Just picked up a 99 sr5. When I bought it she had a CEL for the MAF sensor. Swapped out the sensor, reset the ECU and the CEL is gone. Although the CEL is gone, it's still having some issues. Has a loss of power and a somewhat sporadic idle (800-1000). I've thought it may be a bad TPS, but that would throw a code.. Does it possibly just need adjusted? Or something else?
Loss of power
- Thread starter Josho
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MONTYMTB
New member
I had the same symptoms recently, and it was the TPS. P0120 was the code, but if I remember correctly it didn't trip the CEL right away. How many miles since the reset? Be sure to go with OEM if you replace it, read about problems with other brands when researching.
MONTYMTB
New member
Probably not enough for it to throw the code, but could show as pending if you have a reader. Most definitely go OEM Toyota on sensors. Bought mine from a member here: http://www.toyota-4runner.org/sale-...osition-sensor-89452-35020-ocala-florida.html
He shipped it quick and No issues since installation.
[MENTION=49713]4RUNNERTMAN[/MENTION]
I've been searching for a write up on how to check the resistance on the tps. Does anybody know where I can find this? Also, I unplugged the tps (while the vehicle was running) and the idle went up 100-200 rpms. No other difference though. After plugging it back in, and continuing to let it run, I noticed that the CEL came on. 3 codes; tps, cylinder 1 and cylinder 3 misfire.
BamaDrewski
New member
I have experienced the same "loss of power issue" in the past and through trial and error, I discovered it was the 02 sensors on my rig. Replaced them both (cheapest at Amazon) and the issue disappeared. Also, the fore and aft sensors are the same part number on my V6 (non-California emissions)
The Denso part number is: Denso 234-4162 (Both sensors the same)
Hope this helps.
KMcCormick24
New member
Bad knock sensors
Ive had a similar issue because both my knock sensors went out. I don't have the time to replace them myself nor do I have the money to pay someone $1500 to do it. Is there a way I can tune my engine to get that loss of power back.
Ive had a similar issue because both my knock sensors went out. I don't have the time to replace them myself nor do I have the money to pay someone $1500 to do it. Is there a way I can tune my engine to get that loss of power back.
Little more info: I replaced the spark plugs and after doing so, I unplugged the TPS while it was running. Unplugging the sensor made no difference in the way it ran. Went to parts store and got a replacement tps. Installed, reset ecu, still no difference at all. I drove through 4runner for 15 miles or so. While driving, I could smell the catalytic converter(rotten egg). Also, during WOT, the truck would hesitate and just rev up. Still does not have a CEL.
4Runnermex
New member
It's sounds like clogged cat.. since 99 only come with one. Just had a problem with one and had an aftermarket cat that was hot as can be. Got with my buddy's yard and sold me an OEM for 250.00 used replaced it and got my power back.
Best thing to test is remove the exhaust were it connects to manifold and run it without that to see if your power comes right back. While I'm idle you can rev it up and notice right away if you had a clogged Cat which based our your symptoms you do.
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Toyotayoda
New member
That sounds like a catalytic converter to me, loosen the exhaust bolts ahead of the cat and see if symptoms get better, or pull the upstream O2 sensor. Plenty of clogged catalytic converters won't cause a CEL because of the lack of exhaust flow over the post cat O2 sensor, which monitors the cat, or they throw a CEL for EGR and even MAF.
thegipper
New member
My vote is for clogged cat. There are a couple ways to check it. You can remove the upstream 02 sensor and just secure it somewhere and take it for a drive. If it drives better (power restored) you have a clogged cat. This alows the exhaust gas to escape easily instead of trying to be pushed through a clogged cat.
You can also use a infrared thermometer and take temp readings before and after the cat while it is idling. If your cat is clogged, it will be significantly hotter before the cat than after the cat. If your cat is working properly and not clogged, the temp readings will higher after the cat.
A clogged cat is often one of the most overlooked cause of power loss.
You can also use a infrared thermometer and take temp readings before and after the cat while it is idling. If your cat is clogged, it will be significantly hotter before the cat than after the cat. If your cat is working properly and not clogged, the temp readings will higher after the cat.
A clogged cat is often one of the most overlooked cause of power loss.
Thanks for the input guys. Unfortunately, removing the cat is something that I have already done. It ran the exact same way. Reinstalled the cat and still no change. I'm getting a strange smell as well, sometimes it smells like sulfur, other times it does not. I'm really lost here. I've replaced the MAF sensor, TPS, spark plugs(NGK), and removed the car. What else could it be that would not trigger a CEL!? And the light works. It comes on as soon as I unplug the TPS..
AntleredRuin
New member
How's your fuel pressure? Bad FPS? Mine gave the same basic syptoms, and an intermittent extremely bad gas smell.
My CEL came on by itself once, then went away after a couple miles.
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My CEL came on by itself once, then went away after a couple miles.
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Metallurgist
New member
Definitely sounded like a clogged cat, but if you've bypassed it and still have the problem then maybe not. Have you tested your IAC valve?
I have not. What is the easiest way to test it?
This evening I pulled the iac off. The exterior looks fairly new, but the inside was gunked up a good amount. Cleaned it and the throttle body very well and reinstalled. Not much of a difference.
I did, however, notice that if I rev it up normally, the rpms climb fine-ish. BUT, if I give it a lot of throttle, it bogs down and hesistates badly. Could this be in internal issue with the valves? Maybe need adjusting?
Metallurgist
New member
There's a post somewhere about energizing a post with it off. If it turns it's good, if not it's bad.
Bogging down sounds like an air/fuel issue. If it's not clogged exhaust and assuming IAC and MAF are good, then maybe it's a fuel supply issue? Something like fuel filter or even fuel pump? Starting to grasp for straws with it a bit.
EDIT: Check this post out.
http://www.toyota-4runner.org/3rd-g...ottle-body-adjustment-including-iac-pics.html
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