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LS1 Intake Alignment - ports not aligning to gaskets and leaking
Hi All,
I bought one of the cheap chinesium "Fabricated Sheetmetal Intakes" off of ebay that looks to be a clone of the Holley Sniper and have had nothing but trouble with it. I know you get what you pay form but I though $800AUD was fairly steep for an intake anyway.
Anyhows, I've been chasing vacuum leaks and lean conditions and found yesterday after removing the intake that the individual gaskets/seals for each intake port were right on the edge of the ports on the head. The heads are 241 Higgins ported heads, so the porting may have contributed a little to it, but the intake itself seems to sit about 2-3mm too far back on the engine.
I've tried pulling the intake forward as I put the bolts in to torque it down but doesn't seem to help.
From what I see I have 2 options:
1. Take the intake off and elongate the bolt holes to allow for a bit more adjustment, but this will then require getting the ports aligned perfect "by eye" which is not ideal.
2. Replace the individual rubber seals with one of the Felpro Printoseal intake gaskets which are a single piece per head to cover all the surface area to compensate for offsets.
My only concern with the 2nd option is that the felpro gaskets don't look like they'd have anywhere near as much "squish" and might leak also anyway.
Any thoughts or ideas how to fix this pain in the *** issue?
Yes- get a properly manufactured intake manifold. This one is obviously way out of spec. Anything you do would be a bandaid at this point.
Whoever sold this one should be drawn, quartered, then put thru a tree shredder for seling this crap at such outrageous prices.
Yes- get a properly manufactured intake manifold. This one is obviously way out of spec. Anything you do would be a bandaid at this point.
Whoever sold this one should be drawn, quartered, then put thru a tree shredder for seling this crap at such outrageous prices.
Long term that is the plan but short term I have just under 2 weeks to have the car back together and running for a car event here in Australia and not enough funds or time to get another intake.
I have the stock LS1 intake which I could put back on, but I have to then convert it to a return-line fuel rail, which would mean having to get someone chop and weld on some 6AN fittings which is another pain I'd rather not deal with, and then my tune will be all out of whack going from 102mm to 85mm TB.
So some good news, after completely removing the intake and looking at possibly dremelling the bolt holes I found that the spring washers supplied with the intake were too small, and had actually pressed into the holes, taking away any wiggle room for alignment.
I holepunched them back out and replaced them in addition to inserting a larger washer to span the hole.
Replaced the busted seals with some spare ones I had and it looks like it's a much better fit.
While I've got the intake off I'm going to re-route the fuel lines to the rails a bit to tidy them up out of the way, but should have that done tomorrow and fire up and see.
Worst case scenario it still leaks and I wait for the gasket order to arrive.
So it worked, the MAP reading at idle is 55-60kpa instead of 90kpa but I've still got glowing headers (both sides) once the car gets to temp and goes into closed loop.
What rpm is the tune set up to idle at ? I would think a little richer afr would be in order. What was the ect reading during that video ? If you resolved all of the vacuum leaks, sounds like the tune needs attention.
What rpm is the tune set up to idle at ? I would think a little richer afr would be in order. What was the ect reading during that video ? If you resolved all of the vacuum leaks, sounds like the tune needs attention.
ECT was 102 degrees Celcius (215F)
AFR is set to 14.2 and idle is scaled from 900rpm - 550 at high temp
But this is about a minute's data and when temp is peaking.
I've been told by the tuner assisting me that the drilled hole in the throttle body was not a good idea so I've replaced the throttle body with a new one, and then increased the throttle body opening up to 0.70v
Problem now is the car doesn't want to start.
Before with the hole drilled it would fire up instantly with 0.45v TPS.
I am wondering why the engine speed is so high compared to the commanded idle speed. I thought there might be an intake, but the trims say no
Well I have less of an idea than you
The throttle body is 102mm which might be breathing a bit more air than the stock one and the other thing someone mentioned was that maybe the tune is trying to control excess air intake by adjusting timing to the extremes.
The throttle body is 102mm which might be breathing a bit more air than the stock one and the other thing someone mentioned was that maybe the tune is trying to control excess air intake by adjusting timing to the extremes.
The added timing for both sections where the rpms are 1500+ were 15degrees and then 37degrees at 0% throttle but not sure what is triggering that in the tune.
Full 2.5" exhaust
Wideband on the left bank about 1-1.5foot down the pipe and narrowband on each just slightly down from that.
The not cranking I have a feeling may be damaged crank or cam sensor wiring from the glowing headers, because I checked all the other voltages to make sure nothing got bumped or moved for the PCM. Unfortunately same time I swapped the throttle body over I was putting the dash back together and moving some wiring, and changing out the 4L60E gear selector switch, so I've had a bit of back-tracing to cover in case the no-start is not related to the TB/tune.
When I turn ignition I hear the fuel pump prime, but when cranking there's no pump, so I assume PCM is powering up fine, starter is going, injectors/ignition has power, the only thing missing that is needed that I know of is a crank signal to tell it to do its thing.
Hopefully should have more info this afternoon (in Australia +10GMT) so in about 6 hours.
Sure enough, the 3 wires for the crank angle sensor had a campfire by the glowing red exhaust and too much booze later had a threesome and became stuck as one.
Chopped the wires and resoldered together along with some insulation and rerouting away from the exhaust and she fired up first time.
With the new throttle body with no hole drilled the idle is definitely in the right range, some minor adjustments to the throttle body screw got it reading some IAC counts but I need to read up a bit about when they should occur (open loop/closed loop/straight away etc) to get it dialled in properly.
When I blip the accelerator it still holds revs for longer than it should but only half a second to a second and then returns back.
New log is attached. The LTFT was just sitting on -20% but short terms were 0% so again will need to read up a bit. I might need to reset them to then see what it does. Left bank o2 sensor was a bit high (900-1000mv) and I did have a bit of valvetrain noise on the rear left bank which has me a bit worried, but I'll see if an oil change and topup gets that quieter.
The key indicator it was the crank angle sensor was no RPM logging on HPT scanner.
From the 900mv reading the left bank is max rich. Was the right bank about .500-600mv? Here is a video that might help with the hanging idle Watch this
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LS1 Intake Alignment - ports not aligning to gaskets and leaking 
I'm just swinging in the dark now. Is there exhaust on the vehicle or just open headers?