lexus afm +550cc injector mod not working. using stock AFM housing.

chtulu

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Hey guys, it's been awhile. I have a new supra and just got it back from the shop with light valve job and a metal headgasket put on. While it was in the shop I decided to put on 550cc injectors, an AFPR, bigger fuel pump, bigger intercooler, and a BW s360 turbo on it. When I put on the lexus afm housing it runs lean. roughly 17-18 at idle. ( i have a air/fuel meter). When i swap back to the stock AFM housing i get a reading roughly 14.6-15.0. I have the boost set to 11.6lbs. While cruising it runs like a dream and WOT it's at 10.1-10.8 or so.

Just to recap:



Lexus afm + 550cc injectors + AFPR at 45psi = 17.0/18.0 idle with 14.6 or so at cruise and 10.1 at WOT full boost.

update: Bought another stock afm, tested both and they are within spec at about 4600/4900ohms at 36degrees outside F.


I've replaced the plugs with new NGK V power copper plugs with a 2.6 gap. Before that it had iridium NFK plugs with a 2.0 gap.

Any help would be great!
 
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Bmettie

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Code 31 relates to the sensor not the housing. You're maintaining the sensor and swapping housings, right? Did you clean the AFM? Try a new/different sensor, after that check the wiring from the connector all the way to the ecu.

What did you set fuel pressure to with your AFPR?

I'd also say that the sputtering is related to the AFM issue, stop boosting until you figure this out.
 

suprajim54

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Which injectors are you running? High impedance or Low? I have the High Impedance RX-7 injectors in mine. Everything I read said it should work fine with the resistor pack still connected, but mine had symptoms similar to yours. I removed the resistor pack and although I sometimes read a little lean (16.0-17.0) at idle, all is fine at cruise (cross-counting ~14.7) and WOT is way rich (10.0-11.0).
 

chtulu

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My injectors are 550cc rc low impedence. I used compressed air to try and clean the afm. I'm using stock afm with stock housing right now. It runs even leaner with the lexus housing.

I'm scared to try to clean it with any kind of electronics cleaner simply because I hear it usually ruins it. I've adjusted my fuel pressure from 35 to 44 and it seems to have no affect.

I' drilled out the lexus afm screw cover and screwed it all the way in and will see if that helps with the Lean issue.

so is what people say is that there shouldn't be a code 31 when doing the lexus/injector mod?
 

suprajim54

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There should not be any codes caused by the lexus/550 mod. Like Bmettie says, Code 31 is the sensor, not the housing. ECU is not getting a signal from the AFM. Did you have the code before you put the 550's in? Any issues with the plug at the afm or the wiring to the ECU?
 

chtulu

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Pins look good. There was no code prior to all the upgrades. I'll check the wiring out. Maybe its just a coincidence that the AFM would go out right after I put in everything and start it up for the first time?
 

Rollus

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Try to reset the fuel trim learned values stored by the ECU. Remove the EFI fuse for 15+ seconds.

With 550cc injector, the corect housing to use is the Lex one. AFM Sensor from stock housing should be prefered if known to work.
 

Bmettie

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^ Yes reset the ecu, after that monitor the Vf signal coming out of the ECU (it's at the diag box as well). This will at least tell you how hard the ecu is working to maintain stoich.
 

Suprapowaz!(2)

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Have you made any adjustments to the AFM screw, or AFPR? Those two adjustments will be a delicate balance while maintaining Vf in closed loop. Open loop I'm sure it'll be rich.
What's your current base fuel pressure?
 

Nick M

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I've read everywhere that people should be running rich WITH the lexus housing and 550cc injectors, yet im running lean with the lexus afm +550cc injector combo.
You read wrong. Not that you can't read, but what is written. As already stated, you have a malfunction which is why you have DTC 31.
 

supraguy@aol

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I PM'd Cthulu, asking him to give updates.
I hate unresolved threads. If results aren't posted in the threads, there's no point to using the search function,
and that's why we end up with multiple threads on the same topics, and we're always yelling at people to use search.
 

aheroicrevolt

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I am running Low Impedence 550's from an 87 rx7 turbo2.....and the AFPR and the Lexus housing.
I TOO am extremly lean. 21 pegged out on the Wideband gauge lean. I cant get it to start unless i hold the throttle all the way open and then it coughs and sputters to life. Been trying to solve this issue for years. Car has been down for 2 years. please post your results!
 

Supra mn

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I am running Low Impedence 550's from an 87 rx7 turbo2.....and the AFPR and the Lexus housing.
I TOO am extremly lean. 21 pegged out on the Wideband gauge lean. I cant get it to start unless i hold the throttle all the way open and then it coughs and sputters to life. Been trying to solve this issue for years. Car has been down for 2 years. please post your results!
In regards to this, I had the same problem running the rx7 injectors. People say it works without a problem.. I wasn't so lucky and it seems neither are you.
However, it is an easy fix. Since the injectors are high impedence, and stock are low, you need to unplug the resistor pack, cut off the connector from the wiring harness side, and solder those 4 wires together.
Or if you're like me and don't enjoy hacking up your harness, go to a junk yard and find a plug that'll connect to your wiring harness, solder those 4 wires, and connect them.
Your lean problem should be fixed. Hell, I run overly rich now. But that's nothing some afpr/lex afm/safc adjustments can't fix.
 

Bogwon

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In regards to this, I had the same problem running the rx7 injectors. People say it works without a problem.. I wasn't so lucky and it seems neither are you.
However, it is an easy fix. Since the injectors are high impedence, and stock are low, you need to unplug the resistor pack, cut off the connector from the wiring harness side, and solder those 4 wires together.
Or if you're like me and don't enjoy hacking up your harness, go to a junk yard and find a plug that'll connect to your wiring harness, solder those 4 wires, and connect them.
Your lean problem should be fixed. Hell, I run overly rich now. But that's nothing some afpr/lex afm/safc adjustments can't fix.
It's been awhile since doing the lex/550 mod but I recall that my RX7 550cc injectors were high impedance and didn't require the stock injector resistor pack. I had a very lean running car right after with an AFPR, RX7 550s, Lex AFM, wide band AFR gauge, intake and 3" turbo back. It wasn't until the SAFC II piggyback that I was able to really dial in the AFRs to an acceptable range.

I read also that people experience an extremely rich condition after the lex/550 mod but wasn't the case for my situation. Results may vary.
 

Nick M

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I am running Low Impedence 550's from an 87 rx7 turbo2.....and the AFPR and the Lexus housing.
I TOO am extremly lean. 21 pegged out on the Wideband gauge lean. I cant get it to start unless i hold the throttle all the way open and then it coughs and sputters to life. Been trying to solve this issue for years. Car has been down for 2 years. please post your results!
The Lexus housing and 550 low impedance injectors don't cause a lean condition. You need to look elsewhere. Hope that helps.
 

chtulu

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Back again, sorry I haven't updated this in awhile.

Anyways, the problem still exists. Another update is that I have a code 52 for my knock sensor being open or short. I ordered another one and also will be rewiring both since I replaced the back one only a few months ago. Could this be potentially what would cause the Bucking and richnesss at WoT?
 

supraguy@aol

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Code 52 will cause a limp mode situation, since the knock detect system is compromised, and thus the engine will adjust to avoid potential knock. Not sure if this includes retarded timing, over fueling, or both.
 

atmperformance

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Code 52 will cause a limp mode situation, since the knock detect system is compromised, and thus the engine will adjust to avoid potential knock. Not sure if this includes retarded timing, over fueling, or both.
as someone that had the issue not long ago, yes it does retard timing. you'll be luckily to rev much over 4k as power just falls.
 

Rollus

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Plus, in limp mode, AFR should be proportionnal to throttle position.

I guess for knock it is not really limp mode, but a failsafe ignition timing. In any case, every code has to be adressed in order to have good settings from ECU.
 

chtulu

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I really appreciate all the effort everyone is putting in on this thread. Another question I have is if I just buy the HKS VPC to get rid of the AFM issues can that be used in conjuction with the HKS FCD and AFPR to tune it enough before going complete stand alone? Or do I need a SAFC II WITH the hks VPC?
 

Nick M

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The AFM issues are not because of the AFM, they are because of other things wrong. Unless the reflector or LED is soaked in K&N oil.
 

chtulu

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The AFM issues are not because of the AFM, they are because of other things wrong. Unless the reflector or LED is soaked in K&N oil.
Could you name some things I could be looking at? Unless the knock sensor code 52 can directly affect the code 32? I'm trying to isolate one problem at a time here, if possible. I test the AFM and the resistance is at 4900 at about 34-38 degrees F outside. Where should I look next?
 

chtulu

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Ugh, nevermind about anything on this thread. The Code is 34. My mechanic didn't read the diagnostic right. So now It seems i have a boost leak somewhere. But with such a big turbo at 15lbs I'm guessing its coming from my BoV.
 

chtulu

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So I cleared the sputtering issue at WOT. Wasn't getting enough air via the stock AFM housing. Lexus AFM housing now gives me super lean readings at idle but I can boost all day long with WOT around 10.1 A/F ratio. Any idea why I would be leaning out so hard just sitting there?
 

atmperformance

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you can play with fuel pressure and the housing adjustment screw that will most likely be under epoxy.
 

Rollus

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I would set FP to stock spec, and play with AFM.

Don't forget to reset ECU learned fuel trim by pulling the EFI fuse after modifications on the fuel/air metering system.
 

chtulu

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Ok,

Screw is all the way in, and i adjusted the FP to 30psi idle without vacuum. took out the EFI for 5 minutes and tried again. How long does it usually for the ecu to adjust it's map? Because it hasn't done anything yet when I did this the first time.
 

Nick M

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So now It seems i have a boost leak somewhere. But with such a big turbo at 15lbs I'm guessing its coming from my BoV.
You don't necessarily have an intake leak. With a big turbo you can easily hit overboost fuel cut and it has nothing to do with a leak. The larger housing slows the frequency raising the point at which fuel cut occurs.

Ok,

Screw is all the way in, and i adjusted the FP to 30psi idle without vacuum. took out the EFI for 5 minutes and tried again. How long does it usually for the ecu to adjust it's map? Because it hasn't done anything yet when I did this the first time.
If the screw is all the way, fuel cut happens sooner rather than later. The meter is seeing far more air than a CT-26 can deliver. And for all I know, your fuel pump is not delivering volume. There isn't actually enough information in your posts. There are things to look at from what you have given. If the screw is all the way in, you should not be lean at idle, not even close. 30 psi with the vacuum disconnected is not right. That is fine when there is vacuum on the regulator.
 

chtulu

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You don't necessarily have an intake leak. With a big turbo you can easily hit overboost fuel cut and it has nothing to do with a leak. The larger housing slows the frequency raising the point at which fuel cut occurs.



If the screw is all the way, fuel cut happens sooner rather than later. The meter is seeing far more air than a CT-26 can deliver. And for all I know, your fuel pump is not delivering volume. There isn't actually enough information in your posts. There are things to look at from what you have given. If the screw is all the way in, you should not be lean at idle, not even close. 30 psi with the vacuum disconnected is not right. That is fine when there is vacuum on the regulator.
I apologize, i meant 30psi with vacuum connect at idle per TSRM. http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=73

The lexus AFM with the screw all the way in or out doesn't seem to make a huge difference at idle. I don't hit fuel cut at all with the lexus afm housing. I just run really lean at idle.
 
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chtulu

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Not that I think your AFM is bad but you're not testing the part of it that really matters by doing the above. Second, many of these engines run lean at idle. Why care? You don't drive it there.
I realize Im not hurting it idling lean, but when it dips to 19-20 it almost dies and blows out smoke. It's more of making it somewhat driveable. especially sitting at a stop light. I also don't have a filter on it currently. Would the restriction from a air filter help at all?
 

Suprapowaz!(2)

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What's it doing cruising around. Where are the AFR's, and what is Vf1 displaying? I'd work on getting the idle and cruise happy first. I wouldn't worry about WOT so much right now.

Having the lex afm screw all the way out and fuel pressure that 30psi vac unplugged will lean things out quite a bit at idle and closed loop. But that's how you're maintaining 10.1:1 at WOT with that big turbo. That's still rich though. I would concentrate on getting closed loop to run acceptable AFR's. That's going to leave you with a super rich condition at WOT. It won't run good under heavy load.

You're going to have to go with some kind of piggyback to pull fuel in open loop.

Will you be doing all of this yourself, or having some kind of assistance? Where are you located? Maybe someone in your area be able to help you.
 
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chtulu

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Cruise is fine. 14.6 ish if I'm keeping a steady pace. Partial boost goes to 12 to 12.5 and wot is 10.1. It runs great besides the idle. If it were the tps I assume I'd get a cel for it? Maybe I'm naive in that area.

I have screwed the lexus afm screw all the way in to try and reduce air flow as well as turned the fuel to 30 psi with vacuum connected. Even cranking the fuel to 50 psi doesn't change the idle at all.

I'm in washington state. I haven't really found anyone knowledgeable yet for help on this car. I'm thinking of just buying a safc neo and manually changing the fuel trim for idle.