Failed smog because my idle rpm was too high

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B

bsl394

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Jul 6, 2016
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So I took my new FJ62 in to get smogged today and they couldn't perform the test because the rpms idled at 1300. They said it kept shutting their machine down because it was too high. They believed it needed to be around 800 and recommended a specific mechanic (which they're not allowed to do). Because they recommended a specific mechanic I'm a bit skeptical.

Has anyone had this problem? Is there an easy fix? I'm thinking of trying another shop tomorrow, but if it fails again it's obviously something I'm going to have to deal with. I have no clue what the fix is to this, and my daily driver is stuck in the garage until I can get it smogged/registered.
 
1300 is high on a warm fj62. if you don't have a check engine light and the A/C isn't on, check that throttle is not being kept from returning to stop, and also verify that the check engine lamp works(turn key to on with truck off).
 
if you have a check engine light, put it in diagnostics mode and pull the code and post back here.
 
If the engine idles at 1300 rpm, that's above the upper limit that any smog shop will allow. You don't want your engine idling that high anyway.
 
My AC blows but not very cold. Looks like that might have something to do with it (from what I found online). Thinking I might have to take it in and have someone take a look at it.
 
ok, hold on to that a/c thought- if it had been on during the test, a high idle wouldn't be odd; I'd call it smog tech fail; but if it wasn't on then it's neither here or there. get is fixed before summer tho, it's gunna be HOT...
code 51 is TPS? right guys? sounds about right for the failure mode. now don't go buying a new one. they need to be calibrated and adjusted, and if it's on an old throttle body, that'll need to come off and get cleaned with THROTTLE BODY cleaner NOT CARB cleaner, and reinstalled with a new gasket, and the old TPS reinstalled and adjusted and tested + calibrated. find the ECU wires that belong to the TPS signal wires and disconnect them at both ends and ohm them out to make sure they're good and talking to the ECU and then reset the ECU by unplugging the EFI fuse for 1 minute. put back in diagnostic mode and verify codes are gone, put back out of diagnostic mode and let it warm up. drive it around for about 30-45 minutes, in town, on the highway cruising hauling and puttering thru lots- all the different types of conditions so the ECU can reset its curves then park it for a starbucks coffee. Take note of the idle speed after you start it back up and it gets warm again. search code 51 here and you'll even get write-ups for the procedures. and do yourself a favor and get one of these >
For Sale - 40, 50, 60, and 80 series FSM for a hell of a price.
 
Thanks for the tips!

I pulled the TPS to take a look at it and didn't see anything obvious, though I'm going to pick up on ohm tomorrow to see if it's an electrical issue.

When I start up I'm in the 1300-1500 range, and then drop down to 900 or so after a couple of minutes. Every time I rev the engine I fall back to the 1300-1500 range for a couple of minutes before eventually settling down to 900.
 
it should settle to about 625 after warm and after the dashpot closes post throttle release(takes a few seconds to wind down). read the part about adjusting and calibrating the TPS- alot of people don't realize it's such an involves adjustment, and that you don't just buy a new one and install it. it the Throttle body is dirty and won't close all the way due to gunk build up on the plate lip/rim, then you'll never be able to set the idle position correctly and nothing else will fall in line.
if all of that specs and checks, it could be the air bleed screw has been mucked with and might need to be trimmed, or the AFM has been mucked with. post up pics of the top of the device on top of the air cleaner housing.
 
Mine was doing the same. Adjust the TPS by loosen the top screw. With a wooden block and hammer tap on the TPS until the idle go down to the desire RPM. My return spring on the throttle body was stuck a little bit causing the RPM to stay high. Also check the tranny kick down cable too.

I then removed the throttle cable off the linkage and cleaned the return spring. Make sure u lube it afterwards and put the throttle cable back on. I also cleaned out my throttle body and a complete tune up while I'm doing the works. U can use Seafoam to clean the system as well. I dumped a body in my gas tank. My 88 FJ is running much better and idle like a Lexus. Good luck!
 
Should by TPS visible move when I tap on it? I removed the top screw and have given it a few taps but it's not "moving" and I'm a little worried about swinging away. I'd remove the bottom screw but, well, that thing looks like a major PITA.
 
might be hard to see- it won't need to move alot. it is "seen" by the ohm meter...
 
do not hit it hard.
 
I know it's unlikely to be the cause...But is the hand throttle free and pushed all the way in?
 
LAMBCRUSHER said:
... if you don't have a check engine light and the A/C isn't on, check that throttle is not being kept from returning to stop, and also verify that the check engine lamp works(turn key to on with truck off).
Click to expand...
 
How do I check that the throttle is not being kept from returning to stop? The check engine lamp works, but it doesn't like up when driving.

I was able to remove the top screw of the TPS (finally) but couldn't get the TPS itself to move. I tried removing it again to give it a few harder whacks, only to find that the screw was stripped.

When driving to a good friend who is a mechanic today, I notice that once I shift out of park and into drive my rpms go down to 650-800. In fact, when I start up, I see them go to 650-800 for a split second, then hear the engine rev and they shoot up to 1300 (before going back down once I shift into drive).

Took it to a family friend who is a mechanic and he's going to try to clean the throttle body & mass airflow sensor as he thinks it may not be closing all the way, causing the throttle to idle higher than normal.

Is there any way to determine whether the hand of the throttle is being pushed all the way in? I'm not a big car guy (but I'm trying to learn) so if you could dumb it down for me it would be appreciated.
 
Take the throttle cable off and move it back and forth. At the stopping position, with your thumb pressed it a bit to see if it moved. Then spray it with some wd40 to loosen the possible run or corrosion. When removing the screws on the TPS, make sure to spray it with wd40 and let it sit there for a bit. Then use a long screw driver with leavege to slowly crack it lose. Cleaning the throttle body will definitely help too.
 
I found alot of crud built up on my ISCV which made it hard for it to move. Cleaned crud and reinstalled. Before whacking the tps off the side of the TB, have you tested its terminals with an ohm meter to see if it indeed is out of spec? This type of truck allows one to test and check each thing to verify it works or not BEFORE replacing parts most of the time. I'd be testing that TPS in its current clocking, and adjusting to WHERE IT NEEDED TO BE; not just hoping to give it the magic whack that lines up the stars. following that, I'd make sure the hand throttle wasn't keeping the throttle throttle from closing all the way. Then I'd clean the ISCV and TB and reassemble. if there were still issues, then I might do the diagnostics on the AFM. at each of these points, I'd test the harness and prove it all the way back to the ecu. what you describe seems like these components would be the where the issue might be, but there are other things that control engine speed in these rigs such as coolant temp and timing, so check your levels and your timing and test the coolant temp switch. if there isn't enough coolant in the system to cover the ECUs temp sensor, then it'll think the truck is cold and run it rich. if the ECU temp sensor isn't working(as verified by a diagnostic test) then it'll send jibberish to the ECU which will kick into open loop and enrich the mixture...does your TPS spec out as far as ohms where it is? if so, then move to the next issue...I keep forgetting my truck idles at 625 once warm- I do not have an auto in it. with an Auto, I wouldn't be surprised if it needed to run at 800 ish, which would be normal. 1300 is high for warm park idle/ 800-900 is about right on. HTH
 
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