98runner210

yeah there was no charge. Looks like it is time to get rid of this thing.

MTL_4runner

That seems rather drastic doesn't it!?

Have you had an independent shop do a compression test for you?

If your values come back without any indication of any issue (ie all the values are within 5-10 psi of one another), then I would suggest that a bad fuel injector (s) may be the root of your misfiing problems. Keep in mind the spark plug holes on these motors are deep so if you don't have the right setup to test the compression and just use a rubber hose as is common on many compression testors some may seal and some may not thus causing a false low compression reading in one or more cylinders. You'd always assume the dealer never makes mistakes and always uses the right equipment but a second opinion is always a good investment.

If you do find low readings, then pay someone to look at it with a borescope to verify any damage to the cylinder walls, pistons or valves BEFORE you ever authorize any engine teardowns on your dollar.

BTW, what were the readings from the last compression test they just did?

98runner210

It is at a 3rd shop now. The guy looking at it is really good. He will isolate and then keep going deeper until he figures it out. I don't have the compression readings. Don't think it is an injector cause then I would have a specific cylinder misfiring.

MTL_4runner

Is the misfire random cylinders now?
Double check the crank pulley bolt for sure if they are random!

98runner210

It is mostlyu left bank but all cylinders do misfire. Usual code is P0300 Random Cylinder Misfire. I am keepingmy fingers crossed. The dude working on it now is good but I probably won't see my rig for a few weeks.

98runner210

...still in the shop

rbh261

I finally got mine cleared up. It was two things: a cracked spark plug insulator and an aftermarket O2 sensor. The sensor was a Denso, but it was a problem. It wasn't bad, but it was much slower that the OEM sensor which I replaced it with. Instant difference. I even have seen a difference in MPG on my first half tank.

MTL_4runner

That's interesting......

Good to know what the problem actually was and that you got it all fixed now.

98runner210

i think i am going to call the mechanic and ask him him throughly check out the o2 sensors then. What do u mean cracked insulator? I hhave new plugs, wires, and coils.

edzo

have you got your old wires and parts ?


put those back in (if you know they are not exactly broken)
and re-diagnose before killing yourself

98runner210

.....huh?

edzo

I meant just because you have new stuff doesn't
mean the new stuff is any good

98runner210

i put 2 sets of wires and 2 sets of plugs so I am positive that isn't it.

rbh261

I had a brand new set of Denso plugs in the engine. I started pulling them to look at the color from each cylinder. That's when I noticed one of the insulators was cracked around the electrode. Couldn't see the actual crack, but I saw the tracking in the carbon on the electrode. So, at this point, I have replaced all sensors with Toyota factory parts. I had bought Bosch and Denso from Autozone and it all seemed to cause new sets of problems.

The surging I was getting at appx. 3.2k to 4.5k rpm was actually a direct response to the slow nature of the aftermarket Denso O2 sensor. This was the last item that I replaced with a Toyota part. I reset the ECM and couldn't believe the difference. I had been running the Denso sensor since last March. I never thought it could have been a problem. A friend of mine at work, he is an ASE certified Ford mechanic, said get the Toyota O2 sensor in it and see what happens. He was the one who informed me that the aftermarket sensors are too slow in Toyotas and other imports. Kind of surprised me to find out he knew that much about imports. Glad I asked.

98runner210

I'm still waiting on news from the mechanic. Said he would ahve something for me by friday. That will be day #15. Sucks having friends work on your rig, they gotta put the real customers first.

98runner210

Does the post cat o2 sensor do anything in regards to the running of the vehicle? i know on some cars it just monitors the emissions but won't do anything but light up the CEL if it is out of spec.

MTL_4runner

That is correct, it does nothing but monitor the condition of the converter(s).

98runner210

sigh.....i miss my truck

kenwoodrunner

any diagnosis updates?

98runner210

well last i heard they had the timing belt off. we are on day 20.