I'm pretty well stuck at this moment with my car. When I first start it, it takes a while of turning over to actually start but when it does starts, it usually runs fine for a few minutes. after that I have to feather the throttle to get up to speed or it just bogs compleatly down. Occasionally at stop lights, the rps will be at about 800 and the car sounds like it has a cam, barely idling at all, sometimes even stalling. After a while it gets so bad that i have to pull off to the side of the road when leaving stop lights to turn off the car, and turn it back on. after i do this, the problem goes away for about 5 minutes. It has never been this bad, and up until last night, it only happened about once every three days. I changed the 02 last year, but figure its gone again because my narrowband a/f gauge isn't reading anything at all, but the car is not running lean, it seems like its running way rich. Ive got a walbro 255 in, and am going to switch back to stock to see if that helps once I find it. I believe the most likly cause is a bad 02 but don't want to spend money on it if I don't really need it.

Thanks

Thank you mobil one for rust proofing my driveway.

OBDII ports are there for a reason. Are there any codes (assuming you are still running stock PCM)? It takes a lot of the guess work out of the old days of listening to the motor and wiping your finger on the inside of the tailpipe. Get a Multimeter and get the readings off the sensor if it is suspect.

Additionally if you have a stock fuel system and a walbro, you are likely overdriving the stock FPR and running at a higher fuel pressure. Back in the day when I ran a walbro on my stock fuel system the rail pressure was around 60psi.

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2012 2500HD LML

1. If your narrowband is not showing a reading anymore, then it is likely there is an issue with the 02 sensor.

2. When the 02 goes bad, the ECU overcompensates and dumps fuel to avoid lean conditions. So yea, if its the 02 you would be running rich, not lean.

3. If you are running a stock fuel system and are still using the stock ECU like I'm assuming, there really is no need for the extra pumping power of the Walbro. I'd go back to the stock pump if I was you.

1999 Eclipse GS
Built motor
Hahn 16G Turbo w/ FMIC
Hahn Stage 5 Portfueler (270's & 500's)
Zeitronix Zt-2 wideband w/ 3.5bar MAP
3" SS Turbo Back
CM Stage 4 Clutch and Fidanza Flywheel
Baer Big Brake Kit

Well i checked the codes, the cel is on all the time for code 31 but i got a suprise when i checked them again. Im going to have to get a scan tool to check it out but here is the list. I tripple checked this.

43, misfire
51, fuel system lean ??
21, a lot of o2 possibilities
31, evap (always had this one)
61, its not listed
31 again
and then this one, i have never heard of it before

the light came on for about 4 seconds, then flashed 7 more times. it would be 17, but the light stayed on a long time at first.

24, tps

and thats it. God damn, thats a big fucking list.

Thank you mobil one for rust proofing my driveway.

If you have a TPS code, that may explain a lot of it. A bad TPS will send a schizophrenic voltage to the ECU, causing bad idle, cutting of power at speed, too rich/lean conditions, misfire, then possibly leading to premature cat failure from all the excess fuel being dumped on the cat. You have a big list and a bunch of problems, so I'm suggesting this as one item that can explain the majority of it.

A bad TPS sensor is like a bad coolant sensor on 2gnts - it causes a LOT more havoc than you would expect.

2gnt: '99 RS-T, killed by a toyota, pending rebuild...
Daily: Volt
Daily #2: '99 EVG ebike- STOLEN by PEDRO

I don't suppose the tps is interchangeable from a 98 to a 97 is it?

I replaced the fuel pump with the stock one, and cleaned out the pick up screen at the same time. It seemed to help, but i need to drive it for a while before i can be sure. I still have no reading at all on the a/f. Im going to change the coil and wires with some others i have in the garage and see if that changes anything.

also, compression is where it has been for years. nothing below 165-170.

Thank you mobil one for rust proofing my driveway.

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2012 2500HD LML

Thank you mobil one for rust proofing my driveway.

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-Ryan

Thank you mobil one for rust proofing my driveway.

I had a similar problem 3 months back. It ended up being both the TPS and the IAC. The IAC was way too filthy, so being on the safe side I replaced them both instead of taking a chance by cleaning them and run into the same problem later down the road.

I cleaned the iac and it seemed to help a bit, but it still studdered a bit when stopped, im going to drive it around for a while, and then if it doesnt improve ill change the tps.

Thank you mobil one for rust proofing my driveway.

I had a very similar problem, cant remember the codes right off hand, but the fix for everything turned out to be a new
TPS, Front O2 Sensor, and a set of new wires.
Interestingly enough, that has had me set up quiet nicely now for awhile with no problems.

IAC and TPS do sound like the most likely causes.

But, keep an eye on the MAP sensor. On my car, when the wiring connection for the map sensor was so-so and the circut became open, it would give a running lean code, but for some reason no open circut code. It's not as likely a problem, but something to check out just in case.

"Tutto fa brodo."

Todd Scungio
98 RS
15.173 @ 90.70 MPH

And also a 2011 Ralliart

On my 99 the IAC died and would cause the car to drop WAY low in the rpm, and bog down when I tried to take off. I would have to bounce my foot on the pedal to get it back up in the rpm before I could take off. I would try replacing the IAC. You said that cleaning the Iac helped, but a cleaning will only do so much. I would just replace it.

From V's with 8 cylinders to rotarys that spin, as long as its fast everybody wins.