Hesitation/Dragging feeling

[OlBlue]

Hi, I am having issues with my 91 XE/MT. It idles well, and the RPM seem to respond normally in neutral, but when I try to accelerate it feels like I am towing/dragging something at the bottom of each gear until finally I get to a speed where it seems to "open up" and drive normally. This seems to be the case in each gear.

 

It almost feels like I am shifting up too early,from 1-2nd, 2-3rd etc.

 

From a background perspective...

-changed the engine in this vehicle last summer. Haven't really had a chance to drive it much since then.

-checked over all vacuum lines

-compression tested ok

-changed the fuel pump, and fuel filter 2X

-new plugs all around

-changed air filter

-noticed a some exhaust leaks tonight

-checked codes pulled #34 (Knock Sensor)not sure if there are others (yet).

-Jacked vehicled up and checked all 4 wheels nothing binding or dragging

-I had some "issues" changing the timing belt and I am not 100% sure about that the timing is perfect.

 

I am hoping to get a hand checking the timing this weekend. I am not sure if timing would set off the code 34# or even if a knock sensor problem would be related to the problem I am having?

 

Any suggestions are appreciated.

[1994SEV6]

Hi, I am having issues with my 91 XE/MT. It idles well, and the RPM seem to respond normally in neutral, but when I try to accelerate it feels like I am towing/dragging something at the bottom of each gear until finally I get to a speed where it seems to "open up" and drive normally. This seems to be the case in each gear.

 

It almost feels like I am shifting up too early,from 1-2nd, 2-3rd etc.

 

From a background perspective...

-changed the engine in this vehicle last summer. Haven't really had a chance to drive it much since then.

-checked over all vacuum lines

-compression tested ok

-changed the fuel pump, and fuel filter 2X

-new plugs all around

-changed air filter

-noticed a some exhaust leaks tonight

-checked codes pulled #34 (Knock Sensor)not sure if there are others (yet).

-Jacked vehicled up and checked all 4 wheels nothing binding or dragging

-I had some "issues" changing the timing belt and I am not 100% sure about that the timing is perfect.

 

I am hoping to get a hand checking the timing this weekend. I am not sure if timing would set off the code 34# or even if a knock sensor problem would be related to the problem I am having?

 

Any suggestions are appreciated.

you covered all the basic stuff. Sounds like you might have a timing problem.

I think the least amount you can be off with the timing belt is one tooth. But I think if you are even one tooth off, your engine will run terrible. It won't smash valves just yet, but I think you would have more than a slight dragging feeling.

 

The knock sensor seems like the most plausible thing with the info you gave. If your engine is actually knocking, or if the sensor is faulty, then timing will be retarded and the air/fuel mixture will be affected.

 

When I started to read your post, and I was only done with the top paragraph, I was instantly thinking EGR or some sort of valves like that could be gummed up somehow.

 

Also, check your MAF sensor. I might be getting this mixed up, but if it's dirty or if the wire is loose, then the truck will be fine at idle, but it will stumble and hesitate under load.

Edited January 6, 2012 by 1994SEV6

[OlBlue]

Hey thanks for the quick reply. I guess confirming the timing is the place to start. I think I have a line on a timing gun for the weekend.

I still have the old engine to pull the MAF or other sensors from if necessary so that is good. It seems the 02 sensor can come into play on this as well?

[Tungsten]

You pretty much got it, the knock sensor will retard your spark timing and the power will be terrible until that code is taken care of. Make sure nothing is triggering the knock sensor like a heat shield rattling somewhere or the pipe banging against something. If those vibrations resonate to the engine, the knock sensor will pick them up. That's something you want to look at before considering to replace the sensor.

 

About the timing belt, if you are a tooth off or so, it will have a random misfire and not be able to rev above 4000 rpm or something like that.

 

Don't bother to try to fix anything by turning the distributor to other than where it should be. It doesn't work that way on these (1990+ only) engines.

Edited January 6, 2012 by Tungsten

[Trogdor636]

I keep getting the knock sensor code on my 94. It runs fine, it has a little miss when started on these cold mornings but it goes away quickly. I know when I had it smogged my timing was at 13 degrees, but mine doesn't feel nearly as sluggish as what you are describing. Im hesitant to replace the knock sensor because it seems about everything can set it off.

[adamzan]

If it is off one tooth it will still rev up all the way but it will feel like you're towing a trailer all the time.