93 sport sputters when accelerating etc etc

[xplorernewb]

So it idles a little rough and revs rough when in gear but OK in neutral. If I give it throttle and back off to about 1/4 and back to about 2/3 throttle it sometimes smoothens out. Its also real hard to accelerate fast from a dead stop. Kinda sputters as soon as I let off the clutch and hit the gas and have to shift at high revs in order to make it to 3rd at a decent speed with decent power. I cleaned the IAC and replaced the gasket, no change. I unplugged the IAC and it didn't change a couple times but got definitely idled rougher and lower. Plugged it back in and went back to what it was doing before and couldn't duplicate it again. Its only gave me the check engine light once but went away. It will also drive fine at slower speeds if I kinda feather the pedal. Idle also takes a sec to drop when coming to a stop. Idles rough when it settles.

This started out of nowhere, had to pull over to turn around, accelerated kinda hard due to traffic and it dam near shut down. It used to stutter before I changed the plugs, went away and came back rexently but nowhere near this. I was told it could be the fuel filter or PCM could be failing to adjust AF mix or an o2 sensor or something. Anyone have any ideas?

 

[natenkiki2004]

Really sounds like a TP sensor. Hook a multimeter up and make sure the variability is smooth.

 

[2stroke]

Really sounds like a TP sensor. Hook a multimeter up and make sure the variability is smooth.

This is the first thing that popped into my head as well. If you wipe the inside of your tailpipe with your finger, is it coated in black goo?

 

[xplorernewb]

Yup tailpipe is all black inside, thought it was oil at first. Is there a way to test it without the meter? Im nowhere near home so I have very little to work with.

 

[natenkiki2004]

If you just need to get home, unplugging the TP sensor might be ok. No data is better than wrong data as far as the computer is concerned.

 

[xplorernewb]

I replaced the tps with a new one, seems to be better except now it wants to missfire at WOT only, like its trying to run out of gas. Smooth otherwise. Check engine light came on for about 20 minutes after the install and went away a couple times and hasn't come back since. Idle is a lot smoother as well. Anything else II should be looking at?

 

[xplorernewb]

Maf? Does that come into play within 3/4+ throttle? Im used to carbed engines and it seems to çut out at about where the secondaries are supposed to kick in...

 

[natenkiki2004]

MAF comes into play at all throttle. You can unplug it to do a shadetree diagnosis.

What you should do is a KOER test and see what the computer has to say.

 

[malohnes]

Don't forget to reset cpu after KOER and see if that helps. Unplug battery for 15 + minutes...

 

[xplorernewb]

So me and the wife decided to take it for a drive to the store and the idle was extremely higher than before, so i decided to: unplug the maf- dropped idle to normal and fell on its face as soon as i left my parking spot.

Unplugged iac-fixed the idle but accelerated the same.
Unplugged tps and no change at all.

Did oreillys sell me a bad part??

 

[2stroke]

Do you have a multimeter? The TPS is the easiest part to test on the whole vehicle. As long as its about .8-1 volts closed throttle, and smoothly goes up to full throttle, its good. This test can be done with the engine off. Most of the other sensors will trip a code in the computer. Have you done a KOEO or KOER test?

 

[xplorernewb]

Not yet, and i don't have a multimeter, but i will do the test tomorrow, i was forced to drive it today and one thing i noticed is that at high rpm on the highway it runs the smoothest, check engine light will stay on but at constant high rpm the light will go off and i can feel a click or something in the clutch and ill have some more power until the light comes back on.

 

[xplorernewb]

solved - cracked spark plug. Runs better now i couldn't see the crack but apparently it was bad enough to make it not work properly.