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Discussion Starter #1
I'm very lost with this so finally asking... Maybe there is something obvious that I don't know about.

I had a acceleration issue. I felt like my car for over a week or so was getting slower. My car is lowered and one day I went over this ridicules speed bump very, very slowly and my car came down very hard as the front wheels cleared the speed bump. It hit the bottom of my car very hard and it seemed to change my exhaust note. Maybe 50 miles later I lost all power. At this point my car would just cut out, barely start. I had to floor it to keep it lurching while it would almost die.

I replaced my fuel pump and spark plugs and looked for vacuum leaks. I think I didn't have a code at the time which is why I was guessing what to replace. I believed it was the fuel pump for whatever reason. I then either realized or got an engine code appearing for a clogged cat, I believe p0420. I replaced my stock exhaust headers. This removed the cat code, but now I seem to be stuck in this limp mode. If I floor it, the rev limiter seems to be at 4.5 or 5.5k rpm. It wont really accelerate so I could not really take the car on the road at all. I got a throttle body code (p1126) and I replaced the throttle body (I've tried two different throttle bodies that have all the sensors) and still had the limp mode issue but no check engine light. I don't know if I have to do something to trigger a check engine light? I can't really drive the car either to see if one appears.

I ended up getting the codes below all at once when I was testing if an item I replaced fixed it. To trigger this code, I had done some procedure with disconnecting the battery for X minutes, the brake pedal or turning the key to on for 5 seconds, then off, then on, ect 4 times without starting the car to try to do a hard reset or something. I ended up getting the codes below.

p0122- Throttle Position Sensor/Switch 'A' Circuit Low Input
p0222 - Throttle Pedal Position Sensor/Switch 'B' Low Input
p2127 - Throttle Pedal Position Sensor/Switch 'E' Circuit Input Low
p2135 - Throttle/Pedal Position Sensor/Switch 'A'/'B' Voltage Correlation
p2138 - Throttle Pedal Position Sensor/Switch 'D'/'E' Voltage Correlation


I've replaced so far...
-entire used throttle body with sensors
-another used throttle body with sensors
-spark plug wires with ngk
-ngk iridium spark plugs
-bought pregapped oem spark plugs just in case the other ones had an issue
-tested the o2 sensors
-new oem maf
-checked hoses and connectors (some clips have broken but the connection is together)
-all coil packs
-all coil pack connectors
-valve cover gaskets
-tested the plunger on the OCV, and it appears to be fine

I currently do not have an engine code. I don't know how to trigger an engine code either? From what I've read this leaves the tps, apps, or ecu is causing the issue. I'm leaning towards the ecu, but I thought that would make my dash lights go crazy? Is there any tests I can do further to try and figure it out?
 

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Discussion Starter #5
First off. The cats are bad. If clogged will make it lose power and die. Next, have you put a voltmeter on the TPS to see if the used part is good?
Well I replaced the exhaust manifold which has the 2 cats to fix the p0420 code. As far as the TPS goes, I have not tested any of the 3 I have. BUT I have two throttle bodies with all sensors (so a total of 3 tps sensors) and none of the throttle bodies fix the issue. I never removed the tps, so I assume calibration is correct.

I am wondering if this big bump knocked junk from the exhaust manifold cat into the y-pipe cat.The threads linked at the end seem to indicate this might be the issue.

Have you checked underneath to see if you have crushed the exhaust? Checked the o2 wires havent been broken or anything like that?
^^^^^what he said!
Yes, and the exhaust is ok. I did kinda burn the upstream 4,5,6 o2 when doing the exhaust headers, so I have replaced it this weekend and no difference. I had ordered the upstream for cylinders 1,2,3 but I think they sent me the wrong one, as the connector did not match -_-

For a while I wondered if I somehow swapped the connections of an upstream and downstream but this isn't possible due to the wire length. I did try this new incorrect connector with the downstream connection into the upstream hole on the exhaust manifold of cylinder 1,2,3, and it did not fix the issue.

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So tomorrow or Tuesday I'm going to pull the y-pipe and test it out. I'm just not sure if the y-pipe o2 sensor dangling but connected will cause an issue? Guess I'll have to research and/or test it tomorrow. My car is in storage, making this repair not easy to run into the garage and complete.

I will post here if it fixes it, or when I find the fix.

For those that find this in the future, these following posts are giving me hope that it's the y-pipe. The previews the forum is showing is the original post, not the post I link to.

This post as well
This one too
 

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I would test the TPS sensors you have. Other than calibration. They may have bad contact points inside. I understand you have a couple. But that does not mean anything with used parts. Other than that. If they check out. It would be in the wiring.
 

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Discussion Starter #7
SOLVED: Clogged y-pipe / midpipe

This wasn't giving me a code making it difficult to find. So those that get the P0420 code and then stuck in limp mode. I'd suggest removing your y-pipe / midpipe and seeing if it exits limp mode, which mine did.
133464
133463


I would test the TPS sensors you have. Other than calibration. They may have bad contact points inside. I understand you have a couple. But that does not mean anything with used parts. Other than that. If they check out. It would be in the wiring.
I wasn't exactly sure how to test it but lucky I solved it.
 
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