Question for mechanics, cylinder miss

T

Tomsriv

New member
2000 4runner 4 cyl, 208,000 miles.

I am getting code P0302, miss on cylinder 2. It is a solid check engine light, I understand it will blink if it is a constant problem and be solid if it is not as serious.
I swapped the coil and plug from #1 and cleared the code. It came back a few days later and the engine still ran a little rough. I disconnected the fuel injector on #2 and found it got a lot worse, so I know it is working. I even listened to it click with a listening stick.
I then checked resistance on #1 and # 2 injectors because I can reach them. I got 14.5 on both. The spec says 13.4 to 14.2, so they are slightly out of spec, but only #2 is giving me a problem. I would think the out of range could just be my meter as it is very close to the spec.

Next I did a compression test, I got
#1 180
#2 152
#3 172
#4 166

I put some oil in #2 and the pressure went up to 172 so I think the rings are a little worn. They say no more than 10% difference betwen cylinders. 10% of 180 is 18 which is the difference between 1 and 2, so barely in spec, but I don't think this would cause a miss.

What should I do next? I think I can either let it go, or just replace the injectors for a few hundred dollars and hope it fixes the problem. Is there anything I have overlooked?
 
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A couple of other items you may consider checking are;

The voltage at the ECM terminal for the #2 injector.
The injector injection.
The valve clearance(s).
 
Which two coil packs did you swap, because your #s aren't making sense to me. Cyl #2 is on the side that has traditional wires and #1 is on the side with the 3 coils. I'm guessing you meant you swapped the coil on top of hole #5 (which also fires #2 cly) with the coil on top of # 1 (which also controls #4). Did the code come up the same P0302 after the swap?
 
techno said:
Brian2sun, op's got a 4 banger.
Click to expand...

haha, I'm really on top of it today! :ybrick: Sorry OP, disregard my previous advice. I should have noticed when you didn't list the compression for hole #5 and 6. I think I need to go back to bed! X2 on valve clearance and injector function/ECM circuit.
 
thanks for the replies so far, I'm impressed at all the technical people on this board.
Is there a way to check the injector injection without taking it apart?
I'll look up the spec for voltage to the injector, I believe it should be 5volts. Why check at the ecm? I could just back probe with a needle at the injector connection.
I'm not sure how valve clearance would effect it since the compression problem seemed to be cured when I added oil to the cylinder which helps to seal the rings. I'll keep it in mind though.
 
Checking the voltage at the ECM terminals lets you know whether or not the correct voltage is being sent.
If the values are in spec and the injector resistance is in spec, then you can check the wiring harness for an open and short.

Measuring the injector volume is tricky and really needs the right tools and equipment.

You're right about the valve clearance, but don't rule out the poor compression as a possible culprit. This can produce a misfire condition. The ECM detects misfires by monitoring the crankshaft position sensor and the camshaft position sensor. It looks for changes in the crankshaft rotation. Poor compression will result in less power from that cylinder, hence a slower rotation compared to the other cylinders.
 
I would make a solid bet on valves being tight. With that compression, you may be able to adjust out of it and be ok. If not....its valve grind time
 
techno said:
The ECM detects misfires by monitoring the crankshaft position sensor and the camshaft position sensor. It looks for changes in the crankshaft rotation. Poor compression will result in less power from that cylinder, hence a slower rotation compared to the other cylinders.
Click to expand...

Good point Techno, plus I realized my math was wrong and there is a 16% difference between the best and worst cylinders. This truck has run great up until now. I bought it with 113,000 miles on it in '05. I don't know how well the last owner took care of it. I understand it was a company car of some sort.
I'm going to check the voltages first, then I'll try a shade tree mechanic way of checking the injectors. When I was doing the compression test I disconnected the power to the injectors. I couldn't reach #4 and when I was doing the other cylinders I noticed air and fuel shot out about a foot from the spark plug hole as I turned the engine over. My redneck method would be to see how far #2 shoots air/fuel out the spark plug hole. Not very scientific, but it may give me a hint if the injector is clogged.
 
I ended up taking it to a shop who did a leakdown test. They found #2 cylinder is losing 40% of its air out the exhaust valve. He told me if I adjusted the valves the problem would come back in a few months because there is damage to the valve seat. So a valve job will cost $1400. I'm thinking I have a few options

1. Do just a valve job. Pay him to do it or myself and have the car down for weeks.
2. Buy a rebuilt head and install it myself.
3. Buy a rebuilt engine and install it myself.
4. Clear the code and trade it in on the Dodge Magnum I've always wanted.


I'm leaning towards 3 because its almost easier to just replace the whole engine and it only costs a little bit more. Plus if I sell the car in a couple years I can get more if it has a "rebuilt" engine as opposed to just a valve job.
Anyone have any recommendations on where to look or buy an engine? I'm seeing some deals on Craigslist.
 
Thanks Brian. Its HOUSE OF ENGINE no www. I called both places, house of engines specifies what they include

Rebuild Includes
Reground Crankshaft (exchange)
Rod Bearings
Main Bearings
Rings
Cam Bearings
Pistons
Full Gasket Sets
New Lifters (except roller lift hydraulic lifters)
New timing set / timing belt
Freeze Plugs
Paint Block & Heads
Resurface Heads
Valve & Seats regrinding
Free honing
Oil Pump (on selected models)
New spark plugs / Oil Filters

I asked them what overboring the cylinders costs, they said $200. Also, they don't replace the cam. But since my engine is in pretty good shape I am leaning towards house of engines.

Perez Wholesale just has a bunch of engines and they swap them out really quick. I don't know if I like that because I don't know what I'm getting.
 
Yeah I think a rebuild is a safer/better route than buying a used engine also. Plus how can you go wrong with a 3 year warranty. Most used motors/trannies only come with 90 days. I think I'm probably going to have them do my engine too eventually, but mine's still running good for 200K.
 
I took my runner to House of Engine and they had it done in a week. It runs good. I'm pretty impressed that they did the whole job so seemlessly. I only have two complaints. I have to readjust the hot/cold vent cable because it won't turn all the way to hot. The other thing is that they used green coolant when I specifically bought red toyota coolant and left it on the passenger floorboard. I'm going to drain the green stuff next weekend and put it in my Cadillac.

They called me two days after I dropped it off to tell me what it needed, an overbore for an additional $200 and an oil pump for $125 which wasn't included on my engine. They also tried to upsell me on belts/hoses and sensors. I just did the overbore and the oil pump. Not a bad deal for a rebuilt engine.
 
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