Sluggish power on a 1992 Toyota 4x4 pickup

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  #1  
Old 03-28-11, 09:07 AM
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Sluggish power on a 1992 Toyota 4x4 pickup

What might be some possible causes for sluggishness and lack of power?

This truck had a complete exhaust replacement (cat, muffler, pipes) over a year ago.

It has also had some fuel work done (fuel pump, filter, injectors), and something called a fuel pulsation damper. The odd thing is that, after the fuel work was done, the truck soon became "gutless". And, now, it only gets about 10 miles per gallon.

I was thinking the O2 sensors might be bad and has thrown off the timing a bit. Or, there is a clogged/defective vacuum line somewhere.

I haven't actually had a chance to look at the truck yet. I just wanted to get some ideas before I start.

Suggestions?
 
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Old 03-28-11, 09:34 AM
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At times it can be difficult to distinguish between an engine issue or a transmission issue. That being said, the first thing is to rule out a slipping transmission.

Next is what does the electrode burn look like at the plugs? Are the electrode worn? Worn electrodes mean the plugs are no longer gaped properly. Are the plugs long overdue for a change?

Have you ruled out misfires and vacuum leaks? Did you know that vacuum leaks cause misfires?

Next is to attach a fuel pressure gauge to the fuel rail and drive with the gauge attached. Drive at different speeds and different engine loads and post the fuel PSI values.

Next is to do the same with an engine vacuum pressure gauge.

Next would be to post the results of a compression test.

Are there any error codes? If there are post them so we can see them. Codes could reveal something.

Kind Regards
Diane
 
  #3  
Old 03-28-11, 09:44 AM
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Hi, Diane.

Thanks for the suggestions. I've already considered all of those and then some. I'm just making a list of everything I can check so I don't overlook something.

There is a definite issue with 2nd gear. Hardly any power at all. And, it takes a second or two before 3rd gear really kicks in.

I'm leaning more towards a broken/missing/clogged vacuum line for the tranny.

Any suggestions from that angle?
 
  #4  
Old 03-28-11, 11:49 AM
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I should clarify my last post.

The truck accelerates, but feels like it has lost its bottom end torque. Imagine going from first to third gear, and completely skipping second gear.

That's what it feels like.

I'm sure it's a vacuum line somewhere that has become disconnected or clogged.

Anybody out there have a diagram of the fuel system and any vacuum lines associated with it?

The original diagram is still on the sticker under the hood. But, I'd like a more detailed diagram if I can find one.
 
  #5  
Old 03-28-11, 03:33 PM
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Hi Ron,

For the second or two before third kicks in consider below. I'm busy now, but will get back to regarding your last question.

First thing is when was the last time the clutch, pressure plate and throw out bearing were replaced?


Additional Considerations

Pedal height adjustment
Pedal free play adjustment
Pedal pushrod play adjustment
Rule out a gear oil issue
 
  #6  
Old 03-29-11, 08:14 AM
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I'm thinking more along the lines of a clogged, or malfunctioning, EGR valve and/or EGR vacuum modulator.

The truck has 130k miles on it and the EGR valve components have never been cleaned or replaced. When I have time I'm going to take off those components, clean them and the vacuum lines as thoroughly as I can, and make sure the EGR diaphram is functioning.

If the EGR valve isn't working then I'll replace it. O'Reilly's sure are proud of theirs. AutoZone EGR valves are half of what O'Reilly's charge. And, I found an EGR valve on eBay for even less.

I'm actually busy remodeling the main bath in my house right now. But, I'm already making notes regarding my next project (i.e. fixing the sluggishness on this Toyota truck).
 
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