Lexus AFM, 550cc Lucas, Aero AFPR...

[ojonesjr]

This weekend I did the Lexus AFM, 550cc, and AFPR upgrade. All went well for the most part. Even put in NGK plugs and MSD plug wires. I started the car and Adjusted the AFPR to 32 or so. Some issues I have now are:

The idle one notch above 1 and flickers. I adjusted the AFM screw not much diff... The low idle caused some knocking...When revved to 2000rpms or hire the knocking stopped as the oil pressure went up.
Lastly, seems there is hesitation when I step on the gas.
I have the Walbro fuel pump but have not installed it yet. Just wondering what I should be doing to get my idle up and stop the hesistation.

List of upgrades thus far:
New engine
Upgraded turbo
FIPK
3INCH all the way back
Random high performance cat
HKS SSQV BOV
LEXUS AFM
550cc Lucas Peak and hold
AERO AFPR
Walbro on the way (Not in yet)
Any help is appreciated.

 

[jdub]

Increase your fuel pressure in increments. Mine (same set-up) would start hesitating at higher boost...when I installed the Walbro, solved the problem. I also run my pressure at about 40 psi. You might just have an old, tired fuel pump.

Also, did you drill out the "J" tube to remove the restriction? That can cause fuel flow problems on this set-up, but mostly at higher boost.

While you're there dropping the tank, replace the fuel filter...much easier to get to with the tank off!

 

[ojonesjr]

Increase your fuel pressure in increments. Mine (same set-up) would start hesitating at higher boost...when I installed the Walbro, solved the problem. I also run my pressure at about 40 psi. You might just have an old, tired fuel pump.

Also, did you drill out the "J" tube to remove the restriction? That can cause fuel flow problems on this set-up, but mostly at higher boost.

While you're there dropping the tank, replace the fuel filter...much easier to get to with the tank off!

Nice...!...I did not remove the J tube restriction. Can I just cut the j tube off? I'm happy to know the Walbro may solve the issue. I don't have any plate to replace it with.

 

[GrimJack]

Yes, you can just cut the end off, or bypass it entirely.

 

[ojonesjr]

Ok...Will be doing the Walbro this week sometime. What about the oil pressure being low. Is that a product of the low idle? Don't want to screw up my engine.

 

[jdub]

If it's a clicking sound, you might be hearing your new injectors :naughty:

If you're getting normal oil pressure like in the past, it's probably not a problem.

 

[shaeff]

Increase your fuel pressure in increments. Mine (same set-up) would start hesitating at higher boost...when I installed the Walbro, solved the problem. I also run my pressure at about 40 psi. You might just have an old, tired fuel pump.

Also, did you drill out the "J" tube to remove the restriction? That can cause fuel flow problems on this set-up, but mostly at higher boost.

While you're there dropping the tank, replace the fuel filter...much easier to get to with the tank off!

you're running 40psi on 550's? that's WAY too much fuel pressure! every car is different, but if you need that much pressure on 550's i'm willing to bet something's very wrong, like a clogged fuel filter or something!

i run mine at like 28psi with no vacuum line attached.

-shaeff

 

[jdub]

I was having a problem approaching 18 psi boost (I hit fuel cut at ~ 20 psi); the motor would "hesitate" kinda like a mini fuel cut, but only for a split second. Also had the following readings at 18 psi:
AFR ~ 13.5 Idle was 14.5, normal cruise 14.5
EGT 750 deg C (~ 1380 deg F) at boost

I changed to the Walbro (new fuel filter) and got the same thing. I increased the fuel pressure over a period of days to it's present value of 40 psi at idle. The hesitation stopped and I get the following readings:
AFR 10.5-11.5 at boost, idle 15.5, normal cruise 14.5
EGT 700 deg C (~ 1290 deg F) at boost

My entire fuel system is new and the FPD is removed...the R/C injectors were tested prior to installation. Based on other's experiences, the above numbers look pretty normal for the boost I'm running. Other than my gas mileage being in the pits (which I expected for this set-up), am I missing something? Why are you running no vac line to the FPR?

BTW Shaeff - I read your build-up thread - my motor is built very simular to yours. The head is a street port/polished w/ 1mm oversize valve & TRD springs...I also have Ross pistons and Crower rods on a fully balanced/blue printed bottom end. I'm running a SP 61GT Turbo as well on a stock (fully ported) manifold with a SP downpipe that came with the turbo. I have Cooleze hardpipes on a CarTec intercooler...all 2.5" piping.

 

[jdub]

Follow-up:

This discussion got me thinking, so I looked it up in the TSRM here:
http://www.cygnusx1.net/supra/library/TSRM/fi/FI_073.html

The fuel pressure with the vac hose disconnected should be 33-40 psi for the GTE motor and 23-30 psi with the vac hose connected to the VSV. This is for a motor with 440 injectors and a stock FPR.

I went out and checked the vac hose routing on my motor just for grins and guess what? The vac hose going into the VSV was just hanging there! I connected it and the pressure dropped to 30 psi.

So the fuel pressure on my motor was at the top end of the TSRM spec (40 psi) with the hose disconnected...same when I re-connected the hose. Running 550 injectors, this should not be a problem.

BTW - I probably never would have looked if I had not seen this thread.
Good discussion!

 

[Red Dragon]

Good find there John.

I have my FPR plumbed directly to one of the two vac connections on top of the Thottle Body (removed all the EGR stuff) and it seems to run fine. I am wondering how you guys get such low EGT's under boost.... I always seem to be approaching 1600 when I really get on it. I think I run way to rich (near 10, sometimes under I think b/c my wideband will just "stick" at 10 at WOT sometimes) which could be it, but does anyone know/think that getting it to around 11.5 at WOT will drop my EGT's? I'm only boosting to around 1-1.1 bar.

Also, I've noticed that when puttering around real easy-like, my fuel pressure drops into the low 20's (idle at 29-30 w/vac) and it always kinda worries me. I don't lean out (stays around 15ish). Once on the boost I get up to low 40's, but wondering if this is normal to have a drop from idle pressure at low speed cruising.

I have lex AFM, RC 550's, Mazda Cosmo fuel pump (comparable to Walbro), adjustable FPR, HKS sport turbo, bunch of other stuff.

edit: where are you measuring your EGT? Mine is in the tapped hole in the HKS sport turbo at the exhaust side flange. At highway cruise (3k-ish) I get 1200. What do you guys get for highspeed cruise EGT's? Oh and I have the HKS intercooler/hardpipes

 

[jdub]

The VSV that controls the FPR is part of the "Fuel Pressure Control System"...it has a harness connection to the ECU labeled VSV2.
http://www.cygnusx1.net/supra/library/TSRM/fi/FI_116.html

To be honest...I'm not real sure of the function, but it's not part of the EGR system. That might be why you get the psi drop at normal speeds :dunno:

My EGT probe is on the turbo snail, about an inch from the flange on the engine botton side. The most I've seen is ~1400, but I can't go WOT cause I'll hit fuel cut. I'm installing an AEM EMC in a few weeks to take care of that problem :naughty:

I thought that fuel was one way the 7M keeps temps down...following that logic, running rich would produce a lower EGT. But then again, these motors are so heavily modified, the opposite could be true too. Maybe someone else with more insight will chime in here.

You got your timing advanced over 10 deg?

 

[Red Dragon]

the more fuel for lower temps thing is true, but only to a point, when you run too rich you actaully get higher EGT's so I'm wondering if this is part of my problem. Yes I need to check my base timing, its been a while. That could have something to do with it. As for the VSV and the FPR thing, it never ran very well with all that crap in there, so its all gone and the FPR is plumbed straight in to the TB. Perhaps I should revisit that logic.... Other than the high temps the car seems to run like a champ with this setup....

 

[GrimJack]

The fuel pressure VSV is only used on warm startup. On warm startup, it switches the FPR to use atmospheric pressure instead of manifold pressure to combat heat soak.

Removing it might make your engine harder to start when warm, that's about it.

 

[Red Dragon]

The fuel pressure VSV is only used on warm startup. On warm startup, it switches the FPR to use atmospheric pressure instead of manifold pressure to combat heat soak.

Removing it might make your engine harder to start when warm, that's about it.

awesome, good to know. Thanks.

anyone have an opinion on the effect (numbers wise) getting my AF up from 10 to around 11.5 at WOT would have on my EGTs? I hoping being at 10-ish is around the area where you get higher EGT's in the rich direction, and so raising them will help get my EGT's under control

 

[mmarkk]

^i hit EGT's of 1470-1530 all the time when boosting.
dont even have to go wot for that.
i'm going to try to lower the a/f (10.1-10.5 at boost) and see if the egt's go down.