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FC FI ITS built car, odd behavior 6600 rpm + dyno charts

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FC FI ITS built car, odd behavior 6600 rpm + dyno charts

Old 07-21-15, 06:20 PM
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FC FI ITS built car, odd behavior 6600 rpm + dyno charts

Let's make this efficient.
1986 shell
S5 motor
Built and prepped in early 2000s was very successful in ITS club racing. It was parked in 2005 and we brought it back to life this spring/summer. We cleaned the tank, replaced fuel lines, replaced fuel pump with unit from 2006 Evo IX, had fuel injectors cleaned professionally (Diesels Bow, NH), rebuilt fuel pressure regulator, replaced circuit opening relay.

Car starts And runs well! Today we put it on the dyno!
And here are the charts (I promise to get better pictures)




Absolutely love this trailer!



















Now for red flags: low hp, running lean (pressure set at 50 will drop to 43 ASAP) car stumbles above 6600. Car does not have a timing gauge.

I believe this is a combination faulty ignition and fuel pressure too high.
Current ignition: stock coils, rb plug wires, (new) spark plugs.

I hope I have provided enough information to stir some insight from this excellent community.

James
Nfmotorsport.blogspot.org
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Old 07-21-15, 06:22 PM
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The smooth dyno graph is the pull In 2nd gear. The smoother problematic pull is the 3rd and last pull.
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Old 07-21-15, 07:53 PM
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Check your fuel filter and make sure no rust in tank. Amazing how much fine rust can build up in the tank places hard to reach when sitting....
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Old 07-21-15, 08:05 PM
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FF Is new, all lines but return and feed to filter have been replaced.
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Old 07-22-15, 02:16 PM
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You need more fuel pressure, not less...motor is lean...add fule. What engine control unit are you running?
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Old 07-22-15, 04:16 PM
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Originally Posted by Chuck Baader View Post
You need more fuel pressure, not less...motor is lean...add fule. What engine control unit are you running?
Stock ECU(case says speedsource), Fuel pressure was set at 50 psi during dyno pulls. also po did not have manifold hooked up to FPR. could that cause a lean condition?
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Old 07-23-15, 10:13 AM
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SpeedSource put Motec 4 ECUs in stock boxes back in the day. You need to open the box to see what you have. If you have a Motec, contact Steve Eckerich for tuning. You are 40hp off.
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Old 07-23-15, 10:39 AM
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That dyno is a known pessimist, but I would expect better numbers out of an ITS engine.
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Old 07-23-15, 10:55 AM
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Originally Posted by Chuck Baader View Post
You need more fuel pressure, not less...motor is lean...add fule. What engine control unit are you running?
As I understand fluid dynamics (in fuel related units)lbs/hr decreases as psi increases. This is confirmed by examining fuel pump flow charts published by manufacturers. Also confirmed with a stopwatch hose and measuring cup ;-).
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Old 07-23-15, 11:35 AM
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Fluid dynamics, yes. But this is automotive. I have about 500 pulls on a dyno and I always add pressure (since we are using a given diameter orifice) when we need a richer the mixture. However, you want the correct pressure at the injector for the best gas cone. Generally that is 45ish psi and adjust the injector dwell accordingly.
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Old 07-23-15, 11:42 AM
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Considering, why then whilst running 50 psi a higher output pump and (assuming) failing coils are my Afr's above 13 consistently? I don't know a cart about comp tuning, I see why Dave uses a carb! I would think the failing coils would cause less fuel to burn decreasing my Afr's.
I'm running mostly on observation, my engineering education and a bit of unrtested hypothesis about failing components. I appreciate everyone's insight keep it coming!.
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Old 07-23-15, 02:44 PM
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Originally Posted by NorthernForestMotorsports View Post
As I understand fluid dynamics (in fuel related units)lbs/hr decreases as psi increases. This is confirmed by examining fuel pump flow charts published by manufacturers. Also confirmed with a stopwatch hose and measuring cup ;-).
more fuel pressure = richer. the injectors are open a static amount of time, if you have more pressure behind them more fuel is going to go through them in that time.

the pump is different, it has the pressure working against it (on the output side) opposed to with it (on the input) the higher the pressure the more the pump has to work against.

I agree you need to open up the ECU. if it has a speedsource sticker on it, I would assume they've messed with it. you should look to see how. whether it's just a chip or an entirely different ECU inside. the ECU might be programed to run different injectors or non-stock fuel pressure.

Last edited by eage8; 07-23-15 at 02:46 PM.
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Old 07-23-15, 03:20 PM
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I opened the ecu and confirmed it is a modified stock ecu. The PO said the car had no rev limiter. We had to swap in a spare pump hanging around, it came out of a Mitsubishi EvoIX so there is a flow increase there. Thank you for helping me understand that Eage. As I said in OP fuel tank has been restored fuel lines replaced fuel filter replaced injectors clean and bigger pump should equal rich?!?!?!?!
Can testing of the coils be done without the SST mentioned in the FSM?
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Old 07-23-15, 03:22 PM
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Should I up fp to 55 and see if that gets us a little richer? I think we will install a wideband to save money on dyno time.
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Old 07-23-15, 06:26 PM
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For those experienced dyno guys and tuning forks! because of the turn at the end of my exhaust the sensor was in the immediate exhaust stream. This is significant, I think, because Mike at Kinetic, pointed out that it should be operating in clean air and was not despite the long copper tube he used to extract exhaust gases. In my first Dyno run my AFR's were in the 15's AHHHHH, thats scary! Can this measurement be considered accurate given circumstances?
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Old 07-27-15, 10:11 AM
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Fuel filters, fuel filters, fuel filters (includes fuel pickup's in tank). Even if they look great, either take them out for testing or replace them with new. I won't get into the storys, but on rotarys this has burned me multiple times now, and never ever ever makes sense. My 2c, good luck!

OT- Where in NH are you? Heading to NHMS for track days any time soon?

-Josh
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Old 07-27-15, 10:56 AM
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Thanks for you 2c ;-). I will consider but the current fuel filter has about 2 hours of run time through it. I will look again at the pump sock. As I stated in op most of fuel system is new or restored. I'm seriously considering if my lean readings were a matter of the way wideband was setup. And frankly my Afr's are the least of my concern right now. I need to figure out why it's breaking up above 6.6k. I don't think the breakup is fuel related.
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Old 07-30-15, 09:24 AM
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Originally Posted by corners View Post
OT- Where in NH are you? Heading to NHMS for track days any time soon?

-Josh
Josh,we are about 10 min from nhms but no I don't think so, once we figure out this high rpm issue we will start with autox and rallyx
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Old 08-01-15, 04:18 PM
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Today i disconnected the Trailing coil and the car ran and idled relatively smoothly. We also grounded each coil output individually and noticed the trailing side seemed much weaker and slower. also when we hold the car at any rpm it seems to break up. This furthers my suspicion about coil failure can anyone confirm or deny this?
I can post a video if that helps.
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Old 08-01-15, 06:27 PM
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It sounds like fuel or spark, I would consider swapping the fuel pump to a more commonly used fuel pump?(I could be off base because I'm not well-versed in the Evo pumps capabilities) As well as consider sending the ECU off to be tested for the modifications done.(and it's working properly) I have a few sets of stock coils if you want/need to borrow or purchase for comparative testing let me know
GL Rikk
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Old 08-01-15, 09:20 PM
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I would be interested in what you would ask for a trailing coil pack?

Also could this also be the product of a bad premix ratio? I think I'm about 1oz:1gal of some redline premix that came with the car.
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Old 08-01-15, 09:53 PM
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Idk $25? It will probably cost $15-$20 for shipping so if it doesn't fix the issue send it back to me I'll refund you the $25?
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Old 08-02-15, 02:42 PM
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Another question....what plugs and how old are they?
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Old 08-02-15, 08:35 PM
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Ngks have about 2.5 hours run time total. Sold send me a pm with a paypal email and I'll shoot you 50$ to cover shipping.
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Old 08-04-15, 09:17 AM
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Which NGKs?
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