derrickgott007

Ok here is my dilema...

I want to seafoam my car, it has 122,000 miles on it, and it's stuck in a loop because of a bad CPS (Crank Sensor) and a miss. Should I remove my Cat's before I do this? I read a horror story of a guy who did this and his cat's plugged. My dad has run codes on my car and it comes back with right cat restriction.

So should I pull the cat's due to excessive soot and carbon build up due to Fixed loop problem to avoid plugging them? I'm going to change plugs and wires AFTER seafoaming the engine. My dad seems to think I should pull the exhaust first.

Have any of ya'll experianced this?

Z28LT1_Just_Nasty

The thing with sea foam is, if your converter gets clogged; it was on its way out anyway. If it's already clogged right now, you need to replace it anyway so just take it off, sea foam it and put on the new one after. Sea foam can also take out an oxygen sensor. But again if an o2 sensor goes after you sea foam the engine, it was already on its way out anyway. I've done it to many different cars, with and without cats. I personally never had an issue with it. They were all higher mileage cars as well.

irocbsa

Here's a crazy idea, fix the miss and the CPS before you do anything else.

Injuneer

What is "fixed loop"? You've posted this before, and I asked what you meant, but you never responded. Do you mean "open loop"? If so, why do you feel that Seafoam would cause a problem with the cats that running in "closed loop" would not?

You also mention its in "fixed loop" because of a problem with the CKP sensor. Have you verified that happens when you have the CKP code? The CKP sensor is there to detect misfires.

The_Bishop

What is the big deal with Seafoam, anyhow? Seems like a good way to hurt things.

derrickgott007

I meant Open loop....Whatever it is when it runs full rich. Yeah I get the full rich because the CPS or CPK (the one at the bottom of the front of the engine) is not reading. That is why its not showing the misfire. So in turn its running full rich. The way we found the miss was to shut fuel injectors off one by one with the OBD2 scan tool. Then the arching soon was audible within a few days due to driving it and the wire moving...And my dads hand in there moving stuff around.

Now I just discovered that I need rear brake pads...Oh the joys of buying a used car!

I plan on putting new plug wires and new plugs in very soon, i just need to find a saturday where I don't have anything going on and put the car up on the lift Friday night so it's nice and cold saturday morning.

irocbsa

The car doesn't have a mode where it runs "full rich". Open loop provides a richer mixture during cold starts, but its not "full rich". If you're rich and have an appropriately calibrated ECM, there is a hardware issue. Let me mention this one more time: you need to fix the sensor issues. If the crank sensor is not reading a position, it has a problem. When it comes to outputting a crank position to the ECM, the crank sensor could give two ****s if the engine is sparking or not. After that happends, put simply, it will detect a misfire based on the irregularities that it senses from a cylinder that has the misfire. If you're getting a crank sensor DTC, you need to determine why that's happening. If it was a misfire that was not being reported by the crank sensor you would get a different misfire DTC and NOT a crank sensor code.

So, here's the possibilities as I see it.

1. You have a faulted crank sensor that is either completely failed or feeding erroneous information to the ECM and reporting false misfire. Crank sensor is entirely to blame.
2. Same as above, but faulted crank sensor wiring.
3. You have a bad crank sensor and a real misfire that the crank sensor is unable to detect because its broken.

So, once again, investigate and get rid of the crank sensor code before you go any further. Then, move to plugs and wires.

Stoopalini

What year is your car?

IIRC, the crank position sensor is only used to detect misfires, and will not cause a problem if it is not working properly; except the OBDII system will not be able to detect if a misfire is occuring. Similar thing with the rear O2s, they are only used to detect if a cat is not working properly.

Sounds like you have multiple problems happening with your car, and I wouldn't pour seafoam into the intake until you get the issues worked out 1st.

If you want sound advice from the forum members, I recommend you scan the codes again, and post the #s for us to see.

Also, how do you know the car is running rich?

Thomas.

irocbsa

Edited my post to clarify. What I meant to say is that the crank sensor could be reporting false misfire, not make the misfire worse. Sorry for any confusion.

Diagnosis advice still applies.

Injuneer

Your assumption that "open loop" means its running "full rich" is incorrect. In open loop, once the engine warms up, it runs exactly that way it does in closed loop, with a 14.7:1 (stoichiometric) target A/F ratio. The only difference is that it can't make adjustments to the long term fuel corrections, since the PCM is not using the O2 sensor freedback. Running the engine "full rich" when the CKP sensor fails would be completely illogical, since the function of the CKP sensor is to detect misfires, and warn you that if you don't correct those misfires, its going to run rich and destroy the catalytic converter(s).

Let's start with the basics - what code are you getting for the CKP sensor?

I wouldn't start pouring Seafoam into the engine until I knew what was wrong with it. Stuff has been known to cause more damage that it cures in many instances.

Guest47904

WRONG

IF you have a bad CKP, it will NOT put the PCM into open loop. There's your first incorrect assumption.

Second, how do you know it's in open loop???? Just because it's running rich??

Don't you think the misfire has something to do with it running rich?????