Trouble codes: P0121, P0300, P1406

[LeSabre97mint]

Hello

I have a 97 Lesabre that I have gotten the trouble codes p0121, and p1406 twice. (P0300 was retreived the first time but not the second.) Any one out there have these codes come up? I've found that they go in a cycle. First my CEL comes on and the engine runs really rough, chugging and shaking. Next the engine starts to smooth out. After a few days of driving the light goes out and the car is running fine. This cycle has happened twice. I'm just waiting for it to happen again. When the light went out I cleared the codes. I haven't cleared the codes yet from the second time.

My thoughts are EGR related. Is it possible for something to get stuck in the ECR valve and cause it to stay open?

What about the TP code? P0121 -- TP sensor circuit, insufficient activity?


Thanks for your input.

Regards

Dan



P0121 -- TP sensor circuit, insufficient activity
P0300 -- Engine misfire detected
P1406 -- EGR valve pintle, position circuit

[maxwedge]

You need to a full scan on this and look for tps activity, smooth transition reading, preferably a graphing scanner. Could be the egr is carboned up, you could pull it off and clean up the pintle and shaft. These egrs do have a high failure rate though.

[LeSabre97mint]

Originally Posted by maxwedge

You need to a full scan on this and look for tps activity, smooth transition reading, preferably a graphing scanner. Could be the egr is carboned up, you could pull it off and clean up the pintle and shaft. These egrs do have a high failure rate though.

Max

Thank you for your reply! Do you think the trouble codes are related? What I'm trying to get at is, (and this is an if) the EGR gets stuck open, (and I'm thinking it is because of the rough running) will this affect the TP?

I don't have a graphing scanner, however, I do have a dig multi meter and will do a sweep on the TP.

Dan

[maxwedge]

TPS is a stand alone problem.

[happydog500]

I got a P0300 it was an "intermittent misfire." It turned out to be my spark plugs. I found out they where the same ones that came with the car brand new. 130,000 is not bad for plugs!!!!

Doesn't sound like plugs since you got two different codes more then I got. Just wanted to put in what happend to my P0300 code. Neve know if it could help. Chris.

[LeSabre97mint]

Originally Posted by happydog500

I got a P0300 it was an "intermittent misfire." It turned out to be my spark plugs. I found out they where the same ones that came with the car brand new. 130,000 is not bad for plugs!!!!

Doesn't sound like plugs since you got two different codes more then I got. Just wanted to put in what happend to my P0300 code. Neve know if it could help. Chris.

Chris

Thanks for the reply! The plugs have less then 10,000 miles on them. I only got the P0300 code once. (so far that is)

Regards

Dan

[maxwedge]

Clear it and see what happens. It is actually possible to set that code over very rough roads, long explanation on this.

[LeSabre97mint]

Originally Posted by maxwedge

Clear it and see what happens. It is actually possible to set that code over very rough roads, long explanation on this.

Max

I did clear the codes and got P0121, and p1406, but no P0300 this time around.

If you have the time I would like to know the reason why rough roads would cause codes to be set. You could PM me on this issue if you wish.

Thanks

Dan

[stuzman]

Originally Posted by LeSabre97mint

Max

I did clear the codes and got P0121, and p1406, but no P0300 this time around.

If you have the time I would like to know the reason why rough roads would cause codes to be set. You could PM me on this issue if you wish.

Thanks

Dan

Dan, most manufacturers use the crankshaft sensor to determine if a misfire has occured. The PCM knows through its programming that each cylinder should produce a certain amount of push on the power stroke. When running at some RPM, the PCM knows what the time should be between each cylinder firing under normal conditions. When a cylinder is not doing its job, the rotational velocity of the crankshaft slows down. Each cylinder's timing is stored in a separate accumulator in the CPU and compared with preprogrammed tables to see if a fault condition has occured. When value(s) are different, a MIL is set. The PCM uses the camshaft sensor to determine which cylinder is the culprit.

When the vehicle is traveling over an extremely rough road, the wheel(s) is off the ground for a short amount of time, causing the engine RPM to fluctuate somewhat. This is usually detected as a P0300 (intermittent misfire) since the rotational speed of the crankshaft can happen at any time when the tire(s) leave the ground. Of course, having a P0300 code doesn't necessarily mean excessive road conditions caused this. This is only one possibility for this code. The PCM is only saying that multiple misfires are occuring randomly with the cylinders. So, other factors which could affect all cylinders such as a lean or rich condition, bad wires, bad plugs, etc are possible. Also, transmission codes can be set when an intermittent misfire is detected because the transmission uses the RPM of the engine as one of its inputs to determine shift points.

Since an engine misfire really didn't happen under road conditons, some manufacturers are monitoring the firing voltage of each spark plug to determine if an engine misfire really did occur. For example, if there is a lean condition in some cylinder, this will raise the firing voltage and if the cylinder is rich, the firing voltage will be lower. The firing voltage can also be monitored for other conditions such as a bad wire, fouled spark plug, low compression, etc. All of these conditions can be monitored to set the MIL. In this way, road conditions will not set intermittent engine misfires.

As for your codes, I would suspect that you have two separate conditons. One is for your TPS and the other for the EGR system. I had posted a technique to check out the TPS with a DMM that may help you out. It's located here...

http://www.automotiveforums.com/vbul...7&goto=3548067

Hope this helps you out!

[LeSabre97mint]

Originally Posted by stuzman

Dan, most manufacturers use the crankshaft sensor to determine if a misfire has occured. The PCM knows through its programming that each cylinder should produce a certain amount of push on the power stroke. When running at some RPM, the PCM knows what the time should be between each cylinder firing under normal conditions. When a cylinder is not doing its job, the rotational velocity of the crankshaft slows down. Each cylinder's timing is stored in a separate accumulator in the CPU and compared with preprogrammed tables to see if a fault condition has occured. When value(s) are different, a MIL is set. The PCM uses the camshaft sensor to determine which cylinder is the culprit.

When the vehicle is traveling over an extremely rough road, the wheel(s) is off the ground for a short amount of time, causing the engine RPM to fluctuate somewhat. This is usually detected as a P0300 (intermittent misfire) since the rotational speed of the crankshaft can happen at any time when the tire(s) leave the ground. Of course, having a P0300 code doesn't necessarily mean excessive road conditions caused this. This is only one possibility for this code. The PCM is only saying that multiple misfires are occuring randomly with the cylinders. So, other factors which could affect all cylinders such as a lean or rich condition, bad wires, bad plugs, etc are possible. Also, transmission codes can be set when an intermittent misfire is detected because the transmission uses the RPM of the engine as one of its inputs to determine shift points.

Since an engine misfire really didn't happen under road conditons, some manufacturers are monitoring the firing voltage of each spark plug to determine if an engine misfire really did occur. For example, if there is a lean condition in some cylinder, this will raise the firing voltage and if the cylinder is rich, the firing voltage will be lower. The firing voltage can also be monitored for other conditions such as a bad wire, fouled spark plug, low compression, etc. All of these conditions can be monitored to set the MIL. In this way, road conditions will not set intermittent engine misfires.

As for your codes, I would suspect that you have two separate conditons. One is for your TPS and the other for the EGR system. I had posted a technique to check out the TPS with a DMM that may help you out. It's located here...

http://www.automotiveforums.com/vbul...7&goto=3548067

Hope this helps you out!

Yes the link was very helpful. Now....to get the time to lift the hood....

Regards

Dan

[maxwedge]

Originally Posted by stuzman

Dan, most manufacturers use the crankshaft sensor to determine if a misfire has occured. The PCM knows through its programming that each cylinder should produce a certain amount of push on the power stroke. When running at some RPM, the PCM knows what the time should be between each cylinder firing under normal conditions. When a cylinder is not doing its job, the rotational velocity of the crankshaft slows down. Each cylinder's timing is stored in a separate accumulator in the CPU and compared with preprogrammed tables to see if a fault condition has occured. When value(s) are different, a MIL is set. The PCM uses the camshaft sensor to determine which cylinder is the culprit.

When the vehicle is traveling over an extremely rough road, the wheel(s) is off the ground for a short amount of time, causing the engine RPM to fluctuate somewhat. This is usually detected as a P0300 (intermittent misfire) since the rotational speed of the crankshaft can happen at any time when the tire(s) leave the ground. Of course, having a P0300 code doesn't necessarily mean excessive road conditions caused this. This is only one possibility for this code. The PCM is only saying that multiple misfires are occuring randomly with the cylinders. So, other factors which could affect all cylinders such as a lean or rich condition, bad wires, bad plugs, etc are possible. Also, transmission codes can be set when an intermittent misfire is detected because the transmission uses the RPM of the engine as one of its inputs to determine shift points.

Since an engine misfire really didn't happen under road conditons, some manufacturers are monitoring the firing voltage of each spark plug to determine if an engine misfire really did occur. For example, if there is a lean condition in some cylinder, this will raise the firing voltage and if the cylinder is rich, the firing voltage will be lower. The firing voltage can also be monitored for other conditions such as a bad wire, fouled spark plug, low compression, etc. All of these conditions can be monitored to set the MIL. In this way, road conditions will not set intermittent engine misfires.

As for your codes, I would suspect that you have two separate conditons. One is for your TPS and the other for the EGR system. I had posted a technique to check out the TPS with a DMM that may help you out. It's located here...

http://www.automotiveforums.com/vbul...7&goto=3548067

Hope this helps you out!

Stuzman thanks a bunch with my beat up hands it would have taken me 2 hours to type that.

[stuzman]

Originally Posted by maxwedge

Stuzman thanks a bunch with my beat up hands it would have taken me 2 hours to type that.

No problem Max; it just took a few minutes time and I didn't mind at all.