02 Trailblazer rough idle and check engine light

[rainmaninwa]

This is a post to elaborate the things that I did to correct an extremely rough idle situation when cold. Please note that this is a 02 Trailblazer in PHOENIX, so don't overemphasize the "cold" part of this. It would be better to say a extremely rough idle when first started in the morning. Once the engine was fully "warmed up" the problem gradually diminisihed and went away. This all was accompained by a "CHECK ENGINE SOON" light.

We took the car into a local Autozone and had the codes read. They detected a P1345 "camshaft to crankshaft correlation fault", and a P0014, "Cam phasing error". Both of these indicated a potential problem with the cam and or crank sensor, or either one loose on its fitting, as well as a potentially blocked oil passage withing the camshaft actuator assembly.

We started out with the simple and immediate replacement of both the camshaft and crankshaft position sensors, (about $50) with no noticible change in the problems.

The only other thing that was readily available to replace was the camshaft position acutator selenoid. After dismounting the power steering pump, it was a simple thing to remove. Having read several of the other threads in this forum, I was preapred to replace the unit if upon removing the electrical connector, oil was apparent in the connetor socket of the selenoid. This proved to be the case and I set out to see if I could locate one of these on a Sunday afternoon. Upon arrving at the local Checker auto parts store, the counter man recognized the old unit I was carrying. He asked me if I was experiencing the "check engine soon" light. I told him that we were and what we had done. He said he was an ex Chev Technician, and that he had replaced "dozens" of the solenoids, however that they were not usually the problem. He said that the real problem is the exhaust cam actuator. He explained that these will become plugged with the slightest bit of sludge or even go funk with the use of the wrong weight of oil. He also said that this is a Chevrolet part and that Checker did not carry it.

We returned home and I decided that if I was going to have to obtain a new one anyway, I might as well try to repair the old one. I used a can of gumout spray carb/choke cleaner and went after the very fine screens in the grooves on the side of the barrel of the unit. These were plugged with sludge residue. The gumout did short work of removing all the guck. On the "engine end" of the selenoid unit was a round metal plate with a hex recess in it. Using an allen wrench to remove it, I was confronted with a small spring, and after working at it for a while, tapping it on the bench, etc, the piston cam out of the barrell as well. Spraying Gunk inside the barrell resulted in a torrent of oily sludge being removed. In addition, it gave me the opportunity to spray the same little screens on the barrell from the "inside out", getting them even cleaner. Gunk also took care of the grooves on the piston and removed all the varnish and sludge from the entire unit, including the electrical connector recess. I re-assembeled the whole thing using trans fluid as a assembly lube and re-installed the metal plate, carefully screwing it into the barrell of the selonoid assy. I then used the allen wrench to tighten down the plate to approximately the same position that it was in before it was removed. I did not stake the thing in, and this worries me a little, but I saw no evidence that the factory had staked it originally. I guess time will tell.

Anyway, after re-installation of the selenoid assembly, the engine fired right up and the idle problem was eliminated. This was about two weeks ago. About a week back the "check engine soon" light finally went out, and things have been working fine since.

So, if you have a problem that sounds somewhat similar, I'd recommend doing the selenoid thing first. You might be able to save yourself 50 bucks for cam and crank position sensors. You might also eliminate having Chevrolet charge you big bucks to replace the cam acuator. A BIG JOB on the front of the engine.

[maxwedge]

Welcome to AF, good article, now I ask why was this " gunked up" are we all going to expect this regardless of proper maintenance or was this engine not properly maintained?

[rainmaninwa]

This Trailblazer was purchased used by my daughter a year back, it has 140,000 miles on it and it did'nt appear to be taken care of too well. I have done an oil change with a crancase cleaner additive, as well as a trans fluid/filter change. It was pretty bad. So I guess I would say that if you don't keep the oil changed in your TB, this is something that you might expect to happen. Otherwise, who knows? I can say that cleaning out the acutator selenoid is a realatively easy deal and probably should be done every so often, just on principle. I also suppose that one might conclude that the use of the crankcase cleaner additive in the last oil change "cut loose" some of the gunk in the engine, and that was what had plugged up the selenoid.... A possibility....


Anyway, she's on the road now with no further problems.

[danielsatur]

We used breake cleaner to clean ABS wheel, cam, and crank sensors!

[maxwedge]

I might recommend the use of electrical parts cleaner on the sensors rather than brake clean, here.