LT1-LT4 Modifications 1993-97 Gen II Small Block V8

After installing my new heads...

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Old 04-25-2012, 06:57 AM
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Default After installing my new heads...

I fellow member here mentioned I haven't posted anything since I installed my ported TFS heads...
(Btw- My prior, LT1 Canfield, heads with I/E 2.0/1.60 valves are for sale)

Well, I post both here and camaroz28 so I'm not sure what I've posted here previously I've been battling a lot of little irritating things during and since the head installation. I have taken her to the track but only made a couple of attempts. Both of which were aborted either at half track or earlier.

At the track,
  • 1st gear - Tremendous wheel hop, resulting in a (another) crap 2.xx sixty foot.
  • 2nd gear - Spinning thru quite a bit. Rear end was waving left and right.
  • 3rd gear - NOW we're talking! The car pulled really hard and I was thinking "Hey! I might finally get a sub 11 second pass!!"
  • 4th gear - As soon as I shifted and pressed the gas pedal the nose of the car came down and it sounded like I had lifted the throttle with the car in gear at 100 mph. What... the.. f***....
I just let the car finish the 1/4 with the clutch and 4th gear engaged, letting the engine slow down the car. I pulled off the track and the end-of-track official leaned over, looking under my car and waved me off the road. I pulled up and he said, "one of your pipes is hanging down. Looks like your clamp is still on there though..". I pulled off to the side, got out and under the car. Sure enough my turbo to intercooler pipe (which is fully beaded and has NEVER came off before) had popped off. I got out my tools and mat from the back of the car and quickly put it back on. I checked all the other Tbolt clamps and all were tight. I got back in the staging lanes.... Even with the lack of 4th gear in the pass and me letting the engine slow the car, it still turned a 12.3 at 100mph.

2nd attempt...
I cleaned off the 275/40/17 Nitto DR's and staged, raised the RPM's and dropped the clutch at 5000rpm. INSTANTLY the car felt feeble and way down on power all thru first. I grimaced then shifted to 2nd, same sh*t... I let off and just went down the track at 45 mph. Pulling off the track I let the car idle and looked at all the gauges. Everything normal... vacuum, wide band O2, oil pressure, temperatures... Popped the hood, looked around, listened... nothing wrong. I can ONLY conjuecture that my super hard launch banged the exhuast and introduced a lot of knock retard.

I gathered my gear and stuff and got out on the road, leaving the track. All was normal. I gently and progressively got into boost. Ran perfect. Sigh...


Problems during/after the installation of the heads/intake...
  • First install of everything, I took a test drive and came back. After parking the car, I saw that oil was leaking from the back china wall. I had scuffed the bead of silicone when installing the intake. Removed intake and found that not only was the back was leaking but also the gaskets had oil creeping up thru the gaskets and into the intakes. I suspected the heads had been milled and the angles for the heads/block/intake had been affected.
  • Put new gaskets in after cleaning all surfaces and adding new generous beads of silicone. Took test drive. Wide Band showed lean during part thottle and the motor stumbled consistently from 1,300 to 1,700 rpm.
  • Suspecting it was still pulling air/oil mist from the underside of the intake, I bought more intake gaskets and, on the recommendation of other guys, bought a can of Permatex "Right Stuff". Popped off the intake, finding the oil soaked bottom of the intake gaskets and oil mist in the ports and cleaned everything again. Took the dry, clean prior intake and set her down on the heads and block. Hmm.. fits perfect, no gaps. Must not be any 'milling' factor. Put the ported intake on there and it, too, fit perfect. I added the gaskets, Right Stuff on the ports and silicone beads on the china walls. Took her for a test drive.
  • Still running lean in closed loop in the same RPM range. Sigh.. I bought two new Bosch Narrow band O2 sensors, installed them and took her for a drive. Better O2 readings in data master but still lean and stumbling in than range. <cussing>...
  • Got under car, and disconnected the drivers side O2 so the car wouldn't go into closed loop. Took her for a test drive. Soooo much better. No stumbling. Mind you, this Open Loop setup is what I've been using for the past 3 to 4 years and it's been fine. I just thought reincorporating the o2's would help gas mileage (and it does). I reconnected the drivers O2 and started logging to see what I could modify in the tune to get around this O2 sensor/lean stumble.
  • Took a lengthy drive and the car got worse and worse. Stumbling and showing lean but just on the passenger side Wtf? The exhaust also now sounds 'ratty' like a fair exhaust leak is present. I drive home mulling the possibilities. I 'think' maybe my wastegate is staying open or leaking or is loose. I pull up onto my ramps and get under there and test it with the motor running for leaks. Nope. I grab the wastegate with a towel (to prevent burning me) and try to shake it to see if it's loose. I kill the motor and open the hood, peering down the passenger side looking to see if a header gasket is compromised or something. That's when I see it. My shoddy welding of the passengerside O2 bung is revealed. The O2 sensor is hanging there in open air with the bung still on it, the crossover pipe with a nice(?) exposed open hole. FML.... I pull it off, clean everything with a wire brush and re-weld it correctly. Test drive. MUCH better!
  • Going out for another lengthy drive with data master, the car still has a tiny issue with being lean in that same fricking RPM range. I email Bryan at PCM4less and ask him if the tune needs a tweak for the new heads. He replies and says no need, it's fat enough.
  • Looking at the resulting log, I see something weird. During WOT (Tps is at 100%), in 1st gear, no knock retard, in 2nd gear, no knock retard, in 3rd gear, up to 4100 rpm no knock retard but right after that, I get 3.3 degrees and higher for the next 500 rpm. Looking at the attendant data, the timing/spark advance up to the knock retard was 25 degrees. Just before the knock retard is introduced, the timing/advance had spiked to 40 degrees. What??!
    I looked in my tune and that 40 degree is NOWHERE in the tunes tables. I sent the log and the question about 'where did that come from?' to Bryan and he replied he's never seen that before. Grrr...

Right now, I'm still evaluating the slight leaning out in that low RPM range. In my search I did find something helpful. Ever since I added the 95lb injectors, the car labored to start. Previously, the car started crisply, sounding like it fired before turning a full revolution. I found a table in my tune that Tunerpro named '1st prime pulsewidth' and '2nd prime pulsewidth'. Looking thru google to find out what those related to, I found a guy that had the same issue as myself. He, mistakenly, believed the car was lean so he added values in those cells. The result was it flooded. He went back after adding fresh plugs, then halved the stock values (to 3.13?) and the car lit off perfectly. I followed his recommendation and sure enough, the car fires up immediately, hot or cold

Last edited by mightyquickz28; 04-25-2012 at 09:02 AM.
Old 04-25-2012, 08:03 AM
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are your o2 between the exhaust manifold and turbo??
Old 04-25-2012, 08:55 AM
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The passenger side NB O2 sensor is in the crossover pipe. The drivers side O2 sensor is in the down pipe. Look at this picture... the first O2 sensor, located near the oil filter, is my NB O2 sensor location, the second O2 location, near the end of the down pipe, is my wide band location...
Old 04-25-2012, 09:43 AM
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I would throw the NB in the crossover and WB in the DP.
Old 04-25-2012, 09:59 AM
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I personally dont have a turbo but i do have 4-6 degress of knock retard between 4150-5000 rpm on every single run i have logged with my mac scanner. I had to have it tuned out. I realize that is something that u can't do, but i cant figure it out.
Old 04-25-2012, 10:00 AM
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Jon, Do you mean I should have both NB in the crossover and leave the WB in the down pipe or all 3 sensors in the down pipe?


Originally Posted by RealQuick
I would throw the NB in the crossover and WB in the DP.
Old 04-25-2012, 10:15 AM
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I'd done that same thing back when my motor(s) were Naturally aspirated. With the Turbo, it gets less psi in the lower gears because there is less 'load' on the motor. So 1st gear might only get 9psi, 2nd gear might only get 11psi, 3rd might see 13psi and 4th will get the max (mine is set up to open the waste gate at 15 psi). Although I'm tempted to zero out the knock table, I won't do that while running my normal 93 octane pump gas. I'm going to put in 5 gallons of VP 100+ octane and see if that changes the incidence of knock. If it does, I'll have to accept the fact that it's real detonation. If it still gets the same knock retard, then I'll explore the possibility it's false knock.

That recent log run of WOT and encountering that rogue 40 degree advance has me puzzled. Of COURSE it's going to get detonation on that occasion, since all the prior advances in that gear (and the earlier gears in that same range) were 25 degrees. So random... ;(

Originally Posted by FAD2BLK93
I personally dont have a turbo but i do have 4-6 degress of knock retard between 4150-5000 rpm on every single run i have logged with my mac scanner. I had to have it tuned out. I realize that is something that u can't do, but i cant figure it out.
Old 04-25-2012, 10:28 AM
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Where did you get your hotside from?
Old 04-25-2012, 11:11 AM
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I bought it from Jon, aka "Realquick" here on this board. Super nice guy and great follow up on customer service. I got this as one his first kits. The stuff he does now could rightfully be considered 'Art'.
Old 04-25-2012, 11:54 AM
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Originally Posted by mightyquickz28
Jon, Do you mean I should have both NB in the crossover and leave the WB in the down pipe or all 3 sensors in the down pipe?
WB should be in DP... what you do with the NB's is up to you. I know on the TTi log kits (mine is similar), 1 NB in the crossover, 1 NB in the DP and you put the WB in the DP as well.

The way you have it is the WB only sees what is happening on the pass side. Atleast with the WB on the DP, you see the combined affect of both cylinders. Obviously a WB for each side is ideal...
Old 04-25-2012, 11:55 AM
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Originally Posted by mightyquickz28
I bought it from Jon, aka "Realquick" here on this board. Super nice guy and great follow up on customer service. I got this as one his first kits. The stuff he does now could rightfully be considered 'Art'.
Thanks Dave... I don't know if I would call it art... but it is prettier than the older stuff
Old 04-25-2012, 11:59 AM
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I think you misread or misunderstood my post above. The last location in the the downpipe is where my WB is located. I have the drivers side NB and the WB both in the downpipe as you designed it and the passenger NB is in the crossover, as you designed it.


Originally Posted by RealQuick
WB should be in DP... what you do with the NB's is up to you. I know on the TTi log kits (mine is similar), 1 NB in the crossover, 1 NB in the DP and you put the WB in the DP as well.

The way you have it is the WB only sees what is happening on the pass side. Atleast with the WB on the DP, you see the combined affect of both cylinders. Obviously a WB for each side is ideal...
Old 04-25-2012, 12:14 PM
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Originally Posted by mightyquickz28
I think you misread or misunderstood my post above. The last location in the the downpipe is where my WB is located. I have the drivers side NB and the WB both in the downpipe as you designed it and the passenger NB is in the crossover, as you designed it.
Oh snap! You are right! You are good then...
Old 04-25-2012, 01:49 PM
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You need to put both of the NB sensors in the inlet hot side of the turbo. As close to their respective "manifolds" as possible. Also the increased pressure inside of the feed tube to the hot side will make the sensors read differently than with no pressure. the restriction the turbo puts on the exhaust causes this pressure. when the turbo is 3/4 to full spool it will revert back to normal, so that makes the part throttle/take offs run differently. You will either need to run the car in open loop to avoid this all together or make the tune at those throttle positions move opposite to how the NB sensors change when exposed to the pressure.



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