turnski

I'm still plagued with this idle issue. I have a hesitation, stumble from idle to 2100 rpm, and she wont idle. It's got a brand new Rotary performance motor with stock primary and secondary injectors, as well as a stage 1 street port on it . miles wise it has 4 miles or rolling rubber miles. Ive checked for vacuum leaks. and propper vacuum routing. this is bugging me now . can some one help out with a suggestion .

calpatriot

What year & model? Series 4 or 5? Turbo or NA?

Check the simple stuff first.

1. Check for trouble codes
2. Check the O2 sensor voltage (<0.45v = lean; normal idle condition is rich, around 0.6v)
3. Spark on all 4 plugs?
4. Timing
5. Advance
6. BAC valve operational check (see FSM)
7. Fuel pressures: at no flow (blocked off), regulated and unregulated
8. Check operation of Air Control Valve (depending on model)
9. Plugs OK?
10. Were the injectors professionally cleaned prior to install?
11. Stethescope for operational sounds (clicking) on primary injectors
12. Idle speed adjust
13. Idle mixture adjust
14. Adjust TPS to exactly 1 k ohm at idle throttle

?

turnski

Thank you for the information it helped , this thing acts like it has a vacuum leak, it pops and stumbles and has a real roug idle, it acts like it's only running on one rotor then it will clear it self and idle smoothly for a second or two that it will go back to how it originaly ran.

calpatriot

Sounds like whatever it is is intermittent.

The 'green lamp' test will tell you if the problem is mixture (which could be a symptom of a vac leak). The lamp should be on at idle, and under acceleration. If it is off under those conditions, it is too lean. (This test is similar to the O2 voltage test, but looks at the 'monitor lamp' output from the ECU, which you can access at the center two pins on the check connector--if you have an S4 car).

Any difference in how it idles cold vs. warmed up?

It could also be an EGR valve stuck open; it is supposed to be closed at idle, and if it is not, it will idle rough and maybe die. Its a quick and easy check; see the FSM.

My car (86 NA) acted something similar to that, and it turned out to be the O2 sensor circuit was open. The car would run fine when the ECU decided the O2 sensor was not there, and ran in limp mode (rich); but most of the time once it warmed up it didn't figure out the O2 sensor was out of the circuit, and tried to use it, in which case it ran horribly.

turnski

Gene,

green lamp test what is that, sorry for being ignorant ? And where is the test connector located? is it the white one by the fuse block under the hood or the one next to the pressure sensor ? I'll throw my DVOM on the o2 sensor and see what it's doing at idle when warm so I have a sense where i'm at in the scheme of things. Do these cars have self diagnosis capabilities being that they are that early OBD 1

Thanks,

Vince

calpatriot

First check for trouble codes. See one of these links:
S4 car: http://www.teamfc3s.org/info/article...odes/main.html
S5 car: http://www.johnr.com/cpucodes.html

Identify and correct any trouble codes. Then, connect a single 12v LED to the center two pins in the check connector (green six pin connector, left of the battery, forward of the leading coil with igniter).

The lamp should be on (rich) for idle and acceleration, off (lean) for decelleration, and flashin on and off 8x per 10 sec for steady rpm at 2000 or so (not idle).

The O2 sensor voltage should agree with the green lamp (above .45v = rich, lamp on; below .45v is lean, lamp off). If they don't you have problems with the sensor, its wiring, or the ECU. If they agree, then u can use the green lamp to diagnose the condition that may be causing your idle problem.

It should be on for idle and acceleration. If it is not, you are too lean. If it is on, the mixture is either ok or too rich.

calpatriot

Test connector is green, six-pin, near the left front of the engine compartment, just behind and to the left of the leading coil. It looks like this:


Here is what my 'green lamp' checker looks like:


This is how it hooks into the test connector:


And this is what it looks like, remoted to my dash, when the light is on:

turnski

I'm going to build one of those this weekend, Thank you for your input it has been extremely valuable. yeah i'e got extensive training i just havent worked on one of these for years, and my snap on scanner wont access the OBD 1 program for some reason. I'm just concerned that this motor is so new and fresh that it hasnt fully seated yet, and i might have a lack of compression on the rear rotor. and this might be one cause. but I will check all other avenues while i'm there.

calpatriot

When you make your 'green lamp' checker, make sure you either use a 12v led, or get a standard LED and hook up a 510 ohm resistor in series (thats what i did). If you hook the std LED up to 12v it will instantly become a NLED--non-light emitting diode.

The code checker is made the same way, but with two (traditionally red, but whatever you like) LEDs with their + terminals both connected to the same male connector.

The two led checker is also perfectly useful to use on the TPS adjustment, if you like to use the 'two light' method. I use that for a coarse adjustment, and then the ohmmeter to tweak it to exactly 1 k ohm at idle throttle, with excellent results.

turnski

I like the Nonled .. I'm going to make a couple of these up at school today in our electrical class , so I can do some diagnosis tomorrow. I might rethink my secondary injector choice too. i have a set of 89-91 turbo 550 injectors that just came back from RC that I might stick in instead of the ones that came from the old motor. so all will be the same then i'm going to recheck the O2 sensor voltage and rest the TPS and do a diagnostic check.

turnski

I dont have a lot of swithching on the O2 sensor at idle, I'm wondering if my secondary injectors are dripping causing it to run realy rich at idle, cause I have to lean th mixture solenoid all the way out to get it to smooth out.. But it's still back fires and idles rough. LS1 time maybe.

calpatriot

There should be *no* switching of the O2 sensor at idle. If the car is operating properly, the car should run in open loop at idle, with a steady rich condition reported by the sensor and present on the green lamp test (steady on)

I presume you mean the idle mixture set screw?
Is there spark present on all 4 high tension leads? A misfire can result in unburned fuel in the exhaust...

Leaking/failed (open) injectors might do it... have you scoped all 4 injectors for normal operating sounds?

turnski

Yeah I'm going to have to take a look at the idle mixture screw, and set it to specs (FSM) I'm still thinking low compression in the rear rotor..