Rough Idle + Poor gas mileage + Occasional CEL = ECT sensor?

[SinisterSHO]

Latley I've noticed my car has been idling pretty rough on start up. Its idling right around 900 where it usually does, but I've noticed my vacuum gauge is reading 10 vs 16 that it usually does. Also, I think my gas mileage has gone down slightly, but I haven't really measured it as of late. And lastly, I get an occasional check engine light. As far as I can tell its random, and I haven't had a chance to check the codes yet, and since its hard to tell if it is going to come on at all, I dont know when to check for it.

The only thing i've done to the car is replaced the radiator, which everything is hooked back up. Although, I did catch a wire when I was pulling it out, but this wire goes to my oxygen sensor and to my a/f gauge in the car. I'm not getting a constatnt CEL, so I dont belive the HEGO is unplugged, and the a/f gauge is still working.

I dont know how I could have suddenly gotten a vacuum leak, but to me that wouldnt' explain this either because it only idles rough and has low vacuum when I start it up. If its the ECT sensor, I'll just replace that when I put on my EH runners and BBBs

Thanks in advance

 

[Mr Anonymous]

Even if a CEL fired for only two seconds two weeks ago, as long as you've not lost battery power in the car there should be a stored code.

Start by reading the codes, it's always the best place to start and avoids chasing problems that aren't there or worse replacing things that aren't broken.

 

[SinisterSHO]

Ran codes today.

136 - Oxygen sensor not switching/system lean Left or Front HO2S

159 - Mass Air Flow (MAF) sensor is/was out of range

189 - Fuel system was lean at part throttle - Left or Front HO2S

211 - Ignition PIP signal was erratic or missing

511 - No power to PCM pin 1 or bad PCM (processor)

In my past experience, a bad oxygen sensor always triggered the CEL, but mine has been pretty random. Also, thinking I need to clean MAF.

But dont understand 211 or 511, any insight?

*EDIT* Searched for code 211 and came up with a bad crank sensor. However, I have not noticed any stalling problems.

 

[NotSoSlowSHO]

Id clean the MAF as you mentioned.

Too bad you dont have a Tweecer, you could watch those O2s, and see exactly what they are doing

 

[shoteen95]

I believe the CPS is responsible for the PIP signal (?)

Has it been changed recently. I don't know how those other issues (dirty MAF, old O2's) would affect the PIP signal.

EDIT, derr, you already came to the CPS conclusion anyways. I have gotten the same code for my car and not had any stalling problems either. It used to have a problem starting when warm..but it seemed to magically cure itself after i changed O2's and put in a new TPS.

 

[marvsho17]

Id clean the MAF as you mentioned.

Too bad you dont have a Tweecer, you could watch those O2s, and see exactly what they are doing

Oh, he does.

 

[SinisterSHO]

Oh, he does.

Indeed I do. But, I haven't really done much with it. The couple of times I had plugged it in, the car felt very sluggish. I'm not exactly sure what Ted has changed for the cams.

 

[rangerj]

Add to the above list of diagnostics a check for vacuum leaks, and check the snorkle tube to the throttle body for cracks and/or holes.