1998 Blazer 4x4 4.3 W Hesitation HELP

[nathan2000]

Ok.....Have a problem with this blazer for sometime...When started from sitting over night....there is a hesitation between 1900-2400 rpm. Slight bucking...not to harse but very noticible.(if kicked down the hesitation quites and it pulls like hell(like and vortec4.3) This only happens when under load. It starts on the first second. idles smooth as could be. and revs fine....but when u get it out on the road...weather in D or in any gear at 1900-2400 rpm it hesitates. if you leave it in first and keep it a 2 grand it does continually. (about 3 days ago it threw a p0300 random misfire code) Wait there is more....It has new cap, button,wires, plugs, new coil. tried a ingnition module, tried a new crank angle sensor, cleaned egr plunger....checked fuel pressure at on position and reving...was right above 60psi (but agian that isnt when it messes up.)Always under load. Had a head gasket go bad....so i replaced them(what fun that is)...ran the same b4 and after. Wait more...not after the temp goes it about 195...but after about 30 min of drive or close...allot of times it clears up...runs fine...for the rest of the day till the next morning...its down it the 20-30-40 degree now..but did it when it was warm also

thanks anyone that can help me and the problimatic blazer
Nathan

[swalt]

By chance does it only happen when you have your air conditioning on or front defrost? I have had a similar problem since new. Every 10-15 seconds as the compessor cycles, I get a slight hesitation (usually noticeable around 120km/h. The dealer knows what is causing the problem, but I was told until GM comes out with a software update, there is nothing they can do. Doesn't happen on all their Blazers, but on some. Usually worse when the vehicle is on a slight incline (going uphill) I was basically told it was within spec and acceptable to GM standards.

[nathan2000]

Nope...thats not it...thanks for the help....many vehicles have a slight slight loss of power when the ac clutch ingages...this is pretty much considered normal...

[71vette]

I have the very same problem. I just finished completly rebuilding my 4.3 on a '96 for a head gasket leak on both sides at 85K. Thanks GM. I have all new parts except for the coil and fuel filter. Mine consistanly records P0300, mis-fire on multiple cylinders. It started after about 1000 miles on the rebuild. While I was rebuilding it, I just hung the compressor outside the car and it rained on it 1 time. I noticed some rust coming from the clutch area when I re-installed it, so I'm wondering if the clutch is grabbing the belt every now and then, even when the compressor is off. The book says P0300 is an indication of a difference between the cam and crank sensor, not an indication that there wasn't spark at the right time. It also says that there is real-time data that records a count of mis-fires per cylinder. Don't know anyone who has a tool. One last weird thing. While looking at the wires and such this weekend, I found a pile of sunflower hulls underneath the distributor on the intake. Looks like a mouse needs to find a new home...I hope he hasn't chewed on the wires some where...

[Glenn Peters]

Not that its your problem but something to think about, sticking poppets in the injectors. Pretty common, Mine runs good just has poor fuel mileage.

[Paraquat.]

ahh!
Help! The same exact problem. Only a 97. My last 97 blazer ran mint until 164k when it was totalled.
I don't know what to do about it! I've already replaced over half the engine!


--Steve

[BlazerLT]

Spray carb, brake or throttle body cleaner through the MAF sensor with it out of the vehicle to disslove the gunk off of the MAF sensor wires.

Reset the computer and then enjoy.

[swalt]

Originally Posted by BlazerLT

Spray carb, brake or throttle body cleaner through the MAF sensor with it out of the vehicle to disslove the gunk off of the MAF sensor wires.

Reset the computer and then enjoy.

Emphasize, "out of the vehicle". If you spray it while it is in the vehicle running, you may be surprised by the bang and the number of pieces the airbox blows into. I watched it happen at a dealer once...expensive firework.

[BlazerLT]

It is not my problem if people can't read the whole thing.