Injector Wiring

[Squrlsquash]

Just got my 87 to pass smog again (barely)

it keeps having a nox issue

was told my the tech that it leaned out under any boost

 

I don't have a wideband yet, will hook up autometer narrowband gauge shortly to take a look

 

I think the injector wires were mix-matched when previous owner replaced the pigtails

one injector has two wires of the same color (green/white) if memory serves

 

Can someone with a properly running 87 take a pic and list the colored wires going to their injectors?

[boston]

my 87 car injector wire

 

primery injector ( yellow/white,,yellow/blak)

 

sucondary injector (yellow/green,,yellow/blue)

Edited January 18, 2015 by boston

[Squrlsquash]

green injector is primary, correct?

 

if so, they are reversed

swapped by the shop that did "smog repair diagnostics" last year

wondering how i just passed smog again...

 

thanks for the help

Edited January 18, 2015 by Squrlsquash

[ucw458]

Fix the EGR and make sure the engine isn't running hot and the NOX problem will go away.

[pcristquester]

green injector is primary, correct?

 

if so, they are reversed

swapped by the shop that did "smog repair diagnostics" last year

wondering how i just passed smog again...

 

thanks for the help

black is primary, green is secondary

[Squrlsquash]

okay, had my terms mixed up

 

primary is the black 580cc idle injector

(yellow/white yellow/black)

 

secondary is the green 1080cc above 3k rpm injector

yellow/green yellow/blue)

 

in which case they are wired correctly

 

car has a walbro pump (i was told) and it whines makes all sorts of strange noises, problem?

trying to figure out how to thread a fuel pressure gauge on the fuel rail plug (but its whitworth threads or something weird, i see people who've done it though)

will hook up a narrowband o2 gauge to see if that shows the lean condition

 

anything else i should look into?

[Squrlsquash]

Does the +/- location matter to the injectors?

"

http://i35.photobucket.com/albums/d182/Professor-Quest123/New%20Rsistance%20and%20Clips1/CL-0.jpg

 

http://i35.photobucket.com/albums/d182/Professor-Quest123/New%20Rsistance%20and%20Clips1/CL-00.jpg

 

You SHOULD replace the clips......ONE WIRE AT A TIME, or a least refer to HOW-TO-IDENTIFY-WHAT-WIRE-GOES-WERE! http://starquest.i-x.net/images/smiles/icon_lol.gif

 

YW=YELLOW/WHITE (primary inj. POSITIVE)

YB=YELLOW/BLACK (primary inj. GROUND

YG=YELLOW/GREEN (secondary inj. POSITIVE)

YL=YELLOW/LIGHT BLUE (secondary inj. GROUND)

 

THE PRIMARY INJECTOR IS ON THE LH FENDER SIDE...BLACK IN COLOR! "

http://starquest.i-x.net/viewtopic.php?t=902

Edited January 18, 2015 by Squrlsquash

[StarquestRescue]

No.

 

You have to remove the rail and re tap it for npt. And flush out the chips.

[mikec]

A weak or old O2 sensor will make a StarQuest run high NOx on the Cali smog test cycle. The ECU may not throw the O2 sensor error code either. Remember, the StarQuest uses a simple 1-wire O2 sensor which can only determine if the exhaust indicates rich or lean combustion... but not HOW rich or lean. I.e., when the sensor says "lean" he ECU slowly richens the mixture until the sensor flips to "rich" at which point the ECU starts slowly leaning out the mixture again. So the ECU intentionally cycles between rich-lean-rich-lean so the average is stoich. A slow/old sensor has more trouble detecting "rich" so the rich-lean-rich-lean cycling ends up spending too much time on the lean side. Lean air:fuel burns hotter which promotes NOx formation in the exhaust.

 

The EGR valve's sole purpose is to send exhaust back into the intake manifold since this already-burned stuff can't burn again. Thus it ends us deadweight air in the cylinders, absorbing some of the combustion heat and thus lowering peak temperatures. That in turns lowers NOx formation. So verify your EGR valve and control solenoids function properly. The StarQuest ECU switches the EGR solenoids ON when the engine is warmed up, not idling, and below 2500 RPM or so. Cali dyno smog checks typically happen in the 2000 to 2500 RPM range so the EGR helps for the test...but when you are driving your StarQuest, especially when having fun with it, you're typically well above 2500 RPM so the EGR doesn't affect performance. Sweet.

 

A little too much ignition timing also promots NOx formation. Cali smog test stations have to read the underhood sticker to determine ignition timing and factory allowable tolerance. You can retard your timing 1 or 2 degrees and make a big diff on NOx. If your timing is advanced 5 or more degrees from factory, I can pretty much guarantee a StarQuest will flunk the NOx part of the Cali smog test.

 

So, two years from now when you have your next smog test, double-check the ignition timing, the EGR valve, and install a new O2 sensor if yours is more than 5 or 6 years old/40000 miles.

 

edit: For the Cali dyno smog test there is no reason the engine should be seeing boost pressure either. Not sure how your test guy was driving the car on the dyno if he saw boost pressure on the dash display. The smog test gives your car something like 30 seconds at each MPH test speed; as soon as the car gets 5 or 6 seconds of "passing" emissions that test completes. So even if the emissions suck during the 15 to 25MPH acceleration phase they should clean up within a second or two when a steady 25MPH is reached... your car has the rest of that 30 second window to generate 5 seconds of clean emissions. I doubt the test guy actually knows how/when StarQuests boost.

 

mike c.

[Squrlsquash]

Its got a 2 year old o2 with only a few hundred miles on it

i set timing to 9 degrees btdc

and cleaned the egr

 

did all of this and still failed, then i remembered that i changed to an 89 computer

put the 87 computer back in and it passed (barely, i was told)

 

strange because last year with the same setup i have now it was nearly 0 on all three: hc c02 and nox

 

 

i have no confidence that any of my vac lines are properly routed, alot of hackery was done in the past

i replaced them all, but put them all in the same places i found them

 

have no ac, cruise, or nearly anything else. will look around for some writeups on simplifying vac lines and making sure the egr is properly plumbed

(i have a fully ported intake mani that i want to put on, but the egr was chopped off i want power AND to pass smog)

 

thanks for replies, will order a wideband to prove/disprove lean condition once i sell some more clutch bearing kits (shameless promoting)

Edited January 18, 2015 by Squrlsquash

[ucw458]

The EGR valve's sole purpose is to send exhaust back into the intake manifold since this already-burned stuff can't burn again. Thus it ends us deadweight air in the cylinders, absorbing some of the combustion heat and thus lowering peak temperatures. That in turns lowers NOx formation. So verify your EGR valve and control solenoids function properly. The StarQuest ECU switches the EGR solenoids ON when the engine is warmed up, not idling, and below 2500 RPM or so. Cali dyno smog checks typically happen in the 2000 to 2500 RPM range so the EGR helps for the test...but when you are driving your StarQuest, especially when having fun with it, you're typically well above 2500 RPM so the EGR doesn't affect performance. Sweet.

 

You are usually spot on when describing SQ functions but this one was slightly off. I studied the EGR in depth because I wanted to re-create it on my MPI manifold.

 

The EGR solenoid turns on when the engine is warmed up. It stays on until you turn the car off. What operates the EGR valve is a TB vacuum port about 1/8" in front of the throttle plate. As you open up the throttle the air flowing over that port generates a low vacuum signal that opens the EGR depending on how strong the signal is. The vacuum ports position causes the EGR to only work during cruising. When you are at WOT there is boost pressure on both sides of the EGR diaphram so the valve cannot open. The only control the ECU has over the EGR is disabling it when the engine is cold.

[Squrlsquash]

the ecu controls it? i thought it was the thermovac goober right next to the temp sensor underneath the thermostat Edited January 18, 2015 by Squrlsquash

[mikec]

I dug out my PDF version of the factory manual. Take a look at page 25-11 (emissions chapter). It describes the ECU control over the solenoid. It says "...but the engine speed is low (approximately 3,500 rpm or less)..." is when the ECU uses the solenoid to let EGR function. I remembered the number as being 2500... The solenoid has to be powered/on to disable the ECU, un-ergized the EGR valve functions. I should have written that the ECU uses the solenoids to switch ON the EGR valve - not that the solenoid valve itself is switched ON. Poor word choice. In reality, the solenoid, when ON, basically uses the other top EGR port to bleed the vacuum off the EGR so the EGR valve stays closed. This second port, via the solenoid, and the EGR's lower port both connect to a nipple above the throttle plates - either atmospheric pressure or any boost pressure but never manifold vacuum. It's no different than plugging into the port that normally feeds the turbo wastegate actuator. (this is the "L" lines on the factory vac diagram, the blue "L" lines are collectively a "vacuum return" to bleed vacuum away from parts when those parts should not be functioning.) When the solenoid is ON, the upper and lower sides of the EGR diaphragm are basically connected... ergo there can not be any pressure difference acting on it so the EGR's internal spring forces the valve closed.

 

Part of the intent of this valve isn't so much to kill EGR at high RPMs because EGR isn't needed... no, it's there to protect the EGR valve from boost pressure. Imagine if the EGR valve had only one port like on many other cars... it would see "ported vacuum" from the throttle body as you described:

 

* no vacuum at idle because the port is physically located just above the closed throttle plates EGR is thus closed.

 

* as the throttle plates open, the port is now close to the angled edge of the throttle plate and sees some vacuum. The EGR will start to open assuming the solenoid is OFF.

 

* as the throttle plates get even more open - say 50% - the port is completely below the throttle plate and sees full manifold vacuum. The EGR valve would open fully assuming the solenoid is OFF.

 

* at high throttle openings but lower engine RPMs there is little intake manifold vacuum again so the EGR closes.

 

* under boost pressure there will be pressure in the throttle body nipple. If that were allowed to push on the EGR diaphragm it'd be extra stress on the rubber part and it'd cram the EGR's internal cone-shaped valve tip hard into its seat. (the pintle valve)

 

On StarQuests, the ECU trips the solenoid ON above 3500 RPMs to vent possible boost pressure to both sides of the EGR... so internally the EGR feels no net pressure across the diaphragm and the spring holds the EGR valve closed at the normal pintle valve force. The ECU uses RPMs as a signal as to when significant boost pressure might exist. At at higher RPMs the EGR function isn't as necessary typically - in the 80s the smog tests pretty much applied to "steady cruise" conditions.

 

mike c.

 

edit: the thermostatic sensor (the fragile plastic one) primarliy controls when the evaporative emissions system purge function operates. When the engine warms up, some intake manifold vacuum is allowed to suck out trapped gas fumes from the charcoal canister, cleaning the canister. The lower EGR port does tap into the output of this valve as well so the EGR function is also limited until the coolant temp rises a bit. So the EGR is disabled by both the ECU + solenoid and by the thermosensor on cold engines. Seems redundant, no? Probably a legacy of the StarQuest engine having "evolved" over the years from a basic carbureted system. New vac hoses & valves were added over the years as smog regs evolved... then when the engine was turbocharged and changed to TBI a few add-ons were necessary for the boost issues. The vac hose & emissions system I'd bet was not a "clean sheet" design for the original StarQuest TBI installation... some carried over from the carb days.

 

edit again: when looking at the whole vac diagram (page 25-3) it helps to think of the "B" lines as ported vacuum that enables/operates emissions things based on throttle position. The blue "L" lines bleed vacuum away, under computer or sensor controls, to disable things. Notice too that all "B" lines connect together at one of the multi-port "T" devices, all "L" lines also connect to each other via two Ts. (note: 88-later cars do have an extra blue line at the turbo wastegate control solenoid... this is unrelated to the main "L" hoses. Too bad Mitsu didn't make this some other color!)