what controls fuel mixture?

[expotrek]

on my 89 there is a specific rpm band where there is no power, the harder you push the pedal the more it seems to lag, so im leaning to a lean fuel mixture. It doesnt matter how hard or lightly i try to accelerate its the same result until about 2000 rpm then the motor picks up like its getting fuel again. like you were pulling a trailer and it came unhitched. also it only does it 90% of the time, and if i shut the truck off and start it back up it goes away for a while. and i just put a new fpr on it in febuary, i havent tested it and i know it could still be bad but im leaning towards something electrical. the pumps only about a year old. so my question is what electrical controls fuel mix? i think the injector timing (how long its open) has a lot to do with it but what controls that? its a 89 speed density not mass air. i cant get it to do any of this in the driveway where i can test it and i hate just throwing parts at something...

 

[fastpakr]

Is your check engine light working, and if so, is it on?

 

[expotrek]

it will come on if its been driven about 20 miles or so but goes off when i shut the truck off, even if its just for a second

 

[expotrek]

replaced the ignition module and it didnt make a difference. its getting steadily worse, it was bucking last night like it was going to stall while going down the road in 3rd gear...

 

[fastpakr]

What led you to replacing the ignition module?

Follow the tech article on TRS and check your codes, then post them here.

 

[expotrek]

okay here goes

KOEO
34 egr valve position
41 EGO always lean

KOER
21 engine coolant temp not at normal op temp OR edis fault CPS circut
42 EGO always rich... wait... what? but before you said...
33 EGR valve position not opening or not seated
77 operator error during during dynamic response
52 power steering circuit open or no changes...


so which way do i go now... obviously the egr's high on the list. clean it? coolant temp could be cause its sat for a while now before i ran the test... o2 sensor i dont even know whats up with that 77 and 52 dont really worry me but what about 21 edis fault in the cps circuit, how do i check the crank position sensor... where is it located on the 2.3 i know someone will say "you need a shop manual" and i agree if i could find a chiltons i would get one but all i've seen are haynes, and not only are they not helpful, but more often than not ive found them to be innacurate, especially in electrical testing specs...

 

[BRUTUS_T_HOG]

replace your egr valve and clean out the egr passages

 

[fastpakr]

41 had to have been a stored code. Yeah - I'd take a careful look at your EGR valve and see if it's stuck. Fix that issue and see if it clears KOEO codes, then we'll move onto whatever is left for KOER. FYI, it sounds like you might have run the KOER codes while the engine was cold and missed the flash telling you to cycle the steering wheel and goose the throttle.

 

[shadetree]

It doesnt matter how hard or lightly i try to accelerate its the same result until about 2000 rpm then the motor picks up like its getting fuel again. like you were pulling a trailer and it came unhitched.

Please explain. This truck will not have any power under 2k rpm.shady

 

[expotrek]

well i didnt have much time to mess with it last night but i pulled the electronic side of the egr apart and grabbed the plunder inside with a pair of needle noses and it moved nice and smooth, i dont know if there is anything else to take apart? also i hooked the egr to straight vacuum off the intake,bypassed the switch on the passenger's inner fender, and the truck ran like total sh*t. so i belive its moving around alright.

I was thinking the ignition module because the tach wasnt working either (it is now)

shadetree- lol i know but it used to have more than this and seriously its not a gradual pull into the torque band but like someones flipping a switch, power comes on that fast and that much of a change.

 

[expotrek]

oh and now its started bucking really bad like its stalling out while going down the road and today when it was lagging i kept on the throttle and it started popping and back firing sounded like through the throttle body.... I dont think the truck will start with the passenger side (secondary) coil pack unplugged but will it run with the primary pulled? i might try that to see what it does, maybe narrow it down to ignition

update: i pulled the primary, the one the ps pump, and the truck ran but with no power the whole way through. plugged it back in and it would have power when it wanted to like before. but i was only to take a short drive so maybe is is just a coincidence i dont know if ican have the coil tested or not