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 very rich when cruising, very lean at WOT
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The Bloody Panda


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394 posts [99%]
Lebanon OH

 very rich when cruising, very lean at WOT Reply  Edit


First of all, the setup I'm running just started having this problem today and this hasn't been an issue for the prior 3 years I've been driving the car. I have an air/fuel ratio gauge and I'm off the scale when cruising because of how rich I am, when at WOT I'm off the scale because of how lean I am. The gauge reads anywhere between 10.0 and 18.0.

I have a Silvertop running on a Blacktop ECU with Velocity stacks. Anybody got any advice for me as far as the likely causes of this sudden change? Prior to today I ran around 12.0 when at WOT and I never really paid much attention when cruising but I believe it was just a touch on the rich side.



gaijin_rokurunner




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1990 posts [100%]
UPPER MARLBORO MD

 Re: very rich when cruising, very lean at WOT (The Bloody Panda) » Reply  Edit


you check your O2 sensor
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: very rich when cruising, very lean at WOT (gaijin_rokurunner) » Reply  Edit


It looks like that might be it. I need to get an O2 sensor with 4 wires and soder it to my current plastic connector. Got any suggestions on which Toyota O2 sensor would be both suitable for this and the least expensive at my local auto parts store?

Even better would be if there is one that requires no sodering and will plug into my factory Blacktop wiring harness.

jondee86
Reggae Rules...



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4374 posts [96%]
Wellington, NZ

 Re: very rich when cruising, very lean at WOT (The Bloody Panda) » Reply  Edit


How does the car drive ? Same as usual, or making black smoke, back firing or
missing, weak etc ? If the car drives the same as usual, maybe your a/f gauge
took a dump ?

Cheers... jondee86



jondee86 has been a member for 735,126 days.

Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

gaijin_rokurunner




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1990 posts [100%]
UPPER MARLBORO MD

  » Reply  Edit


I can price and get a new one for you from japan...i heard the MR2 turbo one works but cant confirm that info....might be a cross reference somewhere
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: very rich when cruising, very lean at WOT (jondee86) » Reply  Edit


I'm thinking the car seems weak, but I can't be totally sure. After I saw it going incredibly lean at WOT I didn't want to push it.
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (gaijin_rokurunner) » Reply  Edit


I paid something like a hundred bucks for one a few years ago. I can't remember exactly what it was out of but it might have been a newer Tundra. Depending on the price I would love to get the genuine article from Japan. Please price it and let me know.
gaijin_rokurunner




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1990 posts [100%]
UPPER MARLBORO MD

 Re: (The Bloody Panda) » Reply  Edit


Price is 190 dollars plus about 35 international shipping
Crownvicman289




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1984 posts [58%]
Colorado Springs CO

  » Reply  Edit


I re-pinned a 16V 4 wire O2 sensor to work with the 20V. Drove the same as with the 20V sensor, but was new and bolted to my exhaust in the MR2. OP it sounds like your gauge reads off a narrowband sensor, ditch that and get a wideband or you'll never know what your AFRs are. Even the Greddy medium band would do, but since it's more expensive than an AEM wideband, I'd just go with the AEM which can be had for $200-220 shipped.
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (Crownvicman289) » Reply  Edit


I didn't know the 16V O2 sensor came in a 4 wire configuration.

I am running an AEM wideband for my readings. Ever since I adjusted my timing after installing it 2 years ago my AFR has been good, until now.

The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (gaijin_rokurunner) » Reply  Edit


That is pricey, but seems reasonable. I may take you up on that offer gaijin but I'm going to see how expensive the local option is first.
gaijin_rokurunner




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1990 posts [100%]
UPPER MARLBORO MD

 Re: (The Bloody Panda) » Reply  Edit


let me know thats cost with the conversion....and its OEM so u dont have to worry about funny plugs and stuff....Let me know I will be ordering some stuff in the next week or so and I can order the 02 with it if you decide you want it.
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (gaijin_rokurunner) » Reply  Edit


It's looking like I may have found an alternative. If I do order it and it works I'll let you know then that your source won't be necessary.
foonix


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65 posts [100%]
null null

 Re: very rich when cruising, very lean at WOT (The Bloody Panda) » Reply  Edit


For just a little bit more than that price you can get a wideband controller with a sensor, a guage, and with a traditional O2 signal output. It's just two more wires to power the controller and a wire to patch the traditional style output to the ECU. It may be cheaper in the long run as the sensor its self is cheaper.
gaijin_rokurunner




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1990 posts [100%]
UPPER MARLBORO MD

 Re: (The Bloody Panda) » Reply  Edit


no problem....if you need any other factory parts I have a direct connect to toyota japan...
yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: (gaijin_rokurunner) » Reply  Edit


So you have been running the same WB sensor for a few years now? That is as likely the problem as anything. They are known not to last too long.

Your NB should have no effect at near WOT operation. If you are getting incorrect AFRs at WOT I would look elsewhere. At wot the ECU goes into open loop and ignores the 02 and just goes to pre written maps based almost entirely off the TPS and AFM or TPS and MAP depending on the motor.
I would suspect your WB sensor first though.




http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (yoshimitsuspeed) » Reply  Edit


Excellent advice. Maybe it is just merely my wideband in that case. I didn't know the TPS and MAP would tell the ECU to run a certain way and ignore the narrowband O2. I'm replacing the narrowband O2 today regardless because it's been in the car for around 8 years (getting a Denso model intended for the Subaru WRX). All these years I've had the car though certainly don't add to very many miles. I've definitely put less than 5000 miles on the 86 over the course of nearly a decade.
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (The Bloody Panda) » Reply  Edit


Well, replacing my narrowband and wideband O2 sensors did nothing to improve the A/F ratio readings. I'm going to do an engine diagnostic next and if that tells me nothing I'll replace the MAP sensor and TPS sensor, MAP first since I have one handy. However, I did notice today that a couple times when I floored it the off the scale lean A/F reading was starting to fall back down a little bit but I only ever saw it get down into the 15's. I never took it above 5000rpms though either for fear of damaging my already abused Silvertop.
The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (yoshimitsuspeed) » Reply  Edit


So I tried out two different MAP sensors just now and saw little to no change. However, as I'm learning more about this problem I'm wondering about the way the TPS works. Could the Throttle Position Sensor be slow to respond or if broken could the MAP sensor sort of make up for it but just with slower adjustments to A/F? The situation when I drove tonight that caused the car to run the most lean was when I would quickly go from say 1/4 throttle to 1/2 throttle. When I do this the car reads off the scale lean on the A/F ratio but if I continue to leave the throttle 1/2 open for another second or two it will richen up the mix and run something more reasonable. When I floor it I still can't seem to get any richer than 15 A/F where as before when flooring it I was always in the 12's.

My logic is probably flawed since I don't know much about the way this stuff works. But right now I'm thinking maybe the MAP sensor is making up for the TPS being messed up and telling the ECU to richen up the mix, but it's just taking longer to do than if the ECU could see when I'm quickly changing from 1/4 throttle to 1/2 throttle. Can anybody tell me why this wouldn't be the case?

yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: (The Bloody Panda) » Reply  Edit


Try disconnecting the TPS and see what happens.

How is your MAP sensor hooked up? Where is it's reference? Is it just referencing one cyl or is it tied into all the ports?



http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
jondee86
Reggae Rules...



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4374 posts [96%]
Wellington, NZ

 Re: (The Bloody Panda) » Reply  Edit


Almost sounds like the MAP sensor signal is inverted ?? Maybe you should check
that you haven't accidentally got a couple of the wires at a splice ?

Vcc should be your 5V constant supply from the ECU
PIM the variable signal out from the MAP sensor to the ECU
E2 is the sensor ground on the ECU (not chassis ground)

At atmospheric pressure (WOT), the PIM voltage should be high (>3.0V)
At high vacuum (cruise/idle), the PIM voltage should be low (<1.5V).

The actual values are not critical, just so long as the voltage increases when you
stab the throttle (or get your favorite g/f to apply a vacuum to the tube)

Cheers... jondee86



jondee86 has been a member for 735,126 days.

Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (yoshimitsuspeed) » Reply  Edit


Thank you for the advice, I disconnected the TPS and other than the really high idle my 86 ran as good as it ever has. A/F ratio adjustments became immediate as soon as I would get on the throttle. I'm curious to see what my car runs like after replacing the TPS.

Also, I'm assuming there must be some difference between all these MAP sensors that Toyota has out there. Do you know the part number for the correct MAP sensor for the 4ag Blacktop?

The Bloody Panda


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394 posts [99%]
Lebanon OH

 Re: (The Bloody Panda) » Reply  Edit


I see that the MAP sensor is either 89420-12070 or 89420-12140, maybe both are correct.
yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: (The Bloody Panda) » Reply  Edit


Quote, originally posted by The Bloody Panda »

Also, I'm assuming there must be some difference between all these MAP sensors that Toyota has out there. Do you know the part number for the correct MAP sensor for the 4ag Blacktop?

Yes many different MAP sensors have many different specs.
Some sensors will measure from about 0 PSIA to about 15-16 PSIA which is just over atmospheric pressure at sea level. For something like an NA car or a barometer that is all the range needed. Then some will measure from 0 absolute to several times higher than atmospheric. Others will not start at absolute.
Most sensors operate on a 0-5 v signal but you also would not want to count on that as there could be exceptions.
What this means is if you have a 0-16 PSIA sensor then it might read 4.8 volts at sea level telling your ECU the throttle is at WOT. If you put in a 0-45 PSIA sensor then at sea level WOT it would put out closer to 1.5 volts making the ECU think the throttle plate was closed or less air was traveling into the engine than there really was.

I don't know the part number for the BT MAP though sorry.
I would say see if the new TPS fixes you up. If so I wouldn't worry about it.



http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
 



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