I have an ELM327 based tool. I dont believe any of my current software will pull ABS mod code. but anyways...

I have changed my mind once again...

after furthore testing this problem is definatly FUEL/Air system RELATED!!! I can rev the crap outa the engine in any gear while stopped and she runs fine.

however under loaded throttle (trying to actually move the truck) she spits and stumbles and stalls ONLY at the low end! if i can throttle through the hicup then every thing is fine again untill i slow down to the low end.

HELP! Im trying to do searching but i dont know. I cleared all the codes yesterday, so im going to go for another spin with the software running and see if i can see any abnormalitys in one of the sensore realtime.

I apreciate all the help so far, and i engourgage anyones ideas about what this might be.

maybe im an idiot and this is just another symptom of my cloged cat? maybe i should go beat it with a hammer, lol

again, thanks, and HELP!!!

 

OK, so... she is choking sputtering under darn near any load. i had my girl watch the numbers on the laptop as we drove and she said that the fuel trims were going to -99% when the truck would go nuts.

it was getting really bad (almost wouldnt go up hill at all with out hammering the throttle trough all the bucking) and my gas was at between 1/4-1/2 tank, so i went and got 20$ of gas and coincidence or not the symptoms seemed to lighten up.

i already have a fuel filter that i just havnt replaced yet so im going to do that.

this seems very fuel system related.

the p1406 got thrown again so i did the relearn when i wiped it, but have not drove it again yet.

help! and this may be wierd or unrelated but i feel like this last tank of gas lasted a long time. whether that be it LOOKed like it lasted a long time or whether it did.
help!

 

Go buy a fuel pressure gauge and check it. Sounds like the pump may be about to give up.

All the codes? How many were there?

 

MIL is off, changed fuel filter to no avail. pump is not making any strange noises and sounds like its working fine. (Im not saying it is fine, just that it sounds fine.)

installing fuel pressure guage tomorrow.

I don't know what to say about this problem, I'm at a loss!

 

Had a problem like this once on my old truck. Come to find out it was a spark plug wire breaking down but only under high load (like just giving it enough gas to get up a not to steep hill). When I floored it, the problem went away. You could check the resistance in your plug wires without removing them. Doesn't take too long. Most manuals give a resistence range.

 

i just did a tune-up not to long ago, so i was thinkin maybe it was a bad part (wires,plugs,cap). i used what should have been ACD DP's but who knows maybe its plugs or wires.

she runs and idles great, its just under uphill load or hard throttle. and it doesnt seem to happen till she at least a little warm. like shes fine up the first hill in the am (i think, this is largely based on a few assumtions) but after that i start having trouble.

the bonus is i have to drive like a grandma, so im doing good on mpg lately, lol.


can you explaine this testing without removing the wires? or point me to a resource possibly?

 

I'd sure like to know how to check resistance in the wires without removing. I'm thinking it's not possible.

 

Don't know about an 2001 but I have a Chilton book up to 1995 that gives this procedure. Remove the distributor cap and the wire at the spark plug. Measure resistance from electrode inside the cap to wire end at spark plug. Maximum value should be less than 30,000 ohms and preferably less than 25,000 ohms. Of course the resistance depends on wire length. They give the following values.
0 - 15 in. 3,000 - 10,000 ohms (didn't know you could have a wire 0 in long)
15 - 25 in. 4,000 - 15,000 ohms
25 - 35 in. 6,000 - 20,000 ohms
Wire over 35 on. 6,000 - 25,000 ohms
My 1994 factory Service Manual (Section 6D4 [Engine Ignition System] Spark Plug Wire Resistance Test) calls out the same values only with the wire disconnected at both ends. It also states that if the reading is above 30,000 ohms, or fluctuates between infinity and any value replace the wire regardless of length.
Like I said, I'm not familiar with the models later than mine. If this doesn't work for you ignore it. It worked for me on both my 84 Jimmy 2.8L and 94 Blazer 4.3L Vortec. Just trying to help. Sounds exactly what hapened to me. Felt like the truck hit a brick wall when it missed. Can't believe nobody's heard of this.

 

Ok soo...

Installed fuel pressure gauge.

At idle pressure sits at 50psi.

ignition on, engine off sits at 60psi.

driving sits at ~47psi.

depending on throttle, pressure may fluctuate ~3psi in snaps. ie ( throttle/let off ).

so is this my fuel pump or my fuel pressure regulator? or do i have a poppet leaking pressure?

 

I know you mentioned having a new fuel filter on hand, but have you installed it yet? Your key-on/engine-off pressure looks good, but it seems quite low when under load. This would point towards a supply issue which could be caused by a restricted fuel filter.