School Me!!!!

C

Cheap2000SR5

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Having problems and need help! Here goes...
I have a 2000 SR5 3.4L V6 T4R was running rough when I got it, upon cold start and when driving (couldn't get out of its own way), here's what I've done...
Started out with multiple cylinder misfire code x2 (P0300)
Cylinder #2 Misfire x2 (P0302)
-Cleaned MAF sensor
-Cleaned Throttle body and replaced gasket
-Cleaned IAC and replaced gasket
-Replaced Air Filter
-Checked spark plugs, found single electrode w/huge gap, replaced with dual NGK's
-Ohm'd out coils on primary and secondary... checks good
-Checked spark plug routing 5-2, 1-4, and 3-6... checks good
After this I start it up and idles great, as soon as I put it in gear misses and runs rough, it has 181,xxx miles on it and has never had TB replaced so...
I checked timing, set at TDC, find Crank is reading at "10" on lower cover, so I tear the front of engine down, replace TB, #1, and #2 Idler pulleys, water pump and T-stat, check timing though several revs all check good at 12 o'clock position, and then reassemble front components of engine. I drive about 5 miles, engine gets to operating temp and then starts to miss and engine light comes on, get home check code #2 miss fire, so I swap wires (easy thing first right?) (reading 15.55 OHMs on wire ) drive down the road code #2 MF again, so then I swap coils, drive a mile again #2 MF, so I tear down swap injectors drive a mile #2 MF, my head is bloody from banging it against the wall!! can someone please shed some light on this situation?, It would be greatly appreciated
 
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Id replace the O2 sensors, and the fuel filter, IIRC theres a inline fuel filter on the drivers side on the frame.. Just a thought, hoe you get it running right
 
Pull the connector to the injector for that cylinder and with a DVM, and set on ohms, see what reading you get on the injector prongs.

Have you tried switching the coil packs around?
 
His issue shouldn't be fuel related and you can run fine without o2 sensors Ecu gets stuck in open loop and mileage suffers. I would do a compression and leak down test. I had same issue on talon. High boost misfire. Did everything in the world and leak down test verified a burned valve in the cylinder that was missing. Good luck
 
Is everything fine when the engine is cold (idling, driving)? Does the engine misfire only happens when the engine gets to operating temp?
 
Yes, I've tried swapping coils, injector, and wire, nothing changes

Will be doing cylinder compression test tonight, just picked up tool, will also be doing a vacuum test as well. both O2 sensors are fairly new just don't know what brand yet. I've heard they can be picky if you don't use denso's; will verify that tonight. Is there any test to check O2 sensor? Will post findings when completed. Thanks for all suggestions and input. I troubleshoot equipment for a living so being a part swapper is not in my nature nor budget, but it may come to that is something isn't resolved soon.
 
I had the same issue. Tried new sparkplugs, checked injectors, checked compression (8% loss), tried swapping wires and coils. Saw no change.

Gave up and dragged it to the shop. They replaced the wires and coil despite me telling them that I tried swapping them around...and it runs 100% fine now.

It still makes no sense to me but I can't argue with the fact that it runs fine now.

So I suggest new wires and new coil rather than swapping.
 
Wires were replaced not long ago, can a certain type of wire affect it, I'll check to see what type is on now and post later tonight on what I currently have
 
You would need a scanner that reads live data. If a Bosch or non Denso O2 sensor was used, that could be your problem.

A compression test would verify if the cylinder is dead or dying, hence the stated misfire on #2.

Loosing any coolant?
 
What about the hot rod trick of spraying water on the manifold directly after the head checking each cyl.. If the water simmers the cylinder is firing and is hot. If not. The part of the manifold is not as hot as the others and won't steam/ simmer the water.
 
Cheap2000SR5 said:
Wires were replaced not long ago, can a certain type of wire affect it, I'll check to see what type is on now and post later tonight on what I currently have
Click to expand...

I had ~3 year old NGK wires replaced with brand new NGK wires and a DENSO coil.

Same P0300 and P0302 codes in my case - but a leakdown test showed that the cylinder was fine.

I really doubt it's an O2 sensor issue. You'd not have a misfile JUST on Cyl2 if it was a bad O2 sensor.
 
Don't have P0300 code anymore since TB replacement, just throws P0302 cyl 2 misfire after it get to operating temp, both O2 sensors were replaced not long ago but if its anything like the spark plugs (single electrode w/huge gap) it may be just that, one shop had done all the work on this rig and I'm pretty much having to go back and replace every cheap part they put on with the correct oem stuff. Will be checking brand of O2's tonight and if they are not denso's ill prob change them. I got the rig for $750 so it's all good and not a daily driver so I have time to spend on it, just trying to do it with as little out of pocket $ as possible + don't want to just grow parts at it I want to find a problem that way I know what to look for next time (hopefully there is no next time) but that way this can be a true learning experience
 
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