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I just had the 2 cats in the front hollowed out, but left the middle cat intact. I've now tripped 2 codes - P0155 and P1151. Is it normal to trip the O2 sensor codes now that the insides of the front 2 cats are missing? What effect will this have on my car, and should I have had the middle cat hollowed out as well?
 

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I just had the 2 cats in the front hollowed out, but left the middle cat intact. I've now tripped 2 codes - P0155 and P1151. Is it normal to trip the O2 sensor codes now that the insides of the front 2 cats are missing? What effect will this have on my car, and should I have had the middle cat hollowed out as well?
Yes, since there's no conditioning to the exhaust before the downstream O2 sensors.

And, you're not getting as good a flow as if the cats were working (!!) due to, well, read this page, especially the section on hollowing out cats: http://www.isuzuperformance.com/isupage/tech/exhaust.html

There are MIL eliminators that you can make and/or buy. I'd also either put in a pair of test pipes, or a pair of high flow cats, plus a "Y" adapter.

RwP
 

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Discussion Starter #5
so i should of had strait pipe put in place instead of an open hollow case. When i looked at the honeycomb it looked burnt and some parts somewhat warped and starting to melt. I dont have the money to replace the cats so im kinda stuck.
 

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Will this **** up my engine in the long run?
I think not. I'm running hollowd out cats with the 3rd cat replaced by a y-pipe. This was done 4 years ago and I have no problems. Yeah, I did have a CEL but a tune removed that. If there is an effect on performance I haven't seen it. I still get good mileage despite having not replaced the upstream o2 sensors yet.
 

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they are a rear o2 sensor emulator they trick the computer into thinking that they cats are working properly.
 

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there is a cheaper way to get rid of the check engine light. go to your local parts store and buy 2 18mm spark plug non fouler's. then all you have to do is drill them out so that your O2 sensor fits in them and then install them with your O2 sensors (one on each side of the rear O2s). doing that will put your O2 sensors out far enough to not through your CEL. also I have ran my car now for a year with all 3 of my cats hollowed out with no problems but the noise that you get from the turbulence in the exhaust. I have a tune on my car to eliminate my CEL but I have done the trick with the spark plug non fouler's to a few cars that I have worked on.
 

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Discussion Starter #12
I will keep that in mind thanks.

Holy ****. I have no clue why the car didn't run like this on the way home from the shop, but I just got done taking the car for a drive and its like I'm pulling a ships anchor behind me. Total loss of all power feeling as if it fell flat on It's face. Please tell me if I had the middle cat replaced with a Y would it fix this awful problem and return my car to normal aside from the loud exhaust noise?
 

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Have you done general maintence ie. fuel filter, tune up, clean maf?
 

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Discussion Starter #14
yes I have, when I first bought the car 3 months ago. This all started after I hollowed out the cats, so I'm assuming the extra back pressure is whats causing my car to stumble the whole way home this morning. It doesn't help that the middle cat is still intact and guessing that isn't helping the extra back pressure any either.
 

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Discussion Starter #17
anyone? I plan on having a Y pipe replace the middle cat thats still intact.... I dont see why the coilpack would just suddenly go out after i hollow out the a front cats and all this talk about back pressure..... Will the Y pipe fix the back presure problem yes or no?
 

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when you remove the cats your back pressure goes down not up. as for the car falling on its face, if you have the car in park and hit the gas does it stall out at any RPM. only reason I ask is I gutted my cats because of 2 bad MAF sensors. the car would not go over 3k RPM even in park, so that will give you something else to look into.
 

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I have a multimeter. Is there a way to check the coil packs?
First, isolate the coil pack by disconnecting all the leads. Set the ohmmeter in the low range, and recalibrate if necessary. Connect the ohmmeter leads across the ignition coil primary terminals, and compare the primary resistance reading to specifications (typically less than 2 ohms). Then connect the ohmmeter leads across the coil secondary terminals and compare the secondary resistance reading to specifications (typically 6,000-30,000 ohms). If readings are outside the specified range, the coil is defective and needs to be replaced.

If measuring the secondary resistance of a DIS coil is difficult because of the coils location, try removing the wires from the spark plugs and measure secondary resistance through the plug wires rather than at the secondary terminals on the coils. Just remember to add in a maximum of 8,000 ohms of resistance per foot for the plug wires.

Here is a little trick that will literally show you if a DIS module and its crankshaft sensor circuit are working: connect a halogen headlamp to the spade terminals that mate the DIS module to the coils. A headlamp is recommended here because it puts more of a load on the module than a test lamp. If the headlamp flashes when the engine is cranked, the DIS module and crankshaft position sensor circuit are functioning. Therefore, the problem is in the coils.

If the headlamp does not flash, or there is no voltage to the module or coil pack when the engine is cranked, the problem is most likely in the crankshaft sensor circuit. On most vehicles, a bad crank position sensor will usually set a fault code, so use a scan tool to check for a code. Or, check the crank sensor itself.
 

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Discussion Starter #20 (Edited)
On start up the engine vibrates now it doesn't run as smooth. The idle in park won't go down until I give it a few good revs then it sits below a grand. When I drive a lot of petal gets me nowhere fast almost like something is holding my car back.. it almost feels there's pressure somewhere like its trying to push air through the system but its choking.... I just don't know how to describe it :( . My car ran smooth before with some hesitation, but now after the front two cats were hollowed out it runs like ass and I feel heat coming from underneath my car. After driving about 10-11 miles the temp was around 220 for a brand new 180 thermostat. It feels like it wants to stall while I'm driving. She also shakes a bit after 50 mph.... but I need to get it fixed before I go to work tomorrow night.

Keep in mind though the material inside the front two cats were kinda burnt and in some parts starting to melt. Either way I would have come to this particular problem sooner or later.

If it would be best to replace the middle cat with a Y pipe, or some other solution perhaps I'm more than willing to listen provided you are patient enough to deal with questions.

My scanner only gives me a P0155 code for O2 sensor.
 
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