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Old 03-27-2013, 05:50 PM   #1
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Fuel injector questions

I am fighting the dreaded high idle on my 97 3.4 tacoma. I have checked/replaced the tps, iac, maf, cam sens, crank sens, ECM temp sens. Has new NGK platinum plugs and wires. I have also rearranged the coil packs to see if the misfire followed the coil pack. It did not. Still #6 and #1 all to no avail. Idle is still up around 1700 rpm when warmed up. I scanned it and the coolant sens shows 170-180*. The only codes I'm getting are misfire codes. Cyl 1, cyl 6, and random misfire. If I put a wrench on the end of the tb shaft and force the butterfly fully closed my idle drops down to around 1200. So I have some wear there and need to either put a stronger return spring on it or shim it somehow.

I'm open to suggestions on this issue.

Issue two is a cold start shake. It also seems to be running rich (smell of fuel in exhaust), plus I am only getting about 10mpg. I unplugged all 3 injectors on the passenger side with the engine running and in park. The engine smoothed out and idled better! Correct me if I'm wrong but shouldn't the engine have died with 1/2 the injectors unplugged and not firing?? I believe them to be leaking and causing my rich condition, shake, and terrible mileage. Seem plausible??
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Old 03-27-2013, 06:30 PM   #2
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Very possible
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Old 03-27-2013, 06:30 PM   #3
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Try swapping injectors and see if your misfire follows the changes or stays the same
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Old 03-27-2013, 07:01 PM   #4
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Have you tried running any cleaner through the injectors? Might clean up something and help a little bit if they're stuck open.

And something is very funny if the engine is running while disconnected...

What do your plugs look like now that there are new ones in?
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Old 03-27-2013, 07:13 PM   #5
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That's easy enough for the passenger side. I will have to give that s shot to see if the misfire goes from 1 to 5. I have not pulled the plugs since putting them in about 450 miles ago. I need to do that. And I did just give it a double does of cleaner. I'm only on the 4th tank of fuel since getting the truck. It's had the cold shake and a funky idle since I've had it. The iac was bad and stuck fully shut, it used to idle at 1000 rpm and would not idle cold. With a new Toyota iac the idle jumped up to 1700
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Old 03-27-2013, 09:32 PM   #6
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maybe the computer has to be reset now that there is a new iac? now that it is getting more air, or the proper amount of air, the rpm when up b/c the computer is still using a lot of fuel b/c that is what it used to do?

try disconnecting battery for 30 mins or so and then reconnect and see what happens.

^not sure just thoughts

but generally vacuum leaks and oxygen sensors would be likely causes of funky idle and lean/rich conditions
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Old 03-28-2013, 05:10 AM   #7
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Quote:
Originally Posted by CUtacomaTIGER View Post
maybe the computer has to be reset now that there is a new iac? now that it is getting more air, or the proper amount of air, the rpm when up b/c the computer is still using a lot of fuel b/c that is what it used to do?

try disconnecting battery for 30 mins or so and then reconnect and see what happens.

^not sure just thoughts

but generally vacuum leaks and oxygen sensors would be likely causes of funky idle and lean/rich conditions
I have done this multiple times. And driven about 150 miles since replacing the iac. After unplugging and checking every sensor listed and changing the iac the battery was disconnected for at least 30 minutes every time. One time even over night. With the iac disconnected from the tb but still plugged into the harness I had someone turn the key on while I held it and watched. It drove almost all the way closed leaving a very small gap. Which I assume is normal.
I have also searched high and low for vacuum leaks. This was my first thought too, but Nothing. No hissing sounds either
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Old 03-28-2013, 05:16 AM   #8
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And both o2 sensors looked good on the scanner with no codes for either one. I don't usually luck out with simple solutions haha
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Old 03-28-2013, 05:43 AM   #9
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I think you are blaming the injectors for doing what they are told to do. Having all the injectors screwed up is about nil even 3. Your high idle is probably an air leak some where or a nasty idle motor. The biggest causes of a rich mix is the coolant temp sensor or high fuel pressure. I believe that engine has a vacuum operated enrichment valve at the end of the fuel rail that raises the fuel pressure at WOT might check that out.
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Old 03-28-2013, 07:11 AM   #10
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I am not sure how many miles are one your truck but its the same problem I had when I got mine, with 177,000 miles,
one question before the 2 things that really stood out on servicing the truck. when you replaced the plugs did you use the duel spark?
Now I have been aruond cars and trucks most of my life and I have seen lots of neglect, when I got my truck, its a part time truck, something I enjoy fixing up, and I got her for next to nothing, I wasm't throwing a code but the basic stuff was barley done and what was done was done half-ass. so I changed the o2 sensors, well the ones on the truck were the worst I had ever seen, but the difference in the truck was noticeable. and that got the idle close to perfect, cold and hot.
The last thing I did before winter set in was to put in 3 new coils. And that did it. fires right up, strong cold idle and very smooth hot idle and with the last 2 things my around town mileage has gotten better.
I know there are going to be some rants on me writing this but with the duel coil system you loose one and you are really screwed. Yes I over maintain the car/ trucks I have owned but I believe that a engine running close to 100% will last longer, use less fuel and pollute less. I have never had a injector go bad, but my cuz had a Maxima, still has it, and 2 went bad but it had close to 400,000 miles. and when one died, it died.
I forgot to mention I started step by step doing everything you have done so far.
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Old 03-28-2013, 07:37 AM   #11
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Quote:
Originally Posted by maineah View Post
I think you are blaming the injectors for doing what they are told to do. Having all the injectors screwed up is about nil even 3. Your high idle is probably an air leak some where or a nasty idle motor. The biggest causes of a rich mix is the coolant temp sensor or high fuel pressure. I believe that engine has a vacuum operated enrichment valve at the end of the fuel rail that raises the fuel pressure at WOT might check that out.
I agree that having injectors fail is uncommon. But like it says above the truck has a brand new iac from toyota that is working. I have looked and looked for a vacuum leak. The only air leak I've found is past the butterfly which is most likely the reason for the high idle. But it is not the reason for the misfire. And when checked with the scanner the coolant sensor is showing around 180*. The gauge is also right in the middle.

I will look into the fuel pressure though. I hadn't thought of that
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Old 03-28-2013, 07:49 AM   #12
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one thing poped in my head, when you replaced the IAC did you get the gasket back on tight? very critical, I had a GD Mustang GT for 2 many years and the IAC valve was a pain also, put in a easier place to get to than the Tacoma.
and no it will still run if a injector or 2 is not working, not good at all for it.
I don't want to harp but a misfire is very bad for your cats.
How did the throttle body look I did both over a long weekend, you could have resurfaced a road with the black tar that was in mine.
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Old 03-28-2013, 07:58 AM   #13
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The truck has unknown miles. The Odo shows 240, title says exempt/milage not accurate. But the engine was a junkyard engine I believe. My truck is an early 97 but when I had the engine apart to rebuild it (blown head gaskets and a fair amount of cylinder wear so I went ahead and rebuilt it) I found out it has 98 and newer rods. So I have no clue the milage on the injectors.

And I did replace and double check the iac gasket as well. The intake and tb do not look bad at all. Plus I cleaned them when I had the motor apart
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Old 03-28-2013, 09:10 AM   #14
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Temp sensors are used to set the idle. Scan the IAT(intake air) and ECT(engine coolant) sensors at cold and hot. ECT and IAT should be very close at cold.
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Old 03-28-2013, 09:12 AM   #15
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Did you look for vac leaks yet? Use throttle body cleaner, and listen for RPM changes.
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Old 03-28-2013, 09:44 AM   #16
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those ect sensors can go bad for sure. i had to replace mine but it was also throwing a code telling me too. they are definitely important for cpu to know how much fuel to use.
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Old 03-28-2013, 10:23 AM   #17
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I have done all of that yes. No vacuum leaks and iat, iac are both working fine
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Old 03-28-2013, 11:17 AM   #18
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Did you swap injectors yet?
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Old 03-28-2013, 11:23 AM   #19
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I am a bit rusty and old, and I reread everything and I would lean toward the injectors. Jeff's Maxima was running rich as hell and drinking gas bad before he figured something was up. ( too much weed) my firsthand knowledge is bad with injectors.
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Old 03-28-2013, 11:34 AM   #20
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Quote:
Originally Posted by carrollcustoms View Post
I agree that having injectors fail is uncommon. But like it says above the truck has a brand new iac from toyota that is working. I have looked and looked for a vacuum leak. The only air leak I've found is past the butterfly which is most likely the reason for the high idle. But it is not the reason for the misfire. And when checked with the scanner the coolant sensor is showing around 180*. The gauge is also right in the middle.

I will look into the fuel pressure though. I hadn't thought of that
The temp gauge and the coolant temp sensor are not the same and can you read that coolant temp sensor in real time? Unplug it and see if it makes a difference. The only thing in the system that does not change is the fuel pressure it is the only constant every thing else is variable so it has to be pretty much spot on. The WOT enrichment only bumps the pressure a couple of psi or so but if there is some thing up there it will make a difference when the engine is hot.
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