Air Flow Meter problems

[duza]

Tried a search but no joy. I have noticed that if I disconnect the air flow meter plug, my Hilux has much more acceleration, particularly at take off. Could this mean the Air Flow Meter is cactus, or is something else wrong. This is only a very recent conversion and the motor is out of an early 90s Celsior. I haven't tested for error codes yet, as I don't know how to, but when Sideshow wired up the motor everything was OK.

Ric

 

[och]

Tried a search but no joy. I have noticed that if I disconnect the air flow meter plug, my Hilux has much more acceleration, particularly at take off. Could this mean the Air Flow Meter is cactus, or is something else wrong. This is only a very recent conversion and the motor is out of an early 90s Celsior. I haven't tested for error codes yet, as I don't know how to, but when Sideshow wired up the motor everything was OK.

Ric

It's something else, and I think it's heat related, because I have the same situation, and I already replaced the sensor, with no luck. However, try driving without your MAF for 30 minutes or so, when the engine is nice and hot, and it should lose all the extra acceleration.

 

[SCV8]

I recall a rich, default mode on my SC when I forgot to plug the sensor back in after doing some work.

 

[duza]

SCV8,
Yes if the AFM is disconnected or inoperative, the ECU has a default set of values it uses, which may or may not be rich and therefore may or may not be heavy on fuel. I could just keep driving around with it disconnected, but I would like to get to the bottom of this before I get LPG fitted.
I thought I had fixed it yesterday when I completely substituted the AFM and the Karmen Vortex housing for another. I even opened up the entry point to the housing where the air cleaner (a Commodore V6 one) bolts to the Lexus vortex so the honeycomb is completely clear and replumbed the intake pipes between the AFM and the throttle box, but when I took off hard at the bottom of a large hill close to home, it was still the same, gutless.

OCH,
Assuming all the wiring to the AFM is right, (sideshow will confirm this next Wednesday) then, yes it must be something else. It's not overheating, but the ECU may think so. I don't think it's an O2 sensor, I'm really bushed here. Any more suggestions would be good, guys.
Ric

 

[och]

SCV8,
Yes if the AFM is disconnected or inoperative, the ECU has a default set of values it uses, which may or may not be rich and therefore may or may not be heavy on fuel. I could just keep driving around with it disconnected, but I would like to get to the bottom of this before I get LPG fitted.
I thought I had fixed it yesterday when I completely substituted the AFM and the Karmen Vortex housing for another. I even opened up the entry point to the housing where the air cleaner (a Commodore V6 one) bolts to the Lexus vortex so the honeycomb is completely clear and replumbed the intake pipes between the AFM and the throttle box, but when I took off hard at the bottom of a large hill close to home, it was still the same, gutless.

OCH,
Assuming all the wiring to the AFM is right, (sideshow will confirm this next Wednesday) then, yes it must be something else. It's not overheating, but the ECU may think so. I don't think it's an O2 sensor, I'm really bushed here. Any more suggestions would be good, guys.
Ric

I have done so much trying to fix the problem, and no cigar so far. Read my thread here:

http://lextreme.com/forums/showthread.php?t=8444

And I'm pretty sure it's somehow heat related, because my engine isn't overheating, however it runs very well, and has a lot of torque while its still cold, but once its warmed up, it becomes really gutless, and there's some slight pinging, mostly noticeable at 1200 RPMs.

 

[mshawari1]

Tried a search but no joy. I have noticed that if I disconnect the air flow meter plug, my Hilux has much more acceleration, particularly at take off. Could this mean the Air Flow Meter is cactus, or is something else wrong. This is only a very recent conversion and the motor is out of an early 90s Celsior. I haven't tested for error codes yet, as I don't know how to, but when Sideshow wired up the motor everything was OK.

Ric

Strange !!

If I disconnect my MAF "LS400" the engine can ideal but never accelerate …..​

 

[duza]

I would have thought the motor wouldn't drive but only idle too, but I have done a lot of searching on this forum to confirm my results. I have driven around with it physically disconnected for at least 3 days, now and am paying the price by using heaps of fuel.

Yesterday, the symptoms changed completely, however. Took off after buying some stuff from Repco and the car will rev to about 1500 RPM then it dies and drops to idle with some considerable shaking of the motor. If I slowly increase revs, I can get it up to driving speed, but if I try to accelerate normally, it dies and drops back to idle. With the car stationary, in neutral, I can rev it freely and hold those revs and the problem is the same no matter whether I have the AFM plugged in or not. I suspect it must be a speed sensor type problem, as it only happens when the vehicle is moving, but there are 2 speed sensors on the auto, I think and hopefully when I read the diagnostic codes tonight I will have a better idea of what is going on. One of those sensors was the one I modified and fitted into my transfer case, so I wonder if this is now cactus and was actually my problem all along. I did the mod of cutting down the 4 output sensor which Madmont detailed when mating the Lexus trannie to a Hilux transfer and maybe it has not been working correctly and is now not working at all.

I would also like to know how to connect a check engine light into the diagnostic connector on the engine. I know how to short the 2 terminals to read the codes, but as I don't have an in dash light, would like to fit a temporary one at the diagnostic plug.

Would appreciate any comments by Madmont, Zuffen and Mattmanx or anyone else with some input.
Ric

 

[Peewee]

+B -GLOBE- W

 

[duza]

Ok,
Tonight I did a diagnostic check and came up with:
code 41 - Throttle position sensor
code 47 - Sub throttle position sensor
code 28 - Main O2 sensor

I don't know where the two throttle position sensors are. Anyone please?
Ric

 

[duza]

OK,
Think I solved the problem. Re-plumbed the intake properly this time and replaced the RH O2 sensor. Cleared the diagnostic codes, which was difficult to do. Codes 41 & 47 did not want to clear except by disconnecting battery completely for several minutes, but now there are no faults and Voila, it's actually running OK. Still have no kickdown from 2nd to 1st though. Any ideas? Please someone must have a theory.
Ric

 

[XR8tt]

Check that both TPS are working correctly ???
I guess one would be for auto ???
Run a multimeter over both of them...