ToTo

arnie alt · 10-28-2009, 06:31 PM

"ToTo" is a 99 Silverado 4.8 and 225k on the clock. I just bought it in Kas a few weeks ago. My only problem is it stumbles when starting out. More so when cold. Once it gets past first gear it just goes like "H" I put in new plugs (good ones), Used the latest GM top engine cleaner and injector cleaner as told by dealer. Took to dealer and he got three codes...PO420-PO430 (both cats) and PO155 which is the upstream O2 sensor heater. They felt that the cats may be partially pluged due to high mileage. That must have happened in the past because both cats have been cut out and replaced with ordinary pipe. The upstream O2 sensors are in place but I haven't been able to find the downstream sensors. They also gave the fuel pump a clean bill of health. When I checked the FPR for leaks, I forgot to plug it back in and the truck ran the same. I hooked a vacum gauge to the preasure regulator port and got good vacum. I also went all around the top of the engine with starting fluid and there doesn't seem to be any leaks. I took the fuel filter off and checked. No restriction. Any good ideas? Thanx...arnie

BernieB · 10-28-2009, 07:40 PM

You said "good ones" when you mentioned the plugs, but didn't say what ones. What are they?

gmctrucks · 10-29-2009, 02:44 AM

Quote:

Originally Posted by BernieB

You said "good ones" when you mentioned the plugs, but didn't say what ones. What are they?

Please don't say Bosch GM doesn't like them plugs.

arnie alt · 10-29-2009, 04:31 AM

Champ platinum...I have Bosch plugs in one of my other GM truck. It plows snow among other hard work and no troubles with plugs. The scan at the dealer didn't show misfires.

ChevyMan65 · 10-29-2009, 06:08 PM

Once again, your engine does not know what brand of plugs it has in it. For as many years as i can recall i have used Bosch Platinum Plus plugs in my Chevys with no problems what so ever. I have been reading for years how most of the posters on this forum claim that GM vehicles dont like Bosch plugs, the engine doesnt know what brand they are! Now something to consider, i live in California, we do have a different gasoline formula than most of the country, could this maybe why ive had no problems, when others have. I think Crabtruck lives in Ca. What is your experience, Crab? I would love to have input from you all, from all over north america, didnt forget our canadian friends. Just my 2 cents, Thanks CM65

Crmzendrgone · 10-29-2009, 06:19 PM

If I am not mistaken I think the computers can tell if you have a cat or not by the o2 coming out. could be why you have that code. I know some newer models can tell. A friend pulled his cat off his JEEP(2005) and ran just off the manifold and it through a code. Put it back on and was all good.
I am not big on the brand wars but Champions (From what I have seen) do best in Mopars, AcDelco are good in Gm and autolites are good in fords. I have used Bosche in my pontiac 305 +and I was pleased but didn't run with it to long before it overheated and wasn't the same, then decided to pull it apart but that didn't go far. Life got in my way.

arnie alt · 10-29-2009, 06:35 PM

Update. I got under the truck this AM with a lite and found that all the O2 sensors are in place. Just no cat between them. Tomorrow I hook the fuel preasure gauge up, tape it to the windshield, and go for a ride. I'll see if it holds proper preasure under load. I will also do a volume test. This seems to be an air fuel ratio problem. An engine requires a lot of fuel when cold and starting to accelerate. This is when ToTo falls down. I gave thought to a bad coolant sensor. But I haven't talked myself into that yet. I still lean toward a bad preasure regulator. It doesn't leak, but may not be keeping preasure up under load. I'm not concerned about the check engine lite. Witout cats it will be on. Any one have another idea I haven't thought of....Arnie

bradrhale · 10-30-2009, 11:50 AM

Quote:

Originally Posted by ChevyMan65

Once again, your engine does not know what brand of plugs it has in it.

i beg to differ. shove some autolites in there and see if that chevy engine runs the same.

ChevyMan65 · 10-30-2009, 12:41 PM

If it runs the same or not , the engine does not know what plugs are in it .Im not trying to sound like a know it all because im not, i was hoping to get feedback from every one relating to my response from yesterday about fuel formulas and diff brands of plugs.CM65

BernieB · 10-30-2009, 01:47 PM

There's a difference between knowing what brand of plugs are in it and running well because the plugs aren't well matched to the engine. You're 100% right when you say an engine doesn't "know" what plugs are in it, but if that were the only criteria for the plugs functioning properly then you could just stick in any plug that fits the hole and it would work, and all plugs would be the same design because there'd be no demand for different designs. Obviously that's not true, so the design of the plug is a factor in how well they work in an engine. The experience of most of the forum members has been that Bosch plugs do not work as well in GM's as do Autolite and other brands.

10-28-2009, 06:31 PM	#1
arnie alt Full Member Join Date: Oct 2009 Posts: 10	ToTo "ToTo" is a 99 Silverado 4.8 and 225k on the clock. I just bought it in Kas a few weeks ago. My only problem is it stumbles when starting out. More so when cold. Once it gets past first gear it just goes like "H" I put in new plugs (good ones), Used the latest GM top engine cleaner and injector cleaner as told by dealer. Took to dealer and he got three codes...PO420-PO430 (both cats) and PO155 which is the upstream O2 sensor heater. They felt that the cats may be partially pluged due to high mileage. That must have happened in the past because both cats have been cut out and replaced with ordinary pipe. The upstream O2 sensors are in place but I haven't been able to find the downstream sensors. They also gave the fuel pump a clean bill of health. When I checked the FPR for leaks, I forgot to plug it back in and the truck ran the same. I hooked a vacum gauge to the preasure regulator port and got good vacum. I also went all around the top of the engine with starting fluid and there doesn't seem to be any leaks. I took the fuel filter off and checked. No restriction. Any good ideas? Thanx...arnie

10-28-2009, 07:40 PM	#2
BernieB Senior Member Join Date: Jul 2009 Location: Fredericksburg, VA Posts: 1,906	You said "good ones" when you mentioned the plugs, but didn't say what ones. What are they? __________________ If the guys who design 'em had to take one home, use it every day for 2 years, and do all the maint and repairs themselves, cars would have a button on the dash to change the oil, filters & plugs.

10-29-2009, 04:31 AM	#4
arnie alt Full Member Join Date: Oct 2009 Posts: 10	Champ platinum...I have Bosch plugs in one of my other GM truck. It plows snow among other hard work and no troubles with plugs. The scan at the dealer didn't show misfires. Last edited by arnie alt; 10-29-2009 at 04:33 AM. Reason: additional info

10-29-2009, 06:19 PM	#6
Crmzendrgone Senior Member Join Date: Apr 2009 Location: Arizona Posts: 1,420	If I am not mistaken I think the computers can tell if you have a cat or not by the o2 coming out. could be why you have that code. I know some newer models can tell. A friend pulled his cat off his JEEP(2005) and ran just off the manifold and it through a code. Put it back on and was all good. I am not big on the brand wars but Champions (From what I have seen) do best in Mopars, AcDelco are good in Gm and autolites are good in fords. I have used Bosche in my pontiac 305 +and I was pleased but didn't run with it to long before it overheated and wasn't the same, then decided to pull it apart but that didn't go far. Life got in my way. __________________ ENGINES PRODUCE POWER. MOTORS RECEIVE POWER. https://lastroundbestround.com/Home_Page.html

10-29-2009, 06:35 PM	#7
arnie alt Full Member Join Date: Oct 2009 Posts: 10	ToTo Update. I got under the truck this AM with a lite and found that all the O2 sensors are in place. Just no cat between them. Tomorrow I hook the fuel preasure gauge up, tape it to the windshield, and go for a ride. I'll see if it holds proper preasure under load. I will also do a volume test. This seems to be an air fuel ratio problem. An engine requires a lot of fuel when cold and starting to accelerate. This is when ToTo falls down. I gave thought to a bad coolant sensor. But I haven't talked myself into that yet. I still lean toward a bad preasure regulator. It doesn't leak, but may not be keeping preasure up under load. I'm not concerned about the check engine lite. Witout cats it will be on. Any one have another idea I haven't thought of....Arnie

10-29-2009, 06:08 PM	#5
ChevyMan65 Senior Member Join Date: Aug 2009 Location: Northern California Posts: 64	Once again, your engine does not know what brand of plugs it has in it. For as many years as i can recall i have used Bosch Platinum Plus plugs in my Chevys with no problems what so ever. I have been reading for years how most of the posters on this forum claim that GM vehicles dont like Bosch plugs, the engine doesnt know what brand they are! Now something to consider, i live in California, we do have a different gasoline formula than most of the country, could this maybe why ive had no problems, when others have. I think Crabtruck lives in Ca. What is your experience, Crab? I would love to have input from you all, from all over north america, didnt forget our canadian friends. Just my 2 cents, Thanks CM65

10-30-2009, 12:41 PM	#9
ChevyMan65 Senior Member Join Date: Aug 2009 Location: Northern California Posts: 64	If it runs the same or not , the engine does not know what plugs are in it .Im not trying to sound like a know it all because im not, i was hoping to get feedback from every one relating to my response from yesterday about fuel formulas and diff brands of plugs.CM65

10-30-2009, 01:47 PM	#10
BernieB Senior Member Join Date: Jul 2009 Location: Fredericksburg, VA Posts: 1,906	There's a difference between knowing what brand of plugs are in it and running well because the plugs aren't well matched to the engine. You're 100% right when you say an engine doesn't "know" what plugs are in it, but if that were the only criteria for the plugs functioning properly then you could just stick in any plug that fits the hole and it would work, and all plugs would be the same design because there'd be no demand for different designs. Obviously that's not true, so the design of the plug is a factor in how well they work in an engine. The experience of most of the forum members has been that Bosch plugs do not work as well in GM's as do Autolite and other brands. __________________ If the guys who design 'em had to take one home, use it every day for 2 years, and do all the maint and repairs themselves, cars would have a button on the dash to change the oil, filters & plugs.

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