I'm pretty sure that if you take the vacuum line off the boost sensor, then plug the vac line so you won't have a air leak, that each and everytime that you rev above 3500rpm, the secondary injectors will come online.

I have not done that in some time, but I'm fairly sure the voltage drop won't be nearly as great as when actually driving the car. Give it a twirl and see what happens. There is a procedure in the fsm somewhat similar to this.

 

ok ill try it, i might not beable to do it tonight we are having alot of rain and my garage has standing water in it so i will probably do it tomorrow and post what happens

 

First of all, you need to provide more info on your setup, because as Hailers said, you are going to run into more problems in the future the way you described it. Unless you have really put a lot of boost into your car with this turbo, you have no need for 680 injectors IMHO. What kind of turbo did you use?? I would also be interested in knowing how exactly you set this up--many of us would LOVE to turbo our NA's and if you have found a easier way to do it, then share it!! lol

When you unplugged the secondaries, it did the same thing--that is because they are not coming on anyway. Seriously, I think that mouchyn was onto something--if the ecu reads the vacuum off the pressure sensor as a method of triggering the secondaries, then what will it do when there is PRESSURE instead, then it WILL NOT tell the secondaries to come online. We all know that the secondaries come on around there, but what you need to do is find out WHAT tells the ecu to use them. If it is some sort of RPM activated switch, then you will have to look there, but if it is actuated off the pressure sensor, then that is where I would look first. sure, you use the s-afc to control fuel delivery, but everything else is still run off the ecu.

PLEASE get us more details of how you set this up in your car. Pics also if you have any!!

 

if you read my first post i said what i did i made a custom lower intake manifold that gave me almost enough clearance. i had to make a exhaust manifold spacer about one inch thick. i got a madrel bent 3in stainless steel exhaust for a turbo 2. i have a stock s4 turbo and exhaust manifold that i am rebuilding because it is leaking oil. i ran my coolant feed line off of the heater core coolant line i ran my coolant feed line into the radiator that i tapped a fitting into. i got the oil feed line off of the oil cooler that i made a tee fitting where it feeds into the bottom of the front cover. the oil return line goes into my oil neck because i originally tapped it into the oil pan but i thought that the oil leakage was happening because the oil line was above that fitting. i front mounted a starion intercooler and ran 2 1/4 inch intercooler piping. for the primaries i have 550's and secondaries i have 680's my fuel pump i have a walboro 255lph. i have an adjustable fpr and apexi s-afcII for fuel control. the reason i put the 680's in is because i wanted to make sure i have enough fuel to start with because i am not going to be stupid and take a chance of predetonation or leaning my **** out. if the 680's arent enough i have more 550's i can put in. on the drivetrain side i have a four puck clutch with heavy duty pressure plate new pilot bearing,throw out bearing and transmissions front cover. rubber im running kuhmo ecsta mx's 255/45/17 in the back 225/45/17 in the front the diff i am running an open one right now because i messed up my lsd which im rebuilding after i fix my turbo and and injector problem right now... let me know if i forgot nething... if you want pics i can post them

 

and if you would like to turbo charge ur na easily put a t2 motor in it much easier. i did this because i like a challenge and i am as i am aware the only person to turbo an na the way i have done it. there is an aron guy that did it but he made a 21/2 exhaust spacer notched his frame rail made some little s pipe to connect his exhaust

and the reason for so much fuel is because i am goign to run 12 psi oh and i ported my wastegate

 

yeah I would like pics.....I really wanna see what this looks like!! When you say that a TII swap is easier, how so? I am looking for all the info I can get because I am looking at running forced induction on my GXL. Have been looking into the sc idea but still would consider a turbo setup as well.

Personally I think you may have overdone it with the 680s like that, but at least flooding is better than starving it. also--could you let me know what you have done to tune it so far?? And any other issues you ran into? PM me if ya want ans thanks!!

 

Two things make the secondarys come on line, whether turbo or non-turbo.

One is the rpms. 3500rpms the way I read the 87FSM.

Two, LOAD as determined by the boost/pressure sensor.

There is a procedure in the 87fsm for the non-turbo to check the operation of the secondary injectors. First you disconnect the vac hose to the boost/pressure sensor and plug the line to prevent a vac leak. Second you rev the engine to over 3500rpms and then listen for the clicking of the injectors.

I've done that procedure on a non-turo car before, with the exception that I used a digital meter to observe the secondarys coming online.

I've done the same routine with my turbo cars....pull the vac line off.....plug it....rev to 3500rpm and observe the seconday injectors come on line (voltage drop at the ECU). I've even done this while driving the car and watching the voltage drop at the ECU pins when 3500rpm is reached.

But what is fun, is.......sitting in your driveway, putting PRESSURE on the boost sensor of over 10psi (with no FCD) and getting fuel cut to the rear rotor.....at idle.

 

well i did do that and it seemed like the ecu was trying to turn them on but not grounding them good enough or something because at 3500 rpms on both injectors they would drop 2v but that was it

and tomorrow or maybe later tonight after i get a few in me i will take some pics of my car and post it... i think its getting pretty sweet but thats also coming from me

 

theyt wouldnt drop to two volts they would just drop two volts from 13 to 11

 

I am currently dealing with the EXACT same problem in my friend's 86 GXL. It will rev fine and dandy under no load all the way to 7krpm and then it revs fine under load up until 3800rpm, then it hits some sort of wall. He will be here in a bit because he wants me to work on it today, so what I am gonna try is to pull the vac line off of the pressure sensor and have him rev it up to see what happens.

if it hits the "wall" at this point, we will follow the procedure on grounding out the ECU better and see if that helps. I will post back here with results.

jlgrif86gxlt: what are you going to try now? we should both try a different fix and see if either one of our "fixes" fixes this problem...

 

all i could think of was grounding the ecu better and i really dont know what to do other than that

u need to check the volts on the secondary signal wires at the ecu when the car hits 3800 and see if they drop to 5-7v like hailers posted earlier

test that and post what they tested at

 

but yeah thats kinda weird we both have the same car 86 gxl. what was he doing when this problem started

 

Jameson I told you it would be hard. I hope you get that beast running soon. If you need any help you can call me.

 

yeah thats no joke, this problem is my huge dilema and the turbo is leaking oil but thats an obvious fix right there, rebuild the turbo

 

actually, it was like that when we bought it. We just went and picked up the car yesterday, and I am fairly certain that it is a problem with grounding. The car came from a moist climate and I noticed that some of the engine bay grounds looked kinda cruddy. We are going to reground everything today and tell you how that works out. I don't have a multimeter, so I can't tell you what the voltage is on them

BTW, this car only has 31k original miles on it, and other than this problem it is utterly perfect. Everything else checks out fine and is in tip-top shape.

 

I kind of stopped reading after the first (completely useless) reply, but is simply sounds like the car is way too rich.

With 550CC primaries and a Walbro, that engine is being drowned. Use the S-AFC to lean it out a good 25% up to 2000 RPM, then tune properly from there.

 

I unplugged the pressure sensor, then revved to redline, plugged the sensor back in and revved it again, then went for a spin and now all is well. Dunno WTF the problem was, but it works now

 

well i did lean it out like that and it runs perfectly fine until 3800 then a damn brickwall and the secondary injector signal isnt dropping to 5-7volts like it should. its going from 13v to 11v at 3800

 

About the dropping to around 5v or less........that would be in forth gear or fifth and really getting on the boost prior to reaching 3800 rpm. The primary duty cycle would be up in the 80 to 90 percent range by the time you reach that rpm.....at which time the secondarys come online and then both primary and secondary injector voltage will drop down to the same voltage which would be in the 5v range.

IF you stomp on the pedal at say 3300 rpm, then when you reach 3800 most likely the voltage will not drop as much.....maybe only in the 7-8volt range.

Since you did see a voltage drop down to about 11v, I think you said, then they are probably coming on.

I did a drive around the block so to speak just a moment ago with the hose off the sensor and I agree that if your in say second gear and slowly going to 3800rpm and above.......that the voltage drop is only down to the 10-11v range......but if I put it in third and go down the back stretch around the block and start stomping at around 2500 then when I reach 3800 the drop is closer to 8v give or take.

Sorry, I'm not going to go out on loop 20 and stomp the pedal in forth or fifth with the boost sensor disconnected. There's a touch of risk in that. With the sensor connected up I KNOW that the voltage will drop down in the 5v or less range IF I'm really on it.

I think you've proven that the secondarys ARE coming on since you saw the drop in voltage at the secondays. You must have been in a lower gear or going gently up the rpm scale.

 

its the boost sensor.. same thing happened to me..

 

when i tested it i was flooring it but my diff is out right now hopefully tonight i will be replacing it some i will try it some more

if it was the boost sensor why would they are still do it when the vacuum line is unplugged?

 

hey aaron cake is that hybrid boltign up to your stock manifold

 

did u unplug the plug as well?? it can only be so many things.. ground, injectors, boost sensor, ecu, cable soldering, maybe coils ...but i doubt it be coils because it would always misfire..

 

**f it was the boost sensor why would they are still do it when the vacuum line is
unplugged***

I *think* it's because to make the secondary injectors come on all that is needed is atmospheric pressure AND 3500rpm. See the 87 fsm for this procedure on non turbo cars. Works on turbo cars also.

 

i was thinking that maybe the boost sensor is messed up i dont feel like typing my whole theory out but im puttin a new one on tomorrow and see if that does it