Update:

I tried "tuning around the problem". The fuel curve now looks like the Swiss Alps...basically its the inverse of the A/F trace in the datalogs. The VE goes from ~90 to ~120 in a matter of 100 rpm in some spots. It's rediculous.

While I was successful in reducing the dip in power at 2400 rpm, overall driveability got even worse. The car doesn't even like to start anymore. I don't think tuning around the problem is the answer.

I started pulling it all back apart last night to install the new lower plenum gasket. I pulled the plugs while I was in there. They all looked good except the front passenger side plug looked like it had a light coating of oil on it? I think maybe I will put a new set of plugs in, just in case.

I also spliced some wires into the #3 fuel injector harness so I can measure the voltage across the injector (or hook up a scope) when I get it back together.

 

2400 rpm cell should have ZERO affect on starting. Something else must have been inadvertantly changed.

 

Make sure you coat the gasket with a thin film of oil before installing to get a good seal.

 

What about 1200 and 1600 rpm? Those would have an affect on starting wouldn't they? That's where the other two lean spots are, and I made changes to the fuel map to eliminate those as well.

 

On the Aramid gasket? Is this a recommendation from Motordyne?

 

does your car crank or idle higher than 1200? mine doesn't. I have mine set to 1050 and it definitely doesn't crank that high.

adjust your prime pulse time (first) and if that doesn't work, which it should, then adjust your crank injector time.

I've never had to change my crank injection time. I just adjust my prime pulse and that makes a world of difference. Just pull more fuel out of those cells you see the cursor on and crank, nothing, then pull more. keep doing that to see a change. NEVER touch the gas when doing this. If you still get nothing then go the opposite way. Go back to the value you originally had and add fuel from there.

 

It started much better before I messed with the fuel table. I didn't touch the start settings. So it must have been something I did on the fuel table that affected it. I am going to revert back to my old settings anyway, so hopefully it will start like it used to again.

 

I seem to recall that was part of the install instructions. I did it.

The car cranks at a few hundred rpms per min - no more than that. Cold starts are usually a problem with too little fuel (so add prime pulse and cranking inj time). Hot starts are usually a problem because of too much fuel (so reduce prime pulse and cranking inj time).

 

ambient temps and humidity will make a huge impact. more than you would think.

 

A couple of updates:

I installed the Motordyne aramid lower plenum gasket, along with a fresh set of PLFR6A-11 platinum plugs. I inspected everything thoroughly and followed the multi step torquing procedure for both the upper and lower plenums to a T. I also found a small corner of the stock upper gasket that was folded over just a tiny bit so I fixed that too.

Then I reloaded my original map (the one that I was using for all of the previously attached datalogs) and went for a drive. I didn't even make it 100 yards from my driveway and I could already tell that there was no change. The lean spot(s) are exactly the same as before.

While I was in there I tapped some wires into the injector harness, so I am going to try to measure the voltage across the injectors as I drive. Other than that, the only thing I can think of is maybe reinstalling the stock fuel system to see if it makes a difference?

Is it possible that my timing is off? Can the stock flywheel be installed incorrectly and give false readings for TDC? What is this all about:

http://www.jimwolftechnology.com/wol...tion_check.pdf

Can I use a timing light to check the timing? How do you do that if there are no plug wires to use an inductive pickup?

 

You can still use the inductive pickup, just clamp it around the wire loom going to the #1 coil pack.

 

I found the problem.

Last night I disconnected the fuel return system and reinstalled the stock fuel rail damper. I also reinstalled the stock fpr in the tank and drilled out the top with a 7/64” drill bit as recommended when using the Walbro GSS342 pump.

Then I went for a drive. Lo and behold the lean spot was not only completely gone but it was actually now a rich spot (as it should be, based on the fuel curve I was using). In fact all three “spikes” in the A/F trace have completely disappeared. Look at the datalog – it’s amazing.

Now I am trying to understand why a fuel return system, which so many others are using, was causing such a problem. Why wasn’t I seeing fuel pressure fluctuations on the gauge? One thing that I am going to do is take apart the Aeromotive FPR that came with the kit. The previous owner never installed it, but he did take the top part off to paint it black. I am wondering if he lost a part or reassembled it incorrectly.

All is not well though. I was doing some basic tuning last night and everything was going great. Then I was stopped in a parking lot and I tried to rev the engine and tune the “no load” column. The engine doesn’t want to rev freely, it keeps “sticking” at certain RPM points and doesn’t want to rev higher until I give it a lot more gas. In other words I cannot slowly and gradually increase the engine speed with the throttle. That’s when the CEL started blinking, which I have never seen before. I pulled the codes and there were three that I have never seen before –

Multiple cylinder misfire
Cam angle bank 1 excessively high
Cam angle bank 2 excessively high

This reminds me of Str8dum1’s misfire and cam issues. Figures. I am going to try firmware 1.0.

Oh and I also figured out why I keep throwing the EVAP solenoid code – there is a pin broken off on my Haltech harness, the one that goes to the EVAP solenoid. I guess that’s what I get for buying a used Haltech.

 

I wonder. Does your return system have a damper on or near the rail?

 

^mx594, congrats on finally finding the problem! The aeromotive fpr should be taking the place of the stock damper, please report back with your findings or see if a replacement takes care of that.

 

I had that problem initially...was because it was WAY lean in the no/low load columns. If you're not running the FPR, you are going to have alot of variation in the fuel pressure which makes it harder to tune.

 

The Aeromotive FPR goes in place of the stock damper. Adapter -> hose -> FPR.

From what I have read it is supposed to perform the same damping function as the missing damper did previously.

 

Well, except in my case lol.

 

the cam code is normal if you have changed the cam vales from stock.

Blinking CEL is serious misfire. Dont run like that for long, EGTs go SKY HIGH!

so you are not running your RFS anymore?

hmm, i had that hiccup at ~2700 rpms. I took the top of my Aeromotive to tap the reference port for a SMC connection. But doesnt seem how it would go back together incorrectly. Just 4 bolts, a spring over a diaphram...

 

Yeah I figured blinking CEL = bad so I let it drop back down to idle and then pulled the codes. That is correct, I am no longer using the RFS. By the way the idle A/F is more stable than it has ever been, I don't get the random lean spikes while idling anymore.

I didn't change the cam values last night, and that was the first time I saw those codes. I am not sure why?

 

FWIW, during the misfiring while trying to gradually increase rpm, the A/F read a steady 14.7. That's why I am confused as to why it was misfiring