuts the fuel down to idle pressure?

 

I have also heard the possibility of the crank postion sensor creating this problem. any thoughts?

 

If it's a smooth loss of power, just a bogg without and extra vibration, it's more likely to be fuel related (low pressure, not an air leak) = TPS, possibly. If it's rougher, missing or noisy, it's more likely to be spark related = CPS, possibly. Have someone data log for you, then you'll see it when it happens.

 

no its definitely smooth loss.. but it can buck and surge during the "trouble zone" like a kid learning to drive stick.

is there any definitive way to check for vacuum leaks?

 

Not really any definative way, just listen around, or spray flamable gas around suspect places while engine is on... but you would have other symptoms if it were a leak (bad idle, hanging revs, and/or stalling) and it would be more or less constant. Try a shop or parts store where the mechanic or tech can hook it up to a scanner while you drive it, and try to hit the bad spot.

 

You can read O2 sensor output with datalogging to see indirectly a vacuum leak. Instead of switching both above and below .5 volt (from .1 to .9), a vacuum leak will cause O2 output to stay low mostly under .5 volt. It can be intermittent as hell, they do NOT have to run bad all the time. It depends on how bad the leak is and how close it is to taxing the fuel trim to its' limit. Trim will adjust for it until it hits software limit, then engine begins to run bad as trim cannot adjust further. The TPS switches I've changed all showed the trouble mostly just off idle, as switch spends the most time there and wears the internal carbon track in that spot. Acts just like when the old accelerator pumps used to go bad, a flat spot where engine tries to die just off idle. If that, someone can take a voltmeter to it and measure output. Voltage should smoothly increase from one end to the other, any dropout means switch is bad. You don't clean them, would probably mess them up. When fuel pump was changed, was the ENTIRE module changed or just the pump itself? The initial flat screen filter in the module before fuel ever gets to pump can clog and produce exactly those results especially if they occur mainly with low amounts of gas in the tank. Try driving around with a full tank for awhile and see if anything changes.

 

thanks for the replies. The entire fuel pump assembly was changed. Wouldnt the 02 sensor throw a code though at least a pending code? its really frustrating having this happen and the fiance is about to shoot me if it doesnt get fixed soon.

 

Sounds like a bad tps.

You replace them, not clean them.

They are junk brand new, removing to clean will just make matters worse.

If you're not getting a CEL, that's more than likely the issue.

$20 something from Steve @ Tousley.

- Drew

QFT

 

Just wanted to see if you ever found your problem? I'm having sort of the same issue with my 2002 ZX5 with manual trans. The car will bog down, usually only in first or second gear. Sometimes I have to feather the clutch to prevent a stall and get it going. The car seems to fine at highway speeds. It also only seems to happen when the car is cold. One other symptom I'm having is my idle is constantly fluctuating about 100 to 200 rpm.

Did you ever get yours figured out?

 

It definitely sounds like a feedback item... especially because it is sparratic. I would try a TPS replacement first. It's just a potentiometer... like the volume control on your stereo when you were a kid. When it gets to be several years old, all of a sudden it starts getting scratchy, making noises, varying volume without you even touching it, etc...

If you get nowhere with the TPS, let me know. I am more than willing to help if I can.

Regards,

Kevin

 

Not familiar with this specific application, but if there is an idle air control, see if it is carboned up and sticking. My 4.6 F-150 had the same symptoms, and the IAC was the problem. Removed it, cleaned it with PB Blaster, reinstall, no more problem.

 

I know this sounds crazy check you clutch master cylinder for fluid leaks. If not leaks check the color for bad fluid. The fluid shouldn’t be dark and if so bleed the master cylinder out and I am about sure it will fix your problem

 

Don't quit your day job bub, you have no clue at all. Clutch fluid has never caused a bog in the entire history of cars.