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

[chtulu]

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!

 

[Bmettie]

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]

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]

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]

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?

 

[super.secret.supra.club]

check the pins. sometimes they bend when inserting plug

 

[chtulu]

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]

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]

^ 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)]

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?

 

[Faye]

Really curious what you found out, because mine is doing the exact same thing!!

 

[Nick M]

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]

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]

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]

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]

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]

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]

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]

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]

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.