64k on odometer it seems like its in limp mode but no lights on dash have come on .ses light was on and I checked with scanner it had p300 multiple mis fire 5 had a high miss count cleared code. replaced coil and all plugs with ac 41-103 also went ahead and cleaned the throttle body still no go . Basically I accelerate and it won't go past 10 mph or rev past 1500 ses did start flashing after I cleaned the throttle body so just parked it . How do I check if cat is plugged ?
tb has no power when i accelerate
- Thread starter rojas84
- Start date
Drill a hole in the tubing above the cat, or pull the manifold O2 sensor and run an exhaust backpressure test. Many discussions and videos available with a Google search because all vehicles are susceptible to clogged cats.
Or you can brute force slice the cat out, then run it open pipe and see if the power comes back.
Did this happen all of a sudden?
Or you can brute force slice the cat out, then run it open pipe and see if the power comes back.
Did this happen all of a sudden?
Yes it did turned a corner and just wouldn't accelerate it was running fine prior to this minus the miss
rojas84 said:
Are you saying that the CEL is still flashing now? This means you still have a misfire. I would correct the misfire first before jumping into more expensive items.
If your power decreased dramatically all of the sudden then I would not suspect the Cat at all.
rojas84 said:
Ok, disconnect the battery for about 15 minutes, reconnect and drive until the CEL comes back on (hopefully not at all). Note the engine performance during this time.
Bill might correct me on this but I believe REP mode throws a code and CEL. You will then need to check for codes again. You could have multiple codes waiting to appear so repeat ad nauseam until fixed...
Unless the CEL comes on or flashes right away. Driving with a known misfire can get the cat red hot and that's behavior that can burn the vehicle to the ground. I'd avoid it.CaptainXL said:
It does, but the OP hasn't mentioned the REP light.
A good code reader will show a list of codes, active, pending, and historical. I don't know of a code reader that will only display one at a time but I'm sure there are some cheapies out there.
the roadie said:
Good point but I wouldn't be so paranoid about it. According to your theory then Bill his only recourse is to hook it up to a scan tool that can count live misfires. I have tried doing this with Torque but it is unpredictable. May need to get a professional diagnostic with a scan tool like a Snapon Verus or Tech2/MDI.
No rep light check engine light did come back on now so I need to go get the scanner again and check it will post later what comes up thanks
My profession involves fault tree analysis on things like human safety interlocks on lethal 2KV power supplies, and I have indeed been called too paranoid about vehicle issues.CaptainXL said:
But on another thread just today we have a guy who got suckered into buying a criminally designed lift spacer where his shock already broke and if he had gone over a speed bump and unweighted the strut it would have fallen out of the upper perch to his detriment. 
Or get it towed to a good diagnostic shop.
Agreed. Might not be a free or cheap DIY issue here.
rojas84 said:
Sorry, I saw you said in your original post that you have reduced engine power so I assumed you had a REP light.
Is the CEL now flashing or on steady?
Also, Bill corrected me on an important point. Don't drive the truck anywhere with the CEL flashing. It can kill the Cat. Although I wouldn't expect it to have a complete meltdown within just a few days time.
IllogicTC
Member
- Dec 30, 2013
- 3,452
CaptainXL said:
Yes, there is a reason the CEL tries getting your attention better through flashing. And the cat can plug up with unburnt fuel, and eventually an errant spark or something will light it off, and then suddenly it's not that the cat is clogged so much as the cat is, internally, non-existent. This particular case is easily diagnosed with checks of the upstream and downstream O2 sensors.
Speaking of which, have you examined any of the live data, or have you just been reading codes? Every bit of info helps.
rojas84 said:
I would demand you get your old cat back.
Also, i think i missed it but did you have any o2 codes such as a p0421?
It could have been the o2 sensor but I think they up sold you on a new cat.
Did you get multiple quotes from separate shops? I can see something like this costing a lot.
my TB did the same thing today. After a 25 mile drive no problems, I turned hard into a Starbucks lot and it stalled once. Then on restart the CEL flashed a few times...went off. The truck starting chugging some on the way home..7 or 8 miles of low power, felt like a missfire.
CEL flashed on and off.
- Do I go get the codes read? Or change the plugs and such straight away?
recent new belt, new fluids, no overheating or anything going on other than the above.
Thanks y'all
CEL flashed on and off.
- Do I go get the codes read? Or change the plugs and such straight away?
recent new belt, new fluids, no overheating or anything going on other than the above.
Thanks y'all
Hypnotoad
Member
- Dec 5, 2011
- 1,584
I'd pull codes before throwing parts at it, unless you're plugs need to be changed anyway. Driving with a flashing check engine light isn't a good idea. Pull the codes and report back or do a search for the specific codes. That'll give you a good starting point.
Code is P0303 3rd cylinder misfire. Bought a set of plugs, will try that first, Then a coil I guess if the plugs don't fix it.
I disconnect the battery to reset the codes?
Anything else needed? Thanks and HAPPY 4th of July to all.
I disconnect the battery to reset the codes?
Anything else needed? Thanks and HAPPY 4th of July to all.
Mt TB EXT has 257,004 miles now. At 256,500 miles it started losing power. Then, it would not allow the rpms to go above 3,000 and finally, I was unable to drive over 15 miles per hour. The only codes I had prior to this were 0014 and 1345 which I have been dealing with for over many miles. However, I changed the catalytic converter and the power is back again.
Hypnotoad
Member
- Dec 5, 2011
- 1,584
Before changing out the coil, you can try to switch #3 coil with another and see if the other cylinder misfires. Coils are expensive.
You can clear the codes with a code reader. I use to have them cleared by autozone until I got my own reader, but apparently they don't do that anymore. They just pull codes now.
You could also try running some fuel injector cleaner through you're fuel. I've had good luck with techron.
You can clear the codes with a code reader. I use to have them cleared by autozone until I got my own reader, but apparently they don't do that anymore. They just pull codes now.
You could also try running some fuel injector cleaner through you're fuel. I've had good luck with techron.
Hypnotoad
Member
- Dec 5, 2011
- 1,584
A lot of us here use the torque app, if you have an android phone. All you need is one of these to use it.
http://www.amazon.com/gp/aw/d/B0076KBPNI?cache=1310002caf3c06c3ca458e64bf477354π=SY200_QL40&qid=1404491279&sr=8-1#ref=mp_s_a_1_1
http://www.amazon.com/gp/aw/d/B0076KBPNI?cache=1310002caf3c06c3ca458e64bf477354π=SY200_QL40&qid=1404491279&sr=8-1#ref=mp_s_a_1_1
Good info thanks... I bought that code reader for Android.
I changed the plugs, they were Autolite and needed it. Man those back two were a bitch,,, super tight and tough to get to....I am short and my back was killing me from leaning over, and crawling up on the engine...
Still running crappy though. I will swap the coil and see if the code changes.
How do I know which is number 3? Is it the third from the front?
I changed the plugs, they were Autolite and needed it. Man those back two were a bitch,,, super tight and tough to get to....I am short and my back was killing me from leaning over, and crawling up on the engine...
Still running crappy though. I will swap the coil and see if the code changes.
How do I know which is number 3? Is it the third from the front?
If I need coils the prices are all over the map..Anyone try Diften? There are like 25 bucks a piece...Delco are real high.
KNBlazer
Member
- Feb 8, 2012
- 811
Check these out...Alansd said:
http://www.ebay.com/itm/ACDelco-GM-Original-Equipment-12568062-Ignition-Control-Module-Set-6-/171178220678
I swapped # 3 to # 2..Still missfiring- got the code read and it said multiple mis-fires. Not a specific cylinder like last time. I was hoping the thing would read cyl #2.
I'm not sure whether to go ahead and get the coil or coils at this point. Seems like it makes sense, but not sure from what I see.
Time to take it to a pro?
I'm not sure whether to go ahead and get the coil or coils at this point. Seems like it makes sense, but not sure from what I see.
Time to take it to a pro?
gmcman
Member
- Dec 12, 2011
- 4,656
What he said.Hypnotoad said:
Unless you clear the codes they will continue to pop up. 99% of the time if you have random misfires you either have bad coils or severely worn plugs.
One bad coil and you will get the corresponding code for that coil.
Does it idle smooth, drive smooth? With one coil out if will cough and be very noticeable when driving.
shoot I forgot to clear the codes. I am taking it to Advance auto for the code read. Shouldn't they clear them, then re-read, or do they clear them and then I drive it awhile. then check it again?
Yes it runs rough, and the CEL flashes and then stays on.
Yes it runs rough, and the CEL flashes and then stays on.
gmcman
Member
- Dec 12, 2011
- 4,656
They will likely not clear the codes but a flashing CEL requires attention ASAP. I suspect more than one faulty coil.
With the engine idling pull one coil lead at a time, if no change then that's the bad coil, you will notice right away if 2 coils are out. My buddy has used the coil packs from Advanced for about $40 with no issues.
Did you by chance spray the engine down with the coil leads disconnected allowing water in the connectors?
With the engine idling pull one coil lead at a time, if no change then that's the bad coil, you will notice right away if 2 coils are out. My buddy has used the coil packs from Advanced for about $40 with no issues.
Did you by chance spray the engine down with the coil leads disconnected allowing water in the connectors?
no water. I cleaned the throttle body with some carb spray after the chugging started. It didn't do anything.
I also replaced the spark plugs with new Delcos.
I will disconnect the negative battery lead for a bit and see if the code resets.
I also replaced the spark plugs with new Delcos.
I will disconnect the negative battery lead for a bit and see if the code resets.
gmcman
Member
- Dec 12, 2011
- 4,656
Alansd said:
Keep in mind if the engine is still running rough then you may likely have a bad coil Don't run the motor like this for any extended length of time to avoid damaging the cat.
Check for a bad coil, removing the lead while running should show the bad coils face.
If you clear the codes and one comes back with a P030X, the "X" will depict the cyl number.
Mounce
Member
What's the deal with the parts stores not clearing codes? They did it for me, that was about a month ago though. Would that just apply to states that have emission checks?
the second time I went they cleared the code. It did not come back on right away. but after awhile it came up multiple mis-fires. I dropped it off at the shop I use, to see what they say.
I am betting on replacing all the coils, as they have probably got a lot of years on them.
I am betting on replacing all the coils, as they have probably got a lot of years on them.