jdm_h22

I thought I'd post the graph from my most recent dyno session and see if anyone could tell me what might be happening. The car performs really well, and I know that's more important than any graph. But for the sake of safety and efficiency, I'd like to know if something might be throwing off the top end.

I understand there may be too many variables to diagnose an issue like this over the web. I'll provide as many details as I can.

My setup:

- B16 head
- GSR cams
- LS block
- Eagle rods
- Wiseco 10:1 pistons
- STC Mark I Predator turbo 53lb/min
-Stock ignition
-BKR7E plugs @ .025 gap (I was told this could be the issue)
- ID1000's
- Aeromotive 340 pump
- 93oct pump gas
- Edelbrock Victor X manifold
- 68mm tb
- Ectuned @ 20psi

wantboost

iTrader: (2)

stock ignition probably isn't helping...

what condition are the cap and rotor in?
what plug wires?
what is your base timing and how much advance are you running?

It might be time to consider a set of low resistance plug wires and something like an accel OEM replacement coil.

Or an ICM delete, external Crane coil, and some sort of external ignition box

blackeg

id bring that gap down to about .020 before anything else. i guess im surprised you didnt try diff. gaps while you were still on the dyno

jdm_h22

Thank you both for your replies.

-Cap and rotor have less than 1,000 miles on them.
-Same for the NGK plug wires
-As far as the base and advance timing, I didn't personally tune the car. It was done by a local shop. But I will inquire.

Thank you for the suggestions on the ignition. I will definitely look into that further.

I totally agree on the spark plugs. I called the shop prior to the tuning session and asked what my gap should be and I was told 023-.025. But then after the session when my gap came up in conversation, the tuner was surprised to hear I had it open that far. (.025) And at this point we were finished.

What's frustrating about the whole thing is that I feel like I was rushed on the dyno. We had an issue with the electronic boost solenoid that took 15-20 minutes to track down. And after then my tuner seemed short with me.

I completely understand that the car owner should be ready for the session and when things aren't ready, time is wasted. The tuner's time in particular. But that doesn't negate the fact thatI paid a substantial amount of money to have it tuned right. It bothers me that even with the graph looking the way it did, he was willing to send me away.

Ok, enough venting. Just had to get that out there.

Here's a question, can I close my gap to, say .020 and assume that it won't negatively effect the tune?

Nottheonion

Log your batt voltage and make sure it isnt dropping at high rpm

Dont change anything to your ign system.

Drop the gap down to 18 if you have to.

My bet would be batt voltage tho.

jdm_h22

Good idea on the voltage. I want to say my alternator and battery are fine, but you never know. I do have an under drive pulley on the alternator that came with it when I bought it. I wonder if it has any effect.

Nottheonion

Log a run when its breaking up and youll have your answer

Your alt can be fine and just have too much resistance before voltage reaches the ecu and distributor

jdm_h22

I guess I'll be buying some tuning software with logging capabilities!!

Nottheonion

I assumed you had s300

Get a multimeter,aligator clips and a buddy and you can watch it live

wantboost

iTrader: (2)

Yea I don't know why I didn't think about the plug gap.

Bring it down to .023 and go from there. Personally I wouldn't go lower than .020. Any tighter and it's almost like a bandaid fix.

Definitely log system voltage if you can. Even a slight drop in voltage can cause problems. Also verify the battery terminals are clean and properly tightened. Check your engine/trans/head grounds for corrosion, loose ends, etc. A poor ground could also cause breakup during high load situations.

I haven't really messed with ectune much but IIRC under the ignition settings there should be an entry for synching base distributor timing to the ecu (at least I think, similar to S300, Neptune, etc) which the ECU uses to calculate advance above the base timing. As far as total advance just take a screenshot of your ignition table values. That's all we need to see for that.

I would also inspect the cap and rotor for signs of arcing, erosion, and corrosion from moisture. Even though they are basically new if there's a problem with the oring seal on the cap any moisture that makes it's way inside will cause problems.

As far as the tuner being in a rush if he had a lot of dyno appointments after you then it is somewhat understandable. However his being in a rush should not prevent him from finishing a tune. If he couldn't finish your tune in that session he should have told you to bring it back at a later date so he can fully devote his attention to your dyno time. The biggest thing though is do you feel like you got your money's worth in regards to the overall experience and end result? If not then voice your concern and ask politely if he would mind spending a bit more time refining the tune.

One last thing I would consider is the fuel. If the fuel was contaminated (excess water, lower octane, etc) then it could also cause problems at higher rpm levels and higher loads. Bad gas can either result in the slightest of side effects or make the car absolutely in drivable. Have you used the station you filled up at before? Was fuel being offloaded when you filled up? (When the tanker offloads fuel it can stir up debris and sediment off the bottom of the in ground tanks). Was it raining or very humid at the time?

A dirty fuel filter could also cause your problems. If the filter is just dirty enough then it could result in the high rpm breakup you're experiencing. A totally dirty filter would make it even worse. When was the last time you replaced/inspected the filter? Do you have a fuel pressure gauge so you can see if pressure is low or tapers off at high rpm?


Sorry for the lengthy reply. Just trying to cover all the bases.

TheShodan

iTrader: (14)

As yes, the ***-u-m-ption theory.

Stated in the original post


Stop continually gapping plugs lower and lower. Get the correct supplementals as Wantboost posted. Your plugs will last longer, and your results will be repeatable.

Why keep slamming the gap, when you know the ignition isn't handling everything properly? That truly makes no sense. It's like putting a bandaid on a gun-shot wound. Sure it looks like it could help at first.....while you're losing a pint a blood every 20 minutes..

Nottheonion

Gapping the plugs lower will get it to run till he gets all the other parts in order IF he even needs them.

I dont like to just throw parts at a problem and hope it fixes the issue

Diagnose first

TheShodan

iTrader: (14)

We've done this before. That's why its recommended. Turbo LS himself was making the the ICM delete simply because this issue is so common, and Showing great results to boot, keeping the plug gap a bit more open, and steady ignition in the upper RPM band.

Gapping the plugs doesn't SOLVE anything, it just DELAYS other problems for a while, until something worse happens. Once he looks at the other issues, he can see that the enhancement of his ignition isn't just for now, but down the road when he pushes the car That much harder.

Many use this enhancement until they go to something like COP, and even then, its really more of an option.

TheShodan

iTrader: (14)

Man.. The old Mark I.... *sigh* Brings back memories.

Nottheonion

400 whp is the limit for stock ignition setups?

Thats good to know. Thank you for your response

Turbo-LS

iTrader: (4)

I still make the ICM delete kit FYI. It's a great piece. Still would take that setup over k coils any day

Stock ignition is all new OEM parts will make more than 400 reliably but it doesn't last and gapping plugs way down sucks. An engine had three components. Air fuel spark. If you increase air and fuel you should be increasing spark

ls joker

been gapping my plugs at.28-.30 since 2010 til a month ago on oem igniton components without one breakup issue.

jdm_h22

No apology needed. I really appreciate your input.

It makes sense to cover all the basics first to eliminate any obvious issues. (i.e. wire resistance, cap, rotor)

As far as the fuel system, it's completely new. Tank, pump, line, filter, rail and injectors. All with approximately 1,500 miles on it. Regardless, I'll check my filter to eliminate that possibility.

And lastly, I do have a gauge on the rail. How do I moniter it at high RPM? Perhaps I need a digital gauge in the cab?

Thank you again for your informative posts.

jdm_h22

Really interested in learning more about this ICM delete. Do you have a website? Thread? I'll search later.

Edit: Just found it in your signature link. Sounds great.
I'll pm you later.

jdm_h22

I....LOVE.....this turbo. It's incredible. Though I'm afraid with the upgrades on the roster it may run out of breath soon

BTW, thanks for posting those pictures. I used to be able to find them easily via google but not lately.

wantboost

iTrader: (2)

The ideal way would be with a fuel pressure sensor on the regulator or rail that feeds an input on the ecu. That way you can datalog fuel pressure across a wide range of operation and be able to overlay it with other sensor values.

Next best thing would be an electronic fuel pressure gauge. Only problem here is unless te gauge has a signal output for datalogging with your ecu there's no real way to monitor fuel pressure with precision. You'd be relying on what your brain remembers. I would not recommend a mechanical fuel pressure gauge as allowing fuel to enter the passenger compartment is asking for trouble.

If all else fails put the car back on the dyno and have either yourself or someone watch the gauge throughout the pull. Or have someone video the gauge for review later.

If your fuel system is entirely new I doubt it's a filter problem unless you had sediment in the tank. Did you drain and clean the tank before installing the new parts?

What size is your fuel feed and return?
What is your base fuel pressure?
What sort of fuel filter are you using? An OEM style or an inline AN style?

I've seen people run inline filters on fuel lines that are simply too small. They don't like the look of the large filters so they run the units with the smaller bodies. These small body filters were really designed for use as a supplemental oil filter. The size of the filter media inside the body simply isn't designed to handle the volume of fuel a typical system flows.

Two things happen at that point.

1. The small filter surface area simply chokes off fuel flow. Lack of flow = pressure drop.
2. The small filter surface area means that the filter media becomes full much faster. Clogged filter = pressure drop.

The large body filters are designed with enough filtration surface area to ensure they can flow an adequate amount of fuel without restriction and the filter can trap more contaminants before it becomes a restriction.

Also the filter media material and the particulate size being filtered has an effect.

Now with your larger pump what are you doing for wiring?

That pump really cannot operate to it's maximum potential with the OEM wiring. The small gauge wire simply cannot handle the amperage draw. You should have the pump hard wired to the battery with the fuel pump signal from the ecu closing a relay. Wire gauge should be somewhere around 8ga to 10ga.

jdm_h22

Because I didn't like the look of the original tank, I installed a brand new one. Clean as a whistle inside.

My fuel line is -6AN and stock return.

Base fuel pressure is 48psi.

Don't laugh, but my fuel filter is from a flex fuel Yukon. At the time it made sense and the price was right. It was designed for a V8 and could accommodate E85. Seemed appropriate for my needs. (I had thought of running E85) It is an inline style. I eliminated all banjo fittings in the fuel system except for the one at the pump. On that one I machined the holes to a larger diameter. From reading and just by looking at it, I deduced that the banjo fittings were incredibly restrictive.

My pump is wired through a dedicated relay, 8awg wired to the battery.

I think that covers everything.

LightningTeg

My plugs are gapped down to 0.017ish at 600whp, still on stock ignition. Its been this way for many years. I dont see a problem with it you guys are making it out like his motor is gonna blow from gapping plugs down lol. I've known many many cars running over 500whp on stock ignitions for years. There's one running around here at 800whp but that is an anomaly lol.
Sounds like your plug might not be cold enough either. I ran 8 heat range at that power level on 93 octane.

TheShodan

iTrader: (14)

That's not what I stated, not was that the general interpretation of my statement. It's not about power that shows these limits..

D-Rob

There is so much impractical armchair-expert information flying around here, it's not even funny.

Gap the ******' plugs down, be happy.