Hello,

I just had a set of ARH with cats installed on my 05 a4. we also installed new front o2 sensors, they through a few codes that my installer turned off. [ p0030, p0050, p0135, p0155]

Now after a cold start with a small warm up the car has no power until the engine is hot.
I'll accelerate from the first red light I come go and the car will not go over 1500rpms until i'm at about 35mph, then it accelerates.

Also if i'm sitting still for a long time the car will idle like normal at 500rpms, then it starts going up to and down between 400-600 rpm's. Once that happens, I'll try to accelerate and again its like there is no power till about 20mph.


I'm getting the SCS light on really hot days, I'm blaming my NGK tr55 plugs, I'm going to be checking my spark plug gap today after work. I also have MSD wires, if that changes anything.

I cleaned my air filter after this happened a few times, and I put seafoam in my gas tank to clean the injectors.


Would a dyno tune fix this? is it A/F ratio? is it bad spark? is it a vacuum leak?


( the reason I'm not happy with this is b/c:
1. my car does not work
2. I replaced the headers that were on my car for these b/c the new ones have cats)

I should have left it alone

 

I've heard some people have had issues with the NGK plugs. Try stock plugs.

 

I know the plugs with give me the SCS light, but will it hinder my acceleration?

The reason the NGKs give the SCS light is b/c they create "noise" in the electrical signal, not that the plugs are broken.

 

It sounds like they did not tune the car, but just turned off codes. Did you pay for a tune? If you did, your installer needs to take a look.

A dyno tune will not change part throttle driving, but if you pay for a full tune (drivability + dyno) they should clean up the hesitation, improve the shift points, and set your WOT A/F

 

No, I have not had the car tuned yet.

but this is the 2nd set of headers on the car. the first set did not give me these problems. Also no tune on those headers

 

Ironically, I've heard that some people experience that with stock plugs and actually installed NGK TR55s to solve it LOL.
Though I have heard of issues with MSD wires. I personally would ONLY use fresh/new factory/OEM (or GM Performance) plug wires








I would also let the car fully warm up (not just the engine oil and coolant but the trans and rear as well) before jumping on it anyway, regardless of it's tuning status.

 

I can almost totally assure you that it's NOT the headers that are causing this (unless someone dropped a shop rag inside the cats by accident during the install or something).

 

I'll agree with that too b/c when I'm on the highway at high speeds, i can accelerate with no problems.

I'm just wondering now about the o2 sensors, or if turning the rear o2s off could do anything to cause this

 

Turning off the rear O2's will not cause this.

Why did you switch?

It certainly would be nice to see a data log during warm-up.

 

I switched b/c I wanted to put cats back on the car.

I'd like to get a data log as well, maybe a friend of mine will have HPtuners and we get it.

 

yup get it tuned. but change back to AC Delco plugs and GM Red wires

 

quick update:

Still need help

Car runs like garbage every 150miles. somewhere around 120miles of driving the car "learns" the proper A/F ratio and runs like a champ, but then at about 150miles on the clock it does the crappy sputter with no power, and then for the next 40-50miles on the clock the car runs SO rich that there is no power.

I replaced my Alternator b/c it was going out, that was the cause of my Service Charging System light that would come on every so often.

 

TR55's are not the correct gap for our cars. They're at .060. Maybe you're not getting a complete burn or something?

TR5s are correct for our cars.

 

Those are the front O2 codes, not the rear. It sounds like you probably plugged your O2s into the rear plugs and turned off the front codes when it threw them.

 

I was thinking those sounded like codes from the front o2 sensors!

P0030= Bank 1 Sensor 1 Heater Circuit (Driver's Side Front)
P0050= Bank 2 Sensor 1 Heater Circuit (Passenger Side Front)
P0135= Bank 1 Sensor 1 O2 Sensor Heater Circuit Malfunction
P0155= Bank 2 Sensor 1 O2 Sensor Heater Circuit Malfunction

This is your problem! You should not turn off those codes. They have nothing to do with the rear o2 sensors. You have something hooked up incorrectly. You need to verify that you have the front o2 sensors and extensions properly plugged into the front o2 sensor connectors! Front o2 sensor harness plug runs above the valve cover and is about halfway back.

 

Thanks guys, I did start with the front O2 sensor as my possible problem, but they r connected correctly. My installer did not turn off the codes, but he did prevent the code from display the check engine light

I was told these codes would stop if I get a tune and turn off the rear u2 sensors (which r not plugged in)

 

Those codes are related to the function of the front o2 sensors. Totally unrelated to the rear o2 sensors. You have to realize that even if the codes are disabled from being displayed the condition that caused the code/s still exists and you are still driving around with the malfunction....the ECU just isn't giving you the visual alert. Your front o2 sensors are not working properly. They are critical! Did you buy plug-n-play new fronts or did you buy the ones that you had to solder the connector on?

 

You have circuit codes for the fronts. If you are getting those codes something is not right with the way they are hooked up. They should not set and should not be disabled in any form. The codes for the front O2s will not stop based on anything done with the rear O2s, they are not related.

 

And just to be clear...you absolutely do not need the rear o2 sensors other than to plug the two rear bungs. They serve no purpose on a long tube header setup. There are a handful of codes that you disable related to Banks 1&2 but they all apply to sensor #2...not sensor #1.

 

Sounds to me like you have your front 02 sensors screwed up somehow.

You do NOT need to turn off those codes. Get them turned back on.

You CAN turn off PO420 and PO430 which are the rear o2 inefficiency codes that will trigger with long tube headers.

I suspect you either crossed the wires on the left vs right 02's (my friend did that and it did what you're talking about), or, you pinched or burned the o2 wires.

If your friend has HP Tuners throw the scanner on it and your problem will become apparent real quick.

I don't want to scare you but I wouldn't really drive the car much. You've no doubt fouled your plugs, so get some new ones, and you might be dumping so much fuel you could wash down your cylinder walls (not good) or so lean that you might burn up a valve (likely not, since you aren't getting on the car I'm assuming).

In any case, I suggest you get the codes turned back on, and find out what's not hooked up correctly with the front o2's.