replaced cats - now new code

[Bowed]

2001 silverado 1500 - 4.3 v6 - 4l60 - 155k miles .


I was getting several codes that pointed to bad cats . I replaced the assembly with a factory complete Fischer cat assembly rated to be OE manfacturer quality . I cleared the codes and then drove the truck for a day (25 miles ) without any problems . The next time the truck went out it set code P0300 . What are the chances the cats are not doing the job , or is P0300 usually something else ? Honestly at this point I am clueless to what is going on with this truck . Thanks for any input .

[Boog]

PO300 is a random misfire code. Doesn't tell you which cylinder is the culprit but that there have been misfires. Can come from numerous sources.
http://www.obd-codes.com/p0300

[bwood]

You may need to try and look at the cylinder misfire counts and see which cyclinders are misfiring. This may be the reason for the cat failure.

[Bowed]

Thanks for the reply .


Well I cleared the codes again and drove the truck 7 miles with no service engine light coming on . Stopped for coffee and when I came out the fuel pump was dead as a door nail . Had to get towed and then pay big $$$ for the new fuel pump assembly . I figured that must be the P0300 source and It was finally fixed , so ok , that's that . I drove the truck another 5 miles and still no service light even with the fuel pump failure ( ?? bit strange the failure didn"t trigger it ?? ) . Later in the day I took the truck out and the light comes on , Geeeeeeeee . Well I will see what I can find . Thanks .

[MILLER TIME]

Fuel pumps suck bc they cost too much for these...
Posted via Mobile Device

[bwood]

Originally Posted by Bowed

I drove the truck another 5 miles and still no service light even with the fuel pump failure ( ?? bit strange the failure didn"t trigger it ?? ) .

The fuel pump failure will not set a code. I believe that is the fuel pump relay fails, it will set a code, but not if the pump itself fails.

[Bowed]

Up until yesterday it was only giving a P0300 code and nothing else . Now it is giving P0300 and P1345 so I have an area to work in .

P01345 is

(1) distributor slightly off
(2) cam or crank sensor signal off
(3) signal alignment between dist and cam /crk sensors not matching
(4) timing chain loose

So it appears to be slightly out of time . Is the distributor the most likely on that list ?

[bwood]

Under the rotor in the distributor is a camshaft position sensor. Have your intake gasket been replaced lately, this is usually when this code is set. Check to see if the distributor moves at all (does it rotate in the intake?), it shouldn't. See if there is excessive play at the rotor, a worn distributor gear can cause issues and is not unheard of, especially in a roller equipped engine.

[Bowed]

Originally Posted by bwood

Under the rotor in the distributor is a camshaft position sensor. Have your intake gasket been replaced lately, this is usually when this code is set. Check to see if the distributor moves at all (does it rotate in the intake?), it shouldn't. See if there is excessive play at the rotor, a worn distributor gear can cause issues and is not unheard of, especially in a roller equipped engine.

I have only had the truck 2 months , so I don't know the recent repair history . I checked the distributor and it had about 3/16 of total horizontal play , which I believe is probably ok . cap and rotor check out and no dist fouling . I also put a set of new 41-993 Iridium pluugs in , but Still getting P0300 and sometimes P1345 . If I clear the codes it might go 10 or so miles before tripping the mil .

I purchased a CP9180 Actron scanner . I am still trying to understand the data it is giving but see a couple of things that do not seem right .

At 750 rpm it has 15 to 20 advance
At 1200 + rpm the advance is 35.0

At 750 rpm the map gr/se is 5.15
At 1500 rpm map gr/se is 10.28

the fuel trims jump around rapidly to high numbers


The truck has been running fine thru all of this until this morming . When I started it up today , it was shaking and skipping pretty bad and threw a P0301 for # 1 cyl misfire . I ran it at idle for less than 5 min while I put the scanner on it and the cats suddenly got so hot they were smoking big time , and you could smell them . These are brand new cats and I hope I didn't cook them .

At this point I figure the spider is the cause of the P0301 , but feel that is not the only problem going on here . Could sure use some more input . Thanks to all .

[truckdude239]

If your cats are getting hot and smokeing its not the spider unless its dumping to much fuel your cats are geting hot because of unburnt fuel

[Bowed]

Originally Posted by truckdude239

If your cats are getting hot and smokeing its not the spider unless its dumping to much fuel your cats are geting hot because of unburnt fuel

Yes , I believe that is what is happening .



Edit to my last post - Those last figures I gave were MAF readings - not MAP readings .

[Bowed]

Well I got the truck running good again , but still can't shake the P0300 code


Trouble code p0300 readings from the scan tool data review .


ABSLT TPS % 7.4
ENGINE SPEED RPM 1366
CALC LOAD % 10.9
MAF FLOWGR/SE 17.79
MAP KPA 51
COOLANT oF 203
ST FTRM1 % -4.6
LT FTRM1 % 3.1
ST FTRM2 % -2.2
LT FTRM2 % 2.3
ST FTRM3 % -12.1
LT FTRM3 % -54.6
LT FTRM4 % -24.3
ST FTRM4 % -57.5
VEC SPEED MPH 42
FUEL SYSTEM 1 CLOSED
FUEL SYSTEM 2 CLOSED

So Far
New cat assembly ( old one burnt inside )
New fuel pump and filter ( fuel pump completly died )
Fuel pressure now 58 lb
New delco irridum plugs
New wires
New delco dist cap and rotor
New canister purge selonid ( old one defective )
Cleaned and checked egr
cleaned throttle body and Iac
Removed upper intake and pressure tested spider and regulator ( no leaks )
Dist seems to check out ok
Vacuum is steady at 16 1/2
cleaned and reattached all grounds I could find
cleaned maf and map
seafoam treatment to fuel
no apparent vacuum leaks
no apparent air leaks between maf sensor and throttle body
It looks like the lower intake gasket has been replaced

Spent way too much time on this truck already . At this point I don't want the truck anymore and will be selling it . I paid too much money for the truck and I am way in the hole dollar wise . It's not worth while to send it out for some big repair bill to go further in the hole . Truck is runing very well now , but sometimes there is a very slight roughness at idle and this is hardly noticable . It has good power and fuel economy and you would not think anything was wrong , except for the check engine light . Sometimes the check engine light will flash , but will stop with deceleration to a slow speed . Thanks again .