Engine stumbling weirdness

[3Axis]

Right, so I don't think I ever brought up this weirdness about my car before because it's such a miscellaneous issue.
After my car has been running for at least 10 minutes and I shut it off to go to a parts or pawn shop or something for no longer than five minutes, it starts stumbling between around 2400 and 3000 RPM, kind of like turbo lag, only the car rocks back and forth and then seems to catch up when the tach reaches 3000, I'm wondering if it has anything to do with the exhaust--if that's because of back pressure--or if it's the injectors. I'm kind of paranoid about it. Any ideas? It does seem to go away after a little while and doesn't seem to get worse unless I open the throttle. I usually downshift so the RPM goes above 3000 and hope it goes away.

 

[JGvtec]

Bump.

 

[Kuchtaboy]

do you have a cel?

 

[rockadilla]

Do a tune up, spark plugs, plug wires, injector cleaner, oil change, etc etc. If that doesn't fix it let us know, there could be a different problem but from what you've told us it sounds like u just need a tune up

 

[3Axis]

new spark plugs, oil was changed at 199,000 (now at 200,200). No CELs, I induced seafoam through the brake vacuum and during the time I was just running that car (at 197,000 miles) I had some petroleum additive in the fuel quite often. The stumbing goes away after a little while, and when it does it feels like a turbo has kicked in even though I have the throttle open about 1/5th of it's total range.

 

[thenoxus1]

Is it only near pawn shops? ;p But is your throttle set correctly? I'll go grab my Haynes and see what it says.

 

[3Axis]

Is it only near pawn shops? ;p But is your throttle set correctly? I'll go grab my Haynes and see what it says.

:lol:

my TPS was the source of the idle going up and down constantly. When I checked the calibration it was sending only 0.16 volts at fully closed. I bought a new TPS just to be sure. It's set at 0.46 fully closed (which I know is in the normal setting range). The fuel filter is new, the air filter is new. New NGK spark plugs also. Speaking of that for a moment, I used a pen flashlight to look into the combustion chambers through the spark plug ports and noticed there is a bit of carbon buildup on the piston heads. Will seafoam take that away?

 

[natt2000]

i would try replacing the O2 sensor to fix the stumbling problem. it sounds like a bad fuel/air ratio is being injected at that certain rpm, and if it isnt bad injectors, or a bad fuel pressure regulator it could be the O2 sensor.

 

[emd513]

i had a similar problem with mine but it was at higher rpms. delt with it for almost 6 months and couldnt figure it out till the dam dizzy froze up completely. it was going out the whole time. mine started to get worse though every time i would get on it it would take off for a second then fall on its face and about 6200 it would sorta pick back up.

 

[jdmjim]

does it smoke when this happens

 

[3Axis]

I haven't really been able to notice anything. I was told the O2 sensor was relatively new. What "relatively" means though...

 

[natt2000]

if you can get a cheap O2 sensor, pick it up. sounds like it may be the dizzy as well. pretty much 50/50

 

[3Axis]

the distributor does make some crazy sounds when the engine is started cold. "Tch" "tch". I'll take the cap off and check if there's any play in the rotor. Thanks for the help people. It's still strange. I usually give the engine about 5 minutes to settle in in this cold weather and the engine seems fine. It's only after I start it a second time does it stumble. Not right away though, only about 10 seconds into driving will it stumble between 2600 and 3000.

 

[3Axis]

Okay. Aside from the oxygen sensor for a minute, I pulled the dizzy cap and took a look at the rotor and there's very little play in it at all. But what I did notice there is a gasket in there and it looked like it has been wearing away fast and actually missing in some places. Could this have something to do with it?

 

[qg18de06]

I'm not sure about that gasket, but I had a similar issue in my civic. I really only noticed my engine stumbling between 2600-3000rpms when I was going from 3rd to 4th. My problem was actually caused from the bolts that hold the distributor to the head being loose. After I tightened them up, the problem was gone.

You probably have already, but that is something else to check.