just bought a 91 NA with problems

[sandiegomr2]

oh geeez,

I will rid the car of the 20w50 tonight and put in 5w30, I just drove to work and brought the engine up to 5K rpms for the first time and let it sit at that rpm for 30 seconds while driving. Seems to have helped the hesitation a bit, this car is starting to wake up from the dead.

[sandiegomr2]

Update,

After some more spirited driving with varying rpm's up to 5K, the hesiation seems to be going away, I am thinking there was some gunk in the injectors that cleaned itself out with new fresh gas and some seafoam.

I am going to change the cap and rotor and fuel filter anyways, but it seems to be pulling hard through the whole range now, yippeee,

now I am dreading this brake job, I hate brake work, messy work it is

[Gairloch]

I don't have a ton of experience with it, but the one time I did a valve job on my 5sfe I noticed that it seemed to take a while for the engine to settle in and sound and feel solid. I think that took about 500-750 miles. I ran out of time and money so I couldn't shim the buckets so I even had tap that faded after a while.

If you have concerns about your fueling system Chevron Techron fuel system cleaner is fantastic stuff.

[Final13]

I have the same hesitation problem only mine sometimes hesitates all the way to 3700 give or take. Pulls hard after that, this afternoon I was driving and I noticed that there wasnt any hesitation at all its back and forth, no real consistency other than on take off most of the time. PO replaced plugs wires and and I thought the cap as well but I need to check the reciepts again.

[sandiegomr2]

UPDATE 12/15/06

The re machined 5sfe short block is in with new oversize pistons/rings,bearings, remachined crankshaft,rebuilt head is on, parts are attached, axles back from the machine shop and installed. BRake rotors and pads replaced.

She starts and runs beautifully. Now I only have one major problem left. It appears the CAT is plugged, the manifold ets super hot quickly and exhasut is getting out of the cat somehow because she smokes from that area. This together with major hesitation in low rom range makes me think the CAT is totally plugged with 250K miles on it, so next is to get a cheap used one ( ANYONE HAVE ONE) to pass smog and then gut it, or when I can afford get headers aftermarket CAT and modified 02sensor brackets. For now I just need a cat to pass smog can anyone help.

Oh what is the best brake in procedure for a new engine such as mone, I figure dont go over 65, and keep it below 3000 rpm? is this right

[sandiegomr2]

I woudl bet the hesitation we are experienceing is from a plugged or partially plugged cat. Check the manifold after a drive if it is super hot or glowing red at night a plugged cat is your problem, I am just tryin to figure out how I can get it passed with smog without dropping $270 for a new cat from the dealer.

[Final13]

Mine passed smpg with the plugged cat, dont ask how casue I dont know. Mine gets red hot when Im on the interstate, other than that its manageable. Its cheaper to go with the aftermarket parts and have someone weld in a cat before the muffler. that is where the secondary cat is on the turbo cars. not to mention the california cars. the o2 sensor is before the cat stock so the headers should be fine assuming to get a cat somewhere in the system. Im waiting for the parts to come in and its should be all done for me.

[Gairloch]

Originally Posted by sandiegomr2

I woudl bet the hesitation we are experienceing is from a plugged or partially plugged cat. Check the manifold after a drive if it is super hot or glowing red at night a plugged cat is your problem, I am just tryin to figure out how I can get it passed with smog without dropping $270 for a new cat from the dealer.

You can prolly get a cat that will do the trick from a junkyard for $30.