coug66

So I replaced the primary catalytic converters

then I replaced the MAF. The car starts on the second key turn. The first turn it lights and dies. then I turn it again and it fires up and goes above 1K idle to stay running.

Its like it has a rev limiter on?

The VSC and traction control lights are on and red exclamation light is on.

this cat metal had to go somewhere? my guess its the secondary y pipe cat?





I am thinking the secondary cat is plugged. the primary cat was pretty gouged out.

rkw77080

Have you disconnected the battery and leave it disconnected for a few minutes to force a hard reset of the ECM?

coug66

Well the wife took the lexus because typically it drives just fine up to 3K. well it started acting up cutting out and she pulled over and I swapped cars and drove it home.

It died on me at a light, it stuttered and then cut out out. It took three times to start and barely started.

I am wondering if electrical grease in the MAF plug is a good or bad idea. I shot some MAF cleaner in to see if I could remove it.

I did a hard reset. then it came up with VSC 51? also when I pulled the codes it had p0100 and p0101 I erased but the p0100 remains and wont go away?

A couple times it did start on first key turn but went back to two turns to start.

It still will not accelerate above 3K? like a rev limiter it just wont exceed?


Its raining and dark so I am going to call it a night.

Romanova

Classic case of a clogged cat. So much restriction that the motor can't breathe and gets choked out. Check your third cat and see what happens...

rkw77080

P0100 and P0101 are related to your mass air flow meter. Do you still have the old MAF? Try installing the old MAF to see if things improve.

Jabberwock

First thing I'd do is go to auto parts store that allows easy returns with no or minimal fee and buy a new MAF. Make sure there is no grease remaining in the MAF connector. Buy and use a spray can of electrical connector or MAF cleaner on the connector. Then install it in the parking lot and see if that solves the problem. If not return the MAF and proceed to a specialist muffler shop that can check the downstream cat.

coug66

I am thinking that I can test the plugged y pipe cat by unplugging both y pipe O2 sensors and see if the added flow ports will enable me to exceed 3k? Plus start first turn? It will be loud and throw other codes but my main test will be the flow out the second cat.

rkw77080

I still think you should try putting the "old" MAF back to see if it would resolve your P0100 and P0101 DTCs. It's a 5-minute investment and you can do it standing over the engine bay.

coug66

I replaced the MAF and yes it did make an improvement, the other MAF was having real issues starting and running but this one runs OK up to 3K and it starts on the second turn of the key.

I have three MAFs two cheap and one original.

I will play with the car later,

If the car had a bad MAF, and I reset the code would it be able to tell me that with the engine off and the ignition on?

I reset with a cheap code reader but the code never leaves?

coug66

I took the O2 sensors out and didn't make one bit of difference. It took two key turns to start and did not exceed the rev limiter of 3K.

I have driven motorcycles and RVs to maximum RPM and this is exactly what the Lexus is doing. its rev limiter now seems to be set at 3K???

Romanova

Is it in 'limp' mode because of the nature of the codes?

coug66

Its in limp mode based on the P0100 code. The readout on the MAF is .48 gm/sec consistently no matter where I have the throttle. We disconnected the MAF while the car is running and it didn't even change RPM.

I need to check the wiring for the maf sensor. Is there a way to check voltages at MAF plug?

I am so happy to be getting close to figuring this out. No more P0420 so the Cat replacement solved those codes.

Now if I can just get this MAF fixed I can work on loving this car again.

coug66

A little while back I found this post, but can't remember where or who?

I wonder if I have one bad connection or the whole plug?

MAF:
1) Apply battery voltage across pins 1 and 2 (pin 1 is on the left when the harness clip is on top). Using a voltmeter, connect + to pin 3, connect - to pin 2. Blow into the MAF and check that the voltage fluctuates.
2) Measure resistance across pins 4 and 5. At -20C/-4F, resistance is 13.6-18.4kOhms. At 20C/68F, resistance is 2.21-2.69kOhms. At 60C/140F, resistance is 0.493-0.667kOhms. Replace the MAF if results are not to spec.

rkw77080

These may be useful, too...

coug66

this is exactly what I was after, so so helpful. Thank you!!!