throttle hang?

[vdubnick]

Is there anything that would cause throttle hang other than bad accelerator pedal?

Ive noticed a significant drop in fuel economy (15-25%) over the last few months. I have also noticed the MFA economy readout hangs for up to 4-5 seconds before cutting the fuel and going to "-.--" .. I can feel the fuel cut matching the readout exactly. Also, sometimes it feels a little jerky on engagement, almost like turbo lag when easing into the throttle. I am not sure if this is due to a pedal/throttle body issue, or something else, but I am pretty sure the fuel not cutting is adding up to the loss in economy.

I am wondering if any other sensor is worth looking into.

not sure if these numbers are normal, but im definitely not hitting the limits.

accl pedal at zero

pedal at floor

 

[vdubnick]

no codes, intake valves cleaned about 15k ago.

 

[This is Ryans face]

subscribed.

 

[GolNat]

There is some sort of throttle calibration you can do.

 

[vdubnick]

There is some sort of throttle calibration you can do.

yeah i tried that a few times, didnt seem to change anything, both in the readouts and overall feel.

I am wondering if there is some other sensor/valve that would affect the fuel cut. like a lot of car issues, the symptoms are sometimes strangely related.

 

[vdubnick]

i may have found another issue, or at least something that is a contributing factor.

I have noticed that the intake runner flapper doesnt always go back to 0%, sometimes it hangs around 5-10% and sometimes will bump to zero if i literally hit a bump in the road, or if i cycle the throttle again. I am not sure if this is normal behavior, or if it is a sign of the intake flapper going out. I think the latter, because i know on the new design, there is a vent tube for the vac-acuator, probably to deal with debris clogging up the actuator and causing it to get sticky.

anyone know if the flapper position is used for other parameters? I am wondering if it doesnt "see" the flapper back at zero, it leaves the fuel running, or something else.

 

[vdubnick]

i am also still getting some surging when letting off the throtle and hitting the brakes, like the car is still pushing, like my foot is still on the throttle. same with the 1st gear idle... sometimes it jerks hard like im going WOT and letting off multiple times when i am actually just barely pressing the pedal.

 

[GolNat]

You should throw a code for the intake runner if it isn’t in position at the correct time.

 

[BudgetPhoenix]

What are your fuel trims?
Block 032

 

[vdubnick]

You should throw a code for the intake runner if it isn’t in position at the correct time.

thats what i would think too, but no codes, so there must be some amount of tolerance there.

I need to monitor it more, just the other day, i let off in 3rd gear, around 2-3k rpm, and fuel didnt cut at all, felt like i was still barely on the throttle.

 

[vdubnick]

What are your fuel trims?
Block 032

Value seems static... it does not fluctuate other than the two values below.

When cold,

After warming up

 

[zrickety]

After warming up

You are Unitronic K04, is that correct? How old is your MAF and did this start right after the carbon cleaning?

 

[vdubnick]

You are Unitronic K04, is that correct? How old is your MAF and did this start right after the carbon cleaning?

yes, unitronic, MAF is original, tried cleaning it with MAF cleaner and made no difference. carbon cleaning didnt seem to affect MPG, maybe helped a little, but mainly took care of idle/misfires. it was done well before the throttle hang and decreased mpg was noticed

 

[GolNat]

thats what i would think too, but no codes, so there must be some amount of tolerance there.

I need to monitor it more, just the other day, i let off in 3rd gear, around 2-3k rpm, and fuel didnt cut at all, felt like i was still barely on the throttle.

How you describe it as the car is barley on throttle has happened to me occasionally. I have not felt it recently and I now have an intake flap error. I am also Uni K04 and I did re flash to stock and back to K04 file.

 

[zrickety]

Do you think maybe an injector is sticking? Have you tried some cleaner? I like Lucas.