Schister66

This summer i had my car tuned twice on 2 different setups. Both tunes were done at a trustworthy shop which i have frequented in the past with great results. My problem is as follows:

<U>The Problem</U>

Over the past summer i've taken a few road trips and noticed that after i drive my car at part throttle for a while (hour or more), it starts to run like garbage. It feels like my car is hesitating a lot, and when watching the boost gauge, it will climb from -16 in/Hg when cruising to -10 in/Hg and eventually up to -6 in/Hg. The car will at that point feel as if the weight has been lifted and will accelerate. It seems like an anti-lag system, but i dont have one setup on my car. I thought it was the timing being screwy, but it has to be the fuel.

I decided that it has to be fuel based on 2 things: 1. I'm getting poor gas mileage and 2. When my car begins acting like this, i can let it idle and see the faint black smoke out the exhaust pipe. After thinking about all this, i have decided on a possible cause to the problem, but i want to know what you guys think.

<U>The Question</U>

Would an aging 02 sensor cause the afore mentioned problems?? It has gone throught 2 tuning sessions so it might be fouled out by now. It does have 70,000 miles on it. It is the only thing i can think of that would cause this problem. I want to know what you guys think before i buy a $100 02 sensor.

Thanks

093turbo16

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">

Over the past summer i've taken a few road trips and noticed that after i drive my car at part throttle for a while (hour or more), it starts to run like garbage. It feels like my car is hesitating a lot, and when watching the boost gauge, it will climb from -16 in/Hg when cruising to -10 in/Hg and eventually up to -6 in/Hg. The car will at that point feel as if the weight has been lifted and will accelerate. It seems like an anti-lag system, but i dont have one setup on my car. I thought it was the timing being screwy, but it has to be the fuel.
</TD></TR></TABLE>

Are you able to log your coolant temperature? If you are over-heating, which is pretty common with a huge FMIC and a turbo car you might be climbing up there in the ECT tables, which could put it in a little bit of a limp mode if the tuner put a safety net on the car so if it over heats it starts running rich, retarding timing etc. Just a thought... or it could be as simple as the O2.

:: You can't really go by the factory gauge either, by the time that gauge starts to climb the car is 225+ or so.

Schister66

I haven't logged coolant temps, but as far as i can tell it does not overheat. This problem even occurs on cooler nights. The one mainstay in the whole problem is that it only occurs after long easy use...mostly light throttle or cruise control driving.

Also, i have a small intercooler (JRC 6") which may be blocking some air, but i dont think that overheating has caused this. It isn't something i've thought about though

093turbo16

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Schister66 &raquo;</TD></TR><TR><TD CLASS="quote">I haven't logged coolant temps, but as far as i can tell it does not overheat. This problem even occurs on cooler nights. The one mainstay in the whole problem is that it only occurs after long easy use...mostly light throttle or cruise control driving.

Also, i have a small intercooler (JRC 6") which may be blocking some air, but i dont think that overheating has caused this. It isn't something i've thought about though

</TD></TR></TABLE>

Just reason I bring it up is because on cars that over-heat you will notice that the A/F ratio will go rather rich and throw everything off.

0xenocron

What are you tuned on and have you tried running with your tune in Open Loop?

I hardly ever enable the O2 sensor after a tune unless the setup is still fairly stock and I have customers reporting back 25-35 MPG without running a closed loop O2 sensor on long highway trips.

Schister66

i'm tuned on Crome...i'm going to call my tuner tomorrow and see for sure, but i think i'm tuned with the 02 still working. I'll get back to you guys soon about it....

zexpoweredem2

If you have removed your cat this might be the problem aswell, the way that you can fix this is by installing a spark plug non fowler in between the pipe and your o2 sensor. i had to do this on my 03 civic, because it's telling your car that the gas is running to rich and the cat is not doing it's job of cleaning it up. there for you install the non fowler and it only lets the sensor get a small amount of gasess.

When i installed mine i had to take a 1/2'' drill bit and drill out the fowler some so the sensor would fit in.

I hope this helps you, it was just a part you can look into and only cost about $2.00 from advance auto parts

FaceTuned

iTrader: (4)

you should be running open loop.
ask your tuner.

tepid1

Check the ingition coil.