Hey guys

I'm having a problem and it is beyond irritating as it has become the hold up on the whole build. I searched and tried everything I know to do before posting with no avail...so help me out here. I just finished my single turbo swap and am only tuned for 10lbs as of now.

SO. Last weekend I got in a brand new set of (4) BUR9EPQ plugs to allow me to move up to 12-14 psi (for < 400hp). I changed all of the plugs and went to fire the car...and nothing. Car would turn over but not fire. I pulled the plugs, deflooded the car, cleaned the plugs, and reinstalled them and tried again with the same result, twice.

It was at this point I assumed my new plugs were duds and put in the old ones and surprise it started up right off with no problem.

Fast forward a week of daily driving the car with no issues still on 10lbs (due to 7/9 combination). I decide to try this again and change out the old trailing plugs with the new BUR9EPQ trailings and the car starts just fine, no issues. I then replace the old leading 7 plugs with the other two new BUR9EPQ plugs and then NOTHING. Same as before, car turns over but will not fire.

So I put the old 7's back in the leading holes and now it won't fire as I'm assuming it flooded.

I am at a loss here. Maybe some of the 9's are bad? I really don't know anymore. My car idles around 13.4 AFR and I planned on leaning that up this weekend.

Any suggestions? Am I missing something here? I'm beyond irritated at this issue and this has become a big multi-weekend hold up keeping me from turning it up and tuning for more boost.

-Seth

 

Ok about the spark plugs I stopped using the 7 and the 9's a while back. Try using autolite racing ar3931 you'll be surprised about how great they work and are relatively inexpensive compared to the factory suggested spark plugs. However if your AFRs are at 13.4 you are really lean for a rotary. Mine wouldn't even start on anything over 12.9 AFRs!!! I could be wrong but I don't think you're flooded it sounds to me like you're way too lean. What ecu are you using? Any porting? What mods? Hope this helps

 

I know the 7's help with not flooding & make it easier to start.
Some years ago I used to have trouble with flooding. (I had all 9's) . I threw in a couple of 7's and never flooded again.
I would guess your getting too much fuel during cranking..so the 7s can still start it ok, but the 9s struggle.

 

that is strange, im running NGK 6712's in 9's and 10's heat range, 2200cc primaries, idle is high 11's/low 12's AFR and i have no problems at all

i think your problem is probably plug wires, maybe causing intermittent connection when you swap plugs, and probably discharging into teh chassis somewhere

what coils are you using?

 

13.5 AFR is pretty lean. I tuned my car and many others around 12.8-13.0 when warm.

typically when we start the cars the idle is low 11's with the water vrs. temp correction factor.

Non of us have any problems, we all run 9's all around. hot/cold all start great.

What if you keep your old 7's in there and swap the bottom 9's with the 9's that don't work, see if those 9's have some problems?

if the car runs like always, then it deals with something running all 9's. if it doesn't run, perhaps the 9's are bad.

 

Thanks for the input guys! I've got a different set of 9's on the way and will have some results soon. I'm still leaning towards a bad set of plugs here...I'll look into the autolite plugs, but I had planned to move to the NGK 7420's once I worked out the tuning details.

I'm not sure how a power FC works but for an adaptronic ecu cranking fuel and idle fuel are separate. I'm also thinking idle AFR doesn't have too much affect on the the actual cranking phase. When the car enters the "cranking" phase (triggered by the ignition switch being turned into the cranking position) the ECU reads from the cranking table which contains VE numbers as a function of water temperature then gradually transitions into the fuel in the idle cells based on how you have your short post crank and long post crank values set. I've pulled a substantial amount of fuel out of the base maps recommended cranking fuel values and with the 7/9 combination and my car fires and fires hard after 1-2 seconds of the key being turned.

I don't think my issue here is with idle AFR since the car won't fire or catch at all when those new plugs are in. Regardless of the AFR at idle the motor should at least fire with spark/air/fuel and given that it fires first turn now on 7's and I'm only going from 7's to 9's and that is the only change and I get absolutely no fire...

Swapping to new 9's tomorrow, will see what happens.

Another question. What timing does everyone run during 'cranking'.

-Seth

 

This is a long shot but make sure your ignition harness isn't damaged. You might have a frayed wire or loose pin and be knocking it around when changing plugs.

 

I actually thought about that but haven't investigated yet. I had an incident with a twin power catching on fire a few months back and I've had little faith in my ignition harness since then. Plan is to swap to the AEM coils here soon so I've been trying to make due for the time being.

I'll give it a once over and check the pins, however I doubt this to be the issue since multiple times it would fail with the new plugs in and fire with the old ones.

I meant to get to it today but real life took over and I wasn't able to spend any time with it. A new batch of BUR9EPQ's will be here tomorrow so we shall see if the plugs were the problem of if its a tune/ignition issue.

Thanks for the input!

 

More confused now than ever.

I decided to approach this systematically in order to eliminate anything possible from being the issue. The last the car ran & started perfectly with the new 9's in the trailing position and old 7's in the leading position.

The car had been flooded from the last failed attempt so first and foremost I de-flooded the car by pulling all the plugs and the fuel pump fuse and turning the motor over 3 times for 5 seconds each with 30 seconds in-between each time.

I then swap the old 9's which I know to be functional into the leading position and place the new 9's in the trailing position where they previously functioned fine. I start a log and turn the key with the TPS at 100% so the ECU is in fuel cut mode to clear the chambers after the de-flooding. I then release the pedal to 0% TPS and turn the key. No luck here. Engine turns over and nothing happens. Try with both 0% throttle and 100% throttle (fuel cut) and cannot get the motor to fire. I smell gas and assume its flooded again.

I stop the log, go through the exact de-flooding procedure mentioned above, and swap the old 7's back into the leading position without touching the ignition harness in any way. I get in the car, start another log, depress the throttle to 100% TPS to clear the chambers the same as before and turn the key. Car fires instantly while ECU is in fuel cut mode.

I've combined my logs and labeled everything so that the two can be clearly compared, however I'm having a hard time figuring out why 7/9's work and all 9's does not. I've also attached my ECU file as it is now for reference.

I'd greatly appreciate any advice here...not sure what else to do and this is a REAL irritating problem to have.

Thanks for reading!

-Seth

 

I noticed when looking over the logs that the primary injector duty cycle reads 0.4 and that the injectors are spraying 1 ms during what is supposed to be a complete fuel cut.

I would assume this is supposed to be 0 and 0 and I'm not sure if this small injection would be enough to cause it to flood like it is. Just a thought.

 

This ended up being my issue! I pulled my plug wires off and found that the metal tip on the inside of one of the leading wires had been pushed aside and was not contacting the plug. Why I could get it to fire on the 7's and not the 9's, I do not know, however with the plug wire contact straightened out the car started both hot and cold on all 9's with no issue.

Seems about right, with this car I have seemed to manage all the large stuff pretty quickly and its the small stupid detail that ends up being the hold up!

Thanks for the input guys, I appreciate it.

-Seth