jayhackett03

92 pickup. 22re. (see signature) i was driving back home for 3.5 hours.
2 hours into the trip i notice that it gets "bucky" when i throttle off and throttle on at 70mph. (keep in mind i have an aussie in the rear but its even more bucky than usual).
at 3 hours into the trip back home i hafta slow down for the toll both, so i push the clutch in and it dies. i coast engine off through the automatic payment toll booth. it starts back up and idles VERY low and rough. for the remaining half hour of the trip its still "bucky". at this point i am very low on gas. i drive another 20 miles and fill up at the gas station 1 mile from my house (and check mpg, 14mpg), and its still idling low, rough, and being "throttle bucky".

my gas mileage tonight was 14mpg, which is lower than normal. usually at 70mph its about 15.5mpg. city is usually about 17mpg.

for YEARS I have had a continuous check engine light on for a lean oxygen sensor signal. i've ignored this since i found out a replacement 02 sensor did not fix it.

before i left on this 3.5 hour journey away from home 4 days ago, here's what i did:

• oil change. Quaker 10W-30 (oil is still full and clean)
• quaker oil filter (i would assume its still tight)
• topped off antifreeze (it took a whole gallon, typical for 3000 miles of driving on this truck)
• topped off washer fluid
• dynamic balanced my streetlocked wheels and tires. tough, but i did it.
• replaced a medium sized vacuum hose on the front of the valve cover. this vacuum hose is still attached and in good condition. thats the FIRST thing i checked while i was refilling at the gas station tonight.

i haven't gone outside to do any more diagnosing, its midnight and 35 degrees outside. any ideas where to start?

stevenf

Fuel injectors? Sounds like there playing a role in whatever is wrong with it.

jayhackett03

so the ECU is having the injectors act funny? why would that be?

any other ideas?

stevenf

Im not blaming the injectors on the ECU, Im stating that the loss of MPG, the "bucky" feeling, and shutting off at slow speeds, sounds like something is wrong with the fuel injectors.

Elvota

You might want to pull your codes again and see if any new ones have shown up.

Any similarities in speed, RPM or gas pedal position? By that I mean is the "bucking" repeatable or avoidable by changing one of those factors?

The TPS could be worn or out of adjustment. Maybe a burnt spot at or around 70mph... but that would show up every time the throttle reached that position, if that makes any sense.

Have you thoroughly checked your intake hose for tears? They can be hard to see and deep in the bellows. The extra air will confuse your ECM and give your engine all kinds of operating issues.

Temp seem okay?

Just throwing out some ideas....

jayhackett03

it'd be rare that all 4 injectors would die at the same time. the only thing they have in common is the ECU and the fuel supply.

jayhackett03

all the guage cluster vitals seem fine.

elvota, i will check those things soon.

i should clarify, it only "bucks" when i cross the 10%-30% area. i cruise 70mph at about 70% throttle.

Elvota

Where do you think the anti-freeze might be going? Do you have a leak or a possible HG issue?

jayhackett03

cylinder head was replaced 4 years ago. it does not leak antifreeze, it must be burning it. it has slowly "used" antifreeze since as long as i can remember. no white smoke though.

racingcameron66

mine did the same thing and it was the coil packs check them out next.

racingcameron66

and just throwing something else out there what about the MAF

jayhackett03

you mean the single ignition coil? ok. i'll look into that too.

keep the ideas coming gentlemen. thanks for the help so far.

Elvota

Actually, RacingCameron reminded me of a problem I once had with a loose ground near the coil. Make sure all your related ground points are tight and clean.

When I had the ground problem, it would stutter when I hit a bump... so it was more intermittent than what you are describing.

89whitetoyota

Pull the vaccum line off of your fuel pressure regulator and see if gas comes out of it, you might have a clogged or malfunctioning FPR.

jayhackett03

no gas came out.


i talked to some technicians at my old job and they pointed me towards the air flow sensor. i may try and find one for sale. anyone have one?

jayhackett03

all four wires have spark getting to the end of them. all four spark plugs are BLACK!

jayhackett03

turns out the water pump is leaking. good thing it'll be a parts warranty through Advance Auto Parts. i actually think its just the gasket though.

tnactsuj

as far as the coil goes there is no testing it. if your truck runs it is working. if it doesn't run and there's no spark it is broken. i found that out first hand while searching for possible timing issues.

tnactsuj

almost forgot , about the fpr when you turn the key to on position you should here the pump run for 3-5 seconds then quit.that means fpr is working right . if you ever turn key to on and pump keeps running without stopping your pressure regulator is definitely broken.hope you get the source of your problem

jayhackett03

i thought the pump only runs for roughly 2 seconds regardless of the pressure, when the key is turned to the on position and engine not started.