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Old 01-18-2006, 11:29 AM   #1 (permalink)
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Engine runs rough/miss when warm.

I've done a search but can't find any listings with the same problem.

I have an 89 pickup w/22RE. 4000 miles on rebuilt engine and just installed brand new head with 268c cam last week and problem still exists.

The engine always starts right up. When the engine is cold it idles @ 1500 rpm with very little vibration and no miss heard at the exhaust.

While the engine is still cold I can increase the rpm to 3500 (could most likely go higher) and it still has very little engine vibration and no miss heard at the exhaust.

THE PROBLEM:
As soon as the engine warms up enough for the RPM to drop (3-4 minutes) and go into closed loop, the engine starts to run rough with intermittent miss heard at the exhaust that increases with RPM.

What I have done or replaced:
I have new OEM O2 sensor, OEM TPS, OEM Coolant Temp Sensor.
I have swapped factory cap, rotor and wires for factory wires and high quality brass terminal cap and rotor.
Swapped new NGK plugs for Denso plugs.
New high flow cat with 2 1/4" exhaust and Flowsound muffler.
K&N air filter.
Rebuilt injectors and new fuel filter.
I have removed each vacuum line from the intake and plugged the intake where line was.
Checked AFM meter.
Checked ign coil.
Checked dist pickup coil.
Removed vac line to egr/ applied vac to egr makes engine run rougher.
Pumped propane at every intake joint and fitting I can get to.
Removed upper and lower intake and installed new gaskets.
Adjusted valves 2 different ways 6 or 7 times on 2 different cams and heads.
Adjusted AFM upto 6 teeth C.W. @ C.C.W. ( It is now back to stock)
Adjusted ign. timing everywhere from 3 degrees to 12 degrees.
Done visual inspection of tube running between AFM and T.B. many times.

Any ideas?
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Old 01-18-2006, 12:22 PM   #2 (permalink)
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Quote:
Originally Posted by zoomschwortz
I've done a search but can't find any listings with the same problem.

I have an 89 pickup w/22RE. 4000 miles on rebuilt engine and just installed brand new head with 268c cam last week and problem still exists.

The engine always starts right up. When the engine is cold it idles @ 1500 rpm with very little vibration and no miss heard at the exhaust.

While the engine is still cold I can increase the rpm to 3500 (could most likely go higher) and it still has very little engine vibration and no miss heard at the exhaust.

THE PROBLEM:
As soon as the engine warms up enough for the RPM to drop (3-4 minutes) and go into closed loop, the engine starts to run rough with intermittent miss heard at the exhaust that increases with RPM.

What I have done or replaced:
I have new OEM O2 sensor, OEM TPS, OEM Coolant Temp Sensor.
I have swapped factory cap, rotor and wires for factory wires and high quality brass terminal cap and rotor.
Swapped new NGK plugs for Denso plugs.
New high flow cat with 2 1/4" exhaust and Flowsound muffler.
K&N air filter.
Rebuilt injectors and new fuel filter.
I have removed each vacuum line from the intake and plugged the intake where line was.
Checked AFM meter.
Checked ign coil.
Checked dist pickup coil.
Removed vac line to egr/ applied vac to egr makes engine run rougher.
Pumped propane at every intake joint and fitting I can get to.
Removed upper and lower intake and installed new gaskets.
Adjusted valves 2 different ways 6 or 7 times on 2 different cams and heads.
Adjusted AFM upto 6 teeth C.W. @ C.C.W. ( It is now back to stock)
Adjusted ign. timing everywhere from 3 degrees to 12 degrees.
Done visual inspection of tube running between AFM and T.B. many times.

Any ideas?
cheak the egr valve and the thermal switch that activates it.
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Old 01-18-2006, 06:24 PM   #3 (permalink)
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If you add propane into the intake tube while it is missing does it smooth out. If it does obviously you have a lean condition. If you have a timing light hook it to each cylinder while it is missing to see if you ever loose spark. Also you can hook into the O2 sensor with a volt meter and get an idea if the engine is running lean or rich. 1 volt indicates rich and 0 volts indicates lean. It should cycle between the two while in closed loop. It doesn't sound like a compression problem but have you checked it to rule it out, also do a running compression test, sometimes this will show a problem where a cranking test wont. How much fuel pressure does it have? Maybe cold its ok since the cold start injector is working then when it shuts off you have a lean condition.
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Old 01-19-2006, 06:51 AM   #4 (permalink)
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Dave-O and Manson,
Thank you for the suggestions. I'll give them a try.

Quote:
Originally Posted by Manson
If you add propane into the intake tube while it is missing does it smooth out. If it does obviously you have a lean condition. .
Do you think adding propane at the airbox will work or should I try rigging up some lines that go directly to an intake vacuum port?

Quote:
Originally Posted by Manson
If you have a timing light hook it to each cylinder while it is missing to see if you ever loose spark. .
Great idea, I'll check this out first.

Quote:
Originally Posted by Manson
Also you can hook into the O2 sensor with a volt meter and get an idea if the engine is running lean or rich. 1 volt indicates rich and 0 volts indicates lean. It should cycle between the two while in closed loop..
Where is the best place to do this. Last week I checked the O2 sensor (counted pulses) at the passenger fender per the Toyota manual.

Quote:
Originally Posted by Manson
It doesn't sound like a compression problem but have you checked it to rule it out, also do a running compression test, sometimes this will show a problem where a cranking test wont..
Compression with the new head and cam is 150, 150, 155, 160. Compression with the other milled head and different cam was upper 170's to 181.
"By running compression test" do you mean, check compression on one cylinder while the engine is running on the other three?

Quote:
Originally Posted by Manson
How much fuel pressure does it have? Maybe cold its ok since the cold start injector is working then when it shuts off you have a lean condition.
I checked fuel pressure four months ago. I don't remember the exact number, but it was 2 lbs higher than spec.
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Old 01-19-2006, 05:51 PM   #5 (permalink)
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Well I checked each plug wire with the timing light at an rpm that produced the greatest miss and didn't notice any break in thetiming light pulses.

I then removed the EGR tube from the intake manifold and plugged it with a rubber cork. No difference.

I then started pumping propane into the air box. No difference.

I then removed the rubber hose that runs from the power steering to the intake manifold and started pumping propane into the intake. This made a slight difference at idle but no difference at anything above idle.

I also pumped propane to any and every hose, joint, fitting, seal or connection I could get to. No difference.

Against my better judgement, I emptied a whole can of starting fluid on everything I could get to that looked like it could leak. No difference and as a bonus, I still have my beard, mustache and eyebrows. The hairs been gone ever since a Jay Buhner buzz cut night five or six years ago

How and where do I check the O2 sensor voltage as suggested above?
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Old 01-19-2006, 09:43 PM   #6 (permalink)
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Yes you can check the running compression while running on other 3 cyls. I believe the running compression # should be about 70% of the cranking compression. Verify it is the same as a known good cyl. This will most likely not show a problem due to 2 different heads and cams. Usually if this shows a problem it is due to a valve train problem. Worn cam lobe or broken valve spring. Check the o2 right at the o2 connector. Sounds like you have covered most everything. Good luck.
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Old 01-23-2006, 07:34 PM   #7 (permalink)
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maybe your cam timing is off and when the cold start injector is running it isn't noticable.
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Old 01-23-2006, 10:53 PM   #8 (permalink)
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Mine did the exact same thing a couple of weeks ago ( 1989 4runner 22re 5 speed)

there is a screw called the idle air screw.
turn it counter clockwise to increase the idle speed when its warm.

my fix was that simple.
I guess I could remove it and clean things, but for now, about 3/4 or a turn to open that idle air jet solved my rough idle when warm.

mine would actually die at a red light when warm.
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