1998 gmc 1500 4 x4

gravyk · 12-26-2007, 04:42 PM

Took truck in for what I thought was tranny problems and they called and said it needs catalatic converters. 400.00 on converters was cheaper then a tranny. Well I picked it up and all the sams problems. When you are driving and you punch on the gas your rpms do not go up and the truck does not move any faster. If yo have a light foot everything seems to be fine. Today going 65 I put it to the floor for awhile and the rpms stayed the same and I did not go any faster and I could here a backfire. Codes are po404 and po141. Can anyone help. 1998 gmc 4x4 1500 167,000 miles

75K30 · 12-26-2007, 04:59 PM

Welvcome to the site;

P0404 - Exhaust Gas Recirculation
P0141 - Bad Heater Circuit O2 related.

None of these really have nothing to do with the Cat system, but consider yourself lucky now that you have new ones.
Have the O2 sensors been changed? I have seen plenty of aftermarket sensors not go into "closed loop" mode at the proper time, and stay in "open loop" mode for long periods of time. The ECM sees this as a problem and will issue a code. This could be related to the EGR problem, but you should also see if the EGR is clean, and operational. The faulty EGR could be the problem with the low power.
I did not read that the vehicle downshifts, which would indicate other issues, but your codes would indicate the above problems.

gravyk · 12-26-2007, 08:41 PM

I put on a new egr valve today and drove it everthing was the same put 20 miles on it. So I put the old one back on. The 02 sensors have never been changed. Would a bad o2 sensor cause any of the excelleration problems. What Item would you replace next. Also you are telling me the codes have nothing to due with catalatic converters so then why would a machanic replace them!!! I am kind of stuck do not want to go back the the man that replaced the converters as I am consernd what he will want to replace next.

75K30 · 12-27-2007, 03:32 AM

Ok, you changed the 02 sensor(s), with no change. Did you replace all of them, and did they get replaced with OEM replacements? I ask because, most replacements are from Bosch, and,,,,,for lack of a better term,,,,are junk. Have had several brand new ones complicate an already aggrivating situation.
Can't say these are the exact problems, but the symptoms could still be present if a new aftermarket sensor does not heat up within the span allowed from the factory. The stock ECM uses a given time for these to reach "closed loop" and if one takes it's sweet time, it will trigger a code. Could still operate properly, but will trigger a code if it is slow to heat.
The EGR is more likely to cause the acceleration problem, and if you installed a new one, why not leave it?
A new functional one does not mean it is working correctly. Is it leaking? and does it function properly? A new one with a bad signal, or leak will function just like the old one, giving you a false indication.
Not a real fan of replacing parts with the hope that I am lucky enough to get it right, but also try to use tha diagnostic tools to help me narrow down some components. Usually the codes are fairly close to being correct. At least they get us close with related items.
Real time diagnostics can be run while the vehicle is in use. Instead of trying to read problems, maybe you can find someone to run a "trend" that can show activities while the truck is in use. Very handy diagnostic. Will let you know if it is a hardware or software problem.

gravyk · 12-27-2007, 06:59 AM

I have not replaced any oxygen sensors.....The egr valve is 150.00 is why I took it back off when it did not make a difference. I am just trying to help my self so I do not get took by the mechanic again . He already got 400.00 out of me for converters that did not help the problem at all. Are you telling me that the computer needed to be reset after I install the egr valve to work correctly? What would be your next step. It is telling me o2 sensor 2 bank one witch one would that be and would it cause the excelaration problem any help would be appricated.

nnunez · 12-27-2007, 07:17 AM

FYI - Mine ran bad until I replaced the EGR Solenoid. I tried everything from replacing the EGR and Transducer but nothing worked....

gravyk · 12-27-2007, 02:37 PM

Were is the egr solenoid and what did it cost.

nnunez · 12-28-2007, 10:21 AM

The solenoid is between the EGR and intake. It is a small electrical piece tha shares the vacuum hose......its sometimes called (i believe) Canister Purge Solenoid.
I will see if i can scan or take a pic for you.
I think they cost about $150.....

gravyk · 12-28-2007, 01:40 PM

150.00 is that for oem. Aftermarket was 22.99

gravyk · 01-08-2008, 07:04 PM

Thank all you for your help. I had a chance today to work on it again. I bought spark plugs fuel filter and wires. I put the new fuel fiter on and got a call so I took it to town and guess what the problem with exceleration is now gone. 12.00 filter took care of everything!! Wander what the machanic would have stuck to me if I would have taken it back to him. Conveters were never the problem. How is it possible to make such a big mistake like this coming from a good machanic.

12-26-2007, 04:42 PM	#1
gravyk Junior Member Join Date: Dec 2007 Posts: 7	1998 gmc 1500 4 x4 Took truck in for what I thought was tranny problems and they called and said it needs catalatic converters. 400.00 on converters was cheaper then a tranny. Well I picked it up and all the sams problems. When you are driving and you punch on the gas your rpms do not go up and the truck does not move any faster. If yo have a light foot everything seems to be fine. Today going 65 I put it to the floor for awhile and the rpms stayed the same and I did not go any faster and I could here a backfire. Codes are po404 and po141. Can anyone help. 1998 gmc 4x4 1500 167,000 miles

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12-26-2007, 04:59 PM	#2
75K30 Senior Member Join Date: Jul 2006 Posts: 2,518	Welvcome to the site; P0404 - Exhaust Gas Recirculation P0141 - Bad Heater Circuit O2 related. None of these really have nothing to do with the Cat system, but consider yourself lucky now that you have new ones. Have the O2 sensors been changed? I have seen plenty of aftermarket sensors not go into "closed loop" mode at the proper time, and stay in "open loop" mode for long periods of time. The ECM sees this as a problem and will issue a code. This could be related to the EGR problem, but you should also see if the EGR is clean, and operational. The faulty EGR could be the problem with the low power. I did not read that the vehicle downshifts, which would indicate other issues, but your codes would indicate the above problems.

12-26-2007, 08:41 PM	#3
gravyk Junior Member Join Date: Dec 2007 Posts: 7	I put on a new egr valve today and drove it everthing was the same put 20 miles on it. So I put the old one back on. The 02 sensors have never been changed. Would a bad o2 sensor cause any of the excelleration problems. What Item would you replace next. Also you are telling me the codes have nothing to due with catalatic converters so then why would a machanic replace them!!! I am kind of stuck do not want to go back the the man that replaced the converters as I am consernd what he will want to replace next.

12-27-2007, 03:32 AM	#4
75K30 Senior Member Join Date: Jul 2006 Posts: 2,518	Ok, you changed the 02 sensor(s), with no change. Did you replace all of them, and did they get replaced with OEM replacements? I ask because, most replacements are from Bosch, and,,,,,for lack of a better term,,,,are junk. Have had several brand new ones complicate an already aggrivating situation. Can't say these are the exact problems, but the symptoms could still be present if a new aftermarket sensor does not heat up within the span allowed from the factory. The stock ECM uses a given time for these to reach "closed loop" and if one takes it's sweet time, it will trigger a code. Could still operate properly, but will trigger a code if it is slow to heat. The EGR is more likely to cause the acceleration problem, and if you installed a new one, why not leave it? A new functional one does not mean it is working correctly. Is it leaking? and does it function properly? A new one with a bad signal, or leak will function just like the old one, giving you a false indication. Not a real fan of replacing parts with the hope that I am lucky enough to get it right, but also try to use tha diagnostic tools to help me narrow down some components. Usually the codes are fairly close to being correct. At least they get us close with related items. Real time diagnostics can be run while the vehicle is in use. Instead of trying to read problems, maybe you can find someone to run a "trend" that can show activities while the truck is in use. Very handy diagnostic. Will let you know if it is a hardware or software problem.

12-27-2007, 06:59 AM	#5
gravyk Junior Member Join Date: Dec 2007 Posts: 7	I have not replaced any oxygen sensors.....The egr valve is 150.00 is why I took it back off when it did not make a difference. I am just trying to help my self so I do not get took by the mechanic again . He already got 400.00 out of me for converters that did not help the problem at all. Are you telling me that the computer needed to be reset after I install the egr valve to work correctly? What would be your next step. It is telling me o2 sensor 2 bank one witch one would that be and would it cause the excelaration problem any help would be appricated.

12-27-2007, 07:17 AM	#6
nnunez Senior Member Join Date: Dec 2005 Posts: 307	FYI - Mine ran bad until I replaced the EGR Solenoid. I tried everything from replacing the EGR and Transducer but nothing worked....

12-27-2007, 02:37 PM	#7
gravyk Junior Member Join Date: Dec 2007 Posts: 7	Were is the egr solenoid and what did it cost.

12-28-2007, 10:21 AM	#8
nnunez Senior Member Join Date: Dec 2005 Posts: 307	The solenoid is between the EGR and intake. It is a small electrical piece tha shares the vacuum hose......its sometimes called (i believe) Canister Purge Solenoid. I will see if i can scan or take a pic for you. I think they cost about $150.....

12-28-2007, 01:40 PM	#9
gravyk Junior Member Join Date: Dec 2007 Posts: 7	150.00 is that for oem. Aftermarket was 22.99

01-08-2008, 07:04 PM	#10
gravyk Junior Member Join Date: Dec 2007 Posts: 7	Thank all you for your help. I had a chance today to work on it again. I bought spark plugs fuel filter and wires. I put the new fuel fiter on and got a call so I took it to town and guess what the problem with exceleration is now gone. 12.00 filter took care of everything!! Wander what the machanic would have stuck to me if I would have taken it back to him. Conveters were never the problem. How is it possible to make such a big mistake like this coming from a good machanic.