Grrr... Engine help needed

[Richard Lewis]

Fighting, fighting, fighting with our engine to get it to even idle nicely. Using a GSX-R with a tec-II, new injectors, pump, plug wires, sensors, etc. etc. It seems pretty random with the idle speed, as well as as startup. Occasional backfiring (sometimes large) through intake and exhaust. And a really rough running engine in general.

I was hoping someone could shed some light onto what the advance/fuel curves they are running are like. The manual states the bike is supposed to be at 5* BTDC at idle, which is where I am as well. (ie: initial advance) Ignition curve ramps up to 25* BTDC @ 3000rpm.

The backfiring would indicate way too rich, or too much initial timing I assume... Leaning out doesn't seem to cure much except make it harder to start. (even when warm)

Any and all ideas welcome, particularly with those experienced with the tec-II!

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[Richard Lewis]

Fighting, fighting, fighting with our engine to get it to even idle nicely. Using a GSX-R with a tec-II, new injectors, pump, plug wires, sensors, etc. etc. It seems pretty random with the idle speed, as well as as startup. Occasional backfiring (sometimes large) through intake and exhaust. And a really rough running engine in general.

I was hoping someone could shed some light onto what the advance/fuel curves they are running are like. The manual states the bike is supposed to be at 5* BTDC at idle, which is where I am as well. (ie: initial advance) Ignition curve ramps up to 25* BTDC @ 3000rpm.

The backfiring would indicate way too rich, or too much initial timing I assume... Leaning out doesn't seem to cure much except make it harder to start. (even when warm)

Any and all ideas welcome, particularly with those experienced with the tec-II!

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UVIC Formula SAE Team
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http://uvic.fsae.ca

[Charlie]

Tec-II, ugh. http://fsae.com/groupee_common/emoticons/icon_wink.gif What is your initial advance set at? Try a high number like 20, sounds like you are retarded in cranking. That will also help you engine idle better as long as your injectors are happy at low RPM (not too large)

-Charlie Ping
Auburn University FSAE 1999-present

[Richard Lewis]

Note in the first post, initial advance is set at 5*, the factory setting for the engine. (for right or wrong)

We've had it running at anywhere from 5* to 20* initial advance. Honestly, it doesn't seem to make a huge difference as far as idle quality goes. Injectors are 155cc, which should be plenty small enough to have a nice idle.

The rough idle and backfiring still indicates too rich to me. I can lean it out until it dies, and it doesn't really smooth out much however. AFR readings (granted, just from an O2 sensor) are in the 16:1 range, indicating that we're lean. Maybe I should just ignore the EGO completely and tune by ear... (I know EGO's aren't particularly precise, especially at extremes)

The manual which said 5* inital advance at idle for the bike engine really threw me for a loop... I was thinking 18* was a good starting point.

Oh and Charlie, I'm pretty sure I'm retarded in more than cranking. http://fsae.com/groupee_common/emoticons/icon_wink.gif

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[Dan Deussen @ Weber Motor]

Don't make your life too difficult and stop worrying about about a constant engine idle. You are building a race car, not a street car. Here is what you can do to stop your headache:

1) Open up the idle screw of the throttle body so the engine would idle royghly about 3-4k rpm.

2) Recalibrate your TPS sensor so this setting becomes 0% TPS.

3) Set your spark advance for 0% TPS to 20 degrees between 0 and 2k rpm and to zero degrees from 2k up to redline.

3) Set your injecton timing for 0% TPS to whatever is good from 0 to 2k rpm and then from 2k up set it to zero.

This will not be a nice smooth running idle, but for a race car it is common practice.

Let me know if you have any quiestions.

Dan

[Mechanicaldan]

We too, are seeking an idle, but our engine starts and idles at 3000-4000 RPM, and I think that's the way we will go to competition. We're trying to spend our time tuning the upper portion of the map.

Cyclone Racing
www.cyclone-racing.com/fhome.htm (http://www.cyclone-racing.com/fhome.htm)
Iowa State University
Engine Team Leader

[Angry Joe]

Have you checked for intake leaks? Even a minor one can cause an engine to run like complete crap. Backfiring out the intake AND exhaust is a strong clue. We had this problem (the gaskets between the runners and the head weren't sealing properly) and I was so baffled that I thought God was getting back at us for drowning out Sunday masses in the church across the street.

If you still can't get the car to idle, you could try making a 'crater' in your fuel and advance (drop them off around, say 2k then ramp them back up at 1k) to keep the car from stalling. I don't know if this works first-hand but its worth a shot...

Lehigh Formula SAE

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[Charlie]

We were never able to get a great idle from our Tec-II, although our 2002 car is decent now with 19 lb injectors (too big,, but free http://fsae.com/groupee_common/emoticons/icon_smile.gif ). Our 03 car purrs like a kitten with the MoTeC.

Some problems I've experienced with the TEC-II:

The initial advance I noted was the single box, not the graph. This is the # the TEC-II uses from 0-first datapoint. It needs to be a high number, around 20-30. This is not that same as the bike's initial advance, as that is likely at idle (your first data point should be close to idle, and be a low number like 5-10).

You say it's rough running in general though. This sounds like the cause of your idle problem is somewhere else. Check your crank sensor wiring, if it is backwards, it can cause major headaches (the engine will still run). http://fsae.com/groupee_common/emoticons/icon_redface.gif

-Charlie Ping
Auburn University FSAE 1999-present

[Kevin Hall]

I have had many a headache over the TEC-II, but I have become good friends with it. With the F4, we run 14* of initial advance, which was suggested by Queens. Works well, it's tough cold starting, but once it has run for a minute, it just needs a button push.

Turn off your 20 second starting enrichments at first, because they will drive you crazy, running rich all the time, and trying to pull out fuel from the MAPS to make it idle, and then what do you know, the enrichment goes away, and it leans out again.

I can't stress trigger sensor problems enough. Your gap and wiring will cause way too many problems. My final solution has been a larger wheel outside the crankcase. Stock sensors are designed for large resolution wheels. TEC II sensors don't last in heated oil http://fsae.com/groupee_common/emoticons/icon_smile.gif.

We run an IOT of 0.2, and a PW of 5 or so. I haven't played with those in a while, so I don't remember them exactly.

Don't worry about EGO sensor readings at idle. They mean next to nothing, especially if you have ANY exhaust leaks.

I'm not sure exactly what to recommend. Try a few things......like reversing the polarity of the trigger sensor. Use a smoke pencil and check the intake and exhaust for leaks.

Keep your progress posted!

Kevin Hall
University of Saskatchewan
Engine Guy in Need of Help

[Bam Bam]

So how's that engine simulation program workin out for ya????

I recall telling someone once they should spend more time with their engine and less time trying to simulate it with virtual 4 stroke. However my advice was not taken.

I'll offer a few other pieces of advice investigate whichever ones you want.....
Use your engineering judgement.

there's a few things that will cause backfires capable of blowing off your intake.

9 times out of ten it is your trigger wheel and wiring.



1) Ensure the trigger is wired correctly. It will probably run both ways, one way will cause your engine to run like a moody bitch.

2)Electrical noise. Depending on the sensitivity of the EMS, noise from coils eddy currents etc can cause big interference and invoke moody bitch syndrome

3) Coil wiring and firing order. Make sure the firing order/wiring in the ems matches the firing order of your engine. Even when this is wrong. When running wasted spark, It's not that obvious, the engine still runs pretty well but is a little moody at times.

4) Trigger wheel alignment. If the position of your missing tooth isn't where the ems expects it, your ignition maps will be way off.

5) I've had good luck with 15 degrees BTDC and running an idle speed around 3000 but can get her to chug away as low as 800

6) If all else fail just try suck starting the engine. Just put your mouth on the exhuast, suck and press the starter.....All your problems will disappear. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Richard Lewis]

Not sure if this reference about virtual 4 stroke is for me or not, but since I am not using virtual 4 stroke, I expect not.

1) Trigger wheel is correct. Out of round is fine. Sensor gap is in spec. Tried running it backwards just to see what happened, and had no spark at all.

2) At this point I believe electrical noise is the culprit.

3) Coil wire and firing order is correct and checked many, many times.

4) Trigger wheel is right on spec. 11 teeth BTDC for the sensor.

5) Trying 16* BTDC for timing right now, close enough that it should run I would think.

I believe we have what is known as "spark scatter" as described in the TEC 2 manual. Seems that sometimes we get spark, and sometimes we don't. Usually after sitting we get spark for a little while, then it dies. I highly suspect the plug wires we are using are at fault now. (switched out coil packs, plugs, etc. Tried insulating the boots better in the head wondering if spark was arcing across them, to no avail)

Next question: Has anyone found a GM ended plug wire, solid core, 8mm or larger, and made for a recessed plug like on a bike? What applicaiton is it from? I've tried 4 sets allready and not looking forwards to looking through boxes and boxes again at the parts store, trying to figure what might work.

Anyway, thanks for the info all...

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[Richard Lewis]

New, higher quality plug wires seemed to have solved the problem completely. Thanks all.

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[D Mack - CMT]

What is TEC-II?

[Kevin Hall]

Richard

We use the Accel kit that comes with a roll of wire and some ends. It has the standard GM ends, but you need some serious pliers to get them in properly.

To check for proper sparking before the plug wires, simply remove the wires, and let the coils arc across themselves. This was recommended by the great Peter Visser. If you get spark jumping the 30mm or so between the poles of the coil with good consistency, that rules out alot of problems.

Glad to see you got things going right. Good luck at competition!!

Kevin Hall
University of Saskatchewan
Engine Guy in Need of Help