Thread: Misfires after having new spark plugs & cat put in.. *yay* (+ hard starts)

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P0420 I believe, cat below efficiency threshold if I remember correctly the description. Same one my car had.

what year is dads car? and what brand cat was used?

if a hi flow cat was used and its a 01-03 that might be the issue, that year and hi flow cats dont play well together. unless the cat test is tuned out of the pcm.

then some people just have the cat code pop up randomly, clear it and it dont come back for months. others use a o2 simulator and never have a issue as well. that just pulls the rear o2 out of the exhaust stream to fake out its readings.

i would think the shop would have cleared it when they installed the new cat.

how to make one for less then 10 bucks.

It's an 06, he says he actually had the cat cut out and replaced (supposedly) when he bought the car like 2 years ago and it never went away, so he just bought the same direct fit replacement that I bought a few months ago that hasn't given me any problems. The first guy who did the cat work said it looked like there was a problem with the rear O2 sensor port, not 100% sure as that was a while back.

Well.... I think we know why Whiteout still has the CEL on....and it's not P0420 anymore. But 7 different codes now.

P0300 Random/multi misfire (we just noticed today leaving gas station the engine struggled a tiny bit to accelerate from a stop, and idling is weird)
P0171 System too lean / bank 1
P0131 O2 sensor circuit low voltage bank 1/ sensor 1
P0054 HO2 sensor heater resistance bank1 sensor 2
P0053 HO2 sensor heater resistance bank1 sensor 1
P0036 HO2 heater control circuit bank 1 sensor 2
P0030 HO2 heater control circuit bank 1 sensor 1

XD we get rid of one code and get back 7. But I'm pretty sure we know why this happened and the car is going to go back to the shop where they replaced the catted downpipe... because my dad noticed that apparently, the front O2 sensor wire is going INSIDE the exhaust pipe where the downpipe meets the manifold. They somehow managed to cut or break the sensor's wire and let it get jammed in there and sealed it in there.
We also noticed though we get a bad odor of gas intermittently inside the cabin, that has been giving my dad headaches while driving the past couple of days...we don't know if the exhaust is leaking through where that wire got gobbled up into the pipe or what, but they better resolve both issues asap. I can't believe so many mechanics around here...I'm lucky we never had problems with Pumpkin's cat when we had the same people replace it though.

time to find a new shop. my god.

Originally Posted by Scottydoggs

time to find a new shop. my god.

Haha, yeah. That's one particular shop that specializes in exhaust work that we have only gone to so far for that work. Mr. 5/6 Plugs Changed guy was another shop nearby that my dad wanted to try because he personally knows one of the owners. We've gone to many different shops/mechanics besides those two and they all have their flaws too like these. One guy seemed really nice and never overcharged either but one day we called to ask when we could bring one of the cars for a certain job and he never called back, seemed also uninterested in working on domestic vehicles. That's our main problem here really, all the mechanics hate working on domestics and would much rather only do Japanese cars.

The cat codes will be fixed once the wires are fixed and the fuse to the o2's is replaced.

FWIW you are only an hour and a half from where I am. Could probably fix everything on the car in a couple of hours and hardly charge you anything. It would be worth it just to see your problems stop and give you a chance to enjoy driving the car again.

Aw, thanks for the offer Billboost. My dad actually went to the shop right after work yesterday and had them fix their mistake. Actually I think the shop owner had to step in because they were pretty busy too. But the shop owner told him after this has been corrected (I guess the whole wire wasn't cut/broken, just part of it going in then coming back out of the exhaust pipe) to let him know so he can order a new sensor/wire - likely on him of course.

I might make a new thread or two though on a couple of other things though that I have in mind, just to let this old misfire thread rest in peace haha. We are having some slight trans issues with all three of the cars, though obviously mom and dad have a 4T65E and I have the HD with tapshift, I will probably keep all that on one thread since the problems are similar/probably related. Though I think I actually had a Trans problem thread already....will have to find it and revive it lol

All three are 4T65's the differences between HD and not are very slight. There are other differences for your tapshift, however again... slight.